From: Ian Wienand <ianw@gelato.unsw.edu.au>
To: linux-ia64@vger.kernel.org
Subject: Re: [Linux-ia64] _raw_write_trylock() missing
Date: Wed, 05 Feb 2003 01:46:37 +0000 [thread overview]
Message-ID: <marc-linux-ia64-105590709805814@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-105590709805809@msgid-missing>
On Tue, Feb 04, 2003 at 03:18:22PM +0100, Joel GUILLET wrote:
> What the macro is doing : (at least, what I think it is doing)
>
> - if the actual lock value is equal to "0",
> change the lock value to "00.....0001"
> else do nothing
>
> The code for this : (in include/asm-ia64/spinlock.h)
> "dep r29 = -1, r0, 31, 1\n"
doesn't this make the value of r29 0x80000000? i.e the 1 is at the
wrong end.
> "cmpxchg4.acq result = [rw], r29, ar.ccv\n"
so here you end up swapping 0x8000000 into rw if rw=0
i think maybe just making doing mov r29 = 1 above will do what you
want.
-i
ianw@gelato.unsw.edu.au
http://www.gelato.unsw.edu.au
next prev parent reply other threads:[~2003-02-05 1:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-04 2:53 [Linux-ia64] _raw_write_trylock() missing Peter Chubb
2003-02-04 14:18 ` Joel GUILLET
2003-02-05 1:46 ` Ian Wienand [this message]
2003-02-05 8:39 ` Joel GUILLET
2003-03-04 19:57 ` David Mosberger
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