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From: Avi Kivity <avi@redhat.com>
To: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Matthew Wilcox <matthew@wil.cx>,
	Ralf Baechle <ralf@linux-mips.org>,
	mingo@elte.hu, tglx@linutronix.de, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] X86: Optimise fls(), ffs() and fls64()
Date: Thu, 15 Apr 2010 11:49:56 +0300	[thread overview]
Message-ID: <4BC6D334.8050607@redhat.com> (raw)
In-Reply-To: <3879.1271321292@redhat.com>

On 04/15/2010 11:48 AM, David Howells wrote:
> Avi Kivity<avi@redhat.com>  wrote:
>
>    
>> Even if Intel processors behave that way, other processors (real and
>> emulated) use those manuals as a specification.  Emulated processors are
>> unlikely to touch an undefined register, but real processors may.
>>
>> (qemu tcg appears not to touch the output)
>>      
> Possibly because the AMD64 spec specifies that the destination will be
> unchanged if the source was 0.
>    

Likely.  But we haven't tested all current and future x86 clones, and 
they may be based off the Intel documentation instead of the AMD 
documentation.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

  reply	other threads:[~2010-04-15  8:50 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <4BACCB4E.7010108@draigBrady.com>
2010-03-26 14:42 ` [PATCH 1/3] X86: Optimise fls(), ffs() and fls64() David Howells
2010-03-26 14:42   ` [PATCH 2/3] Adjust the comment on get_order() to describe the size==0 case David Howells
2010-03-26 14:42   ` [PATCH 3/3] Optimise get_order() David Howells
2010-03-26 14:42     ` David Howells
2010-03-26 17:23   ` [PATCH 1/3] X86: Optimise fls(), ffs() and fls64() Linus Torvalds
2010-03-26 17:37     ` Scott Lurndal
2010-03-26 17:42       ` Linus Torvalds
2010-04-06 13:57         ` Jamie Lokier
2010-04-06 14:40           ` Linus Torvalds
2010-03-26 17:42   ` David Howells
2010-03-26 17:45     ` Linus Torvalds
2010-03-26 17:58       ` Ralf Baechle
2010-03-26 18:03         ` Linus Torvalds
2010-03-26 18:16           ` Matthew Wilcox
2010-04-06 13:30           ` Matthew Wilcox
2010-04-14 11:49           ` David Howells
2010-04-14 14:30             ` Avi Kivity
2010-04-15  8:48             ` David Howells
2010-04-15  8:49               ` Avi Kivity [this message]
2010-04-15 11:41                 ` Jamie Lokier
2010-03-26 17:52     ` Matthew Wilcox
2010-04-14 13:13   ` David Howells
2010-01-13 19:39 David Howells
2010-01-13 20:15 ` Geert Uytterhoeven
2010-01-13 21:59 ` David Howells

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