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Re: sysmips call and glibc atomic set

To: Ralf Baechle <ralf@uni-koblenz.de>
Subject: Re: sysmips call and glibc atomic set
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Thu, 28 Dec 2000 13:06:59 +0100 (MET)
Cc: Joe deBlaquiere <jadb@redhat.com>, the list <linux-kernel@vger.kernel.org>, linux-mips@oss.sgi.com, linux-mips@fnet.fr
In-reply-to: <20001226140204.D894@bacchus.dhis.org>
Organization: Technical University of Gdansk
On Tue, 26 Dec 2000, Ralf Baechle wrote:

> The semantics of this syscall were previously defined by Risc/OS and later
> on continued to be used by IRIX.

 Ralf, could you please provide me a copy of a man page for the call?  I
don't have access to either of the systems and a search of the Net
returned nothing. 

> Don't think about SMP without ll/sc.  There's algorithems available for
> that but their complexity leaves them a unpractical, theoretical construct.

 For SMP there is a simple kernel solution available.  It suitable for a
syscall or a ll/sc emulation.  There is no easy userland-only solution
AFAIK.

> Above code will break if the old content of memory has bit 31 set or you take
> pagefaults.  The latter problem is a problem even on UP - think multi-
> threading.

 If the code is written carefully you don't ever get a pagefault that
would break consistency.

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

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