Re: [Qemu-devel] Re: [SeaBIOS] [PATCH 0/8] option rom loading overhaul.

[Anthony Liguori <anthony@codemonkey.ws>]

Kevin O'Connor wrote:
> On Fri, Dec 18, 2009 at 11:12:06AM -0600, Anthony Liguori wrote:
>   
>> BTW, the following works:
>>
>> sudo x86_64-softmmu/qemu-system-x86_64 -hda ~/images/linux.img -snapshot  
>> -m 512 -net nic,model=rtl8139,macaddr=56:54:32:12:34:56 -net  
>> nic,model=e1000,macaddr=56:54:32:12:34:57 -net  
>> nic,model=virtio,macaddr=56:54:32:12:34:58 -boot menu=on -net tap  
>> -kernel /boot/vmlinuz-2.6.27.38-170.2.113.fc10.x86_64 -initrd  
>> /boot/initrd-2.6.27.38-170.2.113.fc10.x86_64.img -append "ro"
>>
>> Using the F12 menu, I can select any of the three option roms and it  
>> network boots or I can select 'Legacy Option ROM' and it will boot from  
>> -kernel.  That is exceedingly cool :-)  We just need to give it a proper  
>> PnP header and advertise it as a BEV device so that we can give it a  
>> meaningful name.
>>     
>
> As it stands now, if the command line has -kernel, it will always boot
> from the kernel regardless of the item one selects in the boot menu.
>   
Ah, I spoke too soon, you are indeed correct.

I was wondering how that could possibly work :-)
> (Legacy roms are always run - the boot menu only selects the order wrt
> BCVs.)  However, converting the rom into a BEV will indeed make it
> selectable.
>
> Also, to see a truly interesting boot menu - try appending something
> like the following to the command line:
>
> -fda disk.dsk -fdb odin1440.img -hdd dos-drivec -cdrom ../../iso/win-vista.iso -drive file=../../iso/win-xp.iso,media=cdrom,index=1
>
> SeaBIOS allows one to boot from either floppy, any harddrive, and any
> cdrom.
>   

Very cool stuff!  We just have to figure out a way to let a user specify 
which of these devices they want to boot from via the qemu command 
line.   Maybe something that encodes a bus type and then an address on 
the bus or something like that.  I think that works okay for PCI and IDE 
buses.  For fw_cfg roms, I guess we could also just expose the filename 
as the address on the fw_cfg bus.

Regards,

Anthony Liguori