From: David Howells <dhowells@redhat.com>
To: "David S. Miller" <davem@davemloft.net>
Cc: matthew@wil.cx, anton@samba.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH] ?mb() -> smp_?mb() conversion
Date: Tue, 22 Mar 2005 18:00:15 +0000 [thread overview]
Message-ID: <12463.1111514415@redhat.com> (raw)
In-Reply-To: <20050322091331.7b2967a1.davem@davemloft.net>
David S. Miller <davem@davemloft.net> wrote:
> > I don't think these actually exist at the moment. My suggestion was that we
> > rename {r,w,}mb() to io_{r,w,}mb().
>
> This is the first time I've seen that ?mb() should order I/O
> accesses. My sparc64 versions certainly don't handle that
> correctly. :-) That being said, I think we're all being
> educated to so me extent in this thread.
The FRV CPUs have a MEMBAR instruction; it takes no parameters and acts as a
mb().
You need this when accessing memory-mapped I/O (which is all I/O). Otherwise
reads and writes to peripherals may cross under some circumstances.
We've implemented the logic of when to insert MEMBAR into the FRV compiler,
using __builtin_read8/16/32() and __builtin_write8/16/32().
David
next prev parent reply other threads:[~2005-03-22 18:00 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-21 22:59 [PATCH] ?mb() -> smp_?mb() conversion Anton Blanchard
2005-03-21 23:06 ` David S. Miller
2005-03-22 10:43 ` David Howells
2005-03-22 13:13 ` Matthew Wilcox
2005-03-22 14:27 ` David Howells
2005-03-22 16:03 ` Anton Blanchard
2005-03-22 16:34 ` Matthew Wilcox
2005-03-22 16:48 ` David Howells
2005-03-22 17:13 ` David S. Miller
2005-03-22 17:44 ` James Bottomley
2005-03-22 18:09 ` Jesse Barnes
2005-03-22 18:00 ` David Howells [this message]
2005-03-22 21:59 ` Paul Mackerras
2005-03-22 18:15 ` Jesse Barnes
2005-03-22 18:24 ` Jesse Barnes
2005-03-23 6:23 ` Paul Mackerras
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=12463.1111514415@redhat.com \
--to=dhowells@redhat.com \
--cc=anton@samba.org \
--cc=davem@davemloft.net \
--cc=linux-arch@vger.kernel.org \
--cc=matthew@wil.cx \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.