Re: [Qemu-devel] [6989] Fix display breakage when resizing the screen (v2) (Avi Kivity)

[Avi Kivity]

Ryan Harper wrote:
> * Avi Kivity <address@hidden> [2009-04-06 10:21]:
>   
> > Stefano Stabellini wrote:
> >     
> > > Can you please let me know a simple way to reproduce the breakage Avi
> > > was trying to fix?
> > >  
> > >       
> > The trigger is kvm-autotest; I think you can easily reproduce it by 
> > booting a guest with vnc (unconnected), and issueing a screendump 
> > through the monitor (use -monitor stdio, not on the console...) every 
> > second.
> >     
>
> yeah, and btw, with this patch merged into kvm-userspace as of today,
> I'm still tripping over it[1] on some guests (RHEL5.3 x86_64 install).
>
>
> 1. http://pastebin.ca/1384339
>
>   

I found the real cause - vga_screen_dump() left values for the current 
display resolution in s->last_width and s->last_height.  This caused the 
next vga_draw_graphic() to render to the 640x400 display surface it had 
without resizing it.

The bug is triggered if you manage to screendump after a screen 
resolution change, but before the next bitblit or console refresh.  If 
no vnc or sdl client is connected, that's just the next bitblt so the 
window is considerably longer.

I'll follow up with a patch.  Anthony, please revert 6989 before 
applying it.  Thanks to Stefano for pointing out the problems with the 
patch.

--
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