linux-kernel - Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in

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Date:	Thu, 27 Dec 2007 11:59:23 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Jeff Garzik <jeff@...zik.org>, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>, gregkh@...e.de,
	linux-pci@...ey.karlin.mff.cuni.cz,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Martin Mares <mj@....cz>, Matthew Wilcox <matthew@....cx>
Subject: Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver
 opt-in

Arjan van de Ven wrote:
>> 2) [non-minor] hmmmm.
>>
>> 	[jgarzik@...e ~]$ lspci -n | wc -l
>> 	23
>>
>> So I would have to perform 23 sysfs twiddles, before I could obtain a 
>> full and unabridged 'lspci -vvvxxx'?
> 
> not you as human, but "lspci" ought to yes.
> 
>> For the userspace interface, the most-often-used knob for diagnostic 
>> purposes will be the easiest one.  And that's
> 
> the easiest one is an option to lspci. Nothing more nothing less.
> 
> Making a global knob in kernel space is a lot more tricky, and in addition
> really there's enough cases where userspace wants the one device anyway
> Doing the "for each device I'm about to dump" in lspci is pretty much as hard as doing
> the global one (if not simpler)

So then if you have a system where MMCONFIG doesn't work and you're not 
using any devices that require extended config space, then doing lspci 
-vvvxxx will blow up the machine? Yuck.

Still don't like this approach. It seems like (partially) covering up 
problems rather than solving them.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@...pamshaw.ca
Home Page: http://www.roberthancock.com/

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