Intel <=> AMD

Posted Mar 3, 2007 9:36 UTC (Sat) by addw (guest, #1771)
Parent article: KVM 15

''guest systems can be moved between Intel and AMD processors with no problems at all.''

What about those programs that use different instructions depending on the CPU ? These generally detect the CPU type when they start, but after a migration they will fail - since they don't redetect again.

Intel <=> AMD

Posted Mar 4, 2007 6:04 UTC (Sun) by avik (guest, #704) [Link]

Programs detect cpu capabilities by means of the cpuid instruction. Since
that instruction is itself virtualized and controlled by the host
userspace, one can tell virtualize a processor with the least capabilities
that are in use on the server farm. Gievn that, programs will only use
instructions that are present on all processors that can be a migration
target.