Date: Wed, 6 Aug 2003 13:08:55 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Adrian Bunk <bunk@fs.tum.de>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: TSCs are a no-no on i386
Message-ID: <20030806110855.GA583@elf.ucw.cz>
References: <20030730135623.GA1873@lug-owl.de> <20030730181006.GB21734@fs.tum.de> <20030730183033.GA970@matchmail.com> <20030730184529.GE21734@fs.tum.de> <1059595260.10447.6.camel@dhcp22.swansea.linux.org.uk>
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Hi!

> >   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)

Hopefully there are not too many SMP-486 machines out there ;-).
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
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