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

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Date:	Fri, 14 Dec 2007 18:36:26 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Rene Herman <rene.herman@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Rene Herman <rene.herman@...il.com>,
	"David P. Reed" <dpreed@...d.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Pavel Machek <pavel@....cz>
Subject: Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on
 some AMD64x2 laptops, etc.

> > i dont think this should matter: old systems that truly _need_ the ISA 
> > delay will be slow enough to not trip up. (nor are they really affected 
> > by these early delays - the delays were more for crappy ISA devices that 
> > get initialized later down, when the delay loop is already calibrated)
> 
> 8253 (DMAC) and 8254 (PIT) have been reported in earlier versions of the 
> thread. By Alan, I believe.

They've been seen to be problems up to PII era machines. I'm not aware of
any newer than that with this problem. We also don't need to touch the
DMAC that early anyway that I can see - just the PIT.

In fact if we have a fast processor we have a TSC and APIC so we don't
need the PIT ?

Alan
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