Re: [Qemu-devel] CPU vendor in KVM

[Jan Kiszka <jan.kiszka@web.de>]

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Please don't top-post.

On 2013-05-04 10:45, 李春奇 <Arthur Chunqi Li> wrote:
> But will the difference between the vendor ID and family number cause
> confusion to the OS in VM?

The confusion is not yet clear to me. About which "-cpu ..." were you
talking?

Jan

> 
> On Sat, May 4, 2013 at 4:05 PM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> On 2013-05-04 09:50, 李春奇 <Arthur Chunqi Li> wrote:
>>> Hi Jan and All,
>>> I find that when enable KVM with qemu, vendor ID of simulated CPU will be
>>> set the same as host, but other features such as level, family, model,
>>> stepping are not changed. This may bring out a confusing result, the
>>> simulated CPU has a vendor name of "GenuineIntel" but with family number
>>> "16".
>>>
>>> I disabled the related code in function cpu_x86_find_by_name:
>>> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>>> index e2302d8..df0e82e 100644
>>> --- a/target-i386/cpu.c
>>> +++ b/target-i386/cpu.c
>>> @@ -1295,7 +1295,8 @@ static int cpu_x86_find_by_name(x86_def_t
>>> *x86_cpu_def, const char *name)
>>>               * KVM's sysenter/syscall emulation in compatibility mode and
>>>               * when doing cross vendor migration
>>>               */
>>> -            if (kvm_enabled()) {
>>> +            //if (kvm_enabled()) {
>>> +            if (0) {
>>>                  uint32_t  ebx = 0, ecx = 0, edx = 0;
>>>                  host_cpuid(0, 0, NULL, &ebx, &ecx, &edx);
>>>                  x86_cpu_vendor_words2str(x86_cpu_def->vendor, ebx, edx,
>>> ecx);
>>>
>>> And the information of CPU remains consistent and the VM runs OK, even
>>> though with nested environment.
>>>
>>> Why should qemu set simulated cpu's vendor same as the host in KVM
>>> environment?
>>
>> The reason (and a way out) is given in the comment above the cited code.
>>
>> Jan
>>
>>
> 
> 
> 



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