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

Gerd Hoffmann kraxel at redhat.com
Mon Oct 11 14:07:14 CEST 2010


> 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


   -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

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?


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