From: Andi Kleen <andi@firstfloor.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Andi Kleen <andi@firstfloor.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
David Newall <david@davidnewall.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Krzysztof Halasa <khc@pm.waw.pl>,
Rene Herman <rene.herman@keyaccess.nl>,
"David P. Reed" <dpreed@reed.com>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops
Date: Tue, 11 Dec 2007 14:50:20 +0100 [thread overview]
Message-ID: <20071211135020.GB16750@one.firstfloor.org> (raw)
In-Reply-To: <20071211134725.GB17992@elf.ucw.cz>
On Tue, Dec 11, 2007 at 02:47:25PM +0100, Pavel Machek wrote:
> On Tue 2007-12-11 14:32:49, Andi Kleen wrote:
> > > The LPC bus behaviour is absolutely and precisely defined. The timing of
> > > the inb is defined in bus clocks which is perfect as the devices needing
> > > delay are running at a fraction of busclock usually busclock/2.
> > >
> > > Older processors did not have a high precision timer so you couldn't
> > > calibrate loop based delays for 1uS.
> >
> > For newer CPUs udelay() would be probably fine though. We seem
> > to have several documented examples now where the bus aborts
> > trigger hardware bugs, and it is always better to avoid such situations.
> >
> > I still think the best strategy would be to switch based on TSC
> > availability. Perhaps move out*_p out of line to avoid code bloat.
>
> Why is TSC significant? udelay() based on bogomips seems to be good
> enough...?
Maybe I'm not sure how accurate it really is on
non TSC system. On the other hand it is unclear that the port 80 IO
is always the same time so it's probably ok to vary a bit.
So most likely going to udelay() unconditionally is fine.
-Andi
next prev parent reply other threads:[~2007-12-11 13:50 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-06 22:38 RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops David P. Reed
2007-12-07 0:15 ` Alan Cox
2007-12-07 10:44 ` Andi Kleen
2007-12-07 14:50 ` David P. Reed
2007-12-05 11:10 ` Pavel Machek
2007-12-08 0:21 ` Andi Kleen
2007-12-07 14:54 ` Andi Kleen
2007-12-07 15:43 ` Rene Herman
2007-12-07 16:28 ` Rene Herman
2007-12-11 0:31 ` H. Peter Anvin
2007-12-11 5:53 ` H. Peter Anvin
2007-12-07 16:04 ` Alan Cox
2007-12-07 16:31 ` Andi Kleen
2007-12-07 17:19 ` Alan Cox
2007-12-07 18:45 ` Rene Herman
2007-12-07 18:42 ` Alan Cox
2007-12-07 19:25 ` Rene Herman
2007-12-07 21:45 ` Alan Cox
2007-12-08 19:25 ` David P. Reed
2007-12-08 19:50 ` Andi Kleen
2007-12-08 20:47 ` David P. Reed
2007-12-08 21:04 ` Alan Cox
2007-12-08 20:26 ` Alan Cox
2007-12-11 5:58 ` H. Peter Anvin
2007-12-09 5:04 ` Rene Herman
2007-12-09 13:22 ` Pavel Machek
2007-12-11 15:14 ` Lennart Sorensen
2007-12-09 12:54 ` Pavel Machek
2007-12-09 13:41 ` Dr. David Alan Gilbert
2007-12-09 15:54 ` Ondrej Zary
2007-12-09 16:59 ` Andi Kleen
2007-12-09 21:25 ` Pavel Machek
2007-12-09 22:29 ` Alan Cox
2007-12-09 23:22 ` Pavel Machek
2007-12-10 12:02 ` Alan Cox
2007-12-10 4:17 ` Rene Herman
2007-12-10 11:30 ` Krzysztof Halasa
2007-12-10 12:08 ` Rene Herman
2007-12-10 18:02 ` Ondrej Zary
2007-12-11 1:10 ` David Newall
2007-12-11 1:25 ` H. Peter Anvin
2007-12-11 1:42 ` David Newall
2007-12-11 1:46 ` H. Peter Anvin
2007-12-11 1:51 ` H. Peter Anvin
2007-12-11 7:40 ` Paul Rolland
2007-12-11 9:50 ` Rene Herman
2007-12-11 12:08 ` David Newall
2007-12-11 13:16 ` Rene Herman
2007-12-11 13:32 ` Paul Rolland
2007-12-11 14:15 ` Rene Herman
2007-12-11 15:28 ` Rene Herman
2007-12-11 15:37 ` Paul Rolland
2007-12-11 15:53 ` Rene Herman
2007-12-11 16:58 ` David P. Reed
2007-12-11 17:01 ` Rene Herman
2007-12-11 17:05 ` H. Peter Anvin
2007-12-11 17:32 ` Alan Cox
2007-12-11 19:19 ` David P. Reed
2007-12-11 19:36 ` Pavel Machek
2007-12-11 20:16 ` Alan Cox
2007-12-11 20:27 ` linux-os (Dick Johnson)
2007-12-11 20:34 ` Rene Herman
2007-12-11 21:03 ` David P. Reed
2007-12-11 23:56 ` David P. Reed
2007-12-12 13:11 ` linux-os (Dick Johnson)
2007-12-12 16:12 ` Alan Cox
2007-12-14 14:33 ` Ingo Molnar
2007-12-16 21:26 ` Pavel Machek
2007-12-17 0:02 ` Alan Cox
2007-12-17 0:03 ` Alan Cox
2007-12-17 0:28 ` Pavel Machek
2007-12-17 14:42 ` Ingo Molnar
2007-12-27 10:39 ` Pavel Machek
2007-12-12 19:42 ` Attitude problems David P. Reed
2007-12-12 20:31 ` linux-os (Dick Johnson)
2007-12-14 16:01 ` linux-os (Dick Johnson)
2007-12-11 16:32 ` RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops John Stoffel
2007-12-11 16:40 ` Rene Herman
2007-12-11 13:50 ` David Newall
2007-12-11 14:14 ` Rene Herman
2007-12-11 14:25 ` Alan Cox
2007-12-12 22:18 ` David Newall
2007-12-12 23:00 ` Alan Cox
2007-12-13 13:13 ` David P. Reed
2007-12-13 13:21 ` Alan Cox
2007-12-14 1:50 ` David P. Reed
2007-12-14 15:16 ` Alan Cox
2007-12-11 15:41 ` linux-os (Dick Johnson)
2007-12-11 16:30 ` Andi Kleen
2007-12-11 16:50 ` Rene Herman
2007-12-11 17:00 ` David P. Reed
2007-12-11 17:04 ` Rene Herman
2007-12-11 17:27 ` Rene Herman
2007-12-11 19:18 ` Pavel Machek
2007-12-11 19:16 ` Pavel Machek
2007-12-11 19:59 ` Rene Herman
2007-12-11 19:59 ` Rene Herman
2007-12-11 20:00 ` Rene Herman
2007-12-11 20:00 ` Rene Herman
2007-12-12 20:07 ` More info on port 80 symptoms on MCP51 machine David P. Reed
2007-12-12 20:26 ` Rene Herman
2007-12-12 20:37 ` David P. Reed
2007-12-12 20:58 ` Rene Herman
2007-12-12 21:01 ` Alan Cox
2007-12-12 21:12 ` H. Peter Anvin
2007-12-12 21:29 ` Alan Cox
2007-12-15 22:34 ` Allen Martin
2007-12-15 22:46 ` H. Peter Anvin
2007-12-16 0:46 ` David P. Reed
2007-12-12 21:05 ` H. Peter Anvin
2007-12-14 22:05 ` Chuck Ebbert
2007-12-15 7:22 ` Rene Herman
2007-12-11 13:14 ` RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops Alan Cox
2007-12-11 13:32 ` Andi Kleen
2007-12-11 13:47 ` Pavel Machek
2007-12-11 13:50 ` Andi Kleen [this message]
2007-12-14 13:33 ` Ingo Molnar
2007-12-11 6:54 ` Rene Herman
2007-12-11 17:01 ` H. Peter Anvin
[not found] <fa./27SNSh+L5T3iqFNPdHClEu+yT0@ifi.uio.no>
2007-12-07 0:23 ` Robert Hancock
2007-12-07 5:09 ` Rene Herman
2007-12-07 5:54 ` David P. Reed
2007-12-07 7:17 ` Rene Herman
2007-12-07 7:34 ` Rene Herman
2007-12-07 10:49 ` Andi Kleen
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