On 29 October 2018 at 15:40, Marc Zyngier <[email protected]> wrote: > My temptation would be not to expose it at all when running on a v7 > core, and return an error rather than zero. > > The other issue is that we currently don't support running 32bit KVM on > any ARMv8 platform, as we strictly check the CPUs we want to run on (A7 > and A15). I remember seeing patches that would allow any host core to be > used (similar to what we have on the 64bit side), but that never made it > in the tree.
Ah, that's convenient in some ways. It means we can define the API to be "for v7, no register available via the ONE_REG API; for v8, always present", provided we add the constant and the support before we turn on any actual v8 CPUs for 32-bit KVM (avoiding the awkward case of "v8 but kernel doesn't expose MVFR2"). I don't think we particularly care about the 32-bit-kvm-on-v8 part, but it would be good to nail down this wrinkle so we don't forget about it, maybe ? thanks -- PMM
