[ubuntu-x] Intel GPU hangs and batchbuffer dumps

[Geir Ove Myhr]

Hi xorgers,

We used to ask for batchbuffer dumps for GPU hang bugs (freezes) on
intel in order to help upstream figure out the cause. It turns out
that these are currently not useful for upstream anymore with Lucid,
since kernel 2.6.32 automatically resets the GPU after a hang is
detected. Chris Wilson has an experimental kernel patch [1] that will
save the state of the batchbuffer to
/sys/kernel/debug/dri/.../i915_error_state [2]. I have tried to
compile 2.6.33-rc8 with the patch, but after following the
instructions on [3] the kernel doesn't boot with my Lucid. Would it be
possible for someone with more kernel knowledge than me to build a
recent kernel with the patch and put it in a semi-official place so
that we can ask people with freeze bugs to record the batchbuffer with
that kernel?

I have updated https://wiki.ubuntu.com/X/Troubleshooting/Freeze to
reflect the situation.

Btw, does anybody know more about how the GPU resetting works? What
happens after a GPU hang is detected and the GPU is reset? Does xorg
need to be restarted or should it in theory recover automatically?

[1]: http://lists.freedesktop.org/archives/intel-gfx/2010-February/005894.html
[2]: http://lists.freedesktop.org/archives/intel-gfx/2010-February/005810.html
[3]: https://wiki.ubuntu.com/KernelTeam/GitKernelBuild

Geir Ove