On Tue, Oct 02, 2012 at 08:45:54PM +0100, Peter Maydell wrote:

On 2 October 2012 20:28, Will Deacon [off-list ref] wrote:

quoted

On Tue, Oct 02, 2012 at 07:31:43PM +0100, Peter Maydell wrote:

quoted

We probably want to be passing in the "base of the cpu-internal
peripherals", rather than "base of the GIC" specifically. For the
A15 these are the same thing, but that's not inherent [compare the
A9 which has more devices at fixed offsets from a configurable
base address].

If you do that, userspace will need a way to probe the emulated CPU so
that is knows exactly which set of peripherals there are and which ones it
needs to emulate. This feels pretty nasty, given that the vgic is handled
more or less completely by the kernel-side of things.

Userspace knows what the emulated CPU is because it tells the
kernel which CPU to provide -- the kernel can say "yes" or "no" but
it can't provide a different CPU to the one we ask for, or
one with bits mising...

Aha, ok, I didn't realise that's how it works. Does userspace just pass the
CPUID or is there an identifier provided by kvm?

/me jumps back into the code.

Thanks,

Will