linux-kernel - Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

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Message-ID: <20071207001533.7737ecf5@the-village.bc.nu>
Date:	Fri, 7 Dec 2007 00:15:33 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	"David P. Reed" <dpreed@...d.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64
 with MCP51 laptops

> Changing the delay instruction sequence from the outb to short jumps 
> might be the safe thing.  But Linus, et al. may have experience with 
> that on other architectures like older Pentiums etc.

Post boot we can use udelay() for this. Earlier I guess we could use
udelay and make sure it starts "safe" before we know the timing.

Alan
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