Re: [Qemu-devel] Re: Re: NE2K PCI and Windows 98SE & Cirrus Logic

[Fabrice Bellard]

Antony T Curtis wrote:
> On Tue, 2004-06-08 at 09:18, Mike Nordell wrote:
>
> > Leigh Dyer wrote:
> >
> >
> > > I can also confirm that the 4Mb video RAM patch committed a couple of
> > > hours ago fixes the Cirrus Logic video with Win2k - it detected the
> > > card at install and seems to be running quite happily with the
> > > standard driver that ships with Win2k.
> >
> > Ah, wonderful! I just tested and can confirm it too. No more slow VGA! :-)
>
>
> I am still having problems with WinXP ... it appears to be trying to to
> vram to vram color-expand pattern bitblts starting from the first byte
> after the end of the current display (ie 800x600x16bit, src =
> 0x000ea600)
> However, when I examine these bytes, they are always zero - which I
> think is partly to blame for the display problems I am having.
>
> To correct this, I have to turn off all acceleration.

It seems to be a bug in the Windows NT Cirrus driver. It uses pattern 
fill for solid fill (as on a 5430), but it does not initialize the 
pattern buffer correctly. I made a kludge in the device emulation by 
initializing the VGA memory to 0xff at boot time.

A possible explanation of that problem is that NT does not recognize the 
VGA card as a true 5446. It may use some undocumented register to do the 
device probing instead of the PCI device ID.

For example, I spent a long time to find that NT uses SR15 to probe the 
memory size (it was a bug indicated by early users...).

Fabrice.