Re: [Qemu-devel] [Qemu-ppc] Bug in qemu-system-ppc in Windows using the SDL2 GUI

[Thomas Huth <thuth@redhat.com>]

On 24.03.2017 09:56, Mark Cave-Ayland wrote:
> On 24/03/17 08:47, Howard Spoelstra wrote:
> 
>> Hi,
>>
>> Running qemu-system-ppc.exe in windows with the SDL2 GUI results in a
>> hangup. I bisected to this commit:
>>
>> 8bb93c6f99a42c2e0943bc904b283cd622d302c5 is the first bad commit
>> commit 8bb93c6f99a42c2e0943bc904b283cd622d302c5
>> Author: Alex Bennée <alex.bennee@linaro.org>
>> Date:   Wed Mar 15 14:48:25 2017 +0000
>>
>>     ui/console: ensure graphic updates don't race with TCG vCPUs
>>
>>     Commit 8d04fb55..
>>
>>       tcg: drop global lock during TCG code execution
>>
>>     ..broke the assumption that updates to the GUI couldn't happen at the
>>     same time as TCG vCPUs where running. As a result the TCG vCPU could
>>     still be updating a directly mapped frame-buffer while the display
>>     side was updating. This would cause artefacts to appear when the
>>     update code assumed that memory block hadn't changed.
>>
>>     The simplest solution is to ensure the two things can't happen at the
>>     same time like the old BQL locking scheme. Here we use the solution
>>     introduced for MTTCG and schedule the update as async_safe_work when
>>     we know no vCPUs can be running.
>>
>>     Reported-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>>     Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>     Message-id: 20170315144825.3108-1-alex.bennee@linaro.org
>>     Cc: BALATON Zoltan <balaton@eik.bme.hu>
>>     Cc: Gerd Hoffmann <kraxel@redhat.com>
>>     Cc: Paolo Bonzini <pbonzini@redhat.com>
>>     Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>
>>     [ kraxel: updated comment clarifying the display adapters are buggy
>>               and this is a temporary workaround ]
>>
>>     Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> Hi Howard,
> 
> Alex posted another patch yesterday to resolve a similar issue:
> https://lists.nongnu.org/archive/html/qemu-devel/2017-03/msg04474.html.
> 
> Does applying the above patch help at all?

Luigi Burdo reported a similar issue here:

https://bugs.launchpad.net/qemu/+bug/1675549

Luigi, could you please try Alex' patch to see whether it fixes your crash?

 Thanks,
  Thomas