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Re: Adding(?) XI support to MIPS-Linux?

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: Adding(?) XI support to MIPS-Linux?
From: "Kevin D. Kissell" <kevink@mips.com>
Date: Wed, 11 Jun 2008 11:35:50 +0200
Cc: "Kevin D. Kissell" <KevinK@paralogos.com>, Brian Foster <brian.foster@innova-card.com>, linux-mips@linux-mips.org, Andrew Dyer <adyer@righthandtech.com>
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Ralf Baechle wrote:
On Mon, Jun 09, 2008 at 09:32:59PM +0200, Kevin D. Kissell wrote:

That is correct, though there has long been interest in having XI/RI as an 
option for non-SmartMIPS cores and I would not be surprised if sooner or later 
it became more generally available.

Cavium has it in their 64-bit core.  I haven't verified this in the docs
but apparently it is meant to be compatible with the old SmartMIPS ASE
for MIPS32.
Do check the documentation. I can't comment officially, but I can observe that, in the hypothetical case where you'd want XI/RI semantics in a 64-bit processor, you might use exactly the same semantics (and therefore the same kernel C code support), but you might want to use different bits for XI/RI in a 64-bit TLB entry than in a 32-bit TLB entry (and therefore different header file definitions).

         Regards,

         Kevin K.

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