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Date: Fri, 7 Dec 2007 18:42:37 +0000 From: Alan Cox <alan@...rguk.ukuu.org.uk> To: Rene Herman <rene.herman@...access.nl> Cc: Andi Kleen <andi@...stfloor.org>, "David P. Reed" <dpreed@...d.com>, 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 On Fri, 07 Dec 2007 19:45:25 +0100 Rene Herman <rene.herman@...access.nl> wrote: > On 07-12-07 18:19, Alan Cox wrote: > > > On Fri, 7 Dec 2007 17:31:16 +0100 > > Andi Kleen <andi@...stfloor.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 > > Isn't 8 generally a bit overly long? I believe the norm is 1? 8uS is an ISA bus transaction. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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