From: "H. Peter Anvin" <hpa@zytor.com>
To: Vegard Nossum <vegard.nossum@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Ingo Molnar <mingo@elte.hu>,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH] kmemcheck: disable fast string operations on P4 CPUs
Date: Sat, 21 Feb 2009 19:13:24 -0800 [thread overview]
Message-ID: <49A0C2D4.20009@zytor.com> (raw)
In-Reply-To: <1235223364-2097-2-git-send-email-vegard.nossum@gmail.com>
Vegard Nossum wrote:
> This patch may allow us to remove the REP emulation code from
> kmemcheck.
> +#ifdef CONFIG_KMEMCHECK
> + /*
> + * P4s have a "fast strings" feature which causes single-
> + * stepping REP instructions to only generate a #DB on
> + * cache-line boundaries.
> + *
> + * Ingo Molnar reported a Pentium D (model 6) and a Xeon
> + * (model 2) with the same problem.
> + */
> + if (c->x86 == 15) {
If this is supposed to refer to the Intel P4 core, you should exclude
the post-P4 cores that also have x86 == 15 (e.g. Core 2 and Core i7).
If those are affected, too, they should be mentioned in the comment.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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next prev parent reply other threads:[~2009-02-22 3:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-21 13:36 Vegard Nossum
2009-02-21 13:36 ` [PATCH] kmemcheck: disable fast string operations on P4 CPUs Vegard Nossum
2009-02-21 16:21 ` Pekka Enberg
2009-02-22 3:13 ` H. Peter Anvin [this message]
2009-02-22 10:51 ` Vegard Nossum
2009-02-21 13:36 ` [PATCH] kmemcheck: rip out REP instruction emulation Vegard Nossum
2009-02-21 16:21 ` Pekka Enberg
2009-02-21 13:36 ` [PATCH] kmemcheck: add hooks for page- and sg-dma-mappings Vegard Nossum
2009-02-21 16:22 ` Pekka Enberg
2009-02-21 17:13 ` Vegard Nossum
2009-02-21 17:15 ` Pekka Enberg
2009-02-21 13:36 ` [PATCH] kmemcheck: add hooks for the page allocator Vegard Nossum
2009-02-21 15:23 ` Ingo Molnar
2009-02-21 16:34 ` Pekka Enberg
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