On Tue, Sep 24, 2013 at 06:01:02AM -0400, Laine Stump wrote: > When I added support for the Q35-based machinetypes to libvirt, I > specifically prohibited attaching any PCI devices (with the exception of > graphics controllers) to the PCIe root complex,
That's wrong I think. Anything attached to RC is an integrated endpoint, and these can be PCI devices. > and had planned to > prevent attaching them to PCIe root ports (ioh3420 device) and PCIe > downstream switch ports (xio-3130 device) as well. I did this because, > even though qemu currently allows attaching a normal PCI device in any > of these three places, the restriction exists for real hardware and I > didn't see any guarantee that qemu wouldn't add the restriction in the > future in order to more closely emulate real hardware. > > However, since I did that, I've learned that many of the qemu "pci" > devices really should be considered as "pci or pcie". Gerd Hoffman lists > some of these cases in a bug he filed against libvirt: > > https://bugzilla.redhat.com/show_bug.cgi?id=1003983 > > I would like to loosen up the restrictions in libvirt, but want to make > sure that I don't allow something that could later be forbidden by qemu > (thus creating a compatibility problem during upgrades). Beyond Gerd's > specific requests to allow ehci, uhci, and hda controllers to attach to > PCIe ports, are there any other devices that I specifically should or > shouldn't allow? (I would rather be conservative in what I allow - it's > easy to allow more things later, but nearly impossible to revoke > permission once it's been allowed). IMO, we really need to grow an interface to query this kind of thing. -- MST