From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Albert Cahalan <acahalan@gmail.com>
Cc: linux-kernel@vger.kernel.org, jbarnes@virtuousgeek.org,
alan@lxorguk.ukuu.org.uk, davem@davemloft.net, jgarzik@pobox.com,
paulus@samba.org, torvalds@osdl.org, akpm@osdl.org,
segher@kernel.crashing.org
Subject: Re: [RFC] MMIO accessors & barriers documentation
Date: Tue, 12 Sep 2006 15:48:02 +1000 [thread overview]
Message-ID: <1158040082.15465.66.camel@localhost.localdomain> (raw)
In-Reply-To: <787b0d920609112233u16a1cbcv2bf4ffa6b378dcd7@mail.gmail.com>
> > 4- io_to_lock_wb() : This barrier provides ordering requirement #4
> > between an MMIO store and a subsequent spin_unlock(). It can be used in
> > conjunction with write accessors of Class 2 and 3.
>
> These can really multiply: read or write, RAM and various types
> of IO space, etc.
No they can't. They are not dependent on the bus type but on the
processor memory model. Only 4 might have some more annoying
dependencies but in practice, it's still manageable. I think I've
defined the 4 base rules that are useful for drivers and the barriers
that provide them. Unless you can show me an example where something
else is needed.
> Let's have a generic arch-provided macro and let gcc do some work
> for us.
>
> Example usage:
> fence(FENCE_READ_RAM|FENCE_READ_PCI_IO, FENCE_WRITE_PCI_MMIO);
<snip>
That's terribly ugly imho.
Ben.
next prev parent reply other threads:[~2006-09-12 5:48 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-12 5:33 [RFC] MMIO accessors & barriers documentation Albert Cahalan
2006-09-12 5:48 ` Benjamin Herrenschmidt [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-09-11 4:03 Benjamin Herrenschmidt
2006-09-11 8:57 ` Alan Cox
2006-09-11 9:17 ` Benjamin Herrenschmidt
2006-09-11 10:07 ` Alan Cox
2006-09-11 9:59 ` Benjamin Herrenschmidt
2006-09-11 17:26 ` Alan Cox
2006-09-11 21:29 ` Benjamin Herrenschmidt
2006-09-12 5:48 ` Eric W. Biederman
2006-09-12 5:56 ` Benjamin Herrenschmidt
2006-09-12 6:27 ` Eric W. Biederman
2006-09-12 7:13 ` Benjamin Herrenschmidt
2006-09-12 15:19 ` Segher Boessenkool
2006-09-12 21:22 ` Benjamin Herrenschmidt
2006-09-13 0:12 ` Segher Boessenkool
2006-09-13 1:34 ` Benjamin Herrenschmidt
2006-09-11 18:39 ` Jesse Barnes
2006-09-11 21:45 ` Benjamin Herrenschmidt
2006-09-11 21:54 ` Jeff Garzik
2006-09-11 22:56 ` Benjamin Herrenschmidt
2006-09-11 23:08 ` Roland Dreier
2006-09-11 23:18 ` Benjamin Herrenschmidt
2006-09-11 23:24 ` Jeff Garzik
2006-09-12 0:46 ` Benjamin Herrenschmidt
2006-09-12 15:32 ` Segher Boessenkool
2006-09-11 22:05 ` Jesse Barnes
2006-09-11 23:01 ` Benjamin Herrenschmidt
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