Comment 42 for bug 982889

@Adam, interesting. Indeed your problem also appears to be distinct from the OP. It looks like you have a hybrid graphics system and both intel and nouveau drivers are loading. It sounds like the nouveau driver isn't detecting any connected outputs and eventually unloads itself. The modesetting driver decides to load up after that for some reason, and immediately proceeds to segfault.

From your comment #39 it sounds like with the patch, X is getting further along? Looking at your original bug (#1125759) you had been seeing this problem early on, which broke everything subsequent to it:

[ 3.579] (II) config/udev: Adding drm device (/dev/dri/card1)
[ 4.377] (II) config/udev: Adding drm device (/dev/dri/card0)
[ 4.377] setversion 1.4 failed <--- oops
[ 4.379] (--) PCI:*(0:0:2:0) 8086:0126:1028:0446 rev 9, Mem @ 0xf1400000/4194304, 0xe0000000/268435456, I/O @ 0x00004000/64
[ 4.379] (--) PCI: (0:1:0:0) 10de:0df5:1028:0446 rev 161, Mem @ 0xf0000000/16777216, 0xc0000000/268435456, 0xd0000000/33554432, I/O @ 0x00003000/128, BIOS @ 0x????????/524288

Now you're seeing this:

[ 3.610] (II) config/udev: Adding drm device (/dev/dri/card1)
[ 5.309] (II) config/udev: Adding drm device (/dev/dri/card0)
[ 5.311] (--) PCI:*(0:0:2:0) 8086:0126:1028:0446 rev 9, Mem @ 0xf1400000/4194304, 0xe0000000/268435456, I/O @ 0x00004000/64
[ 5.311] (--) PCI: (0:1:0:0) 10de:0df5:1028:0446 rev 161, Mem @ 0xf0000000/16777216, 0xc0000000/268435456, 0xd0000000/33554432, I/O @ 0x00003000/128, BIOS @ 0x????????/524288

I would expect the patch to show some debug info if it is applying its fix; it should display a stream of "drm device not ready (#), sleeping for 20us" messages, and then the system should boot up to fully functional (or some permutation thereof). So, I'm not sure we can say the patch fixed it for you; it could be just coincidental. This is a race condition after all, and as such can be influenced by all manner of random things, and maybe it just had lucky timing on that boot.

As to the modesetting segfault, that would be worth tracking as its own bug. Did a crash file get generated for that in /var/crash/ ?