Re: [Qemu-devel] Re: SVM support in 0.12?

[Andre Przywara <andre.przywara@amd.com>]

Jun Koi wrote:
>>>>>> I am running latest Qemu 0.12-rc. My guest VM runs Linux kernel 2.6.31.
>>>>>>
>>>>>> Because Qemu now supports SVM, I expect to see the SVM flag in
>>>>>> /proc/cpuinfo, but that is not the case.
>>>>>>
>>>>>> So it seems SVM support is not enabled by default configuration??
>>>>>>
>>>>> My host and guest are both 32 bit Linux, if that matters.
>>>>>
>>>>> (And this is pure Qemu, without using KVM or KQemu)
>>>> Kqemu actually works with svm emulation.
>>>>
...
>>> qemu -m 500 -cpu qemu32,+svm -cdrom ubuntu.iso
>>>
>>> I verified that /proc/cpuinfo has no svm flag. So SVM doesnt work on 32bit
>>> host.
>>>
>>> I will try that with 64bit host to see how it goes.
>> The host doesn't matter. You can easily run qemu-system-x86_64 on a 32-bit
>> host.
>>
> 
> I can confirm that SVM works well on x86-64 target, but fails on i386 target.

The Linux kernel will only detect SVM if the machine is AMD (see 
linux-2.6/arch/x86/include/asm/virtext.h:cpu_has_svm())
So please try:
$ qemu -m 500 -cpu qemu32,+svm,vendor=AuthenticAMD -cdrom ubuntu.iso
(because the default vendor for qemu32 is Intel, for qemu64 AMD)

Regards,
Andre.

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448 3567 12
----to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Andrew Bowd; Thomas M. McCoy; Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632