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Re: [update] [patch] linux: Cache coherency fixes

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Subject: Re: [update] [patch] linux: Cache coherency fixes
From: Ralf Baechle <ralf@oss.sgi.com>
Date: Thu, 1 Aug 2002 15:25:00 +0200
Cc: linux-mips@fnet.fr, linux-mips@oss.sgi.com
In-reply-to: <Pine.GSO.3.96.1020729161214.22288H-100000@delta.ds2.pg.gda.pl>; from macro@ds2.pg.gda.pl on Mon, Jul 29, 2002 at 04:29:35PM +0200
References: <Pine.GSO.3.96.1020705170554.11897A-100000@delta.ds2.pg.gda.pl> <Pine.GSO.3.96.1020729161214.22288H-100000@delta.ds2.pg.gda.pl>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.2.5.1i
On Mon, Jul 29, 2002 at 04:29:35PM +0200, Maciej W. Rozycki wrote:

>  The following patch fixes all the places the default caching policy is
> used but various local hacks are coded.  Also the sc coherency algorithm
> is configured for R4k processors which was previously left as set (or not)
> by the firmware.  A side effect is <asm-mips64/pgtable-bits.h> is created
> and all conditional CPU options are set somehow.  Tested on an R4400SC
> (for both MIPS and MIPS64) and on an R3400. 
> 
>  Admittedly, CONF_CM_DEFAULT is defined in a bit weird way, but I couldn't
> figure any better one that wouldn't result in a serious but unnecessary
> header bloat.  If anyone has a better idea, please share any suggestions
> here.
> 
>  OK to apply?

Looks mostly right except that the code in config-shared.in which deciedes
if a system is coherent is wrong.  Basically it assumes every R10000 or
every uniprocessor system is non-coherent and that's wrong.  As coherency
between CPUs and for DMA I/O is basically the same thing I've changed your
code from the use of CONFIG_CPU_CACHE_COHERENCY to CONFIG_NONCOHERENT_IO
which did already exist; I don't think we need another config symbol to
handle this.  Will apply once I did a few test builds and patches the
whole thing into 2.5 ...

  Ralf


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