From: John Bradford <john@grabjohn.com>
To: ak@muc.de, david.lang@digitalinsight.com
Cc: alan@lxorguk.ukuu.org.uk, bunk@fs.tum.de, davej@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: RFC: [2.6 patch] better i386 CPU selection
Date: Sun, 14 Sep 2003 09:52:02 +0100 [thread overview]
Message-ID: <200309140852.h8E8q2ep000355@81-2-122-30.bradfords.org.uk> (raw)
> > > I don't like the current user interface that says "if you want to
> > > support both an Athlon and a Pentium 4 in your kernel use the Pentium III
> > > option. And for better optimization, also check the "generic" option".
If we go with the bitmap of processors to support idea, the generic option will be unnecessary.
You would then be able to:
* Support, (I.E. include workarounds for, and not include instructions
that are not supported by), as many or as few processors as you
desire.
* Optimise, (I.E. set alignment, and code generation within the subset
of instructions permitted in the 'Support' selection above), for one
specific processor.
> > The big issue with your ifdefing of workarounds is that it causes subtle
> > support problems. A lot of settings for specific CPUs boot and work
> > fine on other CPUs (possibly with small performance impact, but they're
> > rarely noticeable without explicit benchmarking). Just when you don't
> > include the workarounds for the bugs on these other CPUs it will boot and
> > even run, but fail mysteriously once a month. And that would be a support
> > nightmare.
> it sounds like a nessasary part of this patch would be to detect the CPU
> type and complain VERY loudly if it's not one supported by the build.
>
> This is probably a good idea anyway.
It is a good idea for 99% of kernels, but still needs to be configurable.
Maybe the option should not be present in the kernel configurator, and
require manual editing of the .config file to enable it.
John.
next reply other threads:[~2003-09-14 8:41 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-14 8:52 John Bradford [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-09-14 8:55 RFC: [2.6 patch] better i386 CPU selection John Bradford
[not found] <viay.6qh.11@gated-at.bofh.it>
[not found] ` <vli4.2Ml.15@gated-at.bofh.it>
[not found] ` <vnjR.5Sn.5@gated-at.bofh.it>
[not found] ` <vnD7.6jK.1@gated-at.bofh.it>
[not found] ` <vnMX.6x0.17@gated-at.bofh.it>
[not found] ` <vqKS.2NP.29@gated-at.bofh.it>
2003-09-14 0:07 ` Andi Kleen
2003-09-14 0:10 ` David Lang
2003-09-13 12:51 Adrian Bunk
2003-09-13 14:20 ` Kevin P. Fleming
2003-09-13 17:10 ` Adrian Bunk
2003-09-13 16:11 ` Dave Jones
2003-09-13 16:41 ` Adrian Bunk
2003-09-13 17:21 ` Dave Jones
2003-09-13 18:22 ` Adrian Bunk
2003-09-13 18:35 ` Dave Jones
2003-09-13 21:52 ` Adrian Bunk
2003-09-13 18:21 ` Jeff Garzik
2003-09-13 18:37 ` Dave Jones
2003-09-13 18:53 ` Jeff Garzik
2003-09-13 20:32 ` Alan Cox
2003-09-13 22:07 ` Adrian Bunk
2003-09-13 22:33 ` Jeff Garzik
2003-09-13 18:47 ` Alan Cox
2003-09-13 11:04 Mikael Pettersson
2003-09-13 11:02 Mikael Pettersson
2003-09-13 11:13 ` Adrian Bunk
2003-09-12 21:38 Mikael Pettersson
2003-09-12 23:23 ` Adrian Bunk
2003-09-16 12:42 ` Maciej W. Rozycki
2003-09-12 20:09 Mikael Pettersson
2003-09-12 22:51 ` Adrian Bunk
2003-09-07 21:47 Mikael Pettersson
2003-09-07 21:46 Mikael Pettersson
2003-09-07 21:56 ` Adrian Bunk
2003-09-07 16:47 Mikael Pettersson
2003-09-07 17:43 ` Jamie Lokier
2003-09-07 18:09 ` Alan Cox
2003-09-08 8:17 ` Rogier Wolff
2003-09-08 12:36 ` Alan Cox
2003-09-10 14:17 ` Pavel Machek
2003-09-11 6:28 ` Adrian Bunk
2003-09-11 11:04 ` Dave Jones
2003-09-12 20:41 ` Adrian Bunk
2003-09-11 12:10 ` Maciej W. Rozycki
2003-09-12 19:07 ` Adrian Bunk
2003-09-16 12:34 ` Maciej W. Rozycki
2003-09-11 14:25 ` Alan Cox
2003-09-13 10:37 ` Adrian Bunk
2003-09-07 17:51 ` Adrian Bunk
2003-09-07 11:28 Adrian Bunk
2003-09-07 11:46 ` Jan-Benedict Glaw
2003-09-07 13:17 ` Adrian Bunk
2003-09-07 13:48 ` Jan-Benedict Glaw
2003-09-07 12:42 ` Sam Ravnborg
2003-09-07 12:51 ` Adrian Bunk
2003-09-07 12:42 ` Robert Schwebel
2003-09-07 13:00 ` Adrian Bunk
2003-09-07 13:14 ` Robert Schwebel
2003-09-08 15:26 ` Tom Rini
2003-09-07 17:31 ` Alan Cox
2003-09-07 17:48 ` Robert Schwebel
2003-09-07 18:04 ` Alan Cox
2003-09-07 18:26 ` Robert Schwebel
2003-09-07 19:17 ` Alan Cox
2003-09-07 19:17 ` Alan Cox
2003-09-07 17:25 ` Alan Cox
2003-09-11 6:19 ` Adrian Bunk
2003-09-08 0:46 ` Rusty Russell
2003-09-08 14:29 ` Adrian Bunk
2003-09-09 1:11 ` Rusty Russell
2003-09-11 6:22 ` Adrian Bunk
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