[Qemu-devel] Re: [RFC PATCH 0/5] Introduce canonical device hierarchy string

[Gerd Hoffmann]

  Hi,

> My premise with this attempt is that we walk the hierarchy and use the
> names to create the base of the path.  As we get to the device,
> particularly to the parent bus of the device, we need to start looking at
> properties to ensure uniqueness.

You'll need that for every bus along the way down to the device.  Create 
a virtual machine with two lsi scsi host adapters, then attach a disk 
with scsi id 0 to each.  Just the scsi id isn't good enougth to identify 
the device.  You'll need the lsi pci address too.

> For now, the only properties I've tagged as path
> properties are PCI bus addresses and MAC addresses.

mac address isn't needed here.  You need the property which specifies 
the bus address.  For PCI this obviously is the PCI address.  For scsi 
the scsi id.  For ISA you can use the I/O port base.  virtio-serial the 
port number, ...

cheers,
  Gerd