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Re: R4600SC Indy

To: linux-mips@oss.sgi.com
Subject: Re: R4600SC Indy
From: Jan-Benedict Glaw <jbglaw@lug-owl.de>
Date: Thu, 15 Aug 2002 13:31:21 +0200
In-reply-to: <20020815020642.A23230@marmot.cita.utoronto.ca>
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References: <20020806111959.C15670@marmot.cita.utoronto.ca> <20020815020642.A23230@marmot.cita.utoronto.ca>
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On Thu, 2002-08-15 02:06:42 -0400, Robin Humble <rjh@cita.utoronto.ca>
wrote in message <20020815020642.A23230@marmot.cita.utoronto.ca>:
> On Tue, Aug 06, 2002 at 11:19:59AM -0400, Robin Humble wrote:
> >I have an R4600SC Indy and an R5000 Indy and the R4600SC hasn't worked
> >with a kernel since around 2.4.17 13feb2002. 
> 
> To be precise, the changes that were checked in on 6-mar-2002 broke
> R4600SC support. These changes were to arch/mips/mm/c-r4k.c (and its mips64
> counterpart). The patch below (to 13-aug-02 linux_2_4 CVS) is simply a
> reversal of the changes made on 6-mar-02 and makes my R4600SC Indy work
> just fine.

They broke R4600 Version 1.7 to be exactly, as this CPU has got some
bugs in it's cache flush commands. The result is: you need to disable
interrupts to get the desired result, but that's some kind of PITA
performance-wise, so the workaround for R4k6 V1.7 was dropped later on.

I've got a somewhat better patch introducing all needed routines for the
buggy R4k6 V1.7 and setting them up (more or less correctly).

However, it seems that I did bug somewhere. My patch seems to not be as
stable as expected. I tried to post it at the weekend, but it didn't
show up (size?). I'll try it again these days, though.

MfG, JBG

-- 
Jan-Benedict Glaw   .   jbglaw@lug-owl.de   .   +49-172-7608481
         -- New APT-Proxy written in shell script --
           http://lug-owl.de/~jbglaw/software/ap2/

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