[libvirt] Question on output of virsh capabilities

[Eli Qiao]

hi
I am confused by the libvirt's "virsh capabilities"

help said:

   DESCRIPTION
     Returns capabilities of hypervisor/driver.
I got follow outtput of a host.

     <cpu>
       <arch>x86_64</arch>
       <model>Broadwell-noTSX</model>
       <vendor>Intel</vendor>
       <topology sockets='1' cores='2' threads='2'/>
       <feature name='invtsc'/>
       <feature name='mpx'/>
       <feature name='abm'/>
       <feature name='pdpe1gb'/>
       <feature name='rdrand'/>
       <feature name='f16c'/>
       <feature name='osxsave'/>
       <feature name='pdcm'/>
       <feature name='xtpr'/>
       <feature name='tm2'/>
       <feature name='est'/>
       <feature name='vmx'/>
       <feature name='ds_cpl'/>
       <feature name='monitor'/>
       <feature name='dtes64'/>
       <feature name='pbe'/>
       <feature name='tm'/>
       <feature name='ht'/>
       <feature name='ss'/>
       <feature name='acpi'/>
       <feature name='ds'/>
       <feature name='vme'/>
       <pages unit='KiB' size='4'/>
       <pages unit='KiB' size='2048'/>
       <pages unit='KiB' size='1048576'/>
     </cpu>

but from cat /proc/cpuinfo

flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall 
nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good 
nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 
monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 
sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand 
lahf_lm abm 3dnowprefetch epb intel_pt tpr_shadow vnmi flexpriority ept 
vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid mpx rdseed adx 
smap clflushopt xsaveopt xsavec xgetbv1 dtherm ida arat pln pts hwp 
hwp_notify hwp_act_window hwp_epp

The output of virsh seems missed some of the cpu features so my question 
what doesn't the features of "virsh capibalities" mean?
why not pass all cpu flags?

I see there is a cpu_map.xml in libvirt source, what does it used for?

I have requirements to get all the hypervisors feature, what should I do?

Thanks.

-- 
Best Regards, Eli Qiao (乔立勇)
Intel OTC China

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