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

[Anthony Liguori <anthony@codemonkey.ws>]

Gerd Hoffmann wrote:
> On 12/15/09 03:37, Anthony Liguori wrote:
>> Okay, I think I've figured out how this is supposed to work. With these
>> two patches to SeaBIOS and the patch to qemu, I can run:
>>
>> qemu -net nic,model=rtl8139 -net nic,model=virtio -net nic,model=e1000
>> -boot menu=on
>>
>> And all three option roms load. I can also select which NIC I want to
>> boot from using the F12 menu. This works by not actually loading the
>> option roms in the 1M space, but instead making them mappable through
>> the PCI devices. With PMM and DDIM, the result is that we only have to
>> copy in 2K for each option rom which means we can support up to 48
>> unique option roms. That should be plenty for now.
>>
>> These patches are very rough but I'll clean them up tomorrow. I'm not
>> sure the best way to integrate with the rom infrastructure since we no
>> longer have a physical address to map to. Any suggestions Gerd?
>
> Is this needed in the first place?  Integration into pci like your 
> patch does looks sensible to me.  That wouldn't get us re-loading on 
> reset, but as the guest shouldn't be able to modify the roms I don't 
> think we need this ...
>
> We could also add a "romfile" property to the pci bus and do 
> everything (except setting the default filename) in generic pci code.
>
> I'm more worried about the CONFIG_OPTIONROMS_DEPLOYED patches for 
> seabios, although I don't fully understand what they are doing.  There 
> are non-pci option roms (linuxboot, multiboot, extboot) which qemu 
> will continue to deploy the way roms are deployed today.

That's a good point.  Need to think about how to best handle that.  
SeaBIOS supports up to two static option roms so maybe what we need to 
do is make use of that mechanism for things like linuxboot/extboot.

Regards,

Anthony Liguori