Re: [PATCH 0/3] x86: enlightenment for ticket spinlocks

From: H. Peter Anvin
Date: Sun Jan 31 2010 - 13:45:21 EST


On 01/31/2010 10:02 AM, Jan Beulich wrote:
>>>> "H. Peter Anvin" 01/31/10 2:42 AM >>>
>> + * EBX-EDX: "XenVMMXenVMM" signature, allowing positive identification
>> + * of a Xen host.
>> + */
>> +#define XEN_CPUID_SIGNATURE_EBX 0x566e6558 /* "XenV" */
>> +#define XEN_CPUID_SIGNATURE_ECX 0x65584d4d /* "MMXe" */
>> +#define XEN_CPUID_SIGNATURE_EDX 0x4d4d566e /* "nVMM" */
>>
>> I hope you know this spells "MMXenVMMXenV". The ordering is ecx-edx-ebx
>> (register numbers 1, 2, 3).
>
> According to the documentation I have, the ordering is EBX-EDX-ECX,
> so indeed the spelling would seem broken, but since this is an interface
> header taken directly from Xen, it's got to be (and it works) that way.
> Odd.
>

It's probably a bug that's now cast in stone. That happends. I just
had to be picky. (And yes, it's ebx-edx-ecx; see my second email.)

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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