Date: Sun, 9 Dec 2007 22:29:28 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Pavel Machek <pavel@ucw.cz>
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: <20071209222928.3f7b63a4@the-village.bc.nu>
In-Reply-To: <20071209212513.GC24284@elf.ucw.cz>
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	<20071207160439.71b7f46a@the-village.bc.nu>
	<20071209125458.GB4381@ucw.cz>
	<20071209165908.GA15910@one.firstfloor.org>
	<20071209212513.GC24284@elf.ucw.cz>
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On Sun, 9 Dec 2007 22:25:13 +0100
Pavel Machek <pavel@ucw.cz> wrote:

> On Sun 2007-12-09 17:59:08, Andi Kleen wrote:
> > > I mean, we expect 8usec delay -- historical ISA timing -- but when
> > > _PCI_ card with leds is inserted, it is likely to be faster than old
> > > ISA, right?
> > 
> > Yes, i guess switching to udelay at least on newer systems would
> > be a good idea.  I'm not quite sure about systems without TSC though.
> 
> Something like this? (Warning, will not probably even compile on
> x86-64, I do not have 64-bit compiler near me).

You need to stick in a bug trap to verify that the udelay is not called
before the cpu timer has been set up.
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