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

Alan Cox
2007-12-07T17:25:59Z

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