Re: [libvirt] [PATCH] qemu: fix command line building for iommu devices

On Mon, Oct 03, 2016 at 03:11:37PM +0200, Martin Kletzander wrote: > On Mon, Oct 03, 2016 at 03:02:38PM +0200, Peter Krempa wrote: > > On Mon, Oct 03, 2016 at 13:41:13 +0100, Daniel Berrange wrote: > > > The intel-iommu device has existed since QEMU 2.2.0, but > > > it was only possible to create it with -device since > > > QEMU 2.7.0, thanks to: > > > > > > commit 621d983a1f9051f4cfc3f402569b46b77d8449fc > > > Author: Marcel Apfelbaum <marcel(a)redhat.com&gt; > > > Date: Mon Jun 27 18:38:34 2016 +0300 > > > > > > hw/iommu: enable iommu with -device > > > > > > Use the standard '-device intel-iommu' to create the IOMMU device. > > > The legacy '-machine,iommu=on' can still be used. > > > > > > The libvirt capability check & command line formatting code > > > is thus broken for all QEMU versions 2.2.0 -> 2.6.0 inclusive. > > > > > > This fixes it to use iommu=on instead. > > > > > > Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; > > > --- > > > > Is there any value to make it work with older versions rather than just > > clearing it completely on the versions that don't support it with > > -device? > > > > I had one question as well. Are those invocations migration-compatible? > I can't try it right now, so I figured asking would be faster than > preparing two machines with different QEMU versions =) If they are not, > then I would just say clear it. Not sure, I'll investigate that.