linux-kernel - Re: ARM defconfig files

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Message-ID: <20100603201803.GH25779@flint.arm.linux.org.uk>
Date:	Thu, 3 Jun 2010 21:18:03 +0100
From:	Russell King <rmk@....linux.org.uk>
To:	Daniel Walker <dwalker@...eaurora.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-arm-msm@...r.kernel.org
Subject: Re: ARM defconfig files

On Thu, Jun 03, 2010 at 01:06:48PM -0700, Daniel Walker wrote:
> On Thu, 2010-06-03 at 20:57 +0100, Russell King wrote:
> > config MACH_HALIBUT
> > 	bool "Halibut Board (QCT SURF7201A)"
> > 	select I2C if STD_CONFIG
> > 	select I2C_WHATEVER if STD_CONFIG
> > 	...
> > 
> > That means if you enable STD_CONFIG, you'll get everything that's required
> > selected.  If you then disable STD_CONFIG, I believe Kconfig leaves
> > everything that was selected as still being selected.
> 
> I just did a little test, and it doesn't. Kconfig would un-select all
> the drivers, at least from my test.

That's because it knows what the original state of the symbol is.
Yes, that's a little undesirable for our behaviour - but it can be
worked around - by saving and restarting Kconfig.

Try this:

config STD_CONFIG
	bool "Standard config"
	default y

config DRIVER_A
	tristate "Driver A"

config ARM
	def_bool y
	select DRIVER_A if STD_CONFIG

and in a new directory /path/to/kernel/scripts/kconfig/mconf test.conf
If you turn off STD_CONFIG immediately, it'll turn off DRIVER_A.
However, save out the config, and re-run mconf test.conf.  You'll then
find that DRIVER_A remains set even when STD_CONFIG is turned off.

So, Kconfig does have the behaviour we desire but it's not directly
accessible.

Is it worth persuing?  Will Linus accept this STD_CONFIG idea or did
his lack of reply to it indicate that he's not something he's willing
to entertain?

In any case, this is my last mail on the subject.  I won't be replying
to mail for at least the next four days.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
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