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Re: FPU emulator unsafe for SMP?

To: Ralf Baechle <ralf@oss.sgi.com>
Subject: Re: FPU emulator unsafe for SMP?
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Wed, 20 Feb 2002 15:46:32 +0100 (MET)
Cc: Jun Sun <jsun@mvista.com>, "Kevin D. Kissell" <kevink@mips.com>, linux-mips@oss.sgi.com
In-reply-to: <20020220140917.C15588@dea.linux-mips.net>
Organization: Technical University of Gdansk
Sender: owner-linux-mips@oss.sgi.com
On Wed, 20 Feb 2002, Ralf Baechle wrote:

> The context register is actually intended to be used for indexing a flat
> 4mb array of pagetables on a 32-bit processor.  It's a bit ill-defined
> on R4000-class processors as it assumes a size of 8 bytes per pte, so
> cannot be used in the Linux/MIPS kernel without shifting bits around.

 Ill???  I think someone was just longsighted enough not to limit PTEs to
38-bit physical addresses.  A shift costs a single cycle if we want to
save memory. 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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