repositories / deb_xorg-server.git / blame
| Commit | Line | Data |
|---|---|---|
| a09e091a JB |
1 | Adding EXA support to your X.Org video driver |
| 2 | --------------------------------------------- | |
| 3 | EXA (for EXcellent Architecture or Ex-kaa aXeleration Architecture or | |
| 4 | whatever) aims to extend the life of the venerable XFree86 video drivers by | |
| 5 | introducing a new set of acceleration hooks that efficiently accelerate the X | |
| 6 | Render extension, including solid fills, blits within screen memory and to and | |
| 7 | from system memory, and Porter-Duff compositing and transform operations. | |
| 8 | ||
| 9 | Configuration | |
| 10 | ------------- | |
| 11 | Some drivers implement a per-instance useEXA flag to track whether EXA is | |
| 12 | active or not. | |
| 13 | ||
| 14 | Setting the flag can be done in the driver's Options parsing routine. | |
| 15 | ||
| 16 | Loading EXA | |
| 17 | ------------ | |
| 18 | EXA drivers in the XFree86 DDX should use the loadable module loader to load | |
| 19 | the EXA core. Careful versioning allows the EXA API to be extended without | |
| 20 | breaking the ABI for older versions of drivers. Example code for loading EXA: | |
| 21 | ||
| 22 | static const char *exaSymbols[] = { | |
| 23 | "exaDriverAlloc", | |
| 24 | "exaDriverInit", | |
| 25 | "exaDriverFini", | |
| 26 | "exaOffscreenAlloc", | |
| 27 | "exaOffscreenFree", | |
| 28 | "exaGetPixmapOffset", | |
| 29 | "exaGetPixmapPitch", | |
| 30 | "exaGetPixmapSize", | |
| 31 | "exaMarkSync", | |
| 32 | "exaWaitSync", | |
| 33 | NULL | |
| 34 | }; | |
| 35 | ||
| 36 | if (info->useEXA) { | |
| 37 | info->exaReq.majorversion = 2; | |
| 38 | info->exaReq.minorversion = 0; | |
| 39 | ||
| 40 | if (!LoadSubModule(pScrn->module, "exa", NULL, NULL, NULL, | |
| 41 | &info->exaReq, &errmaj, &errmin)) { | |
| 42 | LoaderErrorMsg(NULL, "exa", errmaj, errmin); | |
| 43 | return FALSE; | |
| 44 | } | |
| 45 | xf86LoaderReqSymLists(exaSymbols, NULL); | |
| 46 | } | |
| 47 | ||
| 48 | EXA is then initialized using exaDriverAlloc and exaDriverInit. See doxygen | |
| 49 | documentation for getting started there. | |
| 50 | ||
| 51 | Further documentation | |
| 52 | ------------ | |
| 53 | The EXA driver interface and public API is documented using doxygen in | |
| 54 | xserver/xorg/exa/. To build the documentation, run: | |
| 55 | doxygen -g | |
| 56 | doxygen Doxyfile | |
| 57 | The resulting documentation will appear an html/index.html under the current | |
| 58 | directory. | |
| 59 | ||
| 60 | EXA initialization | |
| 61 | ------------------ | |
| 62 | Your driver's AccelInit routine must initialize an ExaDriverRec structure if | |
| 63 | EXA support is enabled, with appropriate error handling (i.e. NoAccel and | |
| 64 | NoXvideo should be set to true if EXA fails to initialize for whatever | |
| 65 | reason). | |
| 66 | ||
| 67 | The AccelInit routine also needs to make sure that there's enough offscreen | |
| 68 | memory for certain operations to function, like Xvideo, which should advertise | |
| 69 | a maximum size no larger than can be dealt with given the amount of offscreen | |
| 70 | memory available. | |
| 71 | ||
| 72 | EXA and Xv | |
| 73 | ---------- | |
| 74 | Video support becomes easier with EXA since AllocateFBMemory can use | |
| 75 | exaOffscreenAlloc directly, freeing a previous area if necessary and | |
| 76 | allocating a new one. Likewise, FreeFBMemory can call exaOffscreenFree. | |
| 77 | ||
| 78 | EXA teardown | |
| 79 | ------------ | |
| 80 | At screen close time, EXA drivers should call exaDriverFini with their screen | |
| 81 | pointer, free their EXADriver structure, and do any other necessary teardown. | |
| 82 | ||
| 83 | EXA misc. | |
| 84 | --------- | |
| 85 | In many drivers, DGA support will need to be changed to be aware of the new | |
| 86 | EXA support. | |
| 87 | ||
| 88 | Send updates and corrections to Jesse Barnes <jbarnes@virtuousgeek.org> or | |
| 89 | just check them in if you have permission. |