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From: Arnd Bergmann <arnd@arndb.de>
To: olof@austin.ibm.com (Olof Johansson)
Cc: akpm@osdl.org, trini@kernel.crashing.org,
	linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
	paulus@samba.org, hpa@zytor.com, linuxppc64-dev@ozlabs.org
Subject: Re: [PATCH] PPC/PPC64: Introduce CPU_HAS_FEATURE() macro
Date: Fri, 4 Feb 2005 19:57:06 +0100	[thread overview]
Message-ID: <200502041957.06979.arnd@arndb.de> (raw)
In-Reply-To: <20050204183514.GB17586@austin.ibm.com>

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On Freedag 04 Februar 2005 19:35, Olof Johansson wrote:
> pSeries will need all cpus enabled since we have them all on various
> machines, etc. I guess Powermac/Maple could benefit from it.

Even on pSeries, we already have CONFIG_POWER4_ONLY, which could be
used to optimize away some of the checks at compile time.

I think it makes sense to extend this a bit to look more like the CPU
selection on i386 or s390 where can set the oldest CPU you want to
support. This also fits nicely with the gcc -mcpu= options.

> In the end it depends on how hairy the implementation would get vs 
> performance improvement.

Fortunately, that optimization should be easy to do on top of your
patch, so we don't have to decide now.

	Arnd <><

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  reply	other threads:[~2005-02-04 19:15 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-02-04  7:22 [PATCH] PPC/PPC64: Introduce CPU_HAS_FEATURE() macro Olof Johansson
2005-02-04  8:17 ` Pekka Enberg
2005-02-04 17:20   ` Olof Johansson
2005-02-05  7:48     ` Pekka Enberg
2005-02-05  9:08     ` Benjamin Herrenschmidt
2005-02-04 12:36 ` Arnd Bergmann
2005-02-04 18:35   ` Olof Johansson
2005-02-04 18:57     ` Arnd Bergmann [this message]
2005-02-04 23:50     ` Benjamin Herrenschmidt
2005-02-04 23:49   ` Benjamin Herrenschmidt
2005-02-05  0:22     ` Arnd Bergmann
2005-02-05  1:34       ` Anton Blanchard
2005-02-05 11:04         ` Arnd Bergmann
2005-02-05  1:47       ` Benjamin Herrenschmidt
2005-02-04 14:45 ` Tom Rini
2005-02-05 18:46 ` [PATCH] PPC/PPC64: Abstract cpu_feature checks Olof Johansson
2005-02-06  3:26   ` Olof Johansson
2005-02-06 11:57     ` Arnd Bergmann

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