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Re: LL and SC instruction simulation

To: "Kevin D. Kissell" <kevink@mips.com>
Subject: Re: LL and SC instruction simulation
From: Ralf Baechle <ralf@linux-mips.org>
Date: Mon, 9 Jan 2006 15:30:28 +0000
Cc: Sathesh Babu Edara <satheshbabu.edara@analog.com>, linux-mips-bounce@linux-mips.org, linux-mips@linux-mips.org
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On Mon, Jan 09, 2006 at 03:21:48PM +0000, Ralf Baechle wrote:

> > > Only ll/sc instructions in application software can be emulated, so it
> > > would seem your application is behaving different on 2.4 and 2.6 kernels.
> > 
> > Is there an interface where 2.6 might be telling library code to use system 
> > calls
> > instead LL/SC, where the 2.4 kernel didn't?
> 
> No.

And I think it's not really worth it.  MIPS II did introduce ll/sc in
1991 and it was becoming widely available with MIPS III and some pseudo-
MIPS II R3000 variants also in the embedded markets and MIPS32/MIPS64
were based on that.  So ll/sc-less processors are a very small part of
the market of Linux/MIPS these days, not really worth to optimize for.

  Ralf

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