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CONFIG_MIPS32 implies CONFIG_CPU_HAS_PREFETCH

To: linux-mips@oss.sgi.com
Subject: CONFIG_MIPS32 implies CONFIG_CPU_HAS_PREFETCH
From: Stewart Brodie <stewart.brodie@pace.co.uk>
Date: Wed, 07 Aug 2002 16:04:16 +0100
Sender: owner-linux-mips@oss.sgi.com
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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.

-- 
Stewart Brodie, Senior Software Engineer
Pace Micro Technology PLC
645 Newmarket Road
Cambridge, CB5 8PB, United Kingdom         WWW: http://www.pacemicro.com/


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