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Date: Wed, 7 Mar 2012 16:01:39 +0200
From: Gleb Natapov <gleb@redhat.com>
Message-ID: <20120307140139.GK2521@redhat.com>
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Subject: Re: [Qemu-devel] Is qemu (version 1.0) support to emulate the CPU
 feture "x2APIC"?
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To: developer wang <developer.pw@gmail.com>
Cc: qemu-developer-mail-list <Qemu-devel@nongnu.org>

On Wed, Mar 07, 2012 at 09:54:28PM +0800, developer wang wrote:
> Hi,
> 
>   I want to use qemu (version 1.0) to emulate guest systems with x2APIC enabled.
> 
>   But when I use qemu to emulate CPU's feture "x2APIC", I didn't find
> it in /proc/cpuinfo.
> 
x2apic is supported only if kvm is used and only with in kernel irqchip
emulation (which is still not default in qemu upstream IIRC). Try with
qemu-kvm.

>   And I saw the source code of qemu.
> 
>   I only find a single define (#define CPUID_EXE_X2APIC   (1<<21) )
> 
>   but no other places use this this define.
> 
>   Does this mean qemu now doesn't support to emulate the CPU's feture
> of "x2APIC"?
> 
> 
> 
>   Our host machine is running Debian 6, and the host system has x2APIC support.
> 
>   I use the following command to run qemu:
> 
>     qemu-system-x86_64 -nographic -cpu qemu64,+x2apic -serial
> mon:/dev/tty -hda ~/debian6.qcow2
> 
> After the guest (also Debian 6) boots up, I can't see x2apic in /proc/cpuinfo.
> 
> Our host machine's CPU features:
> 
>     model name      : Intel(R) Xeon(R) CPU E7- 4850  @ 2.00GHz
>     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 arch_perfmon pebs bts
> rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64
> monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2
> x2apic popcnt aes lahf_lm ida arat dts tpr_shadow vnmi flexpriority
> ept vpid
> 
> The CPU feature from the guest emulated by QEMU:
> 
>     model name      : QEMU Virtual CPU version 1.0,1
>     flags           : fpu pse tsc msr pae mce cx8 apic sep mtrr pge
> mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx lm up pni cx16
> popcnt hypervisor lahf_lm svm abm sse4a

--
			Gleb.