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From: Nate Eldredge <neldredge@math.ucsd.edu>
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To: Jung-uk Kim <jkim@freebsd.org>
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Cc: freebsd-acpi@freebsd.org, Alexander Motin <mav@freebsd.org>,
	freebsd-amd64@freebsd.org, Nate Lawson <nate@root.org>
Subject: Re: Semi-working patch for amd64 suspend/resume
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On Wed, 22 Oct 2008, Jung-uk Kim wrote:

> The port 0x80 is usually used for BIOS debugging.
>
> http://www.coreboot.org/FAQ#POST_card
>
> Probably BIOS developer forgot to comment out the lines. :-)

Or it's been left in as a diagnostic tool.  My motherboard has a built-in 
LED display wired up to port 0x80, and it flashes various numbers as it 
passes different stages of booting.  Useful for detecting various types of 
failure, nicer than the beep codes.  It can also be handy for kernel 
debugging, when you can't use printf.  A very thoughtful feature on the 
motherboard designer's part.

Btw, I'm interested to test the patch, and I'll do so when I have a 
chance.  This is a feature I've been awaiting for some time.

-- 

Nate Eldredge
neldredge@math.ucsd.edu