Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc.

[Rene Herman <rene.herman@gmail.com>]

On 15-12-07 09:08, Paul Rolland wrote:
> Hello,
>
> On Fri, 14 Dec 2007 23:29:55 +0000
> Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
> > On Fri, 14 Dec 2007 14:13:46 -0800
> > "H. Peter Anvin" <hpa@zytor.com> wrote:
> >
> > > Pavel Machek wrote:
> > > > On Fri 2007-12-14 10:02:57, H. Peter Anvin wrote:
> > > How long will that take to boot on a 386?
> > Well the dumb approach to fix that would seem to be to initialise it to
> >
> > 	cpu->family   3 -> 50MHz 4 -> 300Mhz 5-> etc...
>
> Just an idea : from what I've read, the problem (port 80 hanging) only occurs
> on 'modern' machines... So why not :
>  - use port 80 for old CPUs (PII, PIII) where it has never really been
>    a problem,
>  - use the cpu->family to do a best match for CPU freq
> thus we could avoid increasing boot time too much...

Yes, just posted a Patch-For-Comments that switches on the availability of a 
TSC (tsc_init sets tsc_disable also for !cpu_has_tsc) which would mean that 
only really old stuff would be using the outb still. A TSC is really all we 
need to have a sensible udelay().

Rene.
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