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Re: [PATCH] Improve atomic.h implementation robustness

To: "Maciej W. Rozycki" <macro@linux-mips.org>
Subject: Re: [PATCH] Improve atomic.h implementation robustness
From: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Date: Thu, 2 Dec 2004 02:02:29 +0100
Cc: Dominic Sweetman <dom@mips.com>, linux-mips@linux-mips.org, ralf@linux-mips.org, Nigel Stephens <nigel@mips.com>, David Ung <davidu@mips.com>
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Maciej W. Rozycki wrote:
[snip]
> > I discussed this with Richard Sandiford a while ago, and the conclusion
> > was to implement an explicit --msym32 option for both gcc and gas to
> > improve register scheduling and get rid of the gas hack. So far, nobody
> > came around to actually do the work for it.
> 
>  ... like this, for example.  But if nobody has implemented it yet, then 
> perhaps nobody is really interested in it? ;-)

The old solution works, and kernel developers tend to use old toolchains.

> > seen additional load/store insn creeping in ll/sc loops. I believe
> > there's a large amount of inline assembly code (not necessarily in the
> > kernel) which relies on similiar assumptions.
> 
>  With explicit relocs you have no problem with any instructions appearing 
> inside inline asms unexpectedly.  That is if you use the "R" constraint -- 
> the "m" one never guaranteed that.

But it happened to work, and is in widespread use.


Thiemo

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