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>
> > 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>
> > ---
>
> 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.