Re: TSCs are a no-no on i386

From: Pavel Machek (pavel@ucw.cz)
Date: Wed Aug 06 2003 - 06:08:55 EST

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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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