Re: [Qemu-devel] [libvirt] ARM KVM GICv3 Support

[Andrew Jones]

On Tue, Feb 02, 2016 at 01:15:49PM +0000, Peter Maydell wrote:
> On 2 February 2016 at 12:59, Andrew Jones <address@hidden> wrote:
> > This actually doesn't matter for the v2 vs. v3 case. The gic-version 
> > property
> > doesn't exist at all for v2-only QEMU. Although maybe the gic-version 
> > property
> > should be reworked. Instead of gic-version=<highest-supported>, we could 
> > create
> > one boolean property per version supported, i.e. gicv2, gicv3, gicv4...
> 
> QEMU 2.5 released with the gic-version property, so we can't just drop
> it now; that would break users' command lines. We'd need a strong
> argument for why it's worth adding new properties that duplicate
> the legacy syntax.

I agree we should have a good argument to justify messing with it, but
until we start versioning mach-virt, then I don't think anybody should
depend on mach-virt command lines working everywhere. Every time we add
a new property, and a user adds it to their command line, then they've
just broken that command line for older QEMU. Yes, I know the upgrade
path is a bit different, but still... Anyway, properties are changeable
with versioned machines.

drew