Date: Sun, 30 Dec 2007 21:28:20 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Rene Herman <rene.herman@keyaccess.nl>, dpreed@reed.com,
       Islam Amer <pharon@gmail.com>, hpa@zytor.com,
       Pavel Machek <pavel@ucw.cz>, Ingo Molnar <mingo@redhat.com>,
       Andi Kleen <andi@firstfloor.org>, Thomas Gleixner <tglx@linutronix.de>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override
Message-ID: <20071230212820.0d53f389@the-village.bc.nu>
In-Reply-To: <20071230203417.GA12949@elte.hu>
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	<20071230152835.GX16946@elte.hu>
	<4777BDA5.4050203@keyaccess.nl>
	<alpine.LFD.1.00.0712301009220.32517@woody.linux-foundation.org>
	<20071230203417.GA12949@elte.hu>
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> fact even io_delay=udelay would be wrong because any problem will be 
> less clearly triggerable and thus less bisectable/debuggable.

And if this eats someones disk because you drive the hardware out of spec
you are going to sit there and tell them to bisect it ? Lovely. 

Ingo - put the christmas wine away and have a coffee. Now think first.
You won't bisect obscure timing triggered problems, and the _p users are
almost all for hardware where performance doesn't matter one iota (eg
CMOS).

This isn't even all down to the chipset internal logic - several of my
boxes have external CMOS NVRAM/RTC chips which are probably the same
design (if a little smaller) as ten years ago.

io_delay = none is exactly the same thing as CPU overclocking. Hard to
debug, unpredictable and stupid.

Alan
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