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

From: H. Peter Anvin
Date: Sat Jan 30 2010 - 20:47:35 EST


On 01/30/2010 05:42 PM, H. Peter Anvin wrote:
>
> + * 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).
>

... and of course I got it wrong, too. It spells "XenVnVMMMMXe".

The proper order is ebx-edx-ecx, in *reverse* numerical order.
Confusing, yes.

-hpa

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

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