exa-driver.txt (3083B)
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.