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>
[-- Attachment #1: Type: text/plain, Size: 749 bytes --]
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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WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: olof@austin.ibm.com (Olof Johansson)
Cc: linuxppc64-dev@ozlabs.org, linuxppc-dev@ozlabs.org,
linux-kernel@vger.kernel.org, akpm@osdl.org,
trini@kernel.crashing.org, paulus@samba.org, anton@samba.org,
hpa@zytor.com
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>
[-- Attachment #1: Type: text/plain, Size: 749 bytes --]
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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next prev parent reply other threads:[~2005-02-04 19:15 UTC|newest]
Thread overview: 36+ 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 7:22 ` Olof Johansson
2005-02-04 8:17 ` Pekka Enberg
2005-02-04 8:17 ` Pekka Enberg
2005-02-04 17:20 ` Olof Johansson
2005-02-04 17:20 ` Olof Johansson
2005-02-05 7:48 ` Pekka Enberg
2005-02-05 7:48 ` Pekka Enberg
2005-02-05 9:08 ` Benjamin Herrenschmidt
2005-02-05 9:08 ` Benjamin Herrenschmidt
2005-02-04 12:36 ` Arnd Bergmann
2005-02-04 12:36 ` Arnd Bergmann
2005-02-04 18:35 ` Olof Johansson
2005-02-04 18:35 ` Olof Johansson
2005-02-04 18:57 ` Arnd Bergmann [this message]
2005-02-04 18:57 ` Arnd Bergmann
2005-02-04 23:50 ` Benjamin Herrenschmidt
2005-02-04 23:50 ` Benjamin Herrenschmidt
2005-02-04 23:49 ` Benjamin Herrenschmidt
2005-02-04 23:49 ` Benjamin Herrenschmidt
2005-02-05 0:22 ` Arnd Bergmann
2005-02-05 0:22 ` Arnd Bergmann
2005-02-05 1:34 ` Anton Blanchard
2005-02-05 1:34 ` Anton Blanchard
2005-02-05 11:04 ` Arnd Bergmann
2005-02-05 11:04 ` Arnd Bergmann
2005-02-05 1:47 ` Benjamin Herrenschmidt
2005-02-05 1:47 ` Benjamin Herrenschmidt
2005-02-04 14:45 ` Tom Rini
2005-02-04 14:45 ` Tom Rini
2005-02-05 18:46 ` [PATCH] PPC/PPC64: Abstract cpu_feature checks Olof Johansson
2005-02-05 18:46 ` Olof Johansson
2005-02-06 3:26 ` Olof Johansson
2005-02-06 3:26 ` Olof Johansson
2005-02-06 11:57 ` Arnd Bergmann
2005-02-06 11:57 ` Arnd Bergmann
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