[Mesa-dev] [Bug 38906] Mesa compilation failure if libudev development files are not installed.

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=38906

--- Comment #5 from Benjamin Franzke <benjaminfranzke at googlemail.com> 2011-07-02 05:40:50 PDT ---
(In reply to comment #3)
> The second build was configured using
> --with-egl-platforms=drm and --disable-gdm.
> 
> Could you describe a bit more in detail why we can't build the drm platform
> without gdm? What exactly are gdm strictly needed for?
> 

Well, as mentioned, gbm is the native egl display type for the drm platform
backend (maybe drm platform should be renamed to gbm someday).
e.g:
   fd = open("/dev/dri/card0", O_RDWR);
   gbm = gbm_create_device(fd);
   edpy = eglGetDisplay(gbm);

> I was under the impression that gdm was only strictly required for certain EGL
> extensions or Wayland?

gbm is intended to replace the EGL_MESA_drm_image extension which was needed to
run egl on DRM/KMS while having control over KMS (in contrast to
EGL_MESA_screen_surface which abstracts KMS).

gbm is not needed for wayland (nor the wayland stuff inside mesa), its just
that wayland compositors will likely use it to create buffers for use with
KMS/OpenWF Display.

> In general, when it comes to EGL I think it's very important that we maintain
> the possibility of a very lean build, so that embedded platforms that will
> never use a certain feature can skip it from the build.

libudev is needed for drm anyway, to figure out which driver to use (This is
since commita433755ec5c48088a0d8a340851a1a8be9e58897).

> Why, should we, for example, need to install libudev development files for
> embedded systems that don't use udev?

Do these embedded systems really need the drm platform, or dont they want the
fbev platform?

> 
> I suggest keeping the gdm parts of the egl drm data structures conditioned on
> gdm being enabled.
> 
> Thanks,
> Thomas

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