Description of problem:
Mesa is built with --enable-gallium-egl in rawhide/21. This flag enables the egl_gallium backend. I think that the egl_gallium backend is deprecated and Fedora should be using the egl_dri2 backend instead.
Running configure --help shows that --disable-gallium-egl is the default and emphasizes that this option is not required to use EGL (because the default egl_dri2 backend already supports the gallium device drivers). The implication is that you need a good reason to enable gallium-egl.
Mesa has been moving over to the egl_dri2 backend for some years. The mesa git logs for egl_dri2 (src/egl/drivers/dri2) and egl_gallium (src/gallium/state-trackers/egl) show that the overwhelming majority of development is now in the egl_dri2 backend. The few cases where egl_gallium offers advantages over egl_dri2 should disappear as development continues on egl_dri2 backend. On the other hand, the disadvantages in the egl_gallium backend may remain in place forever. Indeed, the egl_gallium backend may be dropped at some point to simplify the mesa code base.
The mesa configure disables the egl_gallium backend by default because the default EGL backend changes from egl_dri2 to egl_gallium as soon as --enable-gallium-egl is set (see src/egl/main/egldriver.c). When the egl_gallium backend is enabled then the obscure environment variable EGL_DRIVER=egl_dri2 must be set to be certain of using the egl_dri2 backend.
One major disadvantage in the egl_gallium backend is its failure to implement gbm_surface_create under the drm platform. gbm_surface_create is vital to wayland compositors like weston or cogl. These compositors only run on Fedora rawhide because _eglMatchAndInitialize in src/egl/main/egldriver.c fallbacks to the egl_dri2 backend when the egl_gallium backend refuses to accept the gbm_device that the compositor created to use KMS. If the obscure environment variable GBM_BACKEND=gbm_gallium_drm.so is set then the compositors will create a gbm_device using the gbm_gallium backend. This gbm_device will then be accepted by the egl_gallium backend and the compositors will segfault when they try to call gbm_surface_create.
You should consult with the gallium, dri2 and freedreno developers before disabling the egl_gallium backend, since there may be special cases where the egl_gallium backend is useful. I guess that the arm platform might be one case.
This bug appears to have been reported against 'rawhide' during the Fedora 22 development cycle.
Changing version to '22'.
More information and reason for this action is here:
It looks that this option was removed from mesa and it's no longer used in Fedora >= 21.