[Bug 109949] [skl] Hard lockup (Freeze) after reset failure

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=109949

--- Comment #18 from Arcadiy Ivanov <arcadiy at ivanov.biz> ---
> The original issue is related to GPU hang. But in the attached log I can't find any information about the hang.

>> [...] and send dmesg from boot with drm.debug=0x1e log_buf_len=4M?

@lakshmi

Yes, it's not in the logs. 

Firstly the volume of log generation is such that 1 min after the boot dmesg
logs overflow the buffer.

Secondly there is no way for me to retrieve them if they were somehow
generated. Once the GPU lock happens everything stops. And I do mean EVERYTHING
- the machine is hard-locked with absolutely no possibility of access until
hard power off:
- X is completely frozen
- there is no disk activity
- keyboard is completely unresponsive 
- no ctrl-alt-delete or switching to tty or ctrl-alt-backspace
- plugging in external devices or unplugging them produces no response
- closing laptop doesn't work and the laptop does not suspend

The machine is completely frozen.

> Can you check if you have the crash dump file /sys/class/drm/card0/error?

The contents of `error` does not survive the power-off and I'm not able to
retrieve the data. I'll try to see if I can collect it somehow with inotify on
`/sys/class/drm/card0/error` to see if I can dump it.

The reason I suspect this is a GPU hang is that video playback freezes, the
hardware mouse cursor is still active for a few seconds until the full freeze
takes over the machine.

Is there any reliable way to make card crash dump survive the reboot?

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