I have a 64-bit host that is running a 32-bit OS (Fedora 10). # cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 16 model : 2 model name : AMD Phenom(tm) 9850 Quad-Core Processor stepping : 3 cpu MHz : 2511.416 cache size : 512 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs bogomips : 5022.83 clflush size : 64 power management: ts ttp tm stc 100mhzsteps hwpstate processor : 1 vendor_id : AuthenticAMD cpu family : 16 model : 2 model name : AMD Phenom(tm) 9850 Quad-Core Processor stepping : 3 cpu MHz : 2511.416 cache size : 512 KB physical id : 0 siblings : 4 core id : 1 cpu cores : 4 apicid : 1 initial apicid : 1 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs bogomips : 5023.06 clflush size : 64 power management: ts ttp tm stc 100mhzsteps hwpstate processor : 2 vendor_id : AuthenticAMD cpu family : 16 model : 2 model name : AMD Phenom(tm) 9850 Quad-Core Processor stepping : 3 cpu MHz : 2511.416 cache size : 512 KB physical id : 0 siblings : 4 core id : 3 cpu cores : 4 apicid : 3 initial apicid : 3 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs bogomips : 5023.06 clflush size : 64 power management: ts ttp tm stc 100mhzsteps hwpstate processor : 3 vendor_id : AuthenticAMD cpu family : 16 model : 2 model name : AMD Phenom(tm) 9850 Quad-Core Processor stepping : 3 cpu MHz : 2511.416 cache size : 512 KB physical id : 0 siblings : 4 core id : 2 cpu cores : 4 apicid : 2 initial apicid : 2 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs bogomips : 5023.06 clflush size : 64 power management: ts ttp tm stc 100mhzsteps hwpstate # virsh nodeinfo CPU model: i686 CPU(s): 4 CPU frequency: 2511 MHz CPU socket(s): 1 Core(s) per socket: 4 Thread(s) per core: 1 NUMA cell(s): 1 Memory size: 4147340 kB # virsh capabilities <capabilities> <host> <cpu> <arch>i686</arch> </cpu> </host> <guest> <os_type>hvm</os_type> <arch name='i686'> <wordsize>32</wordsize> <emulator>/usr/bin/qemu</emulator> <machine>pc</machine> <machine>isapc</machine> <domain type='qemu'> </domain> <domain type='kvm'> <emulator>/usr/bin/qemu-kvm</emulator> </domain> </arch> <features> <pae/> <nonpae/> <acpi default='on' toggle='yes'/> <apic default='on' toggle='no'/> </features> </guest> <guest> <os_type>hvm</os_type> <arch name='x86_64'> <wordsize>64</wordsize> <emulator>/usr/bin/qemu-system-x86_64</emulator> <machine>pc</machine> <machine>isapc</machine> <domain type='qemu'> </domain> </arch> <features> <acpi default='on' toggle='yes'/> <apic default='on' toggle='no'/> </features> </guest> <guest> <os_type>hvm</os_type> <arch name='mips'> <wordsize>32</wordsize> <emulator>/usr/bin/qemu-system-mips</emulator> <machine>mips</machine> <domain type='qemu'> </domain> </arch> </guest> <guest> <os_type>hvm</os_type> <arch name='mipsel'> <wordsize>32</wordsize> <emulator>/usr/bin/qemu-system-mipsel</emulator> <machine>mips</machine> <domain type='qemu'> </domain> </arch> </guest> <guest> <os_type>hvm</os_type> <arch name='sparc'> <wordsize>32</wordsize> <emulator>/usr/bin/qemu-system-sparc</emulator> <machine>sun4m</machine> <domain type='qemu'> </domain> </arch> </guest> <guest> <os_type>hvm</os_type> <arch name='ppc'> <wordsize>32</wordsize> <emulator>/usr/bin/qemu-system-ppc</emulator> <machine>g3bw</machine> <machine>mac99</machine> <machine>prep</machine> <domain type='qemu'> </domain> </arch> </guest> </capabilities> Shouldn't the host arch have been detected and identified as x86_64? Regards, Gerry