[RFC PATCH 17/17] KVM: PPC: Add an ioctl for userspace to select which platform to emulate
avi at redhat.com
Thu Jun 30 18:34:53 EST 2011
On 06/29/2011 02:58 PM, Josh Boyer wrote:
> >> This makes me wonder if a similar thing might eventually be usable for
> >> running an i686 or x32 guest on an x86_64 KVM host. I have no idea if
> >> that is even theoretically possible, but if it is it might be better to
> >> rename the ioctl to be architecture agnostic.
> >On x86 this is not required unless we want to "virtualize" pre-CPUID CPUs. Everything as of Pentium has a full bitmap of feature capabilities that KVM gets from user space, including information such as "Can we do 64-bit mode?".
> Ah. Thank you for the explanation.
To clarify a bit further, running an i686 guest on an x86_64 host is not
only theoretically possible, but is done regularly. First, x86_64 is
backwards compatible with i686 (so you can install a 32-bit OS on 64-bit
hardware), and second, you can impersonate 32-bit guest hardware on a
error compiling committee.c: too many arguments to function
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