From: Arnd Bergmann <arnd@arndb.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC PATCH] Kconfig: Enable Kconfig fragments to be used for defconfig
Date: Fri, 16 Jul 2010 22:11:31 +0200
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Cc: Nicolas Pitre <nico@fluxnic.net>,
        "Russell King - ARM Linux" <linux@arm.linux.org.uk>,
        Grant Likely <grant.likely@secretlab.ca>,
        Catalin Marinas <catalin.marinas@arm.com>,
        linuxppc-dev@lists.ozlabs.org,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        linux-kbuild@vger.kernel.org, lkml <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org, Tony Lindgren <tony@atomide.com>,
        Daniel Walker <dwalker@codeaurora.org>,
        "Uwe =?iso-8859-1?q?Kleine-K=F6nig?=" 
	<u.kleine-koenig@pengutronix.de>,
        Stephen Rothwell <sfr@canb.auug.org.au>
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On Friday 16 July 2010 20:46:17 Linus Torvalds wrote:
> Maybe a full "solver" is unnecessary, for example, but just a simple
> "automatically enable the direct dependencies and scream when it's not
> simple any more" would take care of 99% of the common cases, and then
> warn when it needs some manual help.

I think the recursion should also be limited to cases where the
dependency is a valid selectable option, i.e. not for

# this architecture does not support MMIO
config HAS_IOMEM 
	def_bool 'n'

config PCI
	bool "PCI Device drivers"
	depends on HAS_IOMEM

config FOO
	tristate "Some device driver"
	depends on PCI

In this case, it would be straightforward for the solver to enable PCI
for when something selects CONFIG_FOO, but it should print a warning
if this is attempted while HAS_IOMEM is unconditionally disabled,
since that puts it into the "not simple" category.

	Arnd
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