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

On Mon, Oct 03, 2016 at 14:04:02 +0100, Daniel Berrange 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? > > Err that's what this change does I asked incorrectly. I see that this adds support to enabling the iommu via -machine, but I want to know whether that is of any value. I'd just drop the capability and allow it to work since 2.7.0 only as it's a new feature anyways.