XFree86 DDX Design

XFree86 DDX Design The XFree86 Project The X.Org Foundation JimGettys Updates for X11R6.7 &xserver.reldate; X Version 11, Release &fullrelvers; X Server Version &xserver.version; This document describes software undergoing continual evolution, and the interfaces described here are subject to change without notice. This document is intended to cover the interfaces as found in the xorg-server-&xserver.version; release, but is probably not completely in sync with the code base. Preface This document was originally the design spec for the DDX layer of the XFree86 4.0 X server. The X.Org Foundation adopted the XFree86 4.4rc2 version of that server as the basis of the Xorg server project, and has evolved the XFree86 DDX layer greatly since forking. This document thus covers only the current implementation of the XFree86 DDX as found in the Xorg server &xserver.version; release, and no longer matches the XFree86 server itself. The XFree86 Project's broad design principles for XFree86 4.0 were: keep it reasonable We cannot rewrite the complete server We don't want to re-invent the wheel keep it modular As many things as possible should go into modules The basic loader binary should be minimal A clean design with well defined layering is important DDX specific global variables are a nono The structure should be flexible enough to allow future extensions The structure should minimize duplication of common code keep important features in mind multiple screens, including multiple instances of drivers mixing different color depths and visuals on different and ideally even on the same screen better control of the PCI device used better config file parser get rid of all VGA compatibility assumptions While the XFree86 project had a goal of avoiding changes to the DIX layer unless they found major deficiencies there, to avoid divergence from the X.Org sample implementation they were integrating changes from, the X.Org developers now maintain both sides, and make changes where they are most appropriate. This document concentrates on the XFree86 DDX layer used in the Xorg server itself (the code found in hw/xfree86 in the source tree), and developers will also want to refer to the Xserver-spec documentation that covers the DIX layer routines common to all the X servers in the sample implementation. The xorg.conf File The xorg.conf file format is based on the XF86Config format from XFree86 4.4, which is in turn similar to the old XFree86 3.x XF86Config format, with the following changes: &k.device; section The &k.device; sections are similar to what they used to be, and describe hardware-specific information for a single video card. &k.device; Some new keywords are added: Driver "drivername" Specifies the name of the driver to be used for the card. This is mandatory. BusID "busslot" Specifies uniquely the location of the card on the bus. The purpose is to identify particular cards in a multi-headed configuration. The format of the argument is intentionally vague, and may be architecture dependent. For a PCI bus, it is something like "bus@@domain:slot:func". The "@@domain" part can be left out for domain 0. A &k.device; section is considered active if there is a reference to it in an active &k.screen; section. &k.screen; section The &k.screen; sections are similar to what they used to be. They no longer have a &k.driver; keyword, but an &k.identifier; keyword is added. (The &k.driver; keyword may be accepted in place of the &k.identifier; keyword for compatibility purposes.) The identifier can be used to identify which screen is to be active when multiple &k.screen; sections are present. It is possible to specify the active screen from the command line. A default is chosen in the absence of one being specified. A &k.screen; section is considered active if there is a reference to it either from the command line, or from an active &k.serverlayout; section. &k.inputdevice; section The &k.inputdevice; section is a new section that describes configuration information for input devices. It replaces the old Keyboard, Pointer and XInput sections. Like the &k.device; section, it has two mandatory keywords: &k.identifier; and &k.driver;. For compatibility purposes the old Keyboard and Pointer sections are converted by the parser into &k.inputdevice; sections as follows: Keyboard &k.identifier; "Implicit Core Keyboard" &k.driver; "kbd" Pointer &k.identifier; "Implicit Core Pointer" &k.driver; "mouse" An &k.inputdevice; section is considered active if there is a reference to it in an active &k.serverlayout; section. An &k.inputdevice; section may also be referenced implicitly if there is no &k.serverlayout; section, if the command line options is used, or if the &k.serverlayout; section doesn't reference any &k.inputdevice; sections. In this case, the first sections with drivers "kbd" and "mouse" are used as the core keyboard and pointer respectively. &k.serverlayout; section The &k.serverlayout; section is a new section that is used to identify which &k.screen; sections are to be used in a multi-headed configuration, and the relative layout of those screens. It also identifies which &k.inputdevice; sections are to be used. Each &k.serverlayout; section has an identifier, a list of &k.screen; section identifiers, and a list of &k.inputdevice; section identifiers. &k.serverflags; options may also be included in a &k.serverlayout; section, making it possible to override the global values in the &k.serverflags; section. A &k.serverlayout; section can be made active by being referenced on the command line. In the absence of this, a default will be chosen (the first one found). The screen names may optionally be followed by a number specifying the preferred screen number, and optionally by information specifying the physical positioning of the screen, either in absolute terms or relative to another screen (or screens). When no screen number is specified, they are numbered according to the order in which they are listed. The old (now obsolete) method of providing the positioning information is to give the names of the four adjacent screens. The order of these is top, bottom, left, right. Here is an example of a &k.serverlayout; section for two screens using the old method, with the second located to the right of the first: Section "ServerLayout" Identifier "Main Layout" Screen 0 "Screen 1" "" "" "" "Screen 2" Screen 1 "Screen 2" Screen "Screen 3" EndSection The preferred way of specifying the layout is to explicitly specify the screen's location in absolute terms or relative to another screen. In the absolute case, the upper left corner's coordinates are given after the Absolute keyword. If the coordinates are omitted, a value of (0,0) is assumed. An example of absolute positioning follows: Section "ServerLayout" Identifier "Main Layout" Screen 0 "Screen 1" Absolute 0 0 Screen 1 "Screen 2" Absolute 1024 0 Screen "Screen 3" Absolute 2048 0 EndSection In the relative case, the position is specified by either using one of the following keywords followed by the name of the reference screen: RightOf LeftOf Above Below Relative When the Relative keyword is used, the reference screen name is followed by the coordinates of the new screen's origin relative to reference screen. The following example shows how to use some of the relative positioning options. Section "ServerLayout" Identifier "Main Layout" Screen 0 "Screen 1" Screen 1 "Screen 2" RightOf "Screen 1" Screen "Screen 3" Relative "Screen 1" 2048 0 EndSection Options Options are used more extensively. They may appear in most sections now. Options related to drivers can be present in the &k.screen;, &k.device; and &k.monitor; sections and the &k.display; subsections. The order of precedence is &k.display;, &k.screen;, &k.monitor;, &k.device;. Options have been extended to allow an optional value to be specified in addition to the option name. For more details about options, see the Options section for details. Driver Interface The driver interface consists of a minimal set of entry points that are required based on the external events that the driver must react to. No non-essential structure is imposed on the way they are used beyond that. This is a significant difference compared with the old design. The entry points for drawing operations are already taken care of by the framebuffer code. Extensions and enhancements to framebuffer code are outside the scope of this document. This approach to the driver interface provides good flexibility, but does increase the complexity of drivers. To help address this, the XFree86 common layer provides a set of helper functions to take care of things that most drivers need. These helpers help minimise the amount of code duplication between drivers. The use of helper functions by drivers is however optional, though encouraged. The basic philosophy behind the helper functions is that they should be useful to many drivers, that they should balance this against the complexity of their interface. It is inevitable that some drivers may find some helpers unsuitable and need to provide their own code. Events that a driver needs to react to are: ScreenInit An initialisation function is called from the DIX layer for each screen at the start of each server generation. Enter VT The server takes control of the console. Leave VT The server releases control of the console. Mode Switch Change video mode. ViewPort change Change the origin of the physical view port. ScreenSaver state change Screen saver activation/deactivation. CloseScreen A close screen function is called from the DIX layer for each screen at the end of each server generation. In addition to these events, the following functions are required by the XFree86 common layer: Identify Print a driver identifying message. Probe This is how a driver identifies if there is any hardware present that it knows how to drive. PreInit Process information from the xorg.conf file, determine the full characteristics of the hardware, and determine if a valid configuration is present. The VidMode extension also requires: ValidMode Identify if a new mode is usable with the current configuration. The PreInit function (and/or helpers it calls) may also make use of the ValidMode function or something similar. Other extensions may require other entry points. The drivers will inform the common layer of these in such cases. Resource Access Control Introduction Graphics devices are accessed through ranges in I/O or memory space. While most modern graphics devices allow relocation of such ranges many of them still require the use of well established interfaces such as VGA memory and IO ranges or 8514/A IO ranges. With modern buses (like PCI) it is possible for multiple video devices to share access to these resources. The RAC (Resource Access Control) subsystem provides a mechanism for this. Terms and Definitions Bus Bus is ambiguous as it is used for different things: it may refer to physical incompatible extension connectors in a computer system. The RAC system knows two such systems: The ISA bus and the PCI bus. (On the software level EISA, MCA and VL buses are currently treated like ISA buses). Bus may also refer to logically different entities on a single bus system which are connected via bridges. A PCI system may have several distinct PCI buses connecting each other by PCI-PCI bridges or to the host CPU by HOST-PCI bridges. Systems that host more than one bus system link these together using bridges. Bridges are a concern to RAC as they might block or pass specific resources. PCI-PCI bridges may be set up to pass VGA resources to the secondary bus. PCI-ISA buses pass any resources not decoded on the primary PCI bus to the ISA bus. This way VGA resources (although exclusive on the ISA bus) can be shared by ISA and PCI cards. Currently HOST-PCI bridges are not yet handled by RAC as they require specific drivers. Entity The smallest independently addressable unit on a system bus is referred to as an entity. So far we know ISA and PCI entities. PCI entities can be located on the PCI bus by an unique ID consisting of the bus, card and function number. Resource Resource refers to a range of memory or I/O addresses an entity can decode. If a device is capable of disabling this decoding the resource is called shareable. For PCI devices a generic method is provided to control resource decoding. Other devices will have to provide a device specific function to control decoding. If the entity is capable of decoding this range at a different location this resource is considered relocatable. Resources which start at a specific address and occupy a single continuous range are called block resources. Alternatively resource addresses can be decoded in a way that they satisfy the conditions: address & mask == base and base & mask == base Resources addressed in such a way are called sparse resources. Server States The resource access control system knows two server states: the SETUP and the OPERATING state. The SETUP state is entered whenever a mode change takes place or the server exits or does VT switching. During this state all entity resources are under resource access control. During OPERATING state only those entities are controlled which actually have shared resources that conflict with others. Control Flow in the Server and Mandatory Driver Functions At the start of each server generation, main() (dix/main.c) calls the DDX function InitOutput(). This is the first place that the DDX gets control. InitOutput() is expected to fill in the global screenInfo struct, and one screenInfo.screen[] entry for each screen present. Here is what InitOutput() does: Parse the xorg.conf file This is done at the start of the first server generation only. The xorg.conf file is read in full, and the resulting information stored in data structures. None of the parsed information is processed at this point. The parser data structures are opaque to the video drivers and to most of the common layer code. The entire file is parsed first to remove any section ordering requirements. Initial processing of parsed information and command line options This is done at the start of the first server generation only. The initial processing is to determine paths like the ModulePath, etc, and to determine which &k.serverlayout;, &k.screen; and &k.device; sections are active. Enable port I/O access Port I/O access is controlled from the XFree86 common layer, and is all or nothing. It is enabled prior to calling driver probes, at the start of subsequent server generations, and when VT switching back to the Xserver. It is disabled at the end of server generations, and when VT switching away from the Xserver. The implementation details of this may vary on different platforms. General bus probe This is done at the start of the first server generation only. In the case of ix86 machines, this will be a general PCI probe. The full information obtained here will be available to the drivers. This information persists for the life of the Xserver. In the PCI case, the PCI information for all video cards found is available by calling xf86GetPciVideoInfo().

pciVideoPtr *xf86GetPciVideoInfo(void);
returns a pointer to a list of pointers to pciVideoRec entries, of which there is one for each detected PCI video card. The list is terminated with a NULL pointer. If no PCI video cards were detected, the return value is NULL.

After the bus probe, the resource broker is initialised. Load initial set of modules This is done at the start of the first server generation only. The next set of modules loaded are those specified explicitly in the &k.module; section of the config file. The final set of initial modules are the driver modules referenced by the active &k.device; and &k.inputdevice; sections in the config file. Each of these modules is loaded exactly once. Register Video and Input Drivers This is done at the start of the first server generation only. When a driver module is loaded, the loader calls its Setup function. For video drivers, this function calls xf86AddDriver() to register the driver's DriverRec, which contains a small set of essential details and driver entry points required during the early phase of InitOutput(). xf86AddDriver() adds it to the global xf86DriverList[] array. The DriverRec contains the driver canonical name, the Identify(), Probe() and AvailableOptions() function entry points as well as a pointer to the driver's module (as returned from the loader when the driver was loaded) and a reference count which keeps track of how many screens are using the driver. The entry driver entry points are those required prior to the driver allocating and filling in its ScrnInfoRec. For a static server, the xf86DriverList[] array is initialised at build time, and the loading of modules is not done. A similar procedure is used for input drivers. The input driver's Setup function calls xf86AddInputDriver() to register the driver's InputDriverRec, which contains a small set of essential details and driver entry points required during the early phase of InitInput(). xf86AddInputDriver() adds it to the global xf86InputDriverList[] array. For a static server, the xf86InputDriverList[] array is initialised at build time. Both the xf86DriverList[] and xf86InputDriverList[] arrays have been initialised by the end of this stage. Once all the drivers are registered, their ChipIdentify() functions are called.

void ChipIdentify(int flags);
This is expected to print a message indicating the driver name, a short summary of what it supports, and a list of the chipset names that it supports. It may use the xf86PrintChipsets() helper to do this.

void xf86PrintChipsets(const char *drvname, const char *drvmsg, SymTabPtr chips);
This function provides an easy way for a driver's ChipIdentify function to format the identification message.

Initialise Access Control This is done at the start of the first server generation only. The Resource Access Control (RAC) subsystem is initialised before calling any driver functions that may access hardware. All generic bus information is probed and saved (for restoration later). All (shared resource) video devices are disabled at the generic bus level, and a probe is done to find the primary video device. These devices remain disabled for the next step. Video Driver Probe This is done at the start of the first server generation only. The ChipProbe() function of each registered video driver is called.

Bool ChipProbe(DriverPtr drv, int flags);
The purpose of this is to identify all instances of hardware supported by the driver. The flags value is currently either 0, PROBE_DEFAULT or PROBE_DETECT. PROBE_DETECT is used if "-configure" or "-probe" command line arguments are given and indicates to the Probe() function that it should not configure the bus entities and that no xorg.conf information is available. The probe must find the active device sections that match the driver by calling xf86MatchDevice(). The number of matches found limits the maximum number of instances for this driver. If no matches are found, the function should return FALSE immediately. Devices that cannot be identified by using device-independent methods should be probed at this stage (keeping in mind that access to all resources that can be disabled in a device-independent way are disabled during this phase). The probe must be a minimal probe. It should just determine if there is a card present that the driver can drive. It should use the least intrusive probe methods possible. It must not do anything that is not essential, like probing for other details such as the amount of memory installed, etc. It is recommended that the xf86MatchPciInstances() helper function be used for identifying matching PCI devices (see the RAC section). These helpers also checks and claims the appropriate entity. When not using the helper, that should be done with xf86CheckPciSlot() and xf86ClaimPciSlot() for PCI devices (see the RAC section). The probe must register all non-relocatable resources at this stage. If a resource conflict is found between exclusive resources the driver will fail immediately. This is usually best done with the xf86ConfigPciEntity() helper function for PCI. If a chipset is specified in an active device section which the driver considers relevant (ie it has no driver specified, or the driver specified matches the driver doing the probe), the Probe must return FALSE if the chipset doesn't match one supported by the driver. If there are no active device sections that the driver considers relevant, it must return FALSE. Allocate a ScrnInfoRec for each active instance of the hardware found, and fill in the basic information, including the other driver entry points. This is best done with the xf86ConfigPciEntity() for PCI instances. These functions allocate a ScrnInfoRec for active entities. Optionally xf86AllocateScreen() function may also be used to allocate the ScrnInfoRec. Any of these functions take care of initialising fields to defined unused values. Claim the entities for each instance of the hardware found. This prevents other drivers from claiming the same hardware. Must leave hardware in the same state it found it in, and must not do any hardware initialisation. All detection can be overridden via the config file, and that parsed information is available to the driver at this stage. Returns TRUE if one or more instances are found, and FALSE otherwise.

int xf86MatchDevice(const char *drivername, GDevPtr **driversectlist)
This function takes the name of the driver and returns via driversectlist a list of device sections that match the driver name. The function return value is the number of matches found. If a fatal error is encountered the return value is -1. The caller should use xfree() to free *driversectlist when it is no longer needed.

ScrnInfoPtr xf86AllocateScreen(DriverPtr drv, int flags)
This function allocates a new ScrnInfoRec in the xf86Screens[] array. This function is normally called by the video driver ChipProbe() functions. The return value is a pointer to the newly allocated ScrnInfoRec. The scrnIndex, origIndex, module and drv fields are initialised. The reference count in drv is incremented. The storage for any currently allocated privates pointers is also allocated and the privates field initialised (the privates data is of course not allocated or initialised). This function never returns on failure. If the allocation fails, the server exits with a fatal error. The flags value is not currently used, and should be set to zero.

At the completion of this, a list of ScrnInfoRecs have been allocated in the xf86Screens[] array, and the associated entities and fixed resources have been claimed. The following ScrnInfoRec fields must be initialised at this point: driverVersion driverName scrnIndex(*) origIndex(*) drv(*) module(*) name Probe PreInit ScreenInit EnterVT LeaveVT numEntities entityList access (*) These are initialised when the ScrnInfoRec is allocated, and not explicitly by the driver. The following ScrnInfoRec fields must be initialised if the driver is going to use them: SwitchMode AdjustFrame FreeScreen ValidMode Matching Screens This is done at the start of the first server generation only. After the Probe phase is finished, there will be some number of ScrnInfoRecs. These are then matched with the active &k.screen; sections in the xorg.conf, and those not having an active &k.screen; section are deleted. If the number of remaining screens is 0, InitOutput() sets screenInfo.numScreens to 0 and returns. At this point the following fields of the ScrnInfoRecs must be initialised: confScreen Allocate non-conflicting resources This is done at the start of the first server generation only. Before calling the drivers again, the resource information collected from the Probe phase is processed. This includes checking the extent of PCI resources for the probed devices, and resolving any conflicts in the relocatable PCI resources. It also reports conflicts, checks bus routing issues, and anything else that is needed to enable the entities for the next phase. If any drivers registered an EntityInit() function during the Probe phase, then they are called here. Sort the Screens and pre-check Monitor Information This is done at the start of the first server generation only. The list of screens is sorted to match the ordering requested in the config file. The list of modes for each active monitor is checked against the monitor's parameters. Invalid modes are pruned. PreInit This is done at the start of the first server generation only. For each ScrnInfoRec, enable access to the screens entities and call the ChipPreInit() function.

Bool ChipPreInit(ScrnInfoRec screen, int flags);
The purpose of this function is to find out all the information required to determine if the configuration is usable, and to initialise those parts of the ScrnInfoRec that can be set once at the beginning of the first server generation. The number of entities registered for the screen should be checked against the expected number (most drivers expect only one). The entity information for each of them should be retrieved (with xf86GetEntityInfo()) and checked for the correct bus type and that none of the shareable resources registered during the Probe phase was rejected. Access to resources for the entities that can be controlled in a device-independent way are enabled before this function is called. If the driver needs to access any resources that it has disabled in an EntityInit() function that it registered, then it may enable them here providing that it disables them before this function returns. This includes probing for video memory, clocks, ramdac, and all other HW info that is needed. It includes determining the depth/bpp/visual and related info. It includes validating and determining the set of video modes that will be used (and anything that is required to determine that). This information should be determined in the least intrusive way possible. The state of the HW must remain unchanged by this function. Although video memory (including MMIO) may be mapped within this function, it must be unmapped before returning. Driver specific information should be stored in a structure hooked into the ScrnInfoRec's driverPrivate field. Any other modules which require persistent data (ie data that persists across server generations) should be initialised in this function, and they should allocate a privates index to hook their data into by calling xf86AllocateScrnInfoPrivateIndex(). The privates data is persistent. Helper functions for some of these things are provided at the XFree86 common level, and the driver can choose to make use of them. Modules may be loaded at any point in this function, and all modules that the driver will need must be loaded before the end of this function. Either the xf86LoadSubModule() or the xf86LoadDrvSubModule() function should be used to load modules depending on whether a ScrnInfoRec has been set up. A driver may unload a module within this function if it was only needed temporarily, and the xf86UnloadSubModule() function should be used to do that. Otherwise there is no need to explicitly unload modules because the loader takes care of module dependencies and will unload submodules automatically if/when the driver module is unloaded. The bulk of the ScrnInfoRec fields should be filled out in this function. ChipPreInit() returns FALSE when the configuration is unusable in some way (unsupported depth, no valid modes, not enough video memory, etc), and TRUE if it is usable. It is expected that if the ChipPreInit() function returns TRUE, then the only reasons that subsequent stages in the driver might fail are lack or resources (like xalloc failures). All other possible reasons for failure should be determined by the ChipPreInit() function.

The ScrnInfoRecs for screens where the ChipPreInit() fails are removed. If none remain, InitOutput() sets screenInfo.numScreens to 0 and returns. At this point, further fields of the ScrnInfoRecs would normally be filled in. Most are not strictly mandatory, but many are required by other layers and/or helper functions that the driver may choose to use. The documentation for those layers and helper functions indicates which they require. The following fields of the ScrnInfoRecs should be filled in if the driver is going to use them: monitor display depth pixmapBPP bitsPerPixel weight (>8bpp only) mask (>8bpp only) offset (>8bpp only) rgbBits (8bpp only) gamma defaultVisual virtualX virtualY displayWidth frameX0 frameY0 frameX1 frameY1 zoomLocked modePool modes currentMode progClock (TRUE if clock is programmable) chipset ramdac clockchip numClocks (if not programmable) clock[] (if not programmable) videoRam memBase driverPrivate chipID chipRev

pointer xf86LoadSubModule(ScrnInfoPtr pScrn, const char *name); and pointer xf86LoadDrvSubModule(DriverPtr drv, const char *name);
Load a module that a driver depends on. This function loads the module name as a sub module of the driver. The return value is a handle identifying the new module. If the load fails, the return value will be NULL. If a driver needs to explicitly unload a module it has loaded in this way, the return value must be saved and passed to xf86UnloadSubModule() when unloading.

void xf86UnloadSubModule(pointer module);
Unloads the module referenced by module. module should be a pointer returned previously by xf86LoadSubModule() or xf86LoadDrvSubModule() .

Cleaning up Unused Drivers At this point it is known which screens will be in use, and which drivers are being used. Unreferenced drivers (and modules they may have loaded) are unloaded here. Consistency Checks The parameters that must be global to the server, like pixmap formats, bitmap bit order, bitmap scanline unit and image byte order are compared for each of the screens. If a mismatch is found, the server exits with an appropriate message. Check if Resource Control is Needed Determine if resource access control is needed. This is the case if more than one screen is used. If necessary the RAC wrapper module is loaded. AddScreen (ScreenInit) At this point, the valid screens are known. AddScreen() is called for each of them, passing ChipScreenInit() as the argument. AddScreen() is a DIX function that allocates a new screenInfo.screen[] entry (aka pScreen), and does some basic initialisation of it. It then calls the ChipScreenInit() function, with pScreen as one of its arguments. If ChipScreenInit() returns FALSE, AddScreen() returns -1. Otherwise it returns the index of the screen. AddScreen() should only fail because of programming errors or failure to allocate resources (like memory). All configuration problems should be detected BEFORE this point.

Bool ChipScreenInit(ScreenPtr pScreen, int argc, char **argv);
This is called at the start of each server generation. Fill in all of pScreen, possibly doing some of this by calling ScreenInit functions from other layers like mi, framebuffers (cfb, etc), and extensions. Decide which operations need to be placed under resource access control. The classes of operations are the frame buffer operations (RAC_FB), the pointer operations (RAC_CURSOR), the viewport change operations (RAC_VIEWPORT) and the colormap operations (RAC_COLORMAP). Any operation that requires resources which might be disabled during OPERATING state should be set to use RAC. This can be specified separately for memory and IO resources (the racMemFlags and racIoFlags fields of the ScrnInfoRec respectively). Map any video memory or other memory regions. Save the video card state. Enough state must be saved so that the original state can later be restored. Initialise the initial video mode. The ScrnInfoRec's vtSema field should be set to TRUE just prior to changing the video hardware's state.

The ChipScreenInit() function (or functions from other layers that it calls) should allocate entries in the ScreenRec's devPrivates area by calling AllocateScreenPrivateIndex() if it needs per-generation storage. Since the ScreenRec's devPrivates information is cleared for each server generation, this is the correct place to initialise it. After AddScreen() has successfully returned, the following ScrnInfoRec fields are initialised: pScreen racMemFlags racIoFlags The ChipScreenInit() function should initialise the CloseScreen and SaveScreen fields of pScreen. The old value of pScreen->CloseScreen should be saved as part of the driver's per-screen private data, allowing it to be called from ChipCloseScreen(). This means that the existing CloseScreen() function is wrapped. Finalising RAC Initialisation After all the ChipScreenInit() functions have been called, each screen has registered its RAC requirements. This information is used to determine which shared resources are requested by more than one driver and set the access functions accordingly. This is done following these rules: The shareable resources registered by each entity are compared. If a resource is registered by more than one entity the entity will be marked to indicate that it needs to share this resources type (IO or MEM). A resource marked disabled during OPERATING state will be ignored entirely. A resource marked unused will only conflict with an overlapping resource of an other entity if the second is actually in use during OPERATING state. If an unused resource was found to conflict but the entity does not use any other resource of this type the entire resource type will be disabled for that entity. Finishing InitOutput() At this point InitOutput() is finished, and all the screens have been setup in their initial video mode. Mode Switching When a SwitchMode event is received, ChipSwitchMode() is called (when it exists):

Bool ChipSwitchMode(int index, DisplayModePtr mode);
Initialises the new mode for the screen identified by index;. The viewport may need to be adjusted also.

Changing Viewport When a Change Viewport event is received, ChipAdjustFrame() is called (when it exists):

void ChipAdjustFrame(int index, int x, int y);
Changes the viewport for the screen identified by index;. It should be noted that many chipsets impose restrictions on where the viewport may be placed in the virtual resolution, either for alignment reasons, or to prevent the start of the viewport from being positioned within a pixel (as can happen in a 24bpp mode). After calculating the value the chipset's panning registers need to be set to for non-DGA modes, this function should recalculate the ScrnInfoRec's frameX0, frameY0, frameX1 and frameY1 fields to correspond to that value. If this is not done, switching to another mode might cause the position of a hardware cursor to change.

VT Switching When a VT switch event is received, xf86VTSwitch() is called. xf86VTSwitch() does the following: On ENTER: enable port I/O access save and initialise the bus/resource state enter the SETUP server state calls ChipEnterVT() for each screen enter the OPERATING server state validate GCs Restore fb from saved pixmap for each screen Enable all input devices On LEAVE: Save fb to pixmap for each screen validate GCs enter the SETUP server state calls ChipLeaveVT() for each screen disable all input devices restore bus/resource state disables port I/O access

Bool ChipEnterVT(ScrnInfoPtr pScrn);
This function should initialise the current video mode and initialise the viewport, turn on the HW cursor if appropriate, etc. Should it re-save the video state before initialising the video mode?

void ChipLeaveVT(ScrnInfoPtr pScrn);
This function should restore the saved video state. If appropriate it should also turn off the HW cursor, and invalidate any pixmap/font caches.

Optionally, ChipLeaveVT() may also unmap memory regions. If so, ChipEnterVT() will need to remap them. Additionally, if an aperture used to access video memory is unmapped and remapped in this fashion, ChipEnterVT() will also need to notify the framebuffer layers of the aperture's new location in virtual memory. This is done with a call to the screen's ModifyPixmapHeader() function, as follows

(*pScreen->ModifyPixmapHeader)(pScrn->ppix, -1, -1, -1, -1, -1, NewApertureAddress);
where the ppix field in a ScrnInfoRec points to the pixmap used by the screen's SaveRestoreImage() function to hold the screen's contents while switched out.

Other layers may wrap the ChipEnterVT() and ChipLeaveVT() functions if they need to take some action when these events are received. End of server generation At the end of each server generation, the DIX layer calls ChipCloseScreen() for each screen:

Bool ChipCloseScreen(int index, ScreenPtr pScreen);
This function should restore the saved video state and unmap the memory regions. It should also free per-screen data structures allocated by the driver. Note that the persistent data held in the ScrnInfoRec's driverPrivate field should not be freed here because it is needed by subsequent server generations. The ScrnInfoRec's vtSema field should be set to FALSE once the video HW state has been restored. Before freeing the per-screen driver data the saved CloseScreen value should be restored to pScreen->CloseScreen, and that function should be called after freeing the data.

Optional Driver Functions The functions outlined here can be called from the XFree86 common layer, but their presence is optional. Mode Validation When a mode validation helper supplied by the XFree86-common layer is being used, it can be useful to provide a function to check for hw specific mode constraints:

ModeStatus ChipValidMode(ScrnInfoPtr pScrn, DisplayModePtr mode, Bool verbose, int flags);
Check the passed mode for hw-specific constraints, and return the appropriate status value.

This function may also modify the effective timings and clock of the passed mode. These have been stored in the mode's Crtc* and SynthClock elements, and have already been adjusted for interlacing, doublescanning, multiscanning and clock multipliers and dividers. The function should not modify any other mode field, unless it wants to modify the mode timings reported to the user by xf86PrintModes(). The function is called once for every mode in the xorg.conf Monitor section assigned to the screen, with flags set to MODECHECK_INITIAL. It is subsequently called for every mode in the xorg.conf Display subsection assigned to the screen, with flags set to MODECHECK_FINAL. In the second case, the mode will have successfully passed all other tests. In addition, the ScrnInfoRec's virtualX, virtualY and displayWidth fields will have been set as if the mode to be validated were to be the last mode accepted. In effect, calls with MODECHECK_INITIAL are intended for checks that do not depend on any mode other than the one being validated, while calls with MODECHECK_FINAL are intended for checks that may involve more than one mode. Free screen data When a screen is deleted prior to the completion of the ScreenInit phase the ChipFreeScreen() function is called when defined.

void ChipFreeScreen(ScrnInfoPtr pScrn);
Free any driver-allocated data that may have been allocated up to and including an unsuccessful ChipScreenInit() call. This would predominantly be data allocated by ChipPreInit() that persists across server generations. It would include the driverPrivate, and any privates entries that modules may have allocated.

Recommended driver functions The functions outlined here are for internal use by the driver only. They are entirely optional, and are never accessed directly from higher layers. The sample function declarations shown here are just examples. The interface (if any) used is up to the driver. Save Save the video state. This could be called from ChipScreenInit() and (possibly) ChipEnterVT().

void ChipSave(ScrnInfoPtr pScrn);
Saves the current state. This will only be saving pre-server states or states before returning to the server. There is only one current saved state per screen and it is stored in private storage in the screen.

Restore Restore the original video state. This could be called from the ChipLeaveVT() and ChipCloseScreen() functions.

void ChipRestore(ScrnInfoPtr pScrn);
Restores the saved state from the private storage. Usually only used for restoring text modes.

Initialise Mode Initialise a video mode. This could be called from the ChipScreenInit(), ChipSwitchMode() and ChipEnterVT() functions.

Bool ChipModeInit(ScrnInfoPtr pScrn, DisplayModePtr mode);
Programs the hardware for the given video mode.

Data and Data Structures Command line data Command line options are typically global, and are stored in global variables. These variables are read-only and are available to drivers via a function call interface. Most of these command line values are processed via helper functions to ensure that they are treated consistently by all drivers. The other means of access is provided for cases where the supplied helper functions might not be appropriate. Some of them are: xf86Verbose verbosity level xf86Bpp -bpp from the command line xf86Depth -depth from the command line xf86Weight -weight from the command line xf86Gamma -{r,g,b,}gamma from the command line xf86FlipPixels -flippixels from the command line xf86ProbeOnly -probeonly from the command line defaultColorVisualClass -cc from the command line If we ever do allow for screen-specific command line options, we may need to rethink this. These can be accessed in a read-only manner by drivers with the following functions:

int xf86GetVerbosity();
Returns the value of xf86Verbose.

int xf86GetDepth();
Returns the command line setting. If not set on the command line, -1 is returned.

rgb xf86GetWeight();
Returns the command line setting. If not set on the command line, {0, 0, 0} is returned.

Gamma xf86GetGamma();
Returns the or , , command line settings. If not set on the command line, {0.0, 0.0, 0.0} is returned.

Bool xf86GetFlipPixels();
Returns TRUE if is present on the command line, and FALSE otherwise.

Data handling Config file data contains parts that are global, and parts that are Screen specific. All of it is parsed into data structures that neither the drivers or most other parts of the server need to know about. The global data is typically not required by drivers, and as such, most of it is stored in the private xf86InfoRec. The screen-specific data collected from the config file is stored in screen, device, display, monitor-specific data structures that are separate from the ScrnInfoRecs, with the appropriate elements/fields hooked into the ScrnInfoRecs as required. The screen config data is held in confScreenRec, device data in the GDevRec, monitor data in the MonRec, and display data in the DispRec. The XFree86 common layer's screen specific data (the actual data in use for each screen) is held in the ScrnInfoRecs. As has been outlined above, the ScrnInfoRecs are allocated at probe time, and it is the responsibility of the Drivers' Probe() and PreInit() functions to finish filling them in based on both data provided on the command line and data provided from the Config file. The precedence for this is:

command line -> config file -> probed/default data

For most things in this category there are helper functions that the drivers can use to ensure that the above precedence is consistently used. As well as containing screen-specific data that the XFree86 common layer (including essential parts of the server infrastructure as well as helper functions) needs to access, it also contains some data that drivers use internally. When considering whether to add a new field to the ScrnInfoRec, consider the balance between the convenience of things that lots of drivers need and the size/obscurity of the ScrnInfoRec. Per-screen driver specific data that cannot be accommodated with the static ScrnInfoRec fields is held in a driver-defined data structure, a pointer to which is assigned to the ScrnInfoRec's driverPrivate field. This is per-screen data that persists across server generations (as does the bulk of the static ScrnInfoRec data). It would typically also include the video card's saved state. Per-screen data for other modules that the driver uses that is reset for each server generation is hooked into the ScrnInfoRec through its privates field. Once it has stabilised, the data structures and variables accessible to video drivers will be documented here. In the meantime, those things defined in the xf86.h and xf86str.h files are visible to video drivers. Things defined in xf86Priv.h and xf86Privstr.h are NOT intended to be visible to video drivers, and it is an error for a driver to include those files. Accessing global data Some other global state information that the drivers may access via functions is as follows:

Bool xf86ServerIsExiting();
Returns TRUE if the server is at the end of a generation and is in the process of exiting, and FALSE otherwise.

Bool xf86ServerIsResetting();
Returns TRUE if the server is at the end of a generation and is in the process of resetting, and FALSE otherwise.

Bool xf86ServerIsOnlyProbing();
Returns TRUE if the -probeonly command line flag was specified, and FALSE otherwise.

Allocating private data A driver and any module it uses may allocate per-screen private storage in either the ScreenRec (DIX level) or ScrnInfoRec (XFree86 common layer level). ScreenRec storage persists only for a single server generation, and ScrnInfoRec storage persists across generations for the lifetime of the server. The ScreenRec devPrivates data must be reallocated/initialised at the start of each new generation. This is normally done from the ChipScreenInit() function, and Init functions for other modules that it calls. Data allocated in this way should be freed by the driver's ChipCloseScreen() functions, and Close functions for other modules that it calls. A new devPrivates entry is allocated by calling the AllocateScreenPrivateIndex() function.

int AllocateScreenPrivateIndex();
This function allocates a new element in the devPrivates field of all currently existing ScreenRecs. The return value is the index of this new element in the devPrivates array. The devPrivates field is of type DevUnion: typedef union _DevUnion { pointer ptr; long val; unsigned long uval; pointer (*fptr)(void); } DevUnion; which allows the element to be used for any of the above types. It is commonly used as a pointer to data that the caller allocates after the new index has been allocated. This function will return -1 when there is an error allocating the new index.

The ScrnInfoRec privates data persists for the life of the server, so only needs to be allocated once. This should be done from the ChipPreInit() function, and Init functions for other modules that it calls. Data allocated in this way should be freed by the driver's ChipFreeScreen() functions, and Free functions for other modules that it calls. A new privates entry is allocated by calling the xf86AllocateScrnInfoPrivateIndex() function.

int xf86AllocateScrnInfoPrivateIndex();
This function allocates a new element in the privates field of all currently existing ScrnInfoRecs. The return value is the index of this new element in the privates array. The privates field is of type DevUnion: typedef union _DevUnion { pointer ptr; long val; unsigned long uval; pointer (*fptr)(void); } DevUnion; which allows the element to be used for any of the above types. It is commonly used as a pointer to data that the caller allocates after the new index has been allocated. This function will not return when there is an error allocating the new index. When there is an error it will cause the server to exit with a fatal error. The similar function for allocation privates in the ScreenRec (AllocateScreenPrivateIndex()) differs in this respect by returning -1 when the allocation fails.

Keeping Track of Bus Resources Theory of Operation The XFree86 common layer has knowledge of generic access control mechanisms for devices on certain bus systems (currently the PCI bus) as well as of methods to enable or disable access to the buses itself. Furthermore it can access information on resources decoded by these devices and if necessary modify it. When first starting the Xserver collects all this information, saves it for restoration, checks it for consistency, and if necessary, corrects it. Finally it disables all resources on a generic level prior to calling any driver function. When the Probe() function of each driver is called the device sections are matched against the devices found in the system. The driver may probe devices at this stage that cannot be identified by using device independent methods. Access to all resources that can be controlled in a device independent way is disabled. The Probe() function should register all non-relocatable resources at this stage. If a resource conflict is found between exclusive resources the driver will fail immediately. Optionally the driver might specify an EntityInit(), EntityLeave() and EntityEnter() function. EntityInit() can be used to disable any shared resources that are not controlled by the generic access control functions. It is called prior to the PreInit phase regardless if an entity is active or not. When calling the EntityInit(), EntityEnter() and EntityLeave() functions the common level will disable access to all other entities on a generic level. Since the common level has no knowledge of device specific methods to disable access to resources it cannot be guaranteed that certain resources are not decoded by any other entity until the EntityInit() or EntityEnter() phase is finished. Device drivers should therefore register all those resources which they are going to disable. If these resources are never to be used by any driver function they may be flagged ResInit so that they can be removed from the resource list after processing all EntityInit() functions. EntityEnter() should disable decoding of all resources which are not registered as exclusive and which are not handled by the generic access control in the common level. The difference to EntityInit() is that the latter one is only called once during lifetime of the server. It can therefore be used to set up variables prior to disabling resources. EntityLeave() should restore the original state when exiting the server or switching to a different VT. It also needs to disable device specific access functions if they need to be disabled on server exit or VT switch. The default state is to enable them before giving up the VT. In PreInit() phase each driver should check if any shareable resources it has registered during Probe() has been denied and take appropriate action which could simply be to fail. If it needs to access resources it has disabled during EntitySetup() it can do so provided it has registered these and will disable them before returning from PreInit(). This also applies to all other driver functions. Several functions are provided to request resource ranges, register these, correct PCI config space and add replacements for the generic access functions. Resources may be marked disabled or unused during OPERATING stage. Although these steps could also be performed in ScreenInit(), this is not desirable. Following PreInit() phase the common level determines if resource access control is needed. This is the case if more than one screen is used. If necessary the RAC wrapper module is loaded. In ScreenInit() the drivers can decide which operations need to be placed under RAC. Available are the frame buffer operations, the pointer operations and the colormap operations. Any operation that requires resources which might be disabled during OPERATING state should be set to use RAC. This can be specified separately for memory and IO resources. When ScreenInit() phase is done the common level will determine which shared resources are requested by more than one driver and set the access functions accordingly. This is done following these rules: The shareable resources registered by each entity are compared. If a resource is registered by more than one entity the entity will be marked to need to share this resources type (IO or MEM). A resource marked disabled during OPERATING state will be ignored entirely. A resource marked unused will only conflicts with an overlapping resource of an other entity if the second is actually in use during OPERATING state. If an unused resource was found to conflict however the entity does not use any other resource of this type the entire resource type will be disabled for that entity. The driver has the choice among different ways to control access to certain resources: It can rely on the generic access functions. This is probably the most common case. Here the driver only needs to register any resource it is going to use. It can replace the generic access functions by driver specific ones. This will mostly be used in cases where no generic access functions are available. In this case the driver has to make sure these resources are disabled when entering the PreInit() stage. Since the replacement functions are registered in PreInit() the driver will have to enable these resources itself if it needs to access them during this state. The driver can specify if the replacement functions can control memory and/or I/O resources separately. The driver can enable resources itself when it needs them. Each driver function enabling them needs to disable them before it will return. This should be used if a resource which can be controlled in a device dependent way is only required during SETUP state. This way it can be marked unused during OPERATING state. A resource which is decoded during OPERATING state however never accessed by the driver should be marked unused. Since access switching latencies are an issue during Xserver operation, the common level attempts to minimize the number of entities that need to be placed under RAC control. When a wrapped operation is called, the EnableAccess() function is called before control is passed on. EnableAccess() checks if a screen is under access control. If not it just establishes bus routing and returns. If the screen needs to be under access control, EnableAccess() determines which resource types (MEM, IO) are required. Then it tests if this access is already established. If so it simply returns. If not it disables the currently established access, fixes bus routing and enables access to all entities registered for this screen. Whenever a mode switch or a VT-switch is performed the common level will return to SETUP state. Resource Types Resource have certain properties. When registering resources each range is accompanied by a flag consisting of the ORed flags of the different properties the resource has. Each resource range may be classified according to its physical properties i.e., if it addresses memory (ResMem) or I/O space (ResIo), if it addresses a block (ResBlock) or sparse (ResSparse) range, its access properties. There are two known access properties: ResExclusive for resources which may not be shared with any other device and ResShared for resources which can be disabled and therefore can be shared. If it is necessary to test a resource against any type a generic access type ResAny is provided. If this is set the resource will conflict with any resource of a different entity intersecting its range. Further it can be specified that a resource is decoded however never used during any stage (ResUnused) or during OPERATING state (ResUnusedOpr). A resource only visible during the init functions (ie. EntityInit(), EntityEnter() and EntityLeave() should be registered with the flag ResInit. A resource that might conflict with background resource ranges may be flagged with ResBios. This might be useful when registering resources ranges that were assigned by the system Bios. Several predefined resource lists are available for VGA and 8514/A resources in common/xf86Resources.h. Available Functions The functions provided for resource management are listed in their order of use in the driver. Probe Phase In this phase each driver detects those resources it is able to drive, creates an entity record for each of them, registers non-relocatable resources and allocates screens and adds the resources to screens. Two helper functions are provided for matching device sections in the xorg.conf file to the devices:

int xf86MatchPciInstances(const char *driverName, int vendorID, SymTabPtr chipsets, PciChipsets *PCIchipsets, GDevPtr *devList, int numDevs, DriverPtr drvp, int **foundEntities);
This function finds matches between PCI cards that a driver supports and config file device sections. It is intended for use in the ChipProbe() function of drivers for PCI cards. Only probed PCI devices with a vendor ID matching vendorID are considered. devList and numDevs are typically those found from calling xf86MatchDevice(), and represent the active config file device sections relevant to the driver. PCIchipsets is a table that provides a mapping between the PCI device IDs, the driver's internal chipset tokens and a list of fixed resources. When a device section doesn't have a BusID entry it can only match the primary video device. Secondary devices are only matched with device sections that have a matching BusID entry. Once the preliminary matches have been found, a final match is confirmed by checking if the chipset override, ChipID override or probed PCI chipset type match one of those given in the chipsets and PCIchipsets lists. The PCIchipsets list includes a list of the PCI device IDs supported by the driver. The list should be terminated with an entry with PCI ID -1". The chipsets list is a table mapping the driver's internal chipset tokens to names, and should be terminated with a NULL entry. Only those entries with a corresponding entry in the PCIchipsets list are considered. The order of precedence is: config file chipset, config file ChipID, probed PCI device ID. In cases where a driver handles PCI chipsets with more than one vendor ID, it may set vendorID to 0, and OR each devID in the list with (the vendor ID << 16). Entity index numbers for confirmed matches are returned as an array via foundEntities. The PCI information, chipset token and device section for each match are found in the EntityInfoRec referenced by the indices. The function return value is the number of confirmed matches. A return value of -1 indicates an internal error. The returned foundEntities array should be freed by the driver with xfree() when it is no longer needed in cases where the return value is greater than zero.

These two helper functions make use of several core functions that are available at the driver level:

Bool xf86ParsePciBusString(const char *busID, int *bus, int *device, int *func);
Takes a BusID string, and if it is in the correct format, returns the PCI bus, device, func values that it indicates. The format of the string is expected to be "PCI:bus:device:func" where each of bus, device and func are decimal integers. The ":func" part may be omitted, and the func value assumed to be zero, but this isn't encouraged. The "PCI" prefix may also be omitted. The prefix "AGP" is currently equivalent to the "PCI" prefix. If the string isn't a valid PCI BusID, the return value is FALSE.

Bool xf86ComparePciBusString(const char *busID, int bus, int device, int func);
Compares a BusID string with PCI bus, device, func values. If they match TRUE is returned, and FALSE if they don't.

Bool xf86CheckPciSlot(int bus, int device, int func);
Checks if the PCI slot bus:device:func has been claimed. If so, it returns FALSE, and otherwise TRUE.

int xf86ClaimPciSlot(int bus, int device, int func, DriverPtr drvp, int chipset, GDevPtr dev, Bool active);
This function is used to claim a PCI slot, allocate the associated entity record and initialise their data structures. The return value is the index of the newly allocated entity record, or -1 if the claim fails. This function should always succeed if xf86CheckPciSlot() returned TRUE for the same PCI slot.

Bool xf86IsPrimaryPci(void);
This function returns TRUE if the primary card is a PCI device, and FALSE otherwise.

Two helper functions are provided to aid configuring entities:

ScrnInfoPtr xf86ConfigPciEntity(ScrnInfoPtr pScrn, int scrnFlag, int entityIndex, PciChipsets *p_chip, void *res, EntityProc init, EntityProc enter, EntityProc leave, pointer private);
This functions is used to register the entity. The res, init, enter, and leave arguments are unused, and should be NULL. For active entities a ScrnInfoRec is allocated if the pScrn argument is NULL. The return value is TRUE when successful.

These two helper functions make use of several core functions that are available at the driver level:

void xf86AddEntityToScreen(ScrnInfoPtr pScrn, int entityIndex);
This function associates the entity referenced by entityIndex with the screen.

PreInit Phase During this phase the remaining resources should be registered. PreInit() should call xf86GetEntityInfo() to obtain a pointer to an EntityInfoRec for each entity it is able to drive and check if any resource are listed in its resources field. If resources registered in the Probe phase have been rejected in the post-Probe phase (resources is non-NULL), then the driver should decide if it can continue without using these or if it should fail.

EntityInfoPtr xf86GetEntityInfo(int entityIndex);
This function returns a pointer to the EntityInfoRec referenced by entityIndex. The returned EntityInfoRec should be freed with xfree() when no longer needed.

Several functions are provided to simplify resource registration:

Bool xf86IsEntityPrimary(int entityIndex);
This function returns TRUE if the entity referenced by entityIndex is the primary display device (i.e., the one initialised at boot time and used in text mode).

Bool xf86IsScreenPrimary(ScrnInfoPtr pScrn);
This function returns TRUE if the primary entity is registered with the screen referenced by pScrn.

pciVideoPtr xf86GetPciInfoForEntity(int entityIndex);
This function returns a pointer to the pciVideoRec for the specified entity. If the entity is not a PCI device, NULL is returned.

Two functions are provided to obtain a resource range of a given type:

resRange xf86GetBlock(long type, memType size, memType window_start, memType window_end, memType align_mask, resPtr avoid);
This function tries to find a block range of size size and type type in a window bound by window_start and window_end with the alignment specified in align_mask. Optionally a list of resource ranges which should be avoided within the window can be supplied. On failure a zero-length range of type ResEnd will be returned.

resRange xf86GetSparse(long type, memType fixed_bits, memType decode_mask, memType address_mask, resPtr avoid);
This function is like the previous one, but attempts to find a sparse range instead of a block range. Here three values have to be specified: the address_mask which marks all bits of the mask part of the address, the decode_mask which masks out the bits which are hardcoded and are therefore not available for relocation and the values of the fixed bits. The function tries to find a base that satisfies the given condition. If the function fails it will return a zero range of type ResEnd. Optionally it might be passed a list of resource ranges to avoid.

Bool xf86CheckPciMemBase(pciVideoPtr pPci, memType base);
This function checks that the memory base address specified matches one of the PCI base address register values for the given PCI device. This is mostly used to check that an externally provided base address (e.g., from a config file) matches an actual value allocated to a device.

The following two functions are provided for special cases:

void xf86RemoveEntityFromScreen(ScrnInfoPtr pScrn, int entityIndex);
This function may be used to remove an entity from a screen. This only makes sense if a screen has more than one entity assigned or the screen is to be deleted. No test is made if the screen has any entities left.

ScreenInit Phase All that is required in this phase is to setup the RAC flags. Note that it is also permissible to set these flags up in the PreInit phase. The RAC flags are held in the racIoFlags and racMemFlags fields of the ScrnInfoRec for each screen. They specify which graphics operations might require the use of shared resources. This can be specified separately for memory and I/O resources. The available flags are defined in rac/xf86RAC.h. They are: RAC_FB for framebuffer operations (including hw acceleration) RAC_CURSOR for Cursor operations (??? I'm not sure if we need this for SW cursor it depends on which level the sw cursor is drawn) RAC_COLORMAP for colormap operations RAC_VIEWPORT for the call to ChipAdjustFrame() The flags are ORed together. Config file <quote>Option</quote> entries Option entries are permitted in most sections and subsections of the config file. There are two forms of option entries: Option "option-name" A boolean option. Option "option-name" "option-value" An option with an arbitrary value. The option entries are handled by the parser, and a list of the parsed options is included with each of the appropriate data structures that the drivers have access to. The data structures used to hold the option information are opaque to the driver, and a driver must not access the option data directly. Instead, the common layer provides a set of functions that may be used to access, check and manipulate the option data. First, the low level option handling functions. In most cases drivers would not need to use these directly.

XF86OptionPtr xf86FindOption(XF86OptionPtr options, const char *name);
Takes a list of options and an option name, and returns a handle for the first option entry in the list matching the name. Returns NULL if no match is found.

const char *xf86FindOptionValue(XF86OptionPtr options, const char *name);
Takes a list of options and an option name, and returns the value associated with the first option entry in the list matching the name. If the matching option has no value, an empty string ("") is returned. Returns NULL if no match is found.

void xf86MarkOptionUsed(XF86OptionPtr option);
Takes a handle for an option, and marks that option as used.

void xf86MarkOptionUsedByName(XF86OptionPtr options, const char *name);
Takes a list of options and an option name and marks the first option entry in the list matching the name as used.

Next, the higher level functions that most drivers would use.

void xf86CollectOptions(ScrnInfoPtr pScrn, XF86OptionPtr extraOpts);
Collect the options from each of the config file sections used by the screen (pScrn) and return the merged list as pScrn->options. This function requires that pScrn->confScreen, pScrn->display, pScrn->monitor, pScrn->numEntities, and pScrn->entityList are initialised. extraOpts may optionally be set to an additional list of options to be combined with the others. The order of precedence for options is extraOpts, display, confScreen, monitor, device.

void xf86ProcessOptions(int scrnIndex, XF86OptionPtr options, OptionInfoPtr optinfo);
Processes a list of options according to the information in the array of OptionInfoRecs (optinfo). The resulting information is stored in the value fields of the appropriate optinfo entries. The found fields are set to TRUE when an option with a value of the correct type if found, and FALSE otherwise. The type field is used to determine the expected value type for each option. Each option in the list of options for which there is a name match (but not necessarily a value type match) is marked as used. Warning messages are printed when option values don't match the types specified in the optinfo data. NOTE: If this function is called before a driver's screen number is known (e.g., from the ChipProbe() function) a scrnIndex value of -1 should be used. NOTE 2: Given that this function stores into the OptionInfoRecs pointed to by optinfo, the caller should ensure the OptionInfoRecs are (re-)initialised before the call, especially if the caller expects to use the predefined option values as defaults. The OptionInfoRec is defined as follows: typedef struct { double freq; int units; } OptFrequency; typedef union { unsigned long num; char * str; double realnum; Bool bool; OptFrequency freq; } ValueUnion; typedef enum { OPTV_NONE = 0, OPTV_INTEGER, OPTV_STRING, /* a non-empty string */ OPTV_ANYSTR, /* Any string, including an empty one */ OPTV_REAL, OPTV_BOOLEAN, OPTV_PERCENT, OPTV_FREQ } OptionValueType; typedef enum { OPTUNITS_HZ = 1, OPTUNITS_KHZ, OPTUNITS_MHZ } OptFreqUnits; typedef struct { int token; const char* name; OptionValueType type; ValueUnion value; Bool found; } OptionInfoRec, *OptionInfoPtr; OPTV_FREQ can be used for options values that are frequencies. These values are a floating point number with an optional unit name appended. The unit name can be one of "Hz", "kHz", "k", "MHz", "M". The multiplier associated with the unit is stored in freq.units, and the scaled frequency is stored in freq.freq. When no unit is specified, freq.units is set to 0, and freq.freq is unscaled. OPTV_PERCENT can be used for option values that are specified in percent (e.g. "20%"). These values are a floating point number with a percent sign appended. If the percent sign is missing, the parser will fail to match the value. Typical usage is to setup an array of OptionInfoRecs with all fields initialised. The value and found fields get set by xf86ProcessOptions(). For cases where the value parsing is more complex, the driver should specify OPTV_STRING, and parse the string itself. An example of using this option handling is included in the Sample Driver section.

void xf86ShowUnusedOptions(int scrnIndex, XF86OptionPtr options);
Prints out warning messages for each option in the list of options that isn't marked as used. This is intended to show options that the driver hasn't recognised. It would normally be called near the end of the ChipScreenInit() function, but only when serverGeneration == 1

OptionInfoPtr xf86TokenToOptinfo(const OptionInfoRec *table, int token);
Returns a pointer to the OptionInfoRec in table with a token field matching token. Returns NULL if no match is found.

Bool xf86IsOptionSet(const OptionInfoRec *table, int token);
Returns the found field of the OptionInfoRec in table with a token field matching token. This can be used for options of all types. Note that for options of type OPTV_BOOLEAN, it isn't sufficient to check this to determine the value of the option. Returns FALSE if no match is found.

char *xf86GetOptValString(const OptionInfoRec *table, int token);
Returns the value.str field of the OptionInfoRec in table with a token field matching token. Returns NULL if no match is found.

Bool xf86GetOptValInteger(const OptionInfoRec *table, int token, int *value);
Returns via *value the value.num field of the OptionInfoRec in table with a token field matching token. *value is only changed when a match is found so it can be safely initialised with a default prior to calling this function. The function return value is as for xf86IsOptionSet().

Bool xf86GetOptValULong(const OptionInfoRec *table, int token, unsigned long *value);
Like xf86GetOptValInteger(), except the value is treated as an unsigned long.

Bool xf86GetOptValReal(const OptionInfoRec *table, int token, double *value);
Like xf86GetOptValInteger(), except that value.realnum is used.

Bool xf86GetOptValFreq(const OptionInfoRec *table, int token, OptFreqUnits expectedUnits, double *value);
Like xf86GetOptValInteger(), except that the value.freq data is returned. The frequency value is scaled to the units indicated by expectedUnits. The scaling is exact when the units were specified explicitly in the option's value. Otherwise, the expectedUnits field is used as a hint when doing the scaling. In this case, values larger than 1000 are assumed to have be specified in the next smallest units. For example, if the Option value is "10000" and expectedUnits is OPTUNITS_MHZ, the value returned is 10.

Bool xf86GetOptValBool(const OptionInfoRec *table, int token, Bool *value);
This function is used to check boolean options (OPTV_BOOLEAN). If the function return value is FALSE, it means the option wasn't set. Otherwise *value is set to the boolean value indicated by the option's value. No option value is interpreted as TRUE. Option values meaning TRUE are "1", "yes", "on", "true", and option values meaning FALSE are "0", "no", "off", "false". Option names both with the "no" prefix in their names, and with that prefix removed are also checked and handled in the obvious way. *value is not changed when the option isn't present. It should normally be set to a default value before calling this function.

Bool xf86ReturnOptValBool(const OptionInfoRec *table, int token, Bool def);
This function is used to check boolean options (OPTV_BOOLEAN). If the option is set, its value is returned. If the options is not set, the default value specified by def is returned. The option interpretation is the same as for xf86GetOptValBool().

int xf86NameCmp(const char *s1, const char *s2);
This function should be used when comparing strings from the config file with expected values. It works like strcmp(), but is not case sensitive and space, tab, and _ characters are ignored in the comparison. The use of this function isn't restricted to parsing option values. It may be used anywhere where this functionality required.

Modules, Drivers, Include Files and Interface Issues NOTE: this section is incomplete. Include files The following include files are typically required by video drivers:

All drivers should include these: "xf86.h" "xf86_OSproc.h" "xf86_ansic.h" "xf86Resources.h" Wherever inb/outb (and related things) are used the following should be included: "compiler.h" Note: in drivers, this must be included after "xf86_ansic.h". Drivers that need to access the PCI config space need this: "xf86Pci.h" Drivers that initialise a SW cursor need this: "mipointer.h" All drivers using the mi colourmap code need this: "micmap.h" If a driver uses the vgahw module, it needs this: "vgaHW.h" Drivers supporting VGA or Hercules monochrome screens need: "xf1bpp.h" Drivers supporting VGA or EGC 16-colour screens need: "xf4bpp.h" Drivers using cfb need: #define PSZ 8 #include "cfb.h" #undef PSZ Drivers supporting bpp 16, 24 or 32 with cfb need one or more of: "cfb16.h" "cfb24.h" "cfb32.h" If a driver uses the fb manager, it needs this: "xf86fbman.h"

Non-driver modules should include "xf86_ansic.h" to get the correct wrapping of ANSI C/libc functions. All modules must NOT include any system include files, or the following: "xf86Priv.h" "xf86Privstr.h" "xf86_OSlib.h" "Xos.h" In addition, "xf86_libc.h" must not be included explicitly. It is included implicitly by "xf86_ansic.h". Offscreen Memory Manager Management of offscreen video memory may be handled by the XFree86 framebuffer manager. Once the offscreen memory manager is running, drivers or extensions may allocate, free or resize areas of offscreen video memory using the following functions (definitions taken from xf86fbman.h): typedef struct _FBArea { ScreenPtr pScreen; BoxRec box; int granularity; void (*MoveAreaCallback)(struct _FBArea*, struct _FBArea*) void (*RemoveAreaCallback)(struct _FBArea*) DevUnion devPrivate; } FBArea, *FBAreaPtr; typedef void (*MoveAreaCallbackProcPtr)(FBAreaPtr from, FBAreaPtr to) typedef void (*RemoveAreaCallbackProcPtr)(FBAreaPtr) FBAreaPtr xf86AllocateOffscreenArea ( ScreenPtr pScreen, int width, int height, int granularity, MoveAreaCallbackProcPtr MoveAreaCallback, RemoveAreaCallbackProcPtr RemoveAreaCallback, pointer privData ) void xf86FreeOffscreenArea (FBAreaPtr area) Bool xf86ResizeOffscreenArea ( FBAreaPtr area int w, int h ) The function: Bool xf86FBManagerRunning(ScreenPtr pScreen); can be used by an extension to check if the driver has initialized the memory manager. The manager is not available if this returns FALSE and the functions above will all fail. xf86AllocateOffscreenArea() can be used to request a rectangle of dimensions width × height (in pixels) from unused offscreen memory. granularity specifies that the leftmost edge of the rectangle must lie on some multiple of granularity pixels. A granularity of zero means the same thing as a granularity of one - no alignment preference. A MoveAreaCallback can be provided to notify the requester when the offscreen area is moved. If no MoveAreaCallback is supplied then the area is considered to be immovable. The privData field will be stored in the manager's internal structure for that allocated area and will be returned to the requester in the FBArea passed via the MoveAreaCallback. An optional RemoveAreaCallback is provided. If the driver provides this it indicates that the area should be allocated with a lower priority. Such an area may be removed when a higher priority request (one that doesn't have a RemoveAreaCallback) is made. When this function is called, the driver will have an opportunity to do whatever cleanup it needs to do to deal with the loss of the area, but it must finish its cleanup before the function exits since the offscreen memory manager will free the area immediately after. xf86AllocateOffscreenArea() returns NULL if it was unable to allocate the requested area. When no longer needed, areas should be freed with xf86FreeOffscreenArea(). xf86ResizeOffscreenArea() resizes an existing FBArea. xf86ResizeOffscreenArea() returns TRUE if the resize was successful. If xf86ResizeOffscreenArea() returns FALSE, the original FBArea is left unmodified. Resizing an area maintains the area's original granularity, devPrivate, and MoveAreaCallback. xf86ResizeOffscreenArea() has considerably less overhead than freeing the old area then reallocating the new size, so it should be used whenever possible. The function: Bool xf86QueryLargestOffscreenArea( ScreenPtr pScreen, int *width, int *height, int granularity, int preferences, int priority ); is provided to query the width and height of the largest single FBArea allocatable given a particular priority. preferences can be one of the following to indicate whether width, height or area should be considered when determining which is the largest single FBArea available. FAVOR_AREA_THEN_WIDTH FAVOR_AREA_THEN_HEIGHT FAVOR_WIDTH_THEN_AREA FAVOR_HEIGHT_THEN_AREA priority is one of the following:

PRIORITY_LOW
Return the largest block available without stealing anyone else's space. This corresponds to the priority of allocating a FBArea when a RemoveAreaCallback is provided.
PRIORITY_NORMAL
Return the largest block available if it is acceptable to steal a lower priority area from someone. This corresponds to the priority of allocating a FBArea without providing a RemoveAreaCallback.
PRIORITY_EXTREME
Return the largest block available if all FBAreas that aren't locked down were expunged from memory first. This corresponds to any allocation made directly after a call to xf86PurgeUnlockedOffscreenAreas().

The function: Bool xf86PurgeUnlockedOffscreenAreas(ScreenPtr pScreen); is provided as an extreme method to free up offscreen memory. This will remove all removable FBArea allocations. Initialization of the XFree86 framebuffer manager is done via Bool xf86InitFBManager(ScreenPtr pScreen, BoxPtr FullBox); FullBox represents the area of the framebuffer that the manager is allowed to manage. This is typically a box with a width of pScrn->displayWidth and a height of as many lines as can be fit within the total video memory, however, the driver can reserve areas at the extremities by passing a smaller area to the manager. Colormap Handling A generic colormap handling layer is provided within the XFree86 common layer. This layer takes care of most of the details, and only requires a function from the driver that loads the hardware palette when required. To use the colormap layer, a driver calls the xf86HandleColormaps() function.

Bool xf86HandleColormaps(ScreenPtr pScreen, int maxColors, int sigRGBbits, LoadPaletteFuncPtr loadPalette, SetOverscanFuncPtr setOverscan, unsigned int flags);
This function must be called after the default colormap has been initialised. The pScrn->gamma field must also be initialised, preferably by calling xf86SetGamma(). maxColors is the number of entries in the palette. sigRGBbits is the size in bits of each color component in the DAC's palette. loadPalette is a driver-provided function for loading a colormap into the hardware, and is described below. setOverscan is an optional function that may be provided when the overscan color is an index from the standard LUT and when it needs to be adjusted to keep it as close to black as possible. The setOverscan function programs the overscan index. It shouldn't normally be used for depths other than 8. setOverscan should be set to NULL when it isn't needed. flags may be set to the following (which may be ORed together): CMAP_PALETTED_TRUECOLOR the TrueColor visual is paletted and is just a special case of DirectColor. This flag is only valid for bpp > 8. CMAP_RELOAD_ON_MODE_SWITCH reload the colormap automatically after mode switches. This is useful for when the driver is resetting the hardware during mode switches and corrupting or erasing the hardware palette. CMAP_LOAD_EVEN_IF_OFFSCREEN reload the colormap even if the screen is switched out of the server's VC. The palette is not reloaded when the screen is switched back in, nor after mode switches. This is useful when the driver needs to keep track of palette changes. The colormap layer normally reloads the palette after VT enters so it is not necessary for the driver to save and restore the palette when switching VTs. The driver must, however, still save the initial palette during server start up and restore it during server exit.

void LoadPalette(ScrnInfoPtr pScrn, int numColors, int *indices, LOCO *colors, VisualPtr pVisual);
LoadPalette() is a driver-provided function for loading a colormap into hardware. colors is the array of RGB values that represent the full colormap. indices is a list of index values into the colors array. These indices indicate the entries that need to be updated. numColors is the number of the indices to be updated.

void SetOverscan(ScrnInfoPtr pScrn, int overscan);
SetOverscan() is a driver-provided function for programming the overscan index. As described above, it is normally only appropriate for LUT modes where all colormap entries are available for the display, but where one of them is also used for the overscan (typically 8bpp for VGA compatible LUTs). It isn't required in cases where the overscan area is never visible.

DPMS Extension Support code for the DPMS extension is included in the XFree86 common layer. This code provides an interface between the main extension code, and a means for drivers to initialise DPMS when they support it. One function is available to drivers to do this initialisation, and it is always available, even when the DPMS extension is not supported by the core server (in which case it returns a failure result).

Bool xf86DPMSInit(ScreenPtr pScreen, DPMSSetProcPtr set, int flags);
This function registers a driver's DPMS level programming function set. It also checks pScrn->options for the "dpms" option, and when present marks DPMS as being enabled for that screen. The set function is called whenever the DPMS level changes, and is used to program the requested level. flags is currently not used, and should be 0. If the initialisation fails for any reason, including when there is no DPMS support in the core server, the function returns FALSE.

Drivers that implement DPMS support must provide the following function, that gets called when the DPMS level is changed:

void ChipDPMSSet(ScrnInfoPtr pScrn, int level, int flags);
Program the DPMS level specified by level. Valid values of level are DPMSModeOn, DPMSModeStandby, DPMSModeSuspend, DPMSModeOff. These values are defined in "extensions/dpms.h".

DGA Extension Drivers can support the XFree86 Direct Graphics Architecture (DGA) by filling out a structure of function pointers and a list of modes and passing them to DGAInit.

Bool DGAInit(ScreenPtr pScreen, DGAFunctionPtr funcs, DGAModePtr modes, int num); /** The DGAModeRec **/ typedef struct { int num; DisplayModePtr mode; int flags; int imageWidth; int imageHeight; int pixmapWidth; int pixmapHeight; int bytesPerScanline; int byteOrder; int depth; int bitsPerPixel; unsigned long red_mask; unsigned long green_mask; unsigned long blue_mask; int viewportWidth; int viewportHeight; int xViewportStep; int yViewportStep; int maxViewportX; int maxViewportY; int viewportFlags; int offset; unsigned char *address; int reserved1; int reserved2; } DGAModeRec, *DGAModePtr; num Can be ignored. The DGA DDX will assign these numbers. mode A pointer to the DisplayModeRec for this mode. flags The following flags are defined and may be OR'd together: DGA_CONCURRENT_ACCESS Indicates that the driver supports concurrent graphics accelerator and linear framebuffer access. DGA_FILL_RECT DGA_BLIT_RECT DGA_BLIT_RECT_TRANS Indicates that the driver supports the FillRect, BlitRect or BlitTransRect functions in this mode. DGA_PIXMAP_AVAILABLE Indicates that Xlib may be used on the framebuffer. This flag will usually be set unless the driver wishes to prohibit this for some reason. DGA_INTERLACED DGA_DOUBLESCAN Indicates that these are interlaced or double scan modes. imageWidth imageHeight These are the dimensions of the linear framebuffer accessible by the client. pixmapWidth pixmapHeight These are the dimensions of the area of the framebuffer accessible by the graphics accelerator. bytesPerScanline Pitch of the framebuffer in bytes. byteOrder Usually the same as pScrn->imageByteOrder. depth The depth of the framebuffer in this mode. bitsPerPixel The number of bits per pixel in this mode. red_mask green_mask blue_mask The RGB masks for this mode, if applicable. viewportWidth viewportHeight Dimensions of the visible part of the framebuffer. Usually mode->HDisplay and mode->VDisplay. xViewportStep yViewportStep The granularity of x and y viewport positions that the driver supports in this mode. maxViewportX maxViewportY The maximum viewport position supported by the driver in this mode. viewportFlags The following may be OR'd together: DGA_FLIP_IMMEDIATE The driver supports immediate viewport changes. DGA_FLIP_RETRACE The driver supports viewport changes at retrace. offset The offset into the linear framebuffer that corresponds to pixel (0,0) for this mode. address The virtual address of the framebuffer as mapped by the driver. This is needed when DGA_PIXMAP_AVAILABLE is set. /** The DGAFunctionRec **/ typedef struct { Bool (*OpenFramebuffer)( ScrnInfoPtr pScrn, char **name, unsigned char **mem, int *size, int *offset, int *extra ); void (*CloseFramebuffer)(ScrnInfoPtr pScrn); Bool (*SetMode)(ScrnInfoPtr pScrn, DGAModePtr pMode); void (*SetViewport)(ScrnInfoPtr pScrn, int x, int y, int flags); int (*GetViewport)(ScrnInfoPtr pScrn); void (*Sync)(ScrnInfoPtr); void (*FillRect)( ScrnInfoPtr pScrn, int x, int y, int w, int h, unsigned long color ); void (*BlitRect)( ScrnInfoPtr pScrn, int srcx, int srcy, int w, int h, int dstx, int dsty ); void (*BlitTransRect)( ScrnInfoPtr pScrn, int srcx, int srcy, int w, int h, int dstx, int dsty, unsigned long color ); } DGAFunctionRec, *DGAFunctionPtr;
Bool OpenFramebuffer (pScrn, name, mem, size, offset, extra);
OpenFramebuffer() should pass the client everything it needs to know to be able to open the framebuffer. These parameters are OS specific and their meanings are to be interpreted by an OS specific client library. name The name of the device to open or NULL if there is no special device to open. A NULL name tells the client that it should open whatever device one would usually open to access physical memory. mem The physical address of the start of the framebuffer. size The size of the framebuffer in bytes. offset Any offset into the device, if applicable. flags Any additional information that the client may need. Currently, only the DGA_NEED_ROOT flag is defined.

void CloseFramebuffer (pScrn);
CloseFramebuffer() merely informs the driver (if it even cares) that client no longer needs to access the framebuffer directly. This function is optional.

Bool SetMode (pScrn, pMode);
SetMode() tells the driver to initialize the mode passed to it. If pMode is NULL, then the driver should restore the original pre-DGA mode.

void SetViewport (pScrn, x, y, flags);
SetViewport() tells the driver to make the upper left-hand corner of the visible screen correspond to coordinate (x,y) on the framebuffer. flags currently defined are: DGA_FLIP_IMMEDIATE The viewport change should occur immediately. DGA_FLIP_RETRACE The viewport change should occur at the vertical retrace, but this function should return sooner if possible. The (x,y) locations will be passed as the client specified them, however, the driver is expected to round these locations down to the next supported location as specified by the xViewportStep and yViewportStep for the current mode.

int GetViewport (pScrn);
GetViewport() gets the current page flip status. Set bits in the returned int correspond to viewport change requests still pending. For instance, set bit zero if the last SetViewport request is still pending, bit one if the one before that is still pending, etc.

void Sync (pScrn);
This function should ensure that any graphics accelerator operations have finished. This function should not return until the graphics accelerator is idle.

void FillRect (pScrn, x, y, w, h, color);
This optional function should fill a rectangle w × h located at (x,y) in the given color.

void BlitRect (pScrn, srcx, srcy, w, h, dstx, dsty);
This optional function should copy an area w × h located at (srcx,srcy) to location (dstx,dsty). This function will need to handle copy directions as appropriate.

void BlitTransRect (pScrn, srcx, srcy, w, h, dstx, dsty, color);
This optional function is the same as BlitRect except that pixels in the source corresponding to the color key color should be skipped.

The XFree86 X Video Extension (Xv) Device Dependent Layer XFree86 offers the X Video Extension which allows clients to treat video as any another primitive and Put video into drawables. By default, the extension reports no video adaptors as being available since the DDX layer has not been initialized. The driver can initialize the DDX layer by filling out one or more XF86VideoAdaptorRecs as described later in this document and passing a list of XF86VideoAdaptorPtr pointers to the following function: Bool xf86XVScreenInit(ScreenPtr pScreen, XF86VideoAdaptorPtr *adaptPtrs, int num); After doing this, the extension will report video adaptors as being available, providing the data in their respective XF86VideoAdaptorRecs was valid. xf86XVScreenInit() copies data from the structure passed to it so the driver may free it after the initialization. At the moment, the DDX only supports rendering into Window drawables. Pixmap rendering will be supported after a sufficient survey of suitable hardware is completed. The XF86VideoAdaptorRec: typedef struct { unsigned int type; int flags; char *name; int nEncodings; XF86VideoEncodingPtr pEncodings; int nFormats; XF86VideoFormatPtr pFormats; int nPorts; DevUnion *pPortPrivates; int nAttributes; XF86AttributePtr pAttributes; int nImages; XF86ImagePtr pImages; PutVideoFuncPtr PutVideo; PutStillFuncPtr PutStill; GetVideoFuncPtr GetVideo; GetStillFuncPtr GetStill; StopVideoFuncPtr StopVideo; SetPortAttributeFuncPtr SetPortAttribute; GetPortAttributeFuncPtr GetPortAttribute; QueryBestSizeFuncPtr QueryBestSize; PutImageFuncPtr PutImage; QueryImageAttributesFuncPtr QueryImageAttributes; } XF86VideoAdaptorRec, *XF86VideoAdaptorPtr; Each adaptor will have its own XF86VideoAdaptorRec. The fields are as follows: type This can be any of the following flags OR'd together. XvInputMask XvOutputMask These refer to the target drawable and are similar to a Window's class. XvInputMask indicates that the adaptor can put video into a drawable. XvOutputMask indicates that the adaptor can get video from a drawable. XvVideoMask XvStillMask XvImageMask These indicate that the adaptor supports video, still or image primitives respectively. XvWindowMask XvPixmapMask These indicate the types of drawables the adaptor is capable of rendering into. At the moment, Pixmap rendering is not supported and the XvPixmapMask flag is ignored. flags Currently, the following flags are defined: VIDEO_OVERLAID_STILLS Implementing PutStill for hardware that does video as an overlay can be awkward since it's unclear how long to leave the video up for. When this flag is set, StopVideo will be called whenever the destination gets clipped or moved so that the still can be left up until then. VIDEO_OVERLAID_IMAGES Same as VIDEO_OVERLAID_STILLS but for images. VIDEO_CLIP_TO_VIEWPORT Indicates that the clip region passed to the driver functions should be clipped to the visible portion of the screen in the case where the viewport is smaller than the virtual desktop. name The name of the adaptor. nEncodings pEncodings The number of encodings the adaptor is capable of and pointer to the XF86VideoEncodingRec array. The XF86VideoEncodingRec is described later on. For drivers that only support XvImages there should be an encoding named "XV_IMAGE" and the width and height should specify the maximum size source image supported. nFormats pFormats The number of formats the adaptor is capable of and pointer to the XF86VideoFormatRec array. The XF86VideoFormatRec is described later on. nPorts pPortPrivates The number of ports is the number of separate data streams which the adaptor can handle simultaneously. If you have more than one port, the adaptor is expected to be able to render into more than one window at a time. pPortPrivates is an array of pointers or ints - one for each port. A port's private data will be passed to the driver any time the port is requested to do something like put the video or stop the video. In the case where there may be many ports, this enables the driver to know which port the request is intended for. Most commonly, this will contain a pointer to the data structure containing information about the port. In Xv, all ports on a particular adaptor are expected to be identical in their functionality. nAttributes pAttributes The number of attributes recognized by the adaptor and a pointer to the array of XF86AttributeRecs. The XF86AttributeRec is described later on. nImages pImages The number of XF86ImageRecs supported by the adaptor and a pointer to the array of XF86ImageRecs. The XF86ImageRec is described later on. PutVideo PutStill GetVideo GetStill StopVideo SetPortAttribute GetPortAttribute QueryBestSize PutImage QueryImageAttributes These functions define the DDX->driver interface. In each case, the pointer data is passed to the driver. This is the port private for that port as described above. All fields are required except under the following conditions: PutVideo, PutStill and the image routines PutImage and QueryImageAttributes are not required when the adaptor type does not contain XvInputMask. GetVideo and GetStill are not required when the adaptor type does not contain XvOutputMask. GetVideo and PutVideo are not required when the adaptor type does not contain XvVideoMask. GetStill and PutStill are not required when the adaptor type does not contain XvStillMask. PutImage and QueryImageAttributes are not required when the adaptor type does not contain XvImageMask. With the exception of QueryImageAttributes, these functions should return Success if the operation was completed successfully. They can return XvBadAlloc otherwise. QueryImageAttributes returns the size of the XvImage queried. ClipBoxes is an X-Y banded region identical to those used throughout the server. The clipBoxes represent the visible portions of the area determined by drw_x, drw_y, drw_w and drw_h in the Get/Put function. The boxes are in screen coordinates, are guaranteed not to overlap and an empty region will never be passed.

typedef int (* PutVideoFuncPtr)( ScrnInfoPtr pScrn, short vid_x, short vid_y, short drw_x, short drw_y, short vid_w, short vid_h, short drw_w, short drw_h, RegionPtr clipBoxes, pointer data );
This indicates that the driver should take a subsection vid_w by vid_h at location (vid_x,vid_y) from the video stream and direct it into the rectangle drw_w by drw_h at location (drw_x,drw_y) on the screen, scaling as necessary. Due to the large variations in capabilities of the various hardware expected to be used with this extension, it is not expected that all hardware will be able to do this exactly as described. In that case the driver should just do the best it can, scaling as closely to the target rectangle as it can without rendering outside of it. In the worst case, the driver can opt to just not turn on the video.

typedef int (* PutStillFuncPtr)( ScrnInfoPtr pScrn, short vid_x, short vid_y, short drw_x, short drw_y, short vid_w, short vid_h, short drw_w, short drw_h, RegionPtr clipBoxes, pointer data );
This is same as PutVideo except that the driver should place only one frame from the stream on the screen.

typedef int (* GetVideoFuncPtr)( ScrnInfoPtr pScrn, short vid_x, short vid_y, short drw_x, short drw_y, short vid_w, short vid_h, short drw_w, short drw_h, RegionPtr clipBoxes, pointer data );
This is same as PutVideo except that the driver gets video from the screen and outputs it. The driver should do the best it can to get the requested dimensions correct without reading from an area larger than requested.

typedef int (* GetStillFuncPtr)( ScrnInfoPtr pScrn, short vid_x, short vid_y, short drw_x, short drw_y, short vid_w, short vid_h, short drw_w, short drw_h, RegionPtr clipBoxes, pointer data );
This is the same as GetVideo except that the driver should place only one frame from the screen into the output stream.

typedef void (* StopVideoFuncPtr)(ScrnInfoPtr pScrn, pointer data, Bool cleanup);
This indicates the driver should stop displaying the video. This is used to stop both input and output video. The cleanup field indicates that the video is being stopped because the client requested it to stop or because the server is exiting the current VT. In that case the driver should deallocate any offscreen memory areas (if there are any) being used to put the video to the screen. If cleanup is not set, the video is being stopped temporarily due to clipping or moving of the window, etc... and video will likely be restarted soon so the driver should not deallocate any offscreen areas associated with that port.

typedef int (* SetPortAttributeFuncPtr)(ScrnInfoPtr pScrn, Atom attribute,INT32 value, pointer data); typedef int (* GetPortAttributeFuncPtr)(ScrnInfoPtr pScrn, Atom attribute,INT32 *value, pointer data);
A port may have particular attributes such as hue, saturation, brightness or contrast. Xv clients set and get these attribute values by sending attribute strings (Atoms) to the server. Such requests end up at these driver functions. It is recommended that the driver provide at least the following attributes mentioned in the Xv client library docs: XV_ENCODING XV_HUE XV_SATURATION XV_BRIGHTNESS XV_CONTRAST but the driver may recognize as many atoms as it wishes. If a requested attribute is unknown by the driver it should return BadMatch. XV_ENCODING is the attribute intended to let the client specify which video encoding the particular port should be using (see the description of XF86VideoEncodingRec below). If the requested encoding is unsupported, the driver should return XvBadEncoding. If the value lies outside the advertised range BadValue may be returned. Success should be returned otherwise.

typedef void (* QueryBestSizeFuncPtr)(ScrnInfoPtr pScrn, Bool motion, short vid_w, short vid_h, short drw_w, short drw_h, unsigned int *p_w, unsigned int *p_h, pointer data);
QueryBestSize provides the client with a way to query what the destination dimensions would end up being if they were to request that an area vid_w by vid_h from the video stream be scaled to rectangle of drw_w by drw_h on the screen. Since it is not expected that all hardware will be able to get the target dimensions exactly, it is important that the driver provide this function.

typedef int (* PutImageFuncPtr)( ScrnInfoPtr pScrn, short src_x, short src_y, short drw_x, short drw_y, short src_w, short src_h, short drw_w, short drw_h, int image, char *buf, short width, short height, Bool sync, RegionPtr clipBoxes, pointer data );
This is similar to PutStill except that the source of the video is not a port but the data stored in a system memory buffer at buf. The data is in the format indicated by the image descriptor and represents a source of size width by height. If sync is TRUE the driver should not return from this function until it is through reading the data from buf. Returning when sync is TRUE indicates that it is safe for the data at buf to be replaced, freed, or modified.

typedef int (* QueryImageAttributesFuncPtr)( ScrnInfoPtr pScrn, int image, short *width, short *height, int *pitches, int *offsets);
This function is called to let the driver specify how data for a particular image of size width by height should be stored. Sometimes only the size and corrected width and height are needed. In that case pitches and offsets are NULL. The size of the memory required for the image is returned by this function. The width and height of the requested image can be altered by the driver to reflect format limitations (such as component sampling periods that are larger than one). If pitches and offsets are not NULL, these will be arrays with as many elements in them as there are planes in the image format. The driver should specify the pitch (in bytes) of each scanline in the particular plane as well as the offset to that plane (in bytes) from the beginning of the image.

The XF86VideoEncodingRec:

typedef struct { int id; char *name; unsigned short width, height; XvRationalRec rate; } XF86VideoEncodingRec, *XF86VideoEncodingPtr;
The XF86VideoEncodingRec specifies what encodings the adaptor can support. Most of this data is just informational and for the client's benefit, and is what will be reported by XvQueryEncodings. The id field is expected to be a unique identifier to allow the client to request a certain encoding via the XV_ENCODING attribute string.

The XF86VideoFormatRec:

typedef struct { char depth; short class; } XF86VideoFormatRec, *XF86VideoFormatPtr;
This specifies what visuals the video is viewable in. depth is the depth of the visual (not bpp). class is the visual class such as TrueColor, DirectColor or PseudoColor. Initialization of an adaptor will fail if none of the visuals on that screen are supported.

The XF86AttributeRec:

typedef struct { int flags; int min_value; int max_value; char *name; } XF86AttributeListRec, *XF86AttributeListPtr;
Each adaptor may have an array of these advertising the attributes for its ports. Currently defined flags are XvGettable and XvSettable which may be OR'd together indicating that attribute is gettable or settable by the client. The min and max field specify the valid range for the value. Name is a text string describing the attribute by name.

The XF86ImageRec:

typedef struct { int id; int type; int byte_order; char guid[16]; int bits_per_pixel; int format; int num_planes; /* for RGB formats */ int depth; unsigned int red_mask; unsigned int green_mask; unsigned int blue_mask; /* for YUV formats */ unsigned int y_sample_bits; unsigned int u_sample_bits; unsigned int v_sample_bits; unsigned int horz_y_period; unsigned int horz_u_period; unsigned int horz_v_period; unsigned int vert_y_period; unsigned int vert_u_period; unsigned int vert_v_period; char component_order[32]; int scanline_order; } XF86ImageRec, *XF86ImagePtr;
XF86ImageRec describes how video source data is laid out in memory. The fields are as follows: id This is a unique descriptor for the format. It is often good to set this value to the FOURCC for the format when applicable. type This is XvRGB or XvYUV. byte_order This is LSBFirst or MSBFirst. guid This is the Globally Unique IDentifier for the format. When not applicable, all characters should be NULL. bits_per_pixel The number of bits taken up (but not necessarily used) by each pixel. Note that for some planar formats which have fractional bits per pixel (such as IF09) this number may be rounded _down_. format This is XvPlanar or XvPacked. num_planes The number of planes in planar formats. This should be set to one for packed formats. depth The significant bits per pixel in RGB formats (analogous to the depth of a pixmap format). red_mask green_mask blue_mask The red, green and blue bitmasks for packed RGB formats. y_sample_bits u_sample_bits v_sample_bits The y, u and v sample sizes (in bits). horz_y_period horz_u_period horz_v_period The y, u and v sampling periods in the horizontal direction. vert_y_period vert_u_period vert_v_period The y, u and v sampling periods in the vertical direction. component_order Uppercase ascii characters representing the order that samples are stored within packed formats. For planar formats this represents the ordering of the planes. Unused characters in the 32 byte string should be set to NULL. scanline_order This is XvTopToBottom or XvBottomToTop. Since some formats (particular some planar YUV formats) may not be completely defined by the parameters above, the guid, when available, should provide the most accurate description of the format.

The Loader This section describes the interfaces to the module loader. The loader interfaces can be divided into two groups: those that are only available to the XFree86 common layer, and those that are also available to modules. Loader Overview The loader is capable of loading modules in a range of object formats, and knowledge of these formats is built in to the loader. Knowledge of new object formats can be added to the loader in a straightforward manner. This makes it possible to provide OS-independent modules (for a given CPU architecture type). In addition to this, the loader can load modules via the OS-provided dlopen(3) service where available. Such modules are not platform independent, and the semantics of dlopen() on most systems results in significant limitations in the use of modules of this type. Support for dlopen() modules in the loader is primarily for experimental and development purposes. Symbols exported by the loader (on behalf of the core X server) to modules are determined at compile time. Only those symbols explicitly exported are available to modules. All external symbols of loaded modules are exported to other modules, and to the core X server. The loader can be requested to check for unresolved symbols at any time, and the action to be taken for unresolved symbols can be controlled by the caller of the loader. Typically the caller identifies which symbols can safely remain unresolved and which cannot. NOTE: Now that ISO-C allows pointers to functions and pointers to data to have different internal representations, some of the following interfaces will need to be revisited. Semi-private Loader Interface The following is the semi-private loader interface that is available to the XFree86 common layer.

void LoaderInit(void);
The LoaderInit() function initialises the loader, and it must be called once before calling any other loader functions. This function initialises the tables of exported symbols, and anything else that might need to be initialised.

void LoaderSetPath(const char *path);
The LoaderSetPath() function initialises a default module search path. This must be called if calls to other functions are to be made without explicitly specifying a module search path. The search path path must be a string of one or more comma separated absolute paths. Modules are expected to be located below these paths, possibly in subdirectories of these paths.

pointer LoadModule(const char *module, pointer options, const XF86ModReqInfo * modreq, int *errmaj);
The LoadModule() function loads the module called module. The return value is a module handle, and may be used in future calls to the loader that require a reference to a loaded module. The module name module is normally the module's canonical name, which doesn't contain any directory path information, or any object/library file prefixes of suffixes. Currently a full pathname and/or filename is also accepted. This might change. The other parameters are: options An optional parameter that is passed to the newly loaded module's SetupProc function (if it has one). This argument is normally a NULL terminated list of Options, and must be interpreted that way by modules loaded directly by the XFree86 common layer. However, it may be used for application-specific parameter passing in other situations. modreq An optional XF86ModReqInfo* containing version/ABI/vendor information to requirements to check the newly loaded module against. The main purpose of this is to allow the loader to verify that a module of the correct type/version before running its SetupProc function. The XF86ModReqInfo struct is defined as follows: typedef struct { CARD8 majorversion; CARD8 minorversion; CARD16 patchlevel; const char * abiclass; CARD32 abiversion; const char * moduleclass; } XF86ModReqInfo; The information here is compared against the equivalent information in the module's XF86ModuleVersionInfo record (which is described below). The values in comments above indicate don't care settings for each of the fields. The comparisons made are as follows: majorversion Must match the module's majorversion exactly. minorversion The module's minor version must be no less than this value. This comparison is only made if majorversion matches. patchlevel The module's patchlevel must be no less than this value. This comparison is only made if minorversion matches. abiclass String must match the module's abiclass string. abiversion Must be consistent with the module's abiversion (major equal, minor no older). moduleclass String must match the module's moduleclass string. errmaj An optional pointer to a variable holding the major part or the error code. When provided, *errmaj is filled in when LoadModule() fails.

void UnloadModule(pointer mod);
This function unloads the module referred to by the handle mod. All child modules are also unloaded recursively. This function must not be used to directly unload modules that are child modules (i.e., those that have been loaded with the LoadSubModule() described below).

Module Requirements Modules must provide information about themselves to the loader, and may optionally provide entry points for "setup" and "teardown" functions (those two functions are referred to here as SetupProc and TearDownProc). The module information is contained in the XF86ModuleVersionInfo struct, which is defined as follows: typedef struct { const char * modname; /* name of module, e.g. "foo" */ const char * vendor; /* vendor specific string */ CARD32 _modinfo1_; /* constant MODINFOSTRING1/2 to find */ CARD32 _modinfo2_; /* infoarea with a binary editor/sign tool */ CARD32 xf86version; /* contains XF86_VERSION_CURRENT */ CARD8 majorversion; /* module-specific major version */ CARD8 minorversion; /* module-specific minor version */ CARD16 patchlevel; /* module-specific patch level */ const char * abiclass; /* ABI class that the module uses */ CARD32 abiversion; /* ABI version */ const char * moduleclass; /* module class */ CARD32 checksum[4]; /* contains a digital signature of the */ /* version info structure */ } XF86ModuleVersionInfo; The fields are used as follows: modname The module's name. This field is currently only for informational purposes, but the loader may be modified in future to require it to match the module's canonical name. vendor The module vendor. This field is for informational purposes only. _modinfo1_ This field holds the first part of a signature that can be used to locate this structure in the binary. It should always be initialised to MODINFOSTRING1. _modinfo2_ This field holds the second part of a signature that can be used to locate this structure in the binary. It should always be initialised to MODINFOSTRING2. xf86version The XFree86 version against which the module was compiled. This is mostly for informational/diagnostic purposes. It should be initialised to XF86_VERSION_CURRENT, which is defined in xf86Version.h. majorversion The module-specific major version. For modules where this version is used for more than simply informational purposes, the major version should only change (be incremented) when ABI incompatibilities are introduced, or ABI components are removed. minorversion The module-specific minor version. For modules where this version is used for more than simply informational purposes, the minor version should only change (be incremented) when ABI additions are made in a backward compatible way. It should be reset to zero when the major version is increased. patchlevel The module-specific patch level. The patch level should increase with new revisions of the module where there are no ABI changes, and it should be reset to zero when the minor version is increased. abiclass The ABI class that the module requires. The class is specified as a string for easy extensibility. It should indicate which (if any) of the X server's built-in ABI classes that the module relies on, or a third-party ABI if appropriate. Built-in ABI classes currently defined are: ABI_CLASS_NONE no class ABI_CLASS_ANSIC only requires the ANSI C interfaces ABI_CLASS_VIDEODRV requires the video driver ABI ABI_CLASS_XINPUT requires the XInput driver ABI ABI_CLASS_EXTENSION requires the extension module ABI abiversion The version of abiclass that the module requires. The version consists of major and minor components. The major version must match and the minor version must be no newer than that provided by the server or parent module. Version identifiers for the built-in classes currently defined are: ABI_ANSIC_VERSION ABI_VIDEODRV_VERSION ABI_XINPUT_VERSION ABI_EXTENSION_VERSION moduleclass This is similar to the abiclass field, except that it defines the type of module rather than the ABI it requires. For example, although all video drivers require the video driver ABI, not all modules that require the video driver ABI are video drivers. This distinction can be made with the moduleclass. Currently pre-defined module classes are: MOD_CLASS_NONE MOD_CLASS_VIDEODRV MOD_CLASS_XINPUT MOD_CLASS_EXTENSION checksum Not currently used. The module version information, and the optional SetupProc and TearDownProc entry points are found by the loader by locating a data object in the module called "modnameModuleData", where "modname" is the canonical name of the module. Modules must contain such a data object, and it must be declared with global scope, be compile-time initialised, and is of the following type: typedef struct { XF86ModuleVersionInfo * vers; ModuleSetupProc setup; ModuleTearDownProc teardown; } XF86ModuleData; The vers parameter must be initialised to a pointer to a correctly initialised XF86ModuleVersionInfo struct. The other two parameter are optional, and should be initialised to NULL when not required. The other parameters are defined as

typedef pointer (*ModuleSetupProc)(pointer, pointer, int *, int *); typedef void (*ModuleTearDownProc)(pointer); pointer SetupProc(pointer module, pointer options, int *errmaj, int *errmin);
When defined, this function is called by the loader after successfully loading a module. module is a handle for the newly loaded module, and maybe used by the SetupProc if it calls other loader functions that require a reference to it. The remaining arguments are those that were passed to the LoadModule() (or LoadSubModule()), and are described above. When the SetupProc is successful it must return a non-NULL value. The loader checks this, and if it is NULL it unloads the module and reports the failure to the caller of LoadModule(). If the SetupProc does things that need to be undone when the module is unloaded, it should define a TearDownProc, and return a pointer that the TearDownProc can use to undo what has been done. When a module is loaded multiple times, the SetupProc is called once for each time it is loaded.

void TearDownProc(pointer tearDownData);
When defined, this function is called when the loader unloads a module. The tearDownData parameter is the return value of the SetupProc() that was called when the module was loaded. The purpose of this function is to clean up before the module is unloaded (for example, by freeing allocated resources).

Public Loader Interface The following is the Loader interface that is available to any part of the server, and may also be used from within modules.

pointer LoadSubModule(pointer parent, const char *module, const char **subdirlist, const char **patternlist, pointer options, const XF86ModReqInfo * modreq, int *errmaj, int *errmin);
This function is like the LoadModule() function described above, except that the module loaded is registered as a child of the calling module. The parent parameter is the calling module's handle. Modules loaded with this function are automatically unloaded when the parent module is unloaded.

void UnloadSubModule(pointer module);
This function unloads the module with handle module. If that module itself has children, they are also unloaded. It is like UnloadModule(), except that it is safe to use for unloading child modules.

pointer LoaderSymbol(const char *symbol);
This function returns the address of the symbol with name symbol. This may be used to locate a module entry point with a known name.

char **LoaderlistDirs(const char **subdirlist, const char **patternlist);
This function returns a NULL terminated list of canonical modules names for modules found in the default module search path. The subdirlist and patternlist parameters are as described above, and can be used to control the locations and names that are searched. If no modules are found, the return value is NULL. The returned list should be freed by calling LoaderFreeDirList() when it is no longer needed.

void LoaderFreeDirList(char **list);
This function frees a module list created by LoaderlistDirs().

void LoaderReqSymLists(const char **list0, ...);
This function allows the registration of required symbols with the loader. It is normally used by a caller of LoadSubModule(). If any symbols registered in this way are found to be unresolved when LoaderCheckUnresolved() is called then LoaderCheckUnresolved() will report a failure. The function takes one or more NULL terminated lists of symbols. The end of the argument list is indicated by a NULL argument.

void LoaderReqSymbols(const char *sym0, ...);
This function is like LoaderReqSymLists() except that its arguments are symbols rather than lists of symbols. This function is more convenient when single functions are to be registered, especially when the single function might depend on runtime factors. The end of the argument list is indicated by a NULL argument.

void LoaderRefSymLists(const char **list0, ...);
This function allows the registration of possibly unresolved symbols with the loader. When LoaderCheckUnresolved() is run it won't generate warnings for symbols registered in this way unless they were also registered as required symbols. The function takes one or more NULL terminated lists of symbols. The end of the argument list is indicated by a NULL argument.

void LoaderRefSymbols(const char *sym0, ...);
This function is like LoaderRefSymLists() except that its arguments are symbols rather than lists of symbols. This function is more convenient when single functions are to be registered, especially when the single function might depend on runtime factors. The end of the argument list is indicated by a NULL argument.

int LoaderCheckUnresolved(int delayflag);
This function checks for unresolved symbols. It generates warnings for unresolved symbols that have not been registered with LoaderRefSymLists(), and maps them to a dummy function. This behaviour may change in future. If unresolved symbols are found that have been registered with LoaderReqSymLists() or LoaderReqSymbols() then this function returns a non-zero value. If none of these symbols are unresolved the return value is zero, indicating success. The delayflag parameter should normally be set to LD_RESOLV_IFDONE.

LoaderErrorMsg(const char *name, const char *modname, int errmaj, int errmin);
This function prints an error message that includes the text Failed to load module, the module name modname, a message specific to the errmaj value, and the value if errmin. If name is non-NULL, it is printed as an identifying prefix to the message (followed by a :).

Special Registration Functions The loader contains some functions for registering some classes of modules. These may be moved out of the loader at some point.

void LoadExtensionList(const ExtensionModule ext[], int size, Bool builtin);
This registers the entry points for the extension array identified by ext. The ExtensionModule struct is defined as: typedef struct { InitExtension initFunc; char * name; Bool *disablePtr; } ExtensionModule;

Helper Functions This section describe helper functions that video driver might find useful. While video drivers are not required to use any of these to be considered compliant, the use of appropriate helpers is strongly encouraged to improve the consistency of driver behaviour. Functions for printing messages

ErrorF(const char *format, ...);
This is the basic function for writing to the error log (typically stderr and/or a log file). Video drivers should usually avoid using this directly in favour of the more specialised functions described below. This function is useful for printing messages while debugging a driver.

FatalError(const char *format, ...);
This prints a message and causes the Xserver to abort. It should rarely be used within a video driver, as most error conditions should be flagged by the return values of the driver functions. This allows the higher layers to decide how to proceed. In rare cases, this can be used within a driver if a fatal unexpected condition is found.

xf86ErrorF(const char *format, ...);
This is like ErrorF(), except that the message is only printed when the Xserver's verbosity level is set to the default (1) or higher. It means that the messages are not printed when the server is started with the flag. Typically this function would only be used for continuing messages started with one of the more specialised functions described below.

xf86ErrorFVerb(int verb, const char *format, ...);
Like xf86ErrorF(), except the minimum verbosity level for which the message is to be printed is given explicitly. Passing a verb value of zero means the message is always printed. A value higher than 1 can be used for information would normally not be needed, but which might be useful when diagnosing problems.

xf86Msg(MessageType type, const char *format, ...);
This is like xf86ErrorF(), except that the message is prefixed with a marker determined by the value of type. The marker is used to indicate the type of message (warning, error, probed value, config value, etc). Note the xf86Verbose value is ignored for messages of type X_ERROR. The marker values are: X_PROBED Value was probed. X_CONFIG Value was given in the config file. X_DEFAULT Value is a default. X_CMDLINE Value was given on the command line. X_NOTICE Notice. X_ERROR Error message. X_WARNING Warning message. X_INFO Informational message. X_NONE No prefix. X_NOT_IMPLEMENTED The message relates to functionality that is not yetimplemented.

xf86MsgVerb(MessageType type, int verb, const char *format, ...);
Like xf86Msg(), but with the verbosity level given explicitly.

xf86DrvMsg(int scrnIndex, MessageType type, const char *format, ...);
This is like xf86Msg() except that the driver's name (the name field of the ScrnInfoRec) followed by the scrnIndex in parentheses is printed following the prefix. This should be used by video drivers in most cases as it clearly indicates which driver/screen the message is for. If scrnIndex is negative, this function behaves exactly like xf86Msg(). NOTE: This function can only be used after the ScrnInfoRec and its name field have been allocated. Normally, this means that it can not be used before the END of the ChipProbe() function. Prior to that, use xf86Msg(), providing the driver's name explicitly. No screen number can be supplied at that point.

xf86DrvMsgVerb(int scrnIndex, MessageType type, int verb, const char *format, ...);
Like xf86DrvMsg(), but with the verbosity level given explicitly.

Functions for setting values based on command line and config file

Bool xf86SetDepthBpp(ScrnInfoPtr scrp, int depth, int bpp, int fbbpp, int depth24flags);
This function sets the depth, pixmapBPP and bitsPerPixel fields of the ScrnInfoRec. It also determines the defaults for display-wide attributes and pixmap formats the screen will support, and finds the Display subsection that matches the depth/bpp. This function should normally be called very early from the ChipPreInit() function. It requires that the confScreen field of the ScrnInfoRec be initialised prior to calling it. This is done by the XFree86 common layer prior to calling ChipPreInit(). The parameters passed are: depth driver's preferred default depth if no other is given. If zero, use the overall server default. bpp Same, but for the pixmap bpp. fbbpp Same, but for the framebuffer bpp. depth24flags Flags that indicate the level of 24/32bpp support and whether conversion between different framebuffer and pixmap formats is supported. The flags for this argument are defined as follows, and multiple flags may be ORed together: NoDepth24Support No depth 24 formats supported Support24bppFb 24bpp framebuffer supported Support32bppFb 32bpp framebuffer supported SupportConvert24to32 Can convert 24bpp pixmap to 32bpp fb SupportConvert32to24 Can convert 32bpp pixmap to 24bpp fb ForceConvert24to32 Force 24bpp pixmap to 32bpp fb conversion ForceConvert32to24 Force 32bpp pixmap to 24bpp fb conversion It uses the command line, config file, and default values in the correct order of precedence to determine the depth and bpp values. It is up to the driver to check the results to see that it supports them. If not the ChipPreInit() function should return FALSE. If only one of depth/bpp is given, the other is set to a reasonable (and consistent) default. If a driver finds that the initial depth24flags it uses later results in a fb format that requires more video memory than is available it may call this function a second time with a different depth24flags setting. On success, the return value is TRUE. On failure it prints an error message and returns FALSE. The following fields of the ScrnInfoRec are initialised by this function:
depth, bitsPerPixel, display, imageByteOrder, bitmapScanlinePad, bitmapScanlineUnit, bitmapBitOrder, numFormats, formats, fbFormat.

void xf86PrintDepthBpp(scrnInfoPtr scrp);
This function can be used to print out the depth and bpp settings. It should be called after the final call to xf86SetDepthBpp().

Bool xf86SetWeight(ScrnInfoPtr scrp, rgb weight, rgb mask);
This function sets the weight, mask, offset and rgbBits fields of the ScrnInfoRec. It would normally be called fairly early in the ChipPreInit() function for depths > 8bpp. It requires that the depth and display fields of the ScrnInfoRec be initialised prior to calling it. The parameters passed are: weight driver's preferred default weight if no other is given. If zero, use the overall server default. mask Same, but for mask. It uses the command line, config file, and default values in the correct order of precedence to determine the weight value. It derives the mask and offset values from the weight and the defaults. It is up to the driver to check the results to see that it supports them. If not the ChipPreInit() function should return FALSE. On success, this function prints a message showing the weight values selected, and returns TRUE. On failure it prints an error message and returns FALSE. The following fields of the ScrnInfoRec are initialised by this function:
weight, mask, offset.

Bool xf86SetDefaultVisual(ScrnInfoPtr scrp, int visual);
This function sets the defaultVisual field of the ScrnInfoRec. It would normally be called fairly early from the ChipPreInit() function. It requires that the depth and display fields of the ScrnInfoRec be initialised prior to calling it. The parameters passed are: visual driver's preferred default visual if no other is given. If -1, use the overall server default. It uses the command line, config file, and default values in the correct order of precedence to determine the default visual value. It is up to the driver to check the result to see that it supports it. If not the ChipPreInit() function should return FALSE. On success, this function prints a message showing the default visual selected, and returns TRUE. On failure it prints an error message and returns FALSE.

Bool xf86SetGamma(ScrnInfoPtr scrp, Gamma gamma);
This function sets the gamma field of the ScrnInfoRec. It would normally be called fairly early from the ChipPreInit() function in cases where the driver supports gamma correction. It requires that the monitor field of the ScrnInfoRec be initialised prior to calling it. The parameters passed are: gamma driver's preferred default gamma if no other is given. If zero (< 0.01), use the overall server default. It uses the command line, config file, and default values in the correct order of precedence to determine the gamma value. It is up to the driver to check the results to see that it supports them. If not the ChipPreInit() function should return FALSE. On success, this function prints a message showing the gamma value selected, and returns TRUE. On failure it prints an error message and returns FALSE.

void xf86SetDpi(ScrnInfoPtr pScrn, int x, int y);
This function sets the xDpi and yDpi fields of the ScrnInfoRec. The driver can specify preferred defaults by setting x and y to non-zero values. The command line option overrides all other settings. Otherwise, if the DisplaySize entry is present in the screen's &k.monitor; config file section, it is used together with the virtual size to calculate the dpi values. This function should be called after all the mode resolution has been done.

void xf86SetBlackWhitePixels(ScrnInfoPtr pScrn);
This functions sets the blackPixel and whitePixel fields of the ScrnInfoRec according to whether or not the command line options is present.

const char *xf86GetVisualName(int visual);
Returns a printable string with the visual name matching the numerical visual class provided. If the value is outside the range of valid visual classes, NULL is returned.

Primary Mode functions The primary mode helper functions are those which would normally be used by a driver, unless it has unusual requirements which cannot be catered for the by the helpers.

int xf86ValidateModes(ScrnInfoPtr scrp, DisplayModePtr availModes, char **modeNames, ClockRangePtr clockRanges, int *linePitches, int minPitch, int maxPitch, int pitchInc, int minHeight, int maxHeight, int virtualX, int virtualY, unsigned long apertureSize, LookupModeFlags strategy);
This function basically selects the set of modes to use based on those available and the various constraints. It also sets some other related parameters. It is normally called near the end of the ChipPreInit() function. The parameters passed to the function are: availModes List of modes available for the monitor. modeNames List of mode names that the screen is requesting. clockRanges A list of clock ranges allowed by the driver. Each range includes whether interlaced or multiscan modes are supported for that range. See below for more on clockRanges. linePitches List of line pitches supported by the driver. This is optional and should be NULL when not used. minPitch Minimum line pitch supported by the driver. This must be supplied when linePitches is NULL, and is ignored otherwise. maxPitch Maximum line pitch supported by the driver. This is required when minPitch is required. pitchInc Granularity of horizontal pitch values as supported by the chipset. This is expressed in bits. This must be supplied. minHeight minimum virtual height allowed. If zero, no limit is imposed. maxHeight maximum virtual height allowed. If zero, no limit is imposed. virtualX If greater than zero, this is the virtual width value that will be used. Otherwise, the virtual width is chosen to be the smallest that can accommodate the modes selected. virtualY If greater than zero, this is the virtual height value that will be used. Otherwise, the virtual height is chosen to be the smallest that can accommodate the modes selected. apertureSize The size (in bytes) of the aperture used to access video memory. strategy The strategy to use when choosing from multiple modes with the same name. The options are: LOOKUP_DEFAULT ??? LOOKUP_BEST_REFRESH mode with best refresh rate LOOKUP_CLOSEST_CLOCK mode with closest matching clock LOOKUP_LIST_ORDER first usable mode in list The following options can also be combined (OR'ed) with one of the above: LOOKUP_CLKDIV2 Allow halved clocks LOOKUP_OPTIONAL_TOLERANCES Allow missing horizontal sync and/or vertical refresh ranges in the xorg.conf Monitor section LOOKUP_OPTIONAL_TOLERANCES should only be specified when the driver can ensure all modes it generates can sync on, or at least not damage, the monitor or digital flat panel. Horizontal sync and/or vertical refresh ranges specified by the user will still be honoured (and acted upon). This function requires that the following fields of the ScrnInfoRec are initialised prior to calling it: clock[] List of discrete clocks (when non-programmable) numClocks Number of discrete clocks (when non-programmable) progClock Whether the clock is programmable or not monitor Pointer to the applicable xorg.conf monitor section fdFormat Format of the screen buffer videoRam total video memory size (in bytes) xInc Horizontal timing increment in pixels (defaults to 8) This function fills in the following ScrnInfoRec fields: modePool A subset of the modes available to the monitor which are compatible with the driver. modes One mode entry for each of the requested modes, with the status field of each filled in to indicate if the mode has been accepted or not. This list of modes is a circular list. virtualX The resulting virtual width. virtualY The resulting virtual height. displayWidth The resulting line pitch. The first stage of this function checks that the virtualX and virtualY values supplied (if greater than zero) are consistent with the line pitch and maxHeight limitations. If not, an error message is printed, and the return value is -1. The second stage sets up the mode pool, eliminating immediately any modes that exceed the driver's line pitch limits, and also the virtual width and height limits (if greater than zero). For each mode removed an informational message is printed at verbosity level 2. If the mode pool ends up being empty, a warning message is printed, and the return value is 0. The final stage is to lookup each mode name, and fill in the remaining parameters. If an error condition is encountered, a message is printed, and the return value is -1. Otherwise, the return value is the number of valid modes found (0 if none are found). Even if the supplied mode names include duplicates, no two names will ever match the same mode. Furthermore, if the supplied mode names do not yield a valid mode (including the case where no names are passed at all), the function will continue looking through the mode pool until it finds a mode that survives all checks, or until the mode pool is exhausted. A message is only printed by this function when a fundamental problem is found. It is intended that this function may be called more than once if there is more than one set of constraints that the driver can work within. If this function returns -1, the ChipPreInit() function should return FALSE. clockRanges is a linked list of clock ranges allowed by the driver. If a mode doesn't fit in any of the defined clockRanges, it is rejected. The first clockRange that matches all requirements is used. This structure needs to be initialized to NULL when allocated. clockRanges contains the following fields: minClock maxClock The lower and upper mode clock bounds for which the rest of the clockRange parameters apply. Since these are the mode clocks, they are not scaled with the ClockMulFactor and ClockDivFactor. It is up to the driver to adjust these values if they depend on the clock scaling factors. clockIndex (not used yet) -1 for programmable clocks interlaceAllowed TRUE if interlacing is allowed for this range doubleScanAllowed TRUE if doublescan or multiscan is allowed for this range ClockMulFactor ClockDivFactor Scaling factors that are applied to the mode clocks ONLY before selecting a clock index (when there is no programmable clock) or a SynthClock value. This is useful for drivers that support pixel multiplexing or that need to scale the clocks because of hardware restrictions (like sending 24bpp data to an 8 bit RAMDAC using a tripled clock). Note that these parameters describe what must be done to the mode clock to achieve the data transport clock between graphics controller and RAMDAC. For example for 2:1 pixel multiplexing, two pixels are sent to the RAMDAC on each clock. This allows the RAMDAC clock to be half of the actual pixel clock. Hence, ClockMulFactor=1 and ClockDivFactor=2. This means that the clock used for clock selection (ie, determining the correct clock index from the list of discrete clocks) or for the SynthClock field in case of a programmable clock is: (mode->Clock * ClockMulFactor) / ClockDivFactor. PrivFlags This field is copied into the mode->PrivFlags field when this clockRange is selected by xf86ValidateModes(). It allows the driver to find out what clock range was selected, so it knows it needs to set up pixel multiplexing or any other range-dependent feature. This field is purely driver-defined: it may contain flag bits, an index or anything else (as long as it is an INT). Note that the mode->SynthClock field is always filled in by xf86ValidateModes(): it will contain the data transport clock, which is the clock that will have to be programmed in the chip when it has a programmable clock, or the clock that will be picked from the clocks list when it is not a programmable one. Thus: mode->SynthClock = (mode->Clock * ClockMulFactor) / ClockDivFactor

void xf86PruneDriverModes(ScrnInfoPtr scrp);
This function deletes modes in the modes field of the ScrnInfoRec that have been marked as invalid. This is normally run after having run xf86ValidateModes() for the last time. For each mode that is deleted, a warning message is printed out indicating the reason for it being deleted.

void xf86SetCrtcForModes(ScrnInfoPtr scrp, int adjustFlags);
This function fills in the Crtc* fields for all the modes in the modes field of the ScrnInfoRec. The adjustFlags parameter determines how the vertical CRTC values are scaled for interlaced modes. They are halved if it is INTERLACE_HALVE_V. The vertical CRTC values are doubled for doublescan modes, and are further multiplied by the VScan value. This function is normally called after calling xf86PruneDriverModes().

void xf86PrintModes(ScrnInfoPtr scrp);
This function prints out the virtual size setting, and the line pitch being used. It also prints out two lines for each mode being used. The first line includes the mode's pixel clock, horizontal sync rate, refresh rate, and whether it is interlaced, doublescanned and/or multi-scanned. The second line is the mode's Modeline. This function is normally called after calling xf86SetCrtcForModes().

Secondary Mode functions The secondary mode helper functions are functions which are normally used by the primary mode helper functions, and which are not normally called directly by a driver. If a driver has unusual requirements and needs to do its own mode validation, it might be able to make use of some of these secondary mode helper functions.

const char *xf86ModeStatusToString(ModeStatus status);
This function converts the status value to a descriptive printable string.

void xf86DeleteMode(DisplayModePtr *modeList, DisplayModePtr mode);
This function deletes the mode given from the modeList. It never prints any messages, so it is up to the caller to print a message if required.

Functions for handling strings and tokens Tables associating strings and numerical tokens combined with the following functions provide a compact way of handling strings from the config file, and for converting tokens into printable strings. The table data structure is: typedef struct { int token; const char * name; } SymTabRec, *SymTabPtr; A table is an initialised array of SymTabRec. The tokens must be non-negative integers. Multiple names may be mapped to a single token. The table is terminated with an element with a token value of -1 and NULL for the name.

const char *xf86TokenToString(SymTabPtr table, int token);
This function returns the first string in table that matches token. If no match is found, NULL is returned (NOTE, older versions of this function would return the string "unknown" when no match is found).

int xf86StringToToken(SymTabPtr table, const char *string);
This function returns the first token in table that matches string. The xf86NameCmp() function is used to determine the match. If no match is found, -1 is returned.

Functions for finding which config file entries to use These functions can be used to select the appropriate config file entries that match the detected hardware. They are described above in the Probe and Available Functions sections. Probing discrete clocks on old hardware The xf86GetClocks() function may be used to assist in finding the discrete pixel clock values on older hardware.

void xf86GetClocks(ScrnInfoPtr pScrn, int num, Bool (*ClockFunc)(ScrnInfoPtr, int), void (*ProtectRegs)(ScrnInfoPtr, Bool), void (*BlankScreen)(ScrnInfoPtr, Bool), int vertsyncreg, int maskval, int knownclkindex, int knownclkvalue);
This function uses a comparative sampling method to measure the discrete pixel clock values. The number of discrete clocks to measure is given by num. clockFunc is a function that selects the n'th clock. It should also save or restore any state affected by programming the clocks when the index passed is CLK_REG_SAVE or CLK_REG_RESTORE. ProtectRegs is a function that does whatever is required to protect the hardware state while selecting a new clock. BlankScreen is a function that blanks the screen. vertsyncreg and maskval are the register and bitmask to check for the presence of vertical sync pulses. knownclkindex and knownclkvalue are the index and value of a known clock. These are the known references on which the comparative measurements are based. The number of clocks probed is set in pScrn->numClocks, and the probed clocks are set in the pScrn->clock[] array. All of the clock values are in units of kHz.

void xf86ShowClocks(ScrnInfoPtr scrp, MessageType from);
Print out the pixel clocks scrp->clock[]. from indicates whether the clocks were probed or from the config file.

Other helper functions

Bool xf86IsUnblank(int mode);
Returns TRUE when the screen saver mode specified by mode requires the screen be unblanked, and FALSE otherwise. The screen saver modes that require blanking are SCREEN_SAVER_ON and SCREEN_SAVER_CYCLE, and the screen saver modes that require unblanking are SCREEN_SAVER_OFF and SCREEN_SAVER_FORCER. Drivers may call this helper from their SaveScreen() function to interpret the screen saver modes.

The vgahw module The vgahw modules provides an interface for saving, restoring and programming the standard VGA registers, and for handling VGA colourmaps. Data Structures The public data structures used by the vgahw module are vgaRegRec and vgaHWRec. They are defined in vgaHW.h. General vgahw Functions

Bool vgaHWGetHWRec(ScrnInfoPtr pScrn);
This function allocates a vgaHWRec structure, and hooks it into the ScrnInfoRec's privates. Like all information hooked into the privates, it is persistent, and only needs to be allocated once per screen. This function should normally be called from the driver's ChipPreInit() function. The vgaHWRec is zero-allocated, and the following fields are explicitly initialised: ModeReg.DAC[] initialised with a default colourmap ModeReg.Attribute[0x11] initialised with the default overscan index ShowOverscan initialised according to the "ShowOverscan" option paletteEnabled initialised to FALSE cmapSaved initialised to FALSE pScrn initialised to pScrn In addition to the above, vgaHWSetStdFuncs() is called to initialise the register access function fields with the standard VGA set of functions. Once allocated, a pointer to the vgaHWRec can be obtained from the ScrnInfoPtr with the VGAHWPTR(pScrn) macro.

void vgaHWFreeHWRec(ScrnInfoPtr pScrn);
This function frees a vgaHWRec structure. It should be called from a driver's ChipFreeScreen() function.

Bool vgaHWSetRegCounts(ScrnInfoPtr pScrn, int numCRTC, int numSequencer, int numGraphics, int numAttribute);
This function allows the number of CRTC, Sequencer, Graphics and Attribute registers to be changed. This makes it possible for extended registers to be saved and restored with vgaHWSave() and vgaHWRestore(). This function should be called after a vgaHWRec has been allocated with vgaHWGetHWRec(). The default values are defined in vgaHW.h as follows: #define VGA_NUM_CRTC 25 #define VGA_NUM_SEQ 5 #define VGA_NUM_GFX 9 #define VGA_NUM_ATTR 21

Bool vgaHWCopyReg(vgaRegPtr dst, vgaRegPtr src);
This function copies the contents of the VGA saved registers in src to dst. Note that it isn't possible to simply do this with memcpy() (or similar). This function returns TRUE unless there is a problem allocating space for the CRTC and related fields in dst.

void vgaHWSetStdFuncs(vgaHWPtr hwp);
This function initialises the register access function fields of hwp with the standard VGA set of functions. This is called by vgaHWGetHWRec(), so there is usually no need to call this explicitly. The register access functions are described below. If the registers are shadowed in some other port I/O space (for example a PCI I/O region), these functions can be used to access the shadowed registers if hwp->PIOOffset is initialised with offset, calculated in such a way that when the standard VGA I/O port value is added to it the correct offset into the PIO area results. This value is initialised to zero in vgaHWGetHWRec(). (Note: the PIOOffset functionality is present in XFree86 4.1.0 and later.)

void vgaHWSetMmioFuncs(vgaHWPtr hwp, CARD8 *base, int offset);
This function initialised the register access function fields of hwp with a generic MMIO set of functions. hwp->MMIOBase is initialised with base, which must be the virtual address that the start of MMIO area is mapped to. hwp->MMIOOffset is initialised with offset, which must be calculated in such a way that when the standard VGA I/O port value is added to it the correct offset into the MMIO area results. That means that these functions are only suitable when the VGA I/O ports are made available in a direct mapping to the MMIO space. If that is not the case, the driver will need to provide its own register access functions. The register access functions are described below.

Bool vgaHWMapMem(ScrnInfoPtr pScrn);
This function maps the VGA memory window. It requires that the vgaHWRec be allocated. If a driver requires non-default MapPhys or MapSize settings (the physical location and size of the VGA memory window) then those fields of the vgaHWRec must be initialised before calling this function. Otherwise, this function initialiases the default values of 0xA0000 for MapPhys and (64 * 1024) for MapSize. This function must be called before attempting to save or restore the VGA state. If the driver doesn't call it explicitly, the vgaHWSave() and vgaHWRestore() functions may call it if they need to access the VGA memory (in which case they will also call vgaHWUnmapMem() to unmap the VGA memory before exiting).

void vgaHWUnmapMem(ScrnInfoPtr pScrn);
This function unmaps the VGA memory window. It must only be called after the memory has been mapped. The Base field of the vgaHWRec field is set to NULL to indicate that the memory is no longer mapped.

void vgaHWGetIOBase(vgaHWPtr hwp);
This function initialises the IOBase field of the vgaHWRec. This function must be called before using any other functions that access the video hardware. A macro VGAHW_GET_IOBASE() is also available in vgaHW.h that returns the I/O base, and this may be used when the vgahw module is not loaded (for example, in the ChipProbe() function).

void vgaHWUnlock(vgaHWPtr hwp);
This function unlocks the VGA CRTC[0-7] registers, and must be called before attempting to write to those registers.

void vgaHWLock(vgaHWPtr hwp);
This function locks the VGA CRTC[0-7] registers.

void vgaHWEnable(vgaHWPtr hwp);
This function enables the VGA subsystem. (Note, this function is present in XFree86 4.1.0 and later.).

void vgaHWDisable(vgaHWPtr hwp);
This function disables the VGA subsystem. (Note, this function is present in XFree86 4.1.0 and later.).

void vgaHWSave(ScrnInfoPtr pScrn, vgaRegPtr save, int flags);
This function saves the VGA state. The state is written to the vgaRegRec pointed to by save. flags is set to one or more of the following flags ORed together: VGA_SR_MODE the mode setting registers are saved VGA_SR_FONTS the text mode font/text data is saved VGA_SR_CMAP the colourmap (LUT) is saved VGA_SR_ALL all of the above are saved The vgaHWRec and its IOBase fields must be initialised before this function is called. If VGA_SR_FONTS is set in flags, the VGA memory window must be mapped. If it isn't then vgaHWMapMem() will be called to map it, and vgaHWUnmapMem() will be called to unmap it afterwards. vgaHWSave() uses the three functions below in the order vgaHWSaveColormap(), vgaHWSaveMode(), vgaHWSaveFonts() to carry out the different save phases. It is undecided at this stage whether they will remain part of the vgahw module's public interface or not.

void vgaHWSaveMode(ScrnInfoPtr pScrn, vgaRegPtr save);
This function saves the VGA mode registers. They are saved to the vgaRegRec pointed to by save. The registers saved are: MiscOut CRTC[0-0x18] Attribute[0-0x14] Graphics[0-8] Sequencer[0-4] The number of registers actually saved may be modified by a prior call to vgaHWSetRegCounts().

void vgaHWSaveFonts(ScrnInfoPtr pScrn, vgaRegPtr save);
This function saves the text mode font and text data held in the video memory. If called while in a graphics mode, no save is done. The VGA memory window must be mapped with vgaHWMapMem() before to calling this function. On some platforms, one or more of the font/text plane saves may be no-ops. This is the case when the platform's VC driver already takes care of this.

void vgaHWSaveColormap(ScrnInfoPtr pScrn, vgaRegPtr save);
This function saves the VGA colourmap (LUT). Before saving it, it attempts to verify that the colourmap is readable. In rare cases where it isn't readable, a default colourmap is saved instead.

void vgaHWRestore(ScrnInfoPtr pScrn, vgaRegPtr restore, int flags);
This function programs the VGA state. The state programmed is that contained in the vgaRegRec pointed to by restore. flags is the same as described above for the vgaHWSave() function. The vgaHWRec and its IOBase fields must be initialised before this function is called. If VGA_SR_FONTS is set in flags, the VGA memory window must be mapped. If it isn't then vgaHWMapMem() will be called to map it, and vgaHWUnmapMem() will be called to unmap it afterwards. vgaHWRestore() uses the three functions below in the order vgaHWRestoreFonts(), vgaHWRestoreMode(), vgaHWRestoreColormap() to carry out the different restore phases. It is undecided at this stage whether they will remain part of the vgahw module's public interface or not.

void vgaHWRestoreMode(ScrnInfoPtr pScrn, vgaRegPtr restore);
This function restores the VGA mode registers. They are restored from the data in the vgaRegRec pointed to by restore. The registers restored are: MiscOut CRTC[0-0x18] Attribute[0-0x14] Graphics[0-8] Sequencer[0-4] The number of registers actually restored may be modified by a prior call to vgaHWSetRegCounts().

void vgaHWRestoreFonts(ScrnInfoPtr pScrn, vgaRegPtr restore);
This function restores the text mode font and text data to the video memory. The VGA memory window must be mapped with vgaHWMapMem() before to calling this function. On some platforms, one or more of the font/text plane restores may be no-ops. This is the case when the platform's VC driver already takes care of this.

void vgaHWRestoreColormap(ScrnInfoPtr pScrn, vgaRegPtr restore);
This function restores the VGA colourmap (LUT).

void vgaHWInit(ScrnInfoPtr pScrn, DisplayModePtr mode);
This function fills in the vgaHWRec's ModeReg field with the values appropriate for programming the given video mode. It requires that the ScrnInfoRec's depth field is initialised, which determines how the registers are programmed.

void vgaHWSeqReset(vgaHWPtr hwp, Bool start);
Do a VGA sequencer reset. If start is TRUE, the reset is started. If start is FALSE, the reset is ended.

void vgaHWProtect(ScrnInfoPtr pScrn, Bool on);
This function protects VGA registers and memory from corruption during loads. It is typically called with on set to TRUE before programming, and with on set to FALSE after programming.

Bool vgaHWSaveScreen(ScreenPtr pScreen, int mode);
This function blanks and unblanks the screen. It is blanked when mode is SCREEN_SAVER_ON or SCREEN_SAVER_CYCLE, and unblanked when mode is SCREEN_SAVER_OFF or SCREEN_SAVER_FORCER.

void vgaHWBlankScreen(ScrnInfoPtr pScrn, Bool on);
This function blanks and unblanks the screen. It is blanked when on is FALSE, and unblanked when on is TRUE. This function is provided for use in cases where the ScrnInfoRec can't be derived from the ScreenRec (while probing for clocks, for example).

VGA Colormap Functions The vgahw module uses the standard colormap support (see the Colormap Handling section. This is initialised with the following function:

Bool vgaHWHandleColormaps(ScreenPtr pScreen);

VGA Register Access Functions The vgahw module abstracts access to the standard VGA registers by using a set of functions held in the vgaHWRec. When the vgaHWRec is created these function pointers are initialised with the set of standard VGA I/O register access functions. In addition to these, the vgahw module includes a basic set of MMIO register access functions, and the vgaHWRec function pointers can be initialised to these by calling the vgaHWSetMmioFuncs() function described above. Some drivers/platforms may require a different set of functions for VGA access. The access functions are described here.

void writeCrtc(vgaHWPtr hwp, CARD8 index, CARD8 value);
Write value to CRTC register index.

CARD8 readCrtc(vgaHWPtr hwp, CARD8 index);
Return the value read from CRTC register index.

void writeGr(vgaHWPtr hwp, CARD8 index, CARD8 value);
Write value to Graphics Controller register index.

CARD8 readGR(vgaHWPtr hwp, CARD8 index);
Return the value read from Graphics Controller register index.

void writeSeq(vgaHWPtr hwp, CARD8 index, CARD8, value);
Write value to Sequencer register index.

CARD8 readSeq(vgaHWPtr hwp, CARD8 index);
Return the value read from Sequencer register index.

void writeAttr(vgaHWPtr hwp, CARD8 index, CARD8, value);
Write value to Attribute Controller register index. When writing out the index value this function should set bit 5 (0x20) according to the setting of hwp->paletteEnabled in order to preserve the palette access state. It should be cleared when hwp->paletteEnabled is TRUE and set when it is FALSE.

CARD8 readAttr(vgaHWPtr hwp, CARD8 index);
Return the value read from Attribute Controller register index. When writing out the index value this function should set bit 5 (0x20) according to the setting of hwp->paletteEnabled in order to preserve the palette access state. It should be cleared when hwp->paletteEnabled is TRUE and set when it is FALSE.

void writeMiscOut(vgaHWPtr hwp, CARD8 value);
Write value to the Miscellaneous Output register.

CARD8 readMiscOut(vgwHWPtr hwp);
Return the value read from the Miscellaneous Output register.

void enablePalette(vgaHWPtr hwp);
Clear the palette address source bit in the Attribute Controller index register and set hwp->paletteEnabled to TRUE.

void disablePalette(vgaHWPtr hwp);
Set the palette address source bit in the Attribute Controller index register and set hwp->paletteEnabled to FALSE.

void writeDacMask(vgaHWPtr hwp, CARD8 value);
Write value to the DAC Mask register.

CARD8 readDacMask(vgaHWptr hwp);
Return the value read from the DAC Mask register.

void writeDacReadAddress(vgaHWPtr hwp, CARD8 value);
Write value to the DAC Read Address register.

void writeDacWriteAddress(vgaHWPtr hwp, CARD8 value);
Write value to the DAC Write Address register.

void writeDacData(vgaHWPtr hwp, CARD8 value);
Write value to the DAC Data register.

CARD8 readDacData(vgaHWptr hwp);
Return the value read from the DAC Data register.

CARD8 readEnable(vgaHWptr hwp);
Return the value read from the VGA Enable register. (Note: This function is present in XFree86 4.1.0 and later.)

void writeEnable(vgaHWPtr hwp, CARD8 value);
Write value to the VGA Enable register. (Note: This function is present in XFree86 4.1.0 and later.)

Some notes about writing a driver NOTE: some parts of this are not up to date The following is an outline for writing a basic unaccelerated driver for a PCI video card with a linear mapped framebuffer, and which has a VGA core. It is includes some general information that is relevant to most drivers (even those which don't fit that basic description). The information here is based on the initial conversion of the Matrox Millennium driver to the new design. For a fleshing out and sample implementation of some of the bits outlined here, refer to that driver. Note that this is an example only. The approach used here will not be appropriate for all drivers. Each driver must reserve a unique driver name, and a string that is used to prefix all of its externally visible symbols. This is to avoid name space clashes when loading multiple drivers. The examples here are for the ZZZ driver, which uses the ZZZ or zzz prefix for its externally visible symbols. Include files All drivers normally include the following headers: "xf86.h" "xf86_OSproc.h" "xf86_ansic.h" "xf86Resources.h" Wherever inb/outb (and related things) are used the following should be included: "compiler.h" Note: in drivers, this must be included after "xf86_ansic.h". Drivers that need to access PCI vendor/device definitions need this: "xf86PciInfo.h" Drivers that need to access the PCI config space need this: "xf86Pci.h" Drivers using the mi banking wrapper need: "mibank.h" Drivers that initialise a SW cursor need this: "mipointer.h" All drivers using the mi colourmap code need this: "micmap.h" If a driver uses the vgahw module, it needs this: "vgaHW.h" Drivers supporting VGA or Hercules monochrome screens need: "xf1bpp.h" Drivers supporting VGA or EGC 16-colour screens need: "xf4bpp.h" Drivers using cfb need: #define PSZ 8 #include "cfb.h" #undef PSZ Drivers supporting bpp 16, 24 or 32 with cfb need one or more of: "cfb16.h" "cfb24.h" "cfb32.h" The driver's own header file: "zzz.h" Drivers must NOT include the following: "xf86Priv.h" "xf86Privstr.h" "xf86_libc.h" "xf86_OSlib.h" "Xos.h" any OS header Data structures and initialisation The following macros should be defined: #define VERSION <version-as-an-int> #define ZZZ_NAME "ZZZ" /* the name used to prefix messages */ #define ZZZ_DRIVER_NAME "zzz" /* the driver name as used in config file */ #define ZZZ_MAJOR_VERSION <int> #define ZZZ_MINOR_VERSION <int> #define ZZZ_PATCHLEVEL <int> NOTE: ZZZ_DRIVER_NAME should match the name of the driver module without things like the "lib" prefix, the "_drv" suffix or filename extensions. A DriverRec must be defined, which includes the functions required at the pre-probe phase. The name of this DriverRec must be an upper-case version of ZZZ_DRIVER_NAME (for the purposes of static linking). DriverRec ZZZ = { VERSION, ZZZ_DRIVER_NAME, ZZZIdentify, ZZZProbe, ZZZAvailableOptions, NULL, 0 }; Define list of supported chips and their matching ID: static SymTabRec ZZZChipsets[] = { { PCI_CHIP_ZZZ1234, "zzz1234a" }, { PCI_CHIP_ZZZ5678, "zzz5678a" }, { -1, NULL } }; The token field may be any integer value that the driver may use to uniquely identify the supported chipsets. For drivers that support only PCI devices using the PCI device IDs might be a natural choice, but this isn't mandatory. For drivers that support both PCI and other devices (like ISA), some other ID should probably used. When other IDs are used as the tokens it is recommended that the names be defined as an enum type. If the driver uses the xf86MatchPciInstances() helper (recommended for drivers that support PCI cards) a list that maps PCI IDs to chip IDs and fixed resources must be defined: static PciChipsets ZZZPciChipsets[] = { { PCI_CHIP_ZZZ1234, PCI_CHIP_ZZZ1234, RES_SHARED_VGA }, { PCI_CHIP_ZZZ5678, PCI_CHIP_ZZZ5678, RES_SHARED_VGA }, { -1, -1, RES_UNDEFINED } } Define the XF86ModuleVersionInfo struct for the driver. This is required for the dynamically loaded version: static XF86ModuleVersionInfo zzzVersRec = { "zzz", MODULEVENDORSTRING, MODINFOSTRING1, MODINFOSTRING2, XF86_VERSION_CURRENT, ZZZ_MAJOR_VERSION, ZZZ_MINOR_VERSION, ZZZ_PATCHLEVEL, ABI_CLASS_VIDEODRV, ABI_VIDEODRV_VERSION, MOD_CLASS_VIDEODRV, {0,0,0,0} }; Define a data structure to hold the driver's screen-specific data. This must be used instead of global variables. This would be defined in the "zzz.h" file, something like: typedef struct { type1 field1; type2 field2; int fooHack; Bool pciRetry; Bool noAccel; Bool hwCursor; CloseScreenProcPtr CloseScreen; OptionInfoPtr Options; ... } ZZZRec, *ZZZPtr; Define the list of config file Options that the driver accepts. For consistency between drivers those in the list of standard options should be used where appropriate before inventing new options. typedef enum { OPTION_FOO_HACK, OPTION_PCI_RETRY, OPTION_HW_CURSOR, OPTION_NOACCEL } ZZZOpts; static const OptionInfoRec ZZZOptions[] = { { OPTION_FOO_HACK, "FooHack", OPTV_INTEGER, {0}, FALSE }, { OPTION_PCI_RETRY, "PciRetry", OPTV_BOOLEAN, {0}, FALSE }, { OPTION_HW_CURSOR, "HWcursor", OPTV_BOOLEAN, {0}, FALSE }, { OPTION_NOACCEL, "NoAccel", OPTV_BOOLEAN, {0}, FALSE }, { -1, NULL, OPTV_NONE, {0}, FALSE } }; Functions SetupProc For dynamically loaded modules, a ModuleData variable is required. It is should be the name of the driver prepended to "ModuleData". A Setup() function is also required, which calls xf86AddDriver() to add the driver to the main list of drivers. static MODULESETUPPROTO(zzzSetup); XF86ModuleData zzzModuleData = { &zzzVersRec, zzzSetup, NULL }; static pointer zzzSetup(pointer module, pointer opts, int *errmaj, int *errmin) { static Bool setupDone = FALSE; /* This module should be loaded only once, but check to be sure. */ if (!setupDone) { /* * Modules that this driver always requires may be loaded * here by calling LoadSubModule(). */ setupDone = TRUE; xf86AddDriver(&MGA, module, 0); /* * The return value must be non-NULL on success even though * there is no TearDownProc. */ return (pointer)1; } else { if (errmaj) *errmaj = LDR_ONCEONLY; return NULL; } } GetRec, FreeRec A function is usually required to allocate the driver's screen-specific data structure and hook it into the ScrnInfoRec's driverPrivate field. The ScrnInfoRec's driverPrivate is initialised to NULL, so it is easy to check if the initialisation has already been done. After allocating it, initialise the fields. By using xnfcalloc() to do the allocation it is zeroed, and if the allocation fails the server exits. NOTE: When allocating structures from inside the driver which are defined on the common level it is important to initialize the structure to zero. Only this guarantees that the server remains source compatible to future changes in common level structures. static Bool ZZZGetRec(ScrnInfoPtr pScrn) { if (pScrn->driverPrivate != NULL) return TRUE; pScrn->driverPrivate = xnfcalloc(sizeof(ZZZRec), 1); /* Initialise as required */ ... return TRUE; } Define a macro in "zzz.h" which gets a pointer to the ZZZRec when given pScrn: #define ZZZPTR(p) ((ZZZPtr)((p)->driverPrivate)) Define a function to free the above, setting it to NULL once it has been freed: static void ZZZFreeRec(ScrnInfoPtr pScrn) { if (pScrn->driverPrivate == NULL) return; xfree(pScrn->driverPrivate); pScrn->driverPrivate = NULL; } Identify Define the Identify() function. It is run before the Probe, and typically prints out an identifying message, which might include the chipsets it supports. This function is mandatory: static void ZZZIdentify(int flags) { xf86PrintChipsets(ZZZ_NAME, "driver for ZZZ Tech chipsets", ZZZChipsets); } Probe Define the Probe() function. The purpose of this is to find all instances of the hardware that the driver supports, and for the ones not already claimed by another driver, claim the slot, and allocate a ScrnInfoRec. This should be a minimal probe, and it should under no circumstances leave the state of the hardware changed. Because a device is found, don't assume that it will be used. Don't do any initialisations other than the required ScrnInfoRec initialisations. Don't allocate any new data structures. This function is mandatory. NOTE: The xf86DrvMsg() functions cannot be used from the Probe. static Bool ZZZProbe(DriverPtr drv, int flags) { Bool foundScreen = FALSE; int numDevSections, numUsed; GDevPtr *devSections; int *usedChips; int i; /* * Find the config file Device sections that match this * driver, and return if there are none. */ if ((numDevSections = xf86MatchDevice(ZZZ_DRIVER_NAME, &devSections)) <= 0) { return FALSE; } /* * Since this is a PCI card, "probing" just amounts to checking * the PCI data that the server has already collected. If there * is none, return. * * Although the config file is allowed to override things, it * is reasonable to not allow it to override the detection * of no PCI video cards. * * The provided xf86MatchPciInstances() helper takes care of * the details. */ /* test if PCI bus present */ if (xf86GetPciVideoInfo()) { numUsed = xf86MatchPciInstances(ZZZ_NAME, PCI_VENDOR_ZZZ, ZZZChipsets, ZZZPciChipsets, devSections, numDevSections, drv, &usedChips); for (i = 0; i < numUsed; i++) { ScrnInfoPtr pScrn = NULL; if ((pScrn = xf86ConfigPciEntity(pScrn, flags, usedChips[i], ZZZPciChipsets, NULL, NULL, NULL, NULL, NULL))) { /* Allocate a ScrnInfoRec */ pScrn->driverVersion = VERSION; pScrn->driverName = ZZZ_DRIVER_NAME; pScrn->name = ZZZ_NAME; pScrn->Probe = ZZZProbe; pScrn->PreInit = ZZZPreInit; pScrn->ScreenInit = ZZZScreenInit; pScrn->SwitchMode = ZZZSwitchMode; pScrn->AdjustFrame = ZZZAdjustFrame; pScrn->EnterVT = ZZZEnterVT; pScrn->LeaveVT = ZZZLeaveVT; pScrn->FreeScreen = ZZZFreeScreen; pScrn->ValidMode = ZZZValidMode; foundScreen = TRUE; /* add screen to entity */ } } xfree(usedChips); } xfree(devSections); return foundScreen; AvailableOptions Define the AvailableOptions() function. The purpose of this is to return the available driver options back to the -configure option, so that an xorg.conf file can be built and the user can see which options are available for them to use. PreInit Define the PreInit() function. The purpose of this is to find all the information required to determine if the configuration is usable, and to initialise those parts of the ScrnInfoRec that can be set once at the beginning of the first server generation. The information should be found in the least intrusive way possible. This function is mandatory. NOTES: The PreInit() function is only called once during the life of the X server (at the start of the first generation). Data allocated here must be of the type that persists for the life of the X server. This means that data that hooks into the ScrnInfoRec's privates field should be allocated here, but data that hooks into the ScreenRec's devPrivates field should not be allocated here. The driverPrivate field should also be allocated here. Although the ScrnInfoRec has been allocated before this function is called, the ScreenRec has not been allocated. That means that things requiring it cannot be used in this function. Very little of the ScrnInfoRec has been initialised when this function is called. It is important to get the order of doing things right in this function. static Bool ZZZPreInit(ScrnInfoPtr pScrn, int flags) { /* Fill in the monitor field */ pScrn->monitor = pScrn->confScreen->monitor; /* * If using the vgahw module, it will typically be loaded * here by calling xf86LoadSubModule(pScrn, "vgahw"); */ /* * Set the depth/bpp. Use the globally preferred depth/bpp. If the * driver has special default depth/bpp requirements, the defaults should * be specified here explicitly. * We support both 24bpp and 32bpp framebuffer layouts. * This sets pScrn->display also. */ if (!xf86SetDepthBpp(pScrn, 0, 0, 0, Support24bppFb | Support32bppFb)) { return FALSE; } else { if (depth/bpp isn't one we support) { print error message; return FALSE; } } /* Print out the depth/bpp that was set */ xf86PrintDepthBpp(pScrn); /* Set bits per RGB for 8bpp */ if (pScrn->depth <= 8) { /* Take into account a dac_6_bit option here */ pScrn->rgbBits = 6 or 8; } /* * xf86SetWeight() and xf86SetDefaultVisual() must be called * after pScrn->display is initialised. */ /* Set weight/mask/offset for depth > 8 */ if (pScrn->depth > 8) { if (!xf86SetWeight(pScrn, defaultWeight, defaultMask)) { return FALSE; } else { if (weight isn't one we support) { print error message; return FALSE; } } } /* Set the default visual. */ if (!xf86SetDefaultVisual(pScrn, -1)) { return FALSE; } else { if (visual isn't one we support) { print error message; return FALSE; } } /* If the driver supports gamma correction, set the gamma. */ if (!xf86SetGamma(pScrn, default_gamma)) { return FALSE; } /* This driver uses a programmable clock */ pScrn->progClock = TRUE; /* Allocate the ZZZRec driverPrivate */ if (!ZZZGetRec(pScrn)) { return FALSE; } pZzz = ZZZPTR(pScrn); /* Collect all of the option flags (fill in pScrn->options) */ xf86CollectOptions(pScrn, NULL); /* * Process the options based on the information in ZZZOptions. * The results are written to pZzz->Options. If all of the options * processing is done within this function a local variable "options" * can be used instead of pZzz->Options. */ if (!(pZzz->Options = xalloc(sizeof(ZZZOptions)))) return FALSE; (void)memcpy(pZzz->Options, ZZZOptions, sizeof(ZZZOptions)); xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, pZzz->Options); /* * Set various fields of ScrnInfoRec and/or ZZZRec based on * the options found. */ from = X_DEFAULT; pZzz->hwCursor = FALSE; if (xf86IsOptionSet(pZzz->Options, OPTION_HW_CURSOR)) { from = X_CONFIG; pZzz->hwCursor = TRUE; } xf86DrvMsg(pScrn->scrnIndex, from, "Using %s cursor\n", pZzz->hwCursor ? "HW" : "SW"); if (xf86IsOptionSet(pZzz->Options, OPTION_NOACCEL)) { pZzz->noAccel = TRUE; xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "Acceleration disabled\n"); } else { pZzz->noAccel = FALSE; } if (xf86IsOptionSet(pZzz->Options, OPTION_PCI_RETRY)) { pZzz->UsePCIRetry = TRUE; xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "PCI retry enabled\n"); } pZzz->fooHack = 0; if (xf86GetOptValInteger(pZzz->Options, OPTION_FOO_HACK, &pZzz->fooHack)) { xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "Foo Hack set to %d\n", pZzz->fooHack); } /* * Find the PCI slot(s) that this screen claimed in the probe. * In this case, exactly one is expected, so complain otherwise. * Note in this case we're not interested in the card types so * that parameter is set to NULL. */ if ((i = xf86GetPciInfoForScreen(pScrn->scrnIndex, &pciList, NULL)) != 1) { print error message; ZZZFreeRec(pScrn); if (i > 0) xfree(pciList); return FALSE; } /* Note that pciList should be freed below when no longer needed */ /* * Determine the chipset, allowing config file chipset and * chipid values to override the probed information. The config * chipset value has precedence over its chipid value if both * are present. * * It isn't necessary to fill in pScrn->chipset if the driver * keeps track of the chipset in its ZZZRec. */ ... /* * Determine video memory, fb base address, I/O addresses, etc, * allowing the config file to override probed values. * * Set the appropriate pScrn fields (videoRam is probably the * most important one that other code might require), and * print out the settings. */ ... /* Initialise a clockRanges list. */ ... /* Set any other chipset specific things in the ZZZRec */ ... /* Select valid modes from those available */ i = xf86ValidateModes(pScrn, pScrn->monitor->Modes, pScrn->display->modes, clockRanges, NULL, minPitch, maxPitch, rounding, minHeight, maxHeight, pScrn->display->virtualX, pScrn->display->virtualY, pScrn->videoRam * 1024, LOOKUP_BEST_REFRESH); if (i == -1) { ZZZFreeRec(pScrn); return FALSE; } /* Prune the modes marked as invalid */ xf86PruneDriverModes(pScrn); /* If no valid modes, return */ if (i == 0 || pScrn->modes == NULL) { print error message; ZZZFreeRec(pScrn); return FALSE; } /* * Initialise the CRTC fields for the modes. This driver expects * vertical values to be halved for interlaced modes. */ xf86SetCrtcForModes(pScrn, INTERLACE_HALVE_V); /* Set the current mode to the first in the list. */ pScrn->currentMode = pScrn->modes; /* Print the list of modes being used. */ xf86PrintModes(pScrn); /* Set the DPI */ xf86SetDpi(pScrn, 0, 0); /* Load bpp-specific modules */ switch (pScrn->bitsPerPixel) { case 1: mod = "xf1bpp"; break; case 4: mod = "xf4bpp"; break; case 8: mod = "cfb"; break; case 16: mod = "cfb16"; break; case 24: mod = "cfb24"; break; case 32: mod = "cfb32"; break; } if (mod && !xf86LoadSubModule(pScrn, mod)) ZZZFreeRec(pScrn); return FALSE; /* Done */ return TRUE; } MapMem, UnmapMem Define functions to map and unmap the video memory and any other memory apertures required. These functions are not mandatory, but it is often useful to have such functions. static Bool ZZZMapMem(ScrnInfoPtr pScrn) { /* Call xf86MapPciMem() to map each PCI memory area */ ... return TRUE or FALSE; } static Bool ZZZUnmapMem(ScrnInfoPtr pScrn) { /* Call xf86UnMapVidMem() to unmap each memory area */ ... return TRUE or FALSE; } Save, Restore Define functions to save and restore the original video state. These functions are not mandatory, but are often useful. static void ZZZSave(ScrnInfoPtr pScrn) { /* * Save state into per-screen data structures. * If using the vgahw module, vgaHWSave will typically be * called here. */ ... } static void ZZZRestore(ScrnInfoPtr pScrn) { /* * Restore state from per-screen data structures. * If using the vgahw module, vgaHWRestore will typically be * called here. */ ... } ModeInit Define a function to initialise a new video mode. This function isn't mandatory, but is often useful. static Bool ZZZModeInit(ScrnInfoPtr pScrn, DisplayModePtr mode) { /* * Program a video mode. If using the vgahw module, * vgaHWInit and vgaRestore will typically be called here. * Once up to the point where there can't be a failure * set pScrn->vtSema to TRUE. */ ... } ScreenInit Define the ScreenInit() function. This is called at the start of each server generation, and should fill in as much of the ScreenRec as possible as well as any other data that is initialised once per generation. It should initialise the framebuffer layers it is using, and initialise the initial video mode. This function is mandatory. NOTE: The ScreenRec (pScreen) is passed to this driver, but it and the ScrnInfoRecs are not yet hooked into each other. This means that in this function, and functions it calls, one cannot be found from the other. static Bool ZZZScreenInit(ScreenPtr pScreen, int argc, char **argv) { /* Get the ScrnInfoRec */ pScrn = xf86ScreenToScrn(pScreen); /* * If using the vgahw module, its data structures and related * things are typically initialised/mapped here. */ /* Save the current video state */ ZZZSave(pScrn); /* Initialise the first mode */ ZZZModeInit(pScrn, pScrn->currentMode); /* Set the viewport if supported */ ZZZAdjustFrame(pScrn, pScrn->frameX0, pScrn->frameY0); /* * Setup the screen's visuals, and initialise the framebuffer * code. */ /* Reset the visual list */ miClearVisualTypes(); /* * Setup the visuals supported. This driver only supports * TrueColor for bpp > 8, so the default set of visuals isn't * acceptable. To deal with this, call miSetVisualTypes with * the appropriate visual mask. */ if (pScrn->bitsPerPixel > 8) { if (!miSetVisualTypes(pScrn->depth, TrueColorMask, pScrn->rgbBits, pScrn->defaultVisual)) return FALSE; } else { if (!miSetVisualTypes(pScrn->depth, miGetDefaultVisualMask(pScrn->depth), pScrn->rgbBits, pScrn->defaultVisual)) return FALSE; } /* * Initialise the framebuffer. */ switch (pScrn->bitsPerPixel) { case 1: ret = xf1bppScreenInit(pScreen, FbBase, pScrn->virtualX, pScrn->virtualY, pScrn->xDpi, pScrn->yDpi, pScrn->displayWidth); break; case 4: ret = xf4bppScreenInit(pScreen, FbBase, pScrn->virtualX, pScrn->virtualY, pScrn->xDpi, pScrn->yDpi, pScrn->displayWidth); break; case 8: ret = cfbScreenInit(pScreen, FbBase, pScrn->virtualX, pScrn->virtualY, pScrn->xDpi, pScrn->yDpi, pScrn->displayWidth); break; case 16: ret = cfb16ScreenInit(pScreen, FbBase, pScrn->virtualX, pScrn->virtualY, pScrn->xDpi, pScrn->yDpi, pScrn->displayWidth); break; case 24: ret = cfb24ScreenInit(pScreen, FbBase, pScrn->virtualX, pScrn->virtualY, pScrn->xDpi, pScrn->yDpi, pScrn->displayWidth); break; case 32: ret = cfb32ScreenInit(pScreen, FbBase, pScrn->virtualX, pScrn->virtualY, pScrn->xDpi, pScrn->yDpi, pScrn->displayWidth); break; default: print a message about an internal error; ret = FALSE; break; } if (!ret) return FALSE; /* Override the default mask/offset settings */ if (pScrn->bitsPerPixel > 8) { for (i = 0, visual = pScreen->visuals; i < pScreen->numVisuals; i++, visual++) { if ((visual->class | DynamicClass) == DirectColor) { visual->offsetRed = pScrn->offset.red; visual->offsetGreen = pScrn->offset.green; visual->offsetBlue = pScrn->offset.blue; visual->redMask = pScrn->mask.red; visual->greenMask = pScrn->mask.green; visual->blueMask = pScrn->mask.blue; } } } /* * If banking is needed, initialise an miBankInfoRec (defined in * "mibank.h"), and call miInitializeBanking(). */ if (!miInitializeBanking(pScreen, pScrn->virtualX, pScrn->virtualY, pScrn->displayWidth, pBankInfo)) return FALSE; /* * Set initial black & white colourmap indices. */ xf86SetBlackWhitePixels(pScreen); /* * Install colourmap functions. */ ... /* * Initialise cursor functions. This example is for the mi * software cursor. */ miDCInitialize(pScreen, xf86GetPointerScreenFuncs()); /* Initialise the default colourmap */ switch (pScrn->depth) { case 1: if (!xf1bppCreateDefColormap(pScreen)) return FALSE; break; case 4: if (!xf4bppCreateDefColormap(pScreen)) return FALSE; break; default: if (!cfbCreateDefColormap(pScreen)) return FALSE; break; } /* * Wrap the CloseScreen vector and set SaveScreen. */ ZZZPTR(pScrn)->CloseScreen = pScreen->CloseScreen; pScreen->CloseScreen = ZZZCloseScreen; pScreen->SaveScreen = ZZZSaveScreen; /* Report any unused options (only for the first generation) */ if (serverGeneration == 1) { xf86ShowUnusedOptions(pScrn->scrnIndex, pScrn->options); } /* Done */ return TRUE; } SwitchMode Define the SwitchMode() function if mode switching is supported by the driver. static Bool ZZZSwitchMode(ScrnInfoPtr pScrn, DisplayModePtr mode) { return ZZZModeInit(pScrn, mode); } AdjustFrame Define the AdjustFrame() function if the driver supports this. static void ZZZAdjustFrame(ScrnInfoPtr pScrn, int x, int y) { /* Adjust the viewport */ } EnterVT, LeaveVT Define the EnterVT() and LeaveVT() functions. These functions are mandatory. static Bool ZZZEnterVT(ScrnInfoPtr pScrn) { return ZZZModeInit(pScrn, pScrn->currentMode); } static void ZZZLeaveVT(ScrnInfoPtr pScrn) { ZZZRestore(pScrn); } CloseScreen Define the CloseScreen() function: This function is mandatory. Note that it unwraps the previously wrapped pScreen->CloseScreen, and finishes by calling it. static Bool ZZZCloseScreen(ScreenPtr pScreen) { ScrnInfoPtr pScrn = xf86ScreenToScrn(pScreen); if (pScrn->vtSema) { ZZZRestore(pScrn); ZZZUnmapMem(pScrn); } pScrn->vtSema = FALSE; pScreen->CloseScreen = ZZZPTR(pScrn)->CloseScreen; return (*pScreen->CloseScreen)(pScreen); } SaveScreen Define the SaveScreen() function (the screen blanking function). When using the vgahw module, this will typically be: static Bool ZZZSaveScreen(ScreenPtr pScreen, int mode) { return vgaHWSaveScreen(pScreen, mode); } This function is mandatory. Before modifying any hardware register directly this function needs to make sure that the Xserver is active by checking if pScrn is non-NULL and for pScrn->vtSema == TRUE. FreeScreen Define the FreeScreen() function. This function is optional. It should be defined if the ScrnInfoRec driverPrivate field is used so that it can be freed when a screen is deleted by the common layer for reasons possibly beyond the driver's control. This function is not used in during normal (error free) operation. The per-generation data is freed by the CloseScreen() function. static void ZZZFreeScreen(ScrnInfoPtr pScrn) { /* * If the vgahw module is used vgaHWFreeHWRec() would be called * here. */ ZZZFreeRec(pScrn); }