Re: [Qemu-devel] [PATCH 04/13] qdev: add generic qdev_device_add()

[Gerd Hoffmann]

On 07/10/09 22:51, Paul Brook wrote:
> > > I think this is going in the wrong direction. The device tree provides us
> > > with a standard way of identifying which bus to add a device to. We
> > > should be removing uses of pci_create, not adding new ones.
> > Why?
> >
> > Let me guess: Because pci bus numbers are guest-changeable and thus not
> > stable?
>
> Because I don't think this code need to be bus specific.

Parts of the problem are certainly bus-specific though, such as parsing 
bus addresses.

> We also need to figure out the naming of multiple similar devices on the same
> bus. Possibly your "device id" could be used to identify devices on a bus.
> e.g. if we wanted two scsi adapters:
>
>   -device lsi,bus=pci0,id=foo
>   -device lsi,bus=pci0,id=bar
>   -device scsi-disk,bus=pci0/foo/scsi
>   -device scsi-disk,bus=pci0/bar/scsi

I think what we will see used in practice is:

 - either go with the defaults (i.e. don't specify a bus at all
   -> device is attached to the first (and often only)
   pci/scsi/usb/whatever bus.
 - or usage of ids to identify devices and busses.

I think nobody will use stuff like
  -device scsi-disk,bus=/main-system-bus/i440FX-pcihost/pci/lsi/scsi
in practice.

cheers,
  Gerd