Hi,
I think the proper fix must be done in the BIOS (set VRAM to 0xFF at
cirrus mode init). I made a patch for that but I must test it a little more.
Fabrice.
Dugger, Donald D wrote:
Leo-
Yeah, I started there but it turns out there are multiple reasons why
that is the wrong place to fix things:
1) `hw/vga.c' only knows about resolution changes, the bug also appears
if you change the pixel size, e.g. 24 bpp to 16 bpp.
2) Technically, because of the lazy screen update, your change would be
too late. To improve performance the vga code is only called
periodically, not after every VRAM change. It is theoretically possible
for the target to change video mode, assume VRAM got reset, do a bitblt
from non-visible VRAM to visible VRAM and then have the `hw/vga.c' code
get called, overwriting the changes done to visible VRAM.
--
Don Dugger
"Censeo Toto nos in Kansa esse decisse." - D. Gale
[EMAIL PROTECTED]
Ph: (303)440-1368
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
] On Behalf Of Leonardo E. Reiter
Sent: Tuesday, May 09, 2006 2:29 PM
To: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH]Fix for minor video
corruption under Windows
Donald...
thanks... I actually posted a patch to fix this sometime ago, but your
patch seems more thorough and probably more correct. Just FYI, I
attached my patch again. I will test your patch as well.
Thanks again,
Leo Reiter
Donald D. Dugger wrote:
If you change the video resolution while running a Windows
XP image such that
it uses fewer bytes of VRAM (either by using fewer bytes per
pixel or by
lowering the resolution) then some window backgrounds will
become corrupted.
This happens because the Windows XP Cirrus Logic driver
assumes that VRAM is
initialized to 0xff whenever the video mode switches between
VGA and SVGA.
This patch fixes this problem by resetting VRAM whenever a
VGA/SVGA mode switch
occurs.
Signed-off-by: [EMAIL PROTECTED]
--
Leonardo E. Reiter
Vice President of Product Development, CTO
Win4Lin, Inc.
Virtual Computing that means Business
Main: +1 512 339 7979
Fax: +1 512 532 6501
http://www.win4lin.com
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