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Date: Wed, 11 Apr 2001 11:18:09 -0700
From: "H. Peter Anvin" <hpa@transmeta.com>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: "H. Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org
Subject: Re: announce: PPSkit patch for Linux 2.4.2 (pre6)
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Alan Cox wrote:
> 
> > appropriately.)  One could, at least theoretically, make them usable
> > in kernel space only (in user space there is no hope, since you can't
> > know which CPU's TSC you're reading), but these machines seem to be so
> > rare that hardly anyone technical enough to fix it cares.
> 
> Im working on making the 'notsc' automatic. Trying to 'fix' it is just plain
> hard work. With the fixed one however we can still use the tsc for udelay
> as we have per cpu loops_per_jiffy data.
> 
> This btw is why -ac figures out the bus multiplier on your processors. If they
> dont match then we know tsc wants to be off. Just nobody has written the code
> to disable it across all CPUs yet
> 

Yes, there are two cases where we can "fix" it: in the timer interrupt
code, and the loops_per_jiffy stuff.

	-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt
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