Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios

[Gleb Natapov <gleb@redhat.com>]

On Mon, Oct 11, 2010 at 02:07:14PM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> >Floppy? Yes, I think we do.
> 
> And *one* floppy controllers can actually have *two* drives
> connected, although booting from 'b' doesn't work IIRC.
> 
> >>and since one PCI device may
> >>control more then one disk (ATA slave/master, SCSI LUNs). We can do what
> >>EDD specification does. Describe disk as:
> >>     bus type (isa/pci),
> >>     address on a bus (16 bit base address for isa, b/s/f for pci)
> >>     device type (ATA/SCSI/VIRTIO)
> >>     device path (slave/master for ATA, LUN for SCSI, nothing for virtio)
> >
> >If we had a qdev ID for all devices (which I think we should have
> >anyway), would this work or is a string not really handy enough?
> 
> I think we'll need support for that in all drivers supporting boot
> anyway, i.e. have virtio-blk-pci register a boot edd when configured
> that way.  Question is how to configure this.  We could attach the
> boot index to either the blockdev or the device, i.e.
> 
>   -blockdev foo,bootindex=1
> 
> or
> 
>   -device virtio-blk-pci,bootindex=1
> 
> The latter looks more useful to me, boot order is guest state imho,
> also it might expand to PXE booting nicely, i.e.
> 
>   -device e1000,bootindex=2
> 
Yes, boot order is a guest sate managed by BIOS on real HW.

> Which turns up the question how this plays with option roms.
> seabios should be able to order at pci device level at least when
> booting via (pci) option rom.  OK for nics.  Booting from a scsi
> disk with id != 0 using the lsi rom is probably impossible though.
> 
> What about non-pci option roms?  The one used for -kernel for example?
> 
-option-rom rom.bin,bootindex=3?

We can pass boot index along with option rom via fw_cfg interface.

--
			Gleb.