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.
next prev parent reply other threads:[~2010-04-15 8:50 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
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 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
[not found] ` <4BACCB4E.7010108@draigBrady.com>
2010-04-14 13:13 ` David Howells
-- strict thread matches above, loose matches on Subject: below --
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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