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Message-ID: <476438B4.2020600@zytor.com>
Date: Sat, 15 Dec 2007 12:27:32 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Rene Herman <rene.herman@...il.com>
CC: Paul Rolland <rol@...917.net>, Alan Cox <alan@...rguk.ukuu.org.uk>,
Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...e.hu>,
"David P. Reed" <dpreed@...d.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
Rene Herman <rene.herman@...access.nl>, rol@...be.net
Subject: Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80
on some AMD64x2 laptops, etc.
Rene Herman wrote:
>
> Yes, just posted a Patch-For-Comments that switches on the availability
> of a TSC (tsc_init sets tsc_disable also for !cpu_has_tsc) which would
> mean that only really old stuff would be using the outb still. A TSC is
> really all we need to have a sensible udelay().
>
Uhm, no. You have no clue what the speed of the TSC is until you have
been able to calibrate it against a fixed timesource - like the PIT.
-hpa
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