From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from oss.sgi.com (localhost [127.0.0.1]) by oss.sgi.com (8.12.5/8.12.5) with ESMTP id g77FNjRw005525 for ; Wed, 7 Aug 2002 08:23:45 -0700 Received: (from majordomo@localhost) by oss.sgi.com (8.12.5/8.12.3/Submit) id g77FNjdx005524 for linux-mips-outgoing; Wed, 7 Aug 2002 08:23:45 -0700 X-Authentication-Warning: oss.sgi.com: majordomo set sender to owner-linux-mips@oss.sgi.com using -f Received: from dea.linux-mips.net (shaft19-f76.dialo.tiscali.de [62.246.19.76]) by oss.sgi.com (8.12.5/8.12.5) with SMTP id g77FNcRw005515 for ; Wed, 7 Aug 2002 08:23:39 -0700 Received: (from ralf@localhost) by dea.linux-mips.net (8.11.6/8.11.6) id g77FPV716777; Wed, 7 Aug 2002 17:25:31 +0200 Date: Wed, 7 Aug 2002 17:25:31 +0200 From: Ralf Baechle To: Stewart Brodie Cc: linux-mips@oss.sgi.com Subject: Re: CONFIG_MIPS32 implies CONFIG_CPU_HAS_PREFETCH Message-ID: <20020807172531.A16609@dea.linux-mips.net> References: <0de052624b.sbrodie@sbrodie.cam.pace.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <0de052624b.sbrodie@sbrodie.cam.pace.co.uk>; from stewart.brodie@pace.co.uk on Wed, Aug 07, 2002 at 04:04:16PM +0100 X-Spam-Status: No, hits=-4.4 required=5.0 tests=IN_REP_TO version=2.20 X-Spam-Level: Sender: owner-linux-mips@oss.sgi.com Precedence: bulk On Wed, Aug 07, 2002 at 04:04:16PM +0100, Stewart Brodie wrote: > linux_2_4 branch question: In config-shared.in, and previously in config.in, > whether or not the CPU has prefetch instructions seems to be dependent only > on whether CONFIG_MIPS32 is y. However, this causes our kernel builds to die > when compiling memcpy.S because the compiler is objecting to the pref/prefx > instructions. The gcc 2.96 compiler options we are using are -mtune=r4600 > and -mips2. > > Is it simply the case that the processors on all the boards supported in the > MIPS builds all support prefetch? At the moment, I've just put a specific > check in for our particular processor to stop CONFIG_CPU_HAS_PREFETCH from > being set to y and that stops the problem. In earlier (2.4.17 pre-release) > kernels, whether or not to define PREF/PREFX as pref/prefx or the empty > string was determined on a stricter set of criteria based around actual CPU > types rather than a blanket check on being a 32-bit MIPS. The MIPS32 architecture specifies a prefetch instruction. So it's correct (though not necessarily alway the most efficient thing) to assume your system has this instruction available. The compiler option -mips2 which you're specifying however tells the tools that you do not have that instruction, so is wrong. Ralf