[Mesa-dev] RFC - libglvnd and GLXVND vendor enumeration to facilitate GLX multi-vendor PRIME GPU offload
Michel Dänzer
michel at daenzer.net
Tue Feb 12 08:58:04 UTC 2019
On 2019-02-11 5:18 p.m., Andy Ritger wrote:
> On Mon, Feb 11, 2019 at 12:09:26PM +0100, Michel Dänzer wrote:
>> On 2019-02-08 11:43 p.m., Kyle Brenneman wrote:
>>>
>>> Also, is Mesa the only client-side vendor library that works with the
>>> Xorg GLX module? I vaguely remember that there was at least one other
>>> driver that did, but I don't remember the details anymore.
>>
>> AFAIK, the amdgpu-pro OpenGL driver can work with the Xorg GLX module
>> (or its own forked version of it).
>
> Maybe the amdgpu-pro OpenGL driver uses a fork of the Xorg GLX module
> (or sets the "GlxVendorLibrary" X configuration option?), but it doesn't
> look to me like the in-tree Xorg GLX module could report anything other
> than "mesa" for GLX_VENDOR_NAMES_EXT, without custom user configuration.
>
> GLX_VENDOR_NAMES_EXT, which client-side glvnd uses to pick the
> libGLX_${vendor}.so to load, is implemented in the Xorg GLX module
> with this:
>
> xserver/glx/glxcmds.c:__glXDisp_QueryServerString():
>
> case GLX_VENDOR_NAMES_EXT:
> if (pGlxScreen->glvnd) {
> ptr = pGlxScreen->glvnd;
> break;
> }
>
> pGlxScreen->glvnd appears to be assigned here, defaulting to "mesa",
> though allowing an xorg.conf override via the "GlxVendorLibrary" option:
>
> xserver/glx/glxdri2.c:__glXDRIscreenProbe():
>
> xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, options);
> glvnd = xf86GetOptValString(options, GLXOPT_VENDOR_LIBRARY);
> if (glvnd)
> screen->base.glvnd = xnfstrdup(glvnd);
> free(options);
>
> if (!screen->base.glvnd)
> screen->base.glvnd = strdup("mesa");
>
> And swrast unconditionally sets pGlxScreen->glvnd to "mesa":
>
> xserver/glx/glxdriswrast.c:__glXDRIscreenProbe():
>
> screen->base.glvnd = strdup("mesa");
>
> Is there more to this that I'm missing?
I don't think so, I suspect we were just assuming slightly different
definitions of "works". :)
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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