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From: "H. Peter Anvin" <hpa@zytor.com>
To: Hugh Dickins <hugh@veritas.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org
Subject: Re: P6 NOPs again: MPSC?
Date: Mon, 10 Mar 2008 21:17:07 +0100	[thread overview]
Message-ID: <47D59743.7040709@zytor.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0803101853090.15511@blonde.site>

Hugh Dickins wrote:
> I've now noticed that the machine I call MPENTIUM4 for 32-bit kernels
> is called MPSC for 64-bit kernels, and in that case it still doesn't
> get the P6 NOPs which I'm guessing it ought to (yeah, I'm so excited
> about the speedup I can expect from P6 NOPs, can we perhaps have a
> little silvery "Using Genuine P6 NOPs" sticker to put on the box? ;)
> 
> I'm suspecting that the patch below is actually wrong, and that it's
> really the "(X86_64 || !X86_GENERIC) &&" which should be changed;
> but very unsure of my ground and what's right for CPU_GENERIC -
> the 32/64 heritage of x86/Kconfig.cpu rather confuses me.
> 
> Over to you to do the right thing, I'm hoping, please, Peter!
> 

X86_64 && !X86_GENERIC comes from not wanting to be a compatibility 
issue when compiling for generic CPUs.  There are some 32-bit otherwise 
i686-compatible chips (from VIA and Transmeta) which don't have these NOPs.

	-hpa


  reply	other threads:[~2008-03-10 20:28 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-04 19:33 [PATCH] x86: a P4 is a P6 not an i486 Hugh Dickins
2008-03-04 21:01 ` Ingo Molnar
2008-03-04 21:24   ` H. Peter Anvin
2008-03-04 21:32     ` Ingo Molnar
2008-03-10 19:14     ` P6 NOPs again: MPSC? Hugh Dickins
2008-03-10 20:17       ` H. Peter Anvin [this message]
2008-03-10 22:02         ` Hugh Dickins
2008-03-11  6:43           ` H. Peter Anvin
2008-03-11 14:00             ` Hugh Dickins
2008-03-11  9:28           ` Ingo Molnar
2008-03-11 13:45             ` Hugh Dickins

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