linux-kernel - Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

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Date:	Sun, 30 Dec 2007 22:25:36 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Rene Herman <rene.herman@...access.nl>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	dpreed@...d.com, Islam Amer <pharon@...il.com>, hpa@...or.com,
	Pavel Machek <pavel@....cz>, Ingo Molnar <mingo@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override


* Rene Herman <rene.herman@...access.nl> wrote:

> On 30-12-07 21:46, Ingo Molnar wrote:
>> * Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
>>
>>>> So the current plan is to go with an io_delay=udelay default in v2.6.25, 
>>>> to give this a migration window, and io_delay=none in v2.6.26 [and a 
>>>> complete removal of arch/x86/kernel/io_delay.c], once the _p() uses are 
>>>> fixed up. This is gradual enough to notice any regressions we care about 
>>>> and also makes it nicely bisectable and gradual.
>>> You will break systems if you blindly go around disabling _p delays for 
>>> ISA and LPC bus devices. The DEC Hinote laptops for example are well 
>>> known for requiring the correct ISA and other keyboard controller delays. 
>>> I don't expect anyone to test with a hinote or see it until it hits 
>>> Debian or similar 'low resource' friendly devices.
>>
>> well, using io_delay=udelay is not 'blindly disabling'.
>
> On the other hand, the patch you just posted that makes io_delay=none 
> the default _is_ blindly disabling. So that wasn't for consumption?

if you want to see the current x86.git intention then do:

 git-clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git linux-2.6.git
 cd linux-2.6.git
 git-branch x86
 git-checkout x86
 git-pull git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git mm

right now the default is io_delay=udelay.

	Ingo
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