[Qemu-devel] Re: [PATCHv2 0/8 RFC] boot order specification

[Gleb Natapov <gleb@redhat.com>]

On Sun, Oct 31, 2010 at 06:25:53PM -0400, Kevin O'Connor wrote:
> On Sun, Oct 31, 2010 at 01:40:01PM +0200, Gleb Natapov wrote:
> > This is current sate of the patch series for people to comment on.
> > I tried to use open firmware naming scheme to specify device path names.
> > 
> > The patch series produce names like these:
> > for pci machine:
> > /pci@i0cf8/pci-isa-bridge@1/fdc@03f1/floppy@0
> > /pci@i0cf8/pci-isa-bridge@1/fdc@03f1/floppy@1
> > /pci@i0cf8/ata@1,1/ata-disk@1:0
> > /pci@i0cf8/ata@1,1/ata-disk@1:1
> > /pci@i0cf8/virtio-blk@3/virtio-disk@0
> > /pci@i0cf8/ethernet@4/ethernet-phy@0
> > /pci@i0cf8/ethernet@5/ethernet-phy@0
> > 
> > for isa machine:
> > adding '/isa/fdc@03f1/floppy@0' at index 2
> > adding '/isa/fdc@03f1/floppy@1' at index 1
> > adding '/isa/ata@0170/ata-disk@0:0' at index 0
> > adding '/isa/ata@0170/ata-disk@0:1' at index 3
> 
> Hi Gleb,
> 
> How will USB drives be identified?
> 
USB bus has Open Firmware binding. I haven't look at the spec yet, but it
should be easy.

> I'm not sure how SeaBIOS will be able to line up something like
> "/pci@i0cf8/ethernet@4/ethernet-phy@0" to an optionrom BEV.  Also, if
> there is an optionrom with BCVs (eg, a scsi card), I'm not sure how
> that would that would be identified.

The way to parse  "/pci@i0cf8/ethernet@4/ethernet-phy@0" is this: each
element (between /.../) consist of node-name@unit-address. node-name
describes device/bus. unit-address is a device address on preceding node.
So pci@i0cf8 tells us that this is pci bus accessible through io
register 0x0cf8, ethernet@4 tells us that this is ethernet device in pci
slot 4 function 0, (ata@1,1 means ata device in slot 1 function 1).
ethernet-phy@0 means first phy on this ethernet device (usually there is
only one anyway). So if the pci card in slot 4 device 0 has optionrom
with BCV Seabios can associate bootindex with it easily given the 
device path above.

--
			Gleb.