Does anyone know if SLES supports any CPU masking? I have a large pool of sles xen servers on various HP platforms, G6, G7, G8. I can live migrate from older to newer servers but not the other way around. I assume this is because of cpu differences. I''ve been searching and reading about setting cpuid on the VM but it had no affect. I''m assuming it''s being ignored but not sure. I have not done anything to setup or enable cpuid or cpu masking. My xen version is: xen-4.1.5_02-0.5.1 on SLES11SP2. CPU info on two of the hosts. In case this doesn''t come through, the two major differences are (I think): model 45 vs 26 Stepping 7 vs 5 cpuid level 13 vs 11 processor : 1 processor : 1 vendor_id : GenuineIntel vendor_id : GenuineIntel cpu family : 6 cpu family : 6 model : 45 model : 26 model name : Intel(R) Xeon(R) CPU E5-2640 0 @ 2.50GHz model name : Intel(R) Xeon(R) CPU E5540 @ 2.53GHz stepping : 7 stepping : 5 cpu MHz : 2494.080 cpu MHz : 2533.490 cache size : 15360 KB cache size : 8192 KB fpu : yes fpu : yes fpu_exception : yes fpu_exception : yes cpuid level : 13 cpuid level : 11 wp : yes wp : yes flags : fpu de tsc msr pae mce cx8 apic sep mtrr flags : fpu de tsc msr pae mce cx8 apic sep mtrr mca cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx mca cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl nonstop_tsc aperfmperf pni lm constant_tsc rep_good nonstop_tsc aperfmperf pni est ssse3 pclmulqdq est ssse3 cx16 sse4_1 sse4_2 x2apic popcnt aes cx16 sse4_1 sse4_2 popcnt hypervisor lahf_lm ida xsave avx hypervisor lahf_lm ida arat epb xsaveopt pln pts dtherm bogomips : 5050.74 bogomips : 5068.63 clflush size : 64 clflush size : 64 cache_alignment : 64 cache_alignment : 64 address sizes : 46 bits physical, 48 bits virtual address sizes : 40 bits physical, 48 bits virtual power management: power management: Any ideas? Thanks, James