Messages in this thread | | | Subject | RE: [kvm-devel] [PATCH] Refactor hypercall infrastructure | Date | Fri, 14 Sep 2007 17:10:03 -0700 | From | "Nakajima, Jun" <> |
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Jeremy Fitzhardinge wrote: > Nakajima, Jun wrote: > > > > one. Start the kvm leaves at 0x40001000 or something? > > > > > > > > > > > Yeah, that works with me. > > > > > > > To me this is the beginning of fragmentation. Why do we need different > > and VMM-specific Linux paravirtualization for hardware-assisted > > virtualization? That would not be good for Linux. > > > > On the contrary. Xen already has a hypercall interface, and we need to > keep supporting it. If we were to also support a vmm-independent > interface (aka "kvm interface"), then we need to be able to do that in > parallel. If we have a cpuid leaf clash, then its impossible to do so; > if we define the new interface to be disjoint from other current users > of cpuid, then we can support them concurrently. > > J
Today, 3 CPUID leaves starting from 0x4000_0000 are defined in a generic fashion (hypervisor detection, version, and hypercall page), and those are the ones used by Xen today. We should extend those leaves (e.g. starting from 0x4000_0003) for the vmm-independent features as well.
If Xen needs additional Xen-specific features, we need to allocate some leaves for those (e.g. 0x4000_1000)
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