From: Anton Blanchard <anton@samba.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@osdl.org>,
Tom Rini <trini@kernel.crashing.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
linuxppc-dev list <linuxppc-dev@ozlabs.org>,
Paul Mackerras <paulus@samba.org>,
"H. Peter Anvin" <hpa@zytor.com>,
linuxppc64-dev <linuxppc64-dev@ozlabs.org>
Subject: Re: [PATCH] PPC/PPC64: Introduce CPU_HAS_FEATURE() macro
Date: Sat, 5 Feb 2005 12:34:26 +1100 [thread overview]
Message-ID: <20050205013426.GC11318@krispykreme.ozlabs.ibm.com> (raw)
In-Reply-To: <200502050122.27254.arnd@arndb.de>
Hi,
> This is the patch to evaluate CPU_HAS_FEATURE() at compile time whenever
> possible. Testing showed that vmlinux shrinks around 4000 bytes with
> g5_defconfig. I also checked that pSeries code is completely unaltered
> semantically when support for all CPU types is enabled, although a few
> instructions are emitted in a different order by gcc.
>
> I have made cpu_has_feature() an inline function that expects the full
> name of a feature bit while the CPU_HAS_FEATURE() macro still behaves
> the same way as in Olofs original patch for now.
Interesting :) However we already get bug reports with the current
CONFIG_POWER4_ONLY option. I worry about adding more options that users
could get wrong unless there is a noticeable improvement in performance.
Anton
next prev parent reply other threads:[~2005-02-05 1:34 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
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 [this message]
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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