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