On Wed, Jan 19, 2011 at 10:53:30AM -0600, Anthony Liguori wrote: > On 01/19/2011 03:48 AM, Gerd Hoffmann wrote: > >On 01/18/11 18:09, Anthony Liguori wrote: > >>On 01/18/2011 10:56 AM, Jan Kiszka wrote: > >>> > >>>>The device model topology is 100% a hidden architectural detail. > >>>This is true for the sysbus, it is obviously not the case for PCI and > >>>similarly discoverable buses. There we have a guest-explorable topology > >>>that is currently equivalent to the the qdev layout. > >> > >>But we also don't do PCI passthrough so we really haven't even explored > >>how that maps in qdev. I don't know if qemu-kvm has attempted to > >>qdev-ify it. > > > >It is qdev-ified. It is a normal pci device from qdev's point of view. > > > >BTW: is there any reason why (vfio-based) pci passthrough couldn't > >work with tcg? > > > >>The -device interface is a stable interface. Right now, you don't > >>specify any type of identifier of the pci bus when you create a PCI > >>device. It's implied in the interface. > > > >Wrong. You can specify the bus you want attach the device to via > >bus=<name>. This is true for *every* device, including all pci > >devices. If unspecified qdev uses the first bus it finds. > > > >As long as there is a single pci bus only there is simply no need > >to specify it, thats why nobody does that today. > > Right. In terms of specifying bus=, what are we promising re: > compatibility? Will there always be a pci.0? If we add some > PCI-to-PCI bridges in order to support more devices, is libvirt > support to parse the hierarchy and figure out which bus to put the > device on? The answer to your questions probably differ depending on whether '-nodefconfig' and '-nodefaults' are set on the command line. If they are set, then I'd expect to only ever see one PCI bus with name pci.0 forever more, unless i explicitly ask for more. If they are not set, then you might expect to see multiple PCI buses by appear by magic Daniel -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
