Re: [Qemu-devel] [PULL 3/3] cirrus: Fix host CPU blits

[Peter Lieven]

On 14.07.2014 09:29, Benjamin Herrenschmidt wrote:
> On Mon, 2014-07-14 at 09:24 +0200, Peter Lieven wrote:
> > it seems you have digged into the cirrus code recently. Have you an idea how to
> > fix the issue with the graphics corruption for cirrus vga and recent X Server 
> > versions?
> >
> > E.g. take an Ubuntu 14.04 Desktop CD, boot it into live mode and open terminal.
> >
> > I have tried to debug it a little, but I have no clue how to solve this. I 
> > tried to get
> > hands on a real hardware Cirrus Logic Graphics card and test if this happens 
> > there as well,
> > but I had no chance to get one.
> I *think* it is a X server side bug. They broke 24bpp packed pixel
> format. I've seen patches submitted to the Xorg list fairly recently by
> somebody from canonical.
>
> You can test by creating an xorg.conf to force the display to 16bpp
> instead of 24 and see if that helps.

Will do, thanks for the pointer.

Do you see a way to work around this in the graphics driver. E.g. blacklisting 
24bpp modes
etc. Even if X.Org people actually merge the fixes there are 2 years of Linux 
releases out
there that have corrupted graphics.

Peter