[Qemu-devel] Re: vgabios + qemu: issues and plans.

["Sebastian Herbszt" <herbszt@gmx.de>]

Gerd Hoffmann wrote:
>   Hi,
> 
> Today we have two vgabios versions in qemu:  The standard one 
> (vgabios.bin) and the cirrus one (vgabios-cirrus.bin).
> 
> The cirrus vgabios is a PCI ROM.  We can (and do) load it into the ROM 
> PCI bar.  The vgabios checks the pci config space to figure where the 
> linear framebuffer (for vesa graphics) is mapped to.  It knows how to 
> program the cirrus.
> 
> The standard bios isn't a PCI ROM.  We have to load it using the seabios 
> firmware interface.  It expects to find the linear framebuffer at the 
> magic address 0xe0000000.  It uses the bochs extentions to implement 
> vesa graphics support.
> 
> So, what is wrong with this?
> 
> First, I'd like to be able to load the vgabios via PCI ROM bar on all 
> pci vga cards (stdvga, vmware, soon qxl).  The PCI ID in the bios has to 
> match the PCI ID of the card, so we'll need a bunch of vga bios 
> binaries, all identical except for the PCI ID.  Or we need some kind of 
> binary patching.  Otherwise seabios will not load them from the PCI ROM bar.

vgabios could be build multiple times with PCIBIOS set and VENDOR_ID and
DEVICE_ID supplied from the Makefile like it's already done with VGABIOS_DATE.

> Second, I want to get rid of the magic address 0xe0000000 (except for 
> isa-vga).  This is basically just a matter of updating to vgabios 
> version 0.6c.  And this needs one vga bios binary per vga card too as 
> the PCI ID is used to lookup the card (and then the framebuffer address) 
> in PCI config space.
> 
> Comments?  Especially on the binary patching?  Worth it?  Or just build 
> a bunch of binaries?  They are not *that* big after all ...

Few more bios binaries should do no harm. This is currently used for eepro100
(gpxe-eepro100-80861209.rom and gpxe-eepro100-80861229.rom). So maybe
define a similar naming convention for the vgabios.

Sebastian
 
> cheers,
>   Gerd
> 
> 
>