Re: [Qemu-devel] [kvm-unit-tests PATCH v7 00/11] QEMU MTTCG Test cases

[Andrew Jones]

On Mon, Nov 28, 2016 at 01:30:54PM +0000, Peter Maydell wrote:
> On 28 November 2016 at 11:58, Andrew Jones <address@hidden> wrote:
> > On Mon, Nov 28, 2016 at 11:14:48AM +0000, Peter Maydell wrote:
> >> On 28 November 2016 at 11:12, Alex Bennée <address@hidden> wrote:
> >> >
> >> > Andrew Jones <address@hidden> writes:
> >> >> I've skimmed over everything looking at it from a framwork/sytle
> >> >> perspective. I didn't dig in trying to understand the tests though.
> >> >> One general comment, I see many tests introduce MAX_CPUS 8. Why do
> >> >> that? Why not allow all cpus by using NR_CPUS for the array sizes?
> >> >
> >> > Yeah - I can fix those. I wonder what the maximum is with GIC V3?
> >>
> >> So large that you don't want to hardcode it as an array size...
> >
> > 255 with the gic series, not yet merged.
> 
> I was talking about the architectural GICv3 limit, which is larger
> than that by many orders of magnitude. For QEMU it looks like
> MAX_CPUMASK_BITS is now 288 rather than 255.

Ah, yeah. So far we haven't considered testing limits beyond what
KVM supports, VGIC_V3_MAX_CPUS=255. However with TCG, and some
patience, we could attempt to test bigger limits. In that case,
though, we'll want to recompile kvm-unit-tests with a larger NR_CPUS
and run a specific unit test.

mach-virt still has 255 as well, mc->max_cpus = 255, so we'd have
to bump that too if we want to experiment.

Thanks,
drew