Re: [Qemu-devel] No video for Windows 2000 guest

[Programmingkid]

> On Aug 10, 2017, at 3:37 AM, Michael Tokarev <address@hidden> wrote:
> 
> 10.08.2017 06:51, Thomas Huth wrote:
> []
> 
>> I guess you'll end up with QEMU 2.1 as good version and 2.2 as the first
>> "bad" version. According the qemu-doc:
>> 
>> -vga type
>> 
>>    Select type of VGA card to emulate. Valid values for type are
>> 
>>    cirrus
>> 
>>        Cirrus Logic GD5446 Video card. All Windows versions starting
>>        from Windows 95 should recognize and use this graphic card. For
>>        optimal performances, use 16 bit color depth in the guest and
>>        the host OS. (This card was the default before QEMU 2.2)
>> 
>>    std
>> 
>>        Standard VGA card with Bochs VBE extensions. If your guest OS
>>        supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
>>        you want to use high resolution modes (>= 1280x1024x16) then you
>>        should use this option. (This card is the default since QEMU
>>        2.2)
> 
> Both cirrus and stdvga worked in Win2k not-so-recently. Cirrus, IIRC,
> required a driver install, stdvga used "standard vga controller" which,
> in win2k, was always marked with yellow exclamation mark, just because
> the driver itself always sets that mark, "thinking" it is always wrong
> driver.
> 
> So no, it's not the switch from cirrus to std, it's something else.
> 
> /mjt

Here is the commit that causes Windows 2000 video problems: 

commit 94ef4f337fb614f18b765a8e0e878a4c23cdedcd
Author: Gerd Hoffmann <address@hidden>
Date:   Tue May 17 10:54:54 2016 +0200

    vga: add sr_vbe register set
    
    Commit "fd3c136 vga: make sure vga register setup for vbe stays intact
    (CVE-2016-3712)." causes a regression.  The win7 installer is unhappy
    because it can't freely modify vga registers any more while in vbe mode.