[Mesa-dev] New GBM backend for dEQP

[Chad Versace]

Happy Christmas to everyone who's busy squashing dEQP bugs.

I wrote a new GBM backend for dEQP. I even submitted it to dEQP's
upstream Gerrit.  Pyry, dEQP's maintainer, told me over beer earlier
this year that he would accept it if I submitted it, and if it wasn't
too crazy. So, maybe it'll be upstream soon.

If you want to try it out, you can either fetch the patch from Gerrit:
    $ git fetch https://android.googlesource.com/platform/external/deqp refs/changes/43/315743/1

View it on Gerrit:
    https://android-review.googlesource.com/#/c/315743/

Fetch from personal my work-in-progress branch:
    $ git fetch git://git.kiwitree.net/~chadv/deqp refs/heads/wip/gbm

View it on my cgit:
    http://git.kiwitree.net/cgit/~chadv/deqp/log/?h=wip/gbm

GBM today does not support pixmaps nor pbuffers (eglCreatePixmapSurface
and eglCreatePbufferSurface), so the dEQP test coverage with GBM does
not have parity with X11. But, on the other hand, you get to run dEQP
without the headache of X11.

There's probably bugs. No surprises there.

What prompted my painful misadventures into dEQP's circus of abstract
factory registries?

    - Some dEQP tests intermittently fail on X11, most likely due to
      dEQP's misuse of multi-threaded Xlib. See
      <https://bugs.freedesktop.org/show_bug.cgi?id=98331>.
      On the new GBM backend, the test results are consistent. They
      consistently fail ;)

    - Some tests run much faster without the overhead of X11.
      The dEQP-EGL.functional.negative_api.* tests run almost instantly.

    - Intel's Jenkins prefers headless testing over X11.