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Re: [patch] Use XKPHYS for 64-bit TLB flushes

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Subject: Re: [patch] Use XKPHYS for 64-bit TLB flushes
From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 9 Jan 2003 02:36:01 +0100
Cc: Mike Uhler <uhler@mips.com>, Dominic Sweetman <dom@mips.com>, linux-mips@linux-mips.org
In-reply-to: <Pine.GSO.3.96.1030108210002.11293A-100000@delta.ds2.pg.gda.pl>; from macro@ds2.pg.gda.pl on Wed, Jan 08, 2003 at 09:12:03PM +0100
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References: <20030108204408.A27888@linux-mips.org> <Pine.GSO.3.96.1030108210002.11293A-100000@delta.ds2.pg.gda.pl>
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On Wed, Jan 08, 2003 at 09:12:03PM +0100, Maciej W. Rozycki wrote:

>  Well, like it or not, CAMs do not like multiple matches -- up to a
> physical damage even.  So they should be avoided if possible.  While KSEG0
> won't match for any real address translation, there is a non-zero
> probability of executing a tlbp for it as a result of buggy code or
> execution gone wild (root running crashme?). 

I'm told the TLB Shutdown bit in the R4000 is basically implemented as an
overcurrent protection.  That is on many chips even a hit on several
entries won't cause a tlb shutdown until the matches do result in the
TLB drawing more than a certain current.

A tlbp on a KSEG0 address shouldn't happen.  If it's attempted we already
have worse problems.

  Ralf

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