I've been thinking about how to use the cpuid hypercall. Right now the x86 backend does foreach proc bind on this proc do a lot of cpuid calls
It would do instead foreach proc cpuid hypercall on this proc So we would 1) add a cpuid(topology, cpu, inputbuffer, outputbuffer) hook pointer in the topology structure 2) have xen define that hook (using a new function since the topology internals are not visible to plugins). It could be in the xen discover() callback. Or it could be in the instantiate() callback if we want the x86 backend to work when used before the xen backend. I think we just have to be sure we don't enable that hook before we're sure the Xen backend will work. 3) when this hook is defined, the x86 backend doesn't need to bind anymore, but it uses that cpuid hook instead of raw cpuid instructions. We may want to make inputbuffer and outputbuffer generic enough (void* + length) so that the model works for other architectures one day? Xen will know that they correspond to inputbuffer=one-register and outputbuffer=four-registers when running on x86. Brice
