[Qemu-devel] debugging cirrus graphics corruption

[Qemu-devel] debugging cirrus graphics corruption

[Peter Lieven]

Hi,

with recent xserver a lot of people observe a graphics corruption with Cirrus Logic graphics. Especially
in Virtual Machines (easy to test with ubuntu 12.04.3 LTS 64-bit). I am not 100% sure if this is an
emulation problem.

Who can help with debugging? And who eventually has a hardware Cirrus Logic Graphic Card with GD5446
and could verify if the corruption also happens on bare hardware.

The corruption looks as if 3 Byte per Pixel data was copied on a 4 byte per pixel surface.

Thanks,
Peter

Re: [Qemu-devel] debugging cirrus graphics corruption

[Mark]

Hi,

On 21 Nov 2013, Peter Lieven wrote:
>with recent xserver a lot of people observe a graphics corruption with
Cirrus
>Logic graphics. Especially
>in Virtual Machines (easy to test with ubuntu 12.04.3 LTS 64-bit). I am not
>100% sure if this is an emulation problem.
>
>Who can help with debugging? And who eventually has a hardware Cirrus Logic
>Graphic Card with GD5446
>and could verify if the corruption also happens on bare hardware.
>
>The corruption looks as if 3 Byte per Pixel data was copied on a 4 byte per
>pixel surface.

There are definitely quite a few bugs in the current Cirrus Logic graphics
emulation. However they may well get fixed in the near future, if any qemu
devs want to look into it.

The developer of WinUAE (GPL Amiga emulator) recently integrated Cirrus
Logic code from qemu, and in doing that found and fixed various bugs.
Hopefully a detailed list of bugs and fixes will be posted to this list
and/or the qemu bugtracker in due course.

But in the mean time, you can compare the files from WinUAE git with the
current qemu source:
   https://github.com/tonioni/WinUAE/tree/master/qemuvga

There's a forum thread which has some basic description about some of the
bugs:
  http://eab.abime.net/showthread.php?t=69953

Another thread has links to some Cirrus Logic technical manuals including
that for the CL-GD5446, which might be of help if they're not already
widely available:
  http://eab.abime.net/showthread.php?t=67879


-- Mark