[Mesa-maintainers] Recommendations for building Mesa with LIBGLVND support

[Emil Velikov]

On 11 May 2017 at 09:24, Timo Aaltonen <tjaalton at ubuntu.com> wrote:
> On 17.04.2017 21:31, Emil Velikov wrote:
>> On 23 March 2017 at 15:00, Stefan Dirsch <sndirsch at suse.de> wrote:
>>> On Tue, Mar 21, 2017 at 12:16:48PM -0600, Kyle Brenneman wrote:
>>>> Ah, I'd forgotten to address libGLES* in my EGL patch.
>>>>
>>>> As far as I can tell, the libGLES libraries in Mesa are just dispatch stubs,
>>>> and nothing within Mesa depends on them. That is, if an application looked
>>>> up every GLES function using eglGetProcAddress, then you could remove the
>>>> libGLES*.so libraries entirely and it would still run fine.
>>>>
>>>> If that's true, then a libglvnd-based build of Mesa could just skip building
>>>> the libGLES*.so libraries, because libglvnd basically does look up every
>>>> GLES function through the vendor library's eglGetProcAddress.
>>>
>>> Thanks, Kyle! This explains a lot! I have done this now (removed Mesa's GLES
>>> libs and reqplaced them with RPM requires to libglvnd's GLES libs; the same as
>>> Fedora is doing) and it just works. :-)
>>>
>> In case you've missed it - I've pulled Kyle's work [with a small bit
>> of polish] for Mesa 17.1.0-rc1.
>>
>> Note that there's still loose ends - the biggest one in the GLVND
>> library itself. I've got some local WIP that I'll try to test and
>> upstream this week.
>
> Hi, what's the status of this work?
>
> We're preparing GLVND in Debian experimental now that 17.1.0 is out, and
> my plan is to get it in Ubuntu Artful some time this summer.
>
TL;DR; if you can live with broken IGLX and eglGetDisplay + GBM things
are safe to use with Mesa 17.1.0.

A more comprehensive TODO on the topic of libglvnd is below.

- DONE - mesa: merge the EGL libglvnd implementation
- DONE - mesa: investigate if linking the DRI modules against
libglapi.so is safe
- WIP - mesa: do not install GLES libraries/headers/pkg-config files
when libglvnd is enabled
Depends on the header/pkg-config bits below
- TODO - libglvnd: broke indirect GLX, should be fixed once libglvnd
provides libglapi.so.
- WIP - libglvnd: eglGetDisplay has broken GBM support
- TODO - libglvnd: install the pkg-config files
- TODO - libglvnd: (or Khronos) should provide the headers - depends
on the next two items
- TODO - libglvnd: tests to ensure we don't break the ABI
- WIP - Khronos: correctly manage different EGL platforms
Patches are on mesa-dev@, need to push through Khronos
- TODO - Khronos: upstream/ratify the Wayland EGL extensions

The topics involving [upstream] libglvnd do take a while since I'm not
good at selling it to the upstream maintainer :-\

-Emil