e191e296e6
Commit 0c6987df
in June 2008 disabled XAA offscreen pixmaps per default,
as they were broken, leaving XAA only able to accelerate operations
directly on the screen pixmap and nowhere else, eliminating acceleration
for basically every modern toolkit, and any composited environment.
So, it hasn't worked for over four years. No-one's even come close to
fixing it.
RIP.
Signed-off-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
90 lines
3.0 KiB
Plaintext
90 lines
3.0 KiB
Plaintext
Adding EXA support to your X.Org video driver
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---------------------------------------------
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EXA (for EXcellent Architecture or Ex-kaa aXeleration Architecture or
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whatever) aims to extend the life of the venerable XFree86 video drivers by
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introducing a new set of acceleration hooks that efficiently accelerate the X
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Render extension, including solid fills, blits within screen memory and to and
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from system memory, and Porter-Duff compositing and transform operations.
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Configuration
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-------------
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Some drivers implement a per-instance useEXA flag to track whether EXA is
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active or not.
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Setting the flag can be done in the driver's Options parsing routine.
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Loading EXA
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------------
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EXA drivers in the XFree86 DDX should use the loadable module loader to load
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the EXA core. Careful versioning allows the EXA API to be extended without
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breaking the ABI for older versions of drivers. Example code for loading EXA:
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static const char *exaSymbols[] = {
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"exaDriverAlloc",
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"exaDriverInit",
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"exaDriverFini",
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"exaOffscreenAlloc",
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"exaOffscreenFree",
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"exaGetPixmapOffset",
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"exaGetPixmapPitch",
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"exaGetPixmapSize",
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"exaMarkSync",
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"exaWaitSync",
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NULL
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};
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if (info->useEXA) {
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info->exaReq.majorversion = 2;
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info->exaReq.minorversion = 0;
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if (!LoadSubModule(pScrn->module, "exa", NULL, NULL, NULL,
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&info->exaReq, &errmaj, &errmin)) {
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LoaderErrorMsg(NULL, "exa", errmaj, errmin);
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return FALSE;
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}
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xf86LoaderReqSymLists(exaSymbols, NULL);
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}
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EXA is then initialized using exaDriverAlloc and exaDriverInit. See doxygen
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documentation for getting started there.
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Further documentation
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------------
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The EXA driver interface and public API is documented using doxygen in
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xserver/xorg/exa/. To build the documentation, run:
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doxygen -g
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doxygen Doxyfile
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The resulting documentation will appear an html/index.html under the current
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directory.
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EXA initialization
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------------------
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Your driver's AccelInit routine must initialize an ExaDriverRec structure if
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EXA support is enabled, with appropriate error handling (i.e. NoAccel and
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NoXvideo should be set to true if EXA fails to initialize for whatever
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reason).
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The AccelInit routine also needs to make sure that there's enough offscreen
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memory for certain operations to function, like Xvideo, which should advertise
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a maximum size no larger than can be dealt with given the amount of offscreen
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memory available.
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EXA and Xv
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----------
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Video support becomes easier with EXA since AllocateFBMemory can use
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exaOffscreenAlloc directly, freeing a previous area if necessary and
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allocating a new one. Likewise, FreeFBMemory can call exaOffscreenFree.
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EXA teardown
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------------
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At screen close time, EXA drivers should call exaDriverFini with their screen
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pointer, free their EXADriver structure, and do any other necessary teardown.
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EXA misc.
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---------
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In many drivers, DGA support will need to be changed to be aware of the new
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EXA support.
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Send updates and corrections to Jesse Barnes <jbarnes@virtuousgeek.org> or
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just check them in if you have permission.
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