From: "Jonathan Lundell" <jlundell@pobox.com>
To: "Linus Torvalds" <torvalds@transmeta.com>,
"Andrea Arcangeli" <andrea@suse.de>
Cc: "Jeff Dike" <jdike@karaya.com>,
user-mode-linux-user@lists.sourceforge.net,
linux-kernel@vger.kernel.org, "Jan Hubicka" <jh@suse.cz>
Subject: Re: user-mode port 0.44-2.4.7
Date: Mon, 23 Jul 2001 13:15:31 -0700 [thread overview]
Message-ID: <p05100301b78235dce19e@[10.0.0.49]> (raw)
In-Reply-To: <Pine.LNX.4.33.0107231259520.13272-100000@penguin.transmeta.com>
In-Reply-To: <Pine.LNX.4.33.0107231259520.13272-100000@penguin.transmeta.com>
At 1:00 PM -0700 2001-07-23, Linus Torvalds wrote:
>On Mon, 23 Jul 2001, Andrea Arcangeli wrote:
>>
>> gcc can assume 'state' stays constant in memory not just during the
>> 'case'.
>
>The point is that if the kernel has _any_ algorithm where it cares, it's a
>kernel bug. With volatile or without.
>
>SHOW ME THE CASE WHERE IT CARES. Let's fix it. Let's not just hide it with
>"volatile".
in arch/i386/kernel/io_apic.c:
>static int __init timer_irq_works(void)
>{
> unsigned int t1 = jiffies;
>
> sti();
> /* Let ten ticks pass... */
> mdelay((10 * 1000) / HZ);
>
> /*
> * Expect a few ticks at least, to be sure some possible
> * glue logic does not lock up after one or two first
> * ticks in a non-ExtINT mode. Also the local APIC
> * might have cached one ExtINT interrupt. Finally, at
> * least one tick may be lost due to delays.
> */
> if (jiffies - t1 > 4)
> return 1;
>
> return 0;
>}
If jiffies were not volatile, this initializing assignment and the
test at the end could be optimized away, leaving an unconditional
"return 0". A lock is of no help.
--
/Jonathan Lundell.
next prev parent reply other threads:[~2001-07-23 20:15 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-07-23 5:08 user-mode port 0.44-2.4.7 Jeff Dike
2001-07-23 15:56 ` Andrea Arcangeli
2001-07-23 15:59 ` Andrea Arcangeli
2001-07-23 16:17 ` Andrea Arcangeli
2001-07-23 16:51 ` Andrea Arcangeli
2001-07-23 16:33 ` Linus Torvalds
2001-07-23 16:45 ` Andrea Arcangeli
2001-07-23 17:32 ` Linus Torvalds
2001-07-23 17:50 ` Andrea Arcangeli
2001-07-23 18:11 ` Linus Torvalds
2001-07-23 18:27 ` Andrea Arcangeli
2001-07-23 20:00 ` Linus Torvalds
2001-07-23 20:15 ` Jonathan Lundell [this message]
2001-07-23 22:51 ` Linus Torvalds
2001-07-24 3:45 ` Jonathan Lundell
2001-07-24 15:41 ` Davide Libenzi
2001-07-24 15:46 ` Alexander Viro
2001-07-24 16:01 ` Davide Libenzi
2001-07-24 16:08 ` Alexander Viro
2001-07-24 16:52 ` Davide Libenzi
2001-07-24 16:59 ` Linus Torvalds
2001-07-24 17:31 ` Davide Libenzi
2001-07-24 17:38 ` Linus Torvalds
2001-07-24 18:07 ` Anton Altaparmakov
2001-07-23 20:44 ` Chris Friesen
2001-07-23 21:11 ` Andrea Arcangeli
2001-07-23 21:50 ` Richard Gooch
2001-07-23 22:09 ` Andrea Arcangeli
2001-07-23 13:20 ` Rob Landley
2001-07-23 22:27 ` Andrea Arcangeli
2001-07-23 17:50 ` Rob Landley
2001-07-23 23:47 ` Richard Gooch
2001-07-24 0:04 ` Andrea Arcangeli
2001-07-24 9:02 ` Jan Hubicka
2001-07-24 15:35 ` Linus Torvalds
2001-07-24 16:04 ` Linus Torvalds
2001-07-25 22:49 ` Andrea Arcangeli
2001-07-25 23:16 ` Linus Torvalds
2001-07-25 23:37 ` Chris Friesen
2001-07-26 18:28 ` Jan Hubicka
2001-07-26 18:35 ` Alan Cox
2001-07-23 22:53 ` Linus Torvalds
2001-07-23 23:13 ` Alan Cox
2001-07-23 20:25 ` Jeff Dike
[not found] <no.id>
2001-07-23 20:57 ` Alan Cox
2001-07-23 21:14 ` Chris Friesen
2001-07-25 19:12 ` Alan Cox
2001-07-25 23:49 ` Alan Cox
2001-07-25 19:03 James W. Lake
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