From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Adrian Bunk <bunk@fs.tum.de>
Cc: lkml <linux-kernel@vger.kernel.org>
Subject: Re: TSCs are a no-no on i386
Date: 30 Jul 2003 21:01:00 +0100 [thread overview]
Message-ID: <1059595260.10447.6.camel@dhcp22.swansea.linux.org.uk> (raw)
In-Reply-To: <20030730184529.GE21734@fs.tum.de>
On Mer, 2003-07-30 at 19:45, Adrian Bunk wrote:
> Note that this can also allow Step-A 486's to correctly run multi-thread
> applications since cmpxchg has a wrong opcode on this early CPU.
>
> Don't use this to enable multi-threading on an SMP machine, the lock
> atomicity can't be guaranted!
That is of course the other problem with this approach - you can't
really get the intended results without some extremely heavyweight code
(using an IPI to halt all CPU's, doing the access and then resuming
them)
The bigger problem (and certainly with some of the cmov emulation hacks
I've seen) is getting the security checking right when you need to
reprocess the user data - another reason to do it in userspace with a
preload 8)
next prev parent reply other threads:[~2003-07-30 20:07 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-30 13:56 TSCs are a no-no on i386 Jan-Benedict Glaw
2003-07-30 14:18 ` Maciej W. Rozycki
2003-07-30 14:44 ` Jan-Benedict Glaw
2003-07-30 16:58 ` Matthew Garrett
2003-07-30 17:19 ` Alan Cox
2003-07-30 18:10 ` Adrian Bunk
2003-07-30 18:30 ` Mike Fedyk
2003-07-30 18:45 ` Adrian Bunk
2003-07-30 20:01 ` Alan Cox [this message]
2003-07-30 20:33 ` Jan-Benedict Glaw
2003-07-30 22:19 ` J.A. Magallon
2003-07-31 6:11 ` Jan-Benedict Glaw
2003-07-30 23:05 ` Alan Cox
2003-07-31 11:11 ` Richard B. Johnson
2003-07-31 11:26 ` Emulating i486+ insn on i386 (was: TSCs are a no-no on i386) Jan-Benedict Glaw
2003-07-31 11:41 ` TSCs are a no-no on i386 Jan-Benedict Glaw
2003-07-31 0:22 ` Adrian Bunk
2003-07-31 6:22 ` Jan-Benedict Glaw
2003-07-31 7:17 ` Willy Tarreau
2003-07-31 11:38 ` Emulating i486 on i386 (was: TSCs are a no-no on i386) Jan-Benedict Glaw
2003-07-31 11:51 ` Alan Cox
2003-07-31 12:14 ` Jan-Benedict Glaw
2003-07-31 13:01 ` Jan-Benedict Glaw
2003-07-31 15:09 ` Martin Schlemmer
2003-07-31 15:33 ` Jan-Benedict Glaw
2003-08-01 5:37 ` Martin Schlemmer
2003-07-31 15:12 ` Jamie Lokier
2003-07-31 15:32 ` Jan-Benedict Glaw
2003-07-31 15:07 ` TSCs are a no-no on i386 Jamie Lokier
2003-07-31 15:23 ` Willy Tarreau
2003-07-31 15:50 ` Richard B. Johnson
2003-07-31 16:24 ` Jan-Benedict Glaw
2003-08-06 11:08 ` Pavel Machek
2003-08-06 14:33 ` Maciej W. Rozycki
2003-07-30 20:28 ` Jan-Benedict Glaw
2003-07-30 21:50 ` Petr Vandrovec
2003-07-30 23:10 ` Alan Cox
2003-07-31 15:10 ` Jamie Lokier
2003-07-31 16:01 ` Alan Cox
2003-07-31 18:37 ` Jamie Lokier
2003-07-31 19:10 ` Alan Cox
2003-07-31 6:29 ` Jan-Benedict Glaw
2003-07-30 20:27 ` Jan-Benedict Glaw
2003-08-06 16:41 James Bottomley
2003-08-06 16:45 James Bottomley
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