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Re: first packages for mipsel

To: "Kevin D. Kissell" <kevink@mips.com>
Subject: Re: first packages for mipsel
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Fri, 6 Apr 2001 18:40:10 +0200 (MET DST)
Cc: Florian Lohoff <flo@rfc822.org>, debian-mips@lists.debian.org, linux-mips@oss.sgi.com
In-reply-to: <00a401c0be8e$cfc065a0$0deca8c0@Ulysses>
Organization: Technical University of Gdansk
Sender: owner-linux-mips@oss.sgi.com
On Fri, 6 Apr 2001, Kevin D. Kissell wrote:

> What advantage would there be to using sysmips() as opposed
> to doing the ll/sc emulation?  It seems to me that the decode path
> in the kernel would be just as fast, and there would be a single
> "ABI" for all programs - the ll/sc instructions themselves.

 It was discussed a few times already.  It's ugly and is an overkill for
UP machines -- you take at least two faults for ll/sc emulation and only a
single syscall for TAS. 

 Sysmips() is ugly as well but it's a legacy call -- I proposed
implementing _test_and_set() call which would be the underlying
implementation of the ABI _test_and_set() library call for MIPS I systems
(which should probably be the only atomic operation available to the
userland).  Unfortunately the lack of time prevents me from doing it. 

 At least _test_and_set() has well-defined semantics.  It looks
straightforward as well. 

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


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