[SeaBIOS] [PATCH] Support more than one vga card

Sebastian Herbszt herbszt at gmx.de
Wed May 4 00:31:30 CEST 2011

Glauber Costa wrote:
> On Wed, 2011-05-04 at 00:02 +0200, Sebastian Herbszt wrote:
>> Anthony Liguori wrote:
>> > On 05/03/2011 03:23 PM, Sebastian Herbszt wrote:
>> >> Glauber Costa wrote:
>> >>> It is theorectically possible for a system to have more than
>> >>> one pci vga card. In particular, I am interested in the use of SGAbios
>> >>> as a pci device, alongside of a normal vga bios in QEMU.
>> >>
>> >> Can't SGAbios be loaded as an option rom without this change?
>> > 
>> > But then you're loading it as a legacy ROM which is fairly ugly and 
>> > requires additional SeaBIOS hackery.
>> Why is this ugly and which additional hackery does it need?
>> SGAbios is a legacy ROM; the PNP header is disabled and there is no PCIR.
> It is, but does not need to be (I've also patched sgabios to include a
> PCIR). Since it is a device, it is nice to have it plugged it to a bus.
> If for nothing else, for discovering capabilities - A guest using
> sgabios this way is now aware that it has a double-head system.

I don't think "it is a device", more likely a functionality. SGAbios doesn't add a new
device/hardware to the system.
Do you plan to add a new (emulated) PCI device and deploy SGAbios thru its BAR?
Do you plan to add support for "Google Memory Console"?

> Also, let us not focus only in the specifics: Having two pci vga cards
> is a real possibility, there's even a use case for that, as anthony
> mentioned.

If you call the init function of two vga roms, will the last one win and hook int 10h?


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