Date: Fri, 7 Dec 2007 17:19:57 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Andi Kleen <andi@firstfloor.org>
Cc: Andi Kleen <andi@firstfloor.org>, "David P. Reed" <dpreed@reed.com>,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64
 with MCP51 laptops
Message-ID: <20071207171957.73b619b1@the-village.bc.nu>
In-Reply-To: <20071207163116.GB5992@one.firstfloor.org>
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	<20071207163116.GB5992@one.firstfloor.org>
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On Fri, 7 Dec 2007 17:31:16 +0100
Andi Kleen <andi@firstfloor.org> wrote:

> > You don't need to. Port 0x80 historically is about 8uS so just udelay(8)
> > and make sure the initial default delay is conservative enough before the
> 
> How would you make it conservative enough handling let's say a 6Ghz CPU
> that can execute multiple jumps per cycle?

Pick a sane worst case and go with it at boot. We don't have to be
accurate before we tune udelay - over long in uSecs isnt going to hurt,
and most post boot _p's can be replaced by udelay(8) now

Alan
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