From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Roland Dreier <roland@topspin.com>
Cc: Jesse Barnes <jbarnes@engr.sgi.com>,
Albert Cahalan <albert@users.sourceforge.net>,
linux-kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] I/O space write barrier
Date: Wed, 06 Oct 2004 11:45:43 +1000 [thread overview]
Message-ID: <1097027142.16744.1.camel@gaston> (raw)
In-Reply-To: <52r7ocra4q.fsf@topspin.com>
On Wed, 2004-10-06 at 09:57, Roland Dreier wrote:
> I could be wrong but I think that the eieio in the ppc IO write
> functions should be strong enough that mmiowb() can be a no-op.
>
> By the way, are the ordering rules different for ppc32 and ppc64? I
> notice that the ppc32 out_xxx() functions do eieio while the ppc64
> versions do a full sync.
ppc32 and ppc64 are identical by spec, but the current chips smaller
store queues are such that we didn't epxerience on ppc32 the amount
of issues we had on ppc64.
eieio will not order a cacheable store vs. a non-cacheable store by
spec, which is the root of our problem on ppc and why we had to change
some of these into sync's. Extended the semantics of mmiowb() to a more
generic ordering of MMIO vs. "the rest of the world" would help us as
I don't beleive in defining yet-another barrier and have it properly
used by device driver writers.
Ben.
next prev parent reply other threads:[~2004-10-06 1:51 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-04 20:39 [PATCH] I/O space write barrier Albert Cahalan
2004-10-04 21:20 ` Jesse Barnes
2004-10-05 0:32 ` Albert Cahalan
2004-10-05 1:22 ` Benjamin Herrenschmidt
2004-10-05 2:26 ` Jesse Barnes
2004-10-05 3:04 ` Benjamin Herrenschmidt
2004-10-05 15:33 ` Jesse Barnes
2004-10-05 22:41 ` Benjamin Herrenschmidt
2004-10-05 23:09 ` Jesse Barnes
2004-10-05 23:57 ` Roland Dreier
2004-10-06 1:45 ` Benjamin Herrenschmidt [this message]
2004-10-05 2:33 ` Jesse Barnes
-- strict thread matches above, loose matches on Subject: below --
2004-10-21 23:13 Jesse Barnes
2004-10-22 1:01 ` Grant Grundler
2004-10-22 3:05 ` Jesse Barnes
2004-10-22 4:26 ` Greg Banks
2004-10-22 15:26 ` Grant Grundler
2004-10-05 22:38 Jesse Barnes
2004-09-27 18:03 Jesse Barnes
2004-09-29 10:36 ` Greg Banks
2004-09-29 20:35 ` David S. Miller
2004-09-29 20:43 ` Jesse Barnes
2004-09-29 20:50 ` David S. Miller
2004-09-30 2:23 ` Greg Banks
2004-09-29 22:55 ` Jesse Barnes
2004-09-30 7:15 ` Jeremy Higdon
2004-09-30 21:21 ` Guennadi Liakhovetski
2004-10-16 0:38 ` Jeremy Higdon
2004-10-16 3:20 ` Matthew Wilcox
2004-10-16 3:31 ` Jeremy Higdon
2004-09-22 15:45 Jesse Barnes
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