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Message-ID: <475CBDD7.5050602@keyaccess.nl>
Date: Mon, 10 Dec 2007 05:17:27 +0100
From: Rene Herman <rene.herman@keyaccess.nl>
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To: Pavel Machek <pavel@ucw.cz>
CC: Andi Kleen <andi@firstfloor.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       "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
References: <475879CD.9080006@reed.com> <p733auekcly.fsf@bingen.suse.de> <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 09-12-07 22:25, Pavel Machek wrote:

> On Sun 2007-12-09 17:59:08, Andi Kleen wrote:

>> 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).

>  static inline void native_io_delay(void)
>  {
> -	asm volatile("outb %%al,$0x80" : : : "memory");
> +	udelay(8);
>  }

Alan, did you double-check that 8 us? I tried to but I seem to not have 
trustworthy documentation.

Rene.