[Nouveau] Assertion failure in gallium on nv50

[Tavian Barnes]

I upgraded mesa, libdrm, xf86-video-nouveau and the DRM module to
latest git recently (previously I had git versions from Dec 22).  Now,
when I try to run a simple GL program with the DRI driver, it fails:

glxgears: /usr/include/nouveau/nouveau_pushbuf.h:135: BIND_RING:
Assertion `0' failed.

The old, previously working build of mesa and the DRI driver also
failed, which makes me think the problem has to do with the recent
libdrm or DDX changes (or possibly the DRM?).  A backtrace indicates
that the assertion happens in nv50_screen_create(), but I doubt that's
where the bug is as that routine hasn't changed recently.

Program received signal SIGABRT, Aborted.
0x00007ffff727b035 in raise () from /lib/libc.so.6
(gdb) bt
#0  0x00007ffff727b035 in raise () from /lib/libc.so.6
#1  0x00007ffff727c460 in abort () from /lib/libc.so.6
#2  0x00007ffff7274151 in __assert_fail () from /lib/libc.so.6
#3  0x00007ffff5348f7a in nv50_screen_create ()
   from /home/tavianator/abs/mesa-git/pkg/nouveau-dri-git/usr/lib/xorg/modules/dri/nouveau_dri.so
#4  0x00007ffff52fb585 in nouveau_drm_create_screen ()
   from /home/tavianator/abs/mesa-git/pkg/nouveau-dri-git/usr/lib/xorg/modules/dri/nouveau_dri.so
#5  0x00007ffff52f947d in dri_init_screen2 ()
   from /home/tavianator/abs/mesa-git/pkg/nouveau-dri-git/usr/lib/xorg/modules/dri/nouveau_dri.so
#6  0x00007ffff52f675c in dri2CreateNewScreen ()
   from /home/tavianator/abs/mesa-git/pkg/nouveau-dri-git/usr/lib/xorg/modules/dri/nouveau_dri.so
#7  0x00007ffff7ba89e7 in dri2CreateScreen () from /usr/lib/libGL.so.1
#8  0x00007ffff7b84bee in __glXInitialize () from /usr/lib/libGL.so.1
#9  0x00007ffff7b8026d in GetGLXPrivScreenConfig () from /usr/lib/libGL.so.1
#10 0x00007ffff7b811cf in glXChooseVisual () from /usr/lib/libGL.so.1
#11 0x0000000000401cf0 in ?? ()
...

I'm still trying to isolate the commit that caused this, but it's
annoying bisecting three different components.

-- 
Tavian Barnes