From: Matti Aarnio <matti.aarnio@zmailer.org>
To: Bart Trojanowski <bart@jukie.net>
Cc: Manoj Sontakke <manojs@sasken.com>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: which gcc version?
Date: Thu, 5 Apr 2001 15:02:19 +0300 [thread overview]
Message-ID: <20010405150219.B873@mea-ext.zmailer.org> (raw)
In-Reply-To: <Pine.LNX.4.21.0104051930580.2687-100000@pcc65.sasi.com> <Pine.LNX.4.30.0104050732080.13246-100000@localhost>
In-Reply-To: <Pine.LNX.4.30.0104050732080.13246-100000@localhost>; from bart@jukie.net on Thu, Apr 05, 2001 at 07:37:03AM -0400
On Thu, Apr 05, 2001 at 07:37:03AM -0400, Bart Trojanowski wrote:
> On Thu, 5 Apr 2001, Manoj Sontakke wrote:
> gcc requires a function call to do a mul/div on a long long. There is no
> easy way to do a 64bit op of this type on a 32 bit CPU...
Actually there is -- presuming your CPU has lots of registers,
which i386 does not have...
This rule -- "no -lgcc in kernel code" -- is to trap code which
in fast-paths would call those slow routines.
Fastpaths should either not grok such values, or at most use
shifts.
To think of it, there really should be explicitely callable
versions of these with LinuxKernel names for them, not gcc
builtins. That way people would *know* they are doing
something, which is potentially very slow.
(And the API would not change from underneath them.)
> Cheers,
> Bart.
> --
> WebSig: http://www.jukie.net/~bart/sig/
/Matti Aarnio
next prev parent reply other threads:[~2001-04-05 12:03 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-04-05 10:56 Manoj Sontakke
2001-04-05 5:48 ` Alexander Viro
2001-04-05 14:09 ` Manoj Sontakke
2001-04-05 11:37 ` Bart Trojanowski
2001-04-05 12:02 ` Matti Aarnio [this message]
2001-04-05 12:26 ` David Woodhouse
2001-04-05 12:31 ` Matti Aarnio
2001-04-05 13:09 ` Richard B. Johnson
2001-04-05 11:45 ` Matti Aarnio
2001-04-05 11:50 ` christophe barbe
2001-11-23 12:53 Which " Roy Sigurd Karlsbakk
2001-11-23 12:57 ` Arjan van de Ven
2001-11-23 13:51 ` war
2001-11-23 19:43 ` J Sloan
2001-11-23 13:59 ` Anton Altaparmakov
2001-11-23 14:11 ` war
2001-11-23 15:14 ` Arjan van de Ven
2001-11-23 15:30 ` Gábor Lénárt
2001-11-23 15:34 ` Arjan van de Ven
2001-11-23 19:50 ` J Sloan
2001-11-23 20:34 ` John Jasen
2001-11-23 21:55 ` J Sloan
2001-11-24 3:08 ` John Jasen
2001-11-24 12:24 ` Paul G. Allen
2001-11-26 18:31 ` Alan Cox
2001-11-27 8:42 ` Ahmed Masud
2001-11-23 16:10 ` Anton Altaparmakov
2001-11-23 14:43 ` Anton Altaparmakov
2001-11-23 16:23 ` Jeff Garzik
2001-11-23 18:30 ` Daniel Phillips
2001-11-23 18:56 ` Anton Altaparmakov
2001-11-23 19:28 ` Daniel Phillips
2001-11-23 20:14 ` Andrew Morton
2001-11-23 20:24 ` Anton Altaparmakov
2001-11-23 20:35 ` Andrew Morton
2001-11-23 21:09 ` David Weinehall
2001-11-24 16:01 ` Luigi Genoni
2001-11-24 16:09 ` Daniel Phillips
2001-11-24 17:32 ` Luigi Genoni
2001-11-23 17:12 RaúlNúñez de Arenas Coronado
2001-11-23 18:02 ` M. Edward (Ed) Borasky
2001-11-23 18:14 ` Thorsten Glaser
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