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From: "Jan Beulich" <JBeulich@novell.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: <mingo@elte.hu>, <jeremy@goop.org>, <tglx@linutronix.de>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/3] x86: enlightenment for ticket spinlocks
Date: Mon, 01 Feb 2010 07:56:34 +0000	[thread overview]
Message-ID: <4B669742020000780002CEEB@vpn.id2.novell.com> (raw)
In-Reply-To: <4B65CF5B.3000804@zytor.com>

>>> "H. Peter Anvin" <hpa@zytor.com> 31.01.10 19:43 >>>
>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.)

The "good" thing is that this is not on leaf 0, but on leaf 0x4000??00,
i.e. "normal" code would never display this garbled string.

Jan


  reply	other threads:[~2010-02-01  7:56 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-31 18:02 Jan Beulich
2010-01-31 18:43 ` H. Peter Anvin
2010-02-01  7:56   ` Jan Beulich [this message]
2010-02-01 16:40     ` H. Peter Anvin
  -- strict thread matches above, loose matches on Subject: below --
2010-01-29  8:00 Jan Beulich
2010-01-31  1:42 ` H. Peter Anvin
2010-01-31  1:45   ` H. Peter Anvin

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