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Date:      Wed, 4 Oct 2000 09:25:58 +0100 (BST)
From:      Doug Rabson <dfr@nlsystems.com>
To:        John Baldwin <jhb@freebsd.org>
Cc:        new-bus@freebsd.org, msmith@freebsd.org
Subject:   Re: Generic memory barrier helper functions
Message-ID:  <Pine.BSF.4.21.0010040924060.94692-100000@salmon.nlsystems.com>
In-Reply-To: <XFMail.001003013402.jhb@FreeBSD.org>

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On Tue, 3 Oct 2000, John Baldwin wrote:

> After talking with Mike, I whipped up some quick and dirty helper
> functions for a MI memory barrier API.  Basically, you have the following
> four functions:
> 
> barrier_acquire() - a read barrier
> barrier_release() - a write barrier
> barrier_fence() - a read/write barrier
> barrier_flush() - a barrier that flushes the CPU's cache
> 
> I have a simple patch to implement all of these on both x86 and alpha
> with the exception of barrier_flush() on the alpha at
> http://www.FreeBSD.org/~jhb/patches/barrier.patch and inlined here:

It seems like a good idea although I'm not quite sure the functions should
go in bus.h. I would probably have thought of putting them in atomic.h
since one of their most important uses is for SMP communication.

-- 
Doug Rabson				Mail:  dfr@nlsystems.com
					Phone: +44 20 8348 6160




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