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Re: Malta crashes on the latest 2.4 kernel

To: Ralf Baechle <ralf@oss.sgi.com>
Subject: Re: Malta crashes on the latest 2.4 kernel
From: Carsten Langgaard <carstenl@mips.com>
Date: Thu, 11 Jul 2002 09:50:22 +0200
Cc: "H. J. Lu" <hjl@lucon.org>, Jun Sun <jsun@mvista.com>, linux-mips@oss.sgi.com
References: <3D2CBF73.50001@mvista.com> <20020710164900.A28911@lucon.org> <20020711043601.B3207@dea.linux-mips.net>
Sender: owner-linux-mips@oss.sgi.com
Ralf Baechle wrote:

> On Wed, Jul 10, 2002 at 04:49:00PM -0700, H. J. Lu wrote:
>
> > > See the crash scene.  Anybody knows the cause?  It is strange to see the
> > > reserved exception.
> > >
> >
> > The 2.4 kernel checked out around Jul  4 09:28 PDT works fine on Malta.
>
> Jun's patch certainly is correct for some MIPS32 CPUs; others may get
> away without this one.  Previous experience with pipeline hazards on MIPS
> processors has shown that at times hazards may change even between minor
> revisions of a CPU; documentation isn't always trustworthy about such
> minor details of the pipeline.

I actually discovered the hazard problem on a 4Kc, based on some older RTL, but
the hazard some how disappear on a newer revision.
So you are absolutely right.

>
>   Ralf

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