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From: David Woodhouse <dwmw2@infradead.org>
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To: "David S. Miller" <davem@redhat.com>
Cc: Chris Wedgwood <cw@f00f.org>, Jeff Garzik <jgarzik@mandrakesoft.com>,
        bjornw@axis.com, linux-kernel@vger.kernel.org,
        linux-mtd@lists.infradead.org
Subject: Re: Missing cache flush. 
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Date: Tue, 05 Jun 2001 10:05:35 +0100
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davem@redhat.com said:
>  One way to do this, (even portably :-) is via displacement flushes.
> Linus mentioned this.

> Basically if you know the L2 cache size and the assosciativity you can
> do this as long as you can get a "2 * L2 cache size * assosciativity"
> piece of contiguous physical memory.  When you need this "simon says"
> flush, you basically read this physical memory span and this will
> guarentee that all dirty data has exited the L2 cache. 

Fine. So it should be possible to do it on all architectures with 
physically-indexed caches - that's good. Architectures with 
virtually-indexed caches are going to have explicit cache management 
functionality anyway, presumably :)

Obviously the algorithm you describe should not be implemented in
arch-independent drivers. It should be in include/asm-*, for those
architectures which _can't_ do it with a single cache management instruction
(or loop of same).

What shall we call this function? The intuitive "flush_dcache_range" appears
to have already been taken.

--
dwmw2