Re: Proper support for PCI-based option rom loading (was Re: [Qemu-devel] Re: qdev property bug?)

[Gerd Hoffmann <kraxel@redhat.com>]

On 12/15/09 23:51, Sebastian Herbszt wrote:
> Qemu will map rom1.bin to PC_ROM_MIN_OPTION (0xc8000) and map rom2.bin
> to 0xd0000.

No.

rom1.bin will be loaded to max(0xc8000, 0xc0000 + cirrus-bios-size)
aligned to 2k, which (with cirrus) is 0xc90000.

rom2.bin will be loaded after rom1.bin (also 2k aligned), so the address 
will depend on rom1.bin size.

> Either qemu will map vga bios to PC_ROM_MIN_VGA (0xc0000) or
> SeaBIOS will map it there (with pci 3.0 it could map it somewhere else,
> but i doubt thats
> a good idea). In case the vga bios size is below 0x8000, some rom space
> is lost.

Because it is larger than 0x8000 option roms will be overwritten when 
loaded to 0xc8000

> SeaBIOS
> will scan the option rom space starting at PC_ROM_MIN_OPTION and adjust
> its RomEnd in
> case a rom is found. Then it will start the pci scan and map pci option
> roms after RomEnd.

Doesn't fly.

I think either qemu or seabios should load *all* roms. I think the idea 
to provide non-pci roms via fw_cfg and let seabios load them is the best 
idea we had so far.

cheers,
   Gerd