[Qemu-devel] [Question] why x2apic's set by default without host support(on Nehalem CPU).

["Peter Huang(Peng)" <peter.huangpeng@huawei.com>]

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Hi, Everyone

I have been encountered a problem recently.
My box uses Nehalem E5520 CPU, and this model doesn't support x2apic feature.
I created a VM on KVM, and uses cpu mode=pass-through, I can get the right cpu
model from the VM, but I can also see that the CPU in the vm supports x2apic.

This seems werid.
>From QEMU's CPU model definition, Nehalem also doesn't support x2apic.

Can anyone explain it?

Thanks to you all!

Below is the cpuinfo from host and guest:
host:
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 rdtscp lm constant_tsc
arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64
monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2
popcnt lahf_lm dtherm tpr_shadow vnmi flexpriority ept vpid

vm:
fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush
mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon rep_good
 nopl pni ssse3 cx16 sse4_1 sse4_2 *x2apic *popcnt hypervisor lahf_lm

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