From: Jesse Barnes <jbarnes@engr.sgi.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Albert Cahalan <albert@users.sourceforge.net>,
linux-kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] I/O space write barrier
Date: Tue, 5 Oct 2004 08:33:49 -0700 [thread overview]
Message-ID: <200410050833.49654.jbarnes@engr.sgi.com> (raw)
In-Reply-To: <1096945479.24537.15.camel@gaston>
On Monday, October 4, 2004 8:04 pm, Benjamin Herrenschmidt wrote:
> > I agree, it's hard to get right, especially when you've got a large base
> > of drivers with hard to find assumptions about ordering.
> >
> > What about mmiowb()? Should it be eieio? I don't want to post another
> > patch if I don't have to...
>
> I don't understand the whole story...
>
> If normal accesses aren't relaxed (and I think they shouldn't be), then
> there is no point in a barrier here.... If you need an explicit barrier
> for explicitely relaxed accesses, then yes.
This macro is only supposed to deal with writes from different CPUs that may
arrive out of order, nothing else. It sounds like PPC won't allow that
normally, so I can be an empty definition.
> That doesn't solve my need of MMIO vs. memory unless you are trying to
> cover that as well, in which case it should be a sync.
No, I think that has to be covered separately.
Jesse
next prev parent reply other threads:[~2004-10-05 15:37 UTC|newest]
Thread overview: 49+ 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 [this message]
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
2004-10-05 2:33 ` Jesse Barnes
-- strict thread matches above, loose matches on Subject: below --
2004-10-21 23:13 Jesse Barnes
2004-10-21 23:13 ` Jesse Barnes
2004-10-22 1:01 ` Grant Grundler
2004-10-22 1:01 ` Grant Grundler
2004-10-22 3:05 ` Jesse Barnes
2004-10-22 3:05 ` Jesse Barnes
2004-10-22 4:26 ` Greg Banks
2004-10-22 4:26 ` Greg Banks
2004-10-22 15:26 ` Grant Grundler
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
2004-09-23 18:48 Jesse Barnes
2004-09-23 19:03 ` James Bottomley
2004-09-23 19:07 ` Jesse Barnes
2004-09-23 19:27 ` James Bottomley
2004-09-23 19:41 ` Jesse Barnes
2004-09-23 19:57 ` Jeremy Higdon
2004-09-23 22:22 ` Jeremy Higdon
2004-09-23 23:36 ` James Bottomley
2004-09-24 5:03 ` Jeremy Higdon
2004-09-23 19:55 ` Jeremy Higdon
2004-09-23 20:09 ` Jesse Barnes
2004-09-27 0:45 ` Benjamin Herrenschmidt
2004-09-27 15:41 ` Jesse Barnes
2004-09-22 15:45 Jesse Barnes
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