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From: "Hua Zhong" <hzhong@cisco.com>
To: <linux-kernel@vger.kernel.org>
Cc: <paulus@samba.org>
Subject: Memory barrier on ppc and general
Date: Fri, 10 Sep 2004 17:47:25 -0700	[thread overview]
Message-ID: <004201c49798$e7ff06d0$7b3a47ab@amer.cisco.com> (raw)

Hi list:

I have a question about memory barrier.

1. first, this is a ppc-specific question. From the source of Linux ppc, I
see mb() and rmb() are defined as "sync", while "wmb()" is defined as
"eieio", but from the manual I see why eieio can't be used for rmb() and
mb() also. Could someone enlighten me?

2. second, does the memory barrier also work for for memory-mapped IO
registers? For example, a wmb() guarantees two stores to memory are
in-order, but say the second store is actually a hardware register. Would
the barrier still work?

Thanks for your answer.

Hua


                 reply	other threads:[~2004-09-11  0:47 UTC|newest]

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