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

[Mark Cave-Ayland]

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 <address@hidden>
> 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 <address@hidden>
>     Signed-off-by: Alex Bennée <address@hidden>
>     Message-id: address@hidden
>     Cc: BALATON Zoltan <address@hidden>
>     Cc: Gerd Hoffmann <address@hidden>
>     Cc: Paolo Bonzini <address@hidden>
>     Signed-off-by: Alex Bennée <address@hidden>
> 
>     [ kraxel: updated comment clarifying the display adapters are buggy
>               and this is a temporary workaround ]
> 
>     Signed-off-by: Gerd Hoffmann <address@hidden>

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?


ATB,

Mark.