[RFC PATCH] Kconfig: Enable Kconfig fragments to be used for defconfig

[Grant Likely]

On Tue, Jul 13, 2010 at 5:14 PM, Daniel Walker <dwalker at codeaurora.org> wrote:
> On Tue, 2010-07-13 at 17:04 -0600, Grant Likely wrote:
>
>> - I haven't figured out a way for the fragment to force an option to
>>   be "n", or to set a value, for example "CONFIG_LOG_BUF_SHIFT=16".
>>   This may require changing the syntax.
>> - It still doesn't resolve dependencies.  A solver would help with this.
>>   For the time being I work around the problem by running the generated
>>   config through 'oldconfig' and looking for differences.  If the files
>>   differ (ignoring comments and generateconfig_* options) after oldconfig,
>>   then the <board>_defconfig target returns a failure.  (but leaves the
>>   new .config intact so the user can resolve it with menuconfig).  This
>>   way at least the user is told when a Kconfig fragment is invalid.
>
> The solver would fix the whole issues with the defconfigs , we wouldn't
> need this Kconfig change .. From my perspective we shouldn't be fooling
> around with anything but the solver approach ..

The solver would complement Kconfig fragments, but it doesn't
implement all the functionality.  For instance, it doesn't help a
board config picking up a bunch of options from an SoC or Architecture
config file, especially things that are developer/maintainer choices
as opposed to hard requirements).  Solver on its own is an incremental
improvement over what we currently have, but it doesn't solve the
whole problem.

> It just doesn't feel like Kconfig was meant to do this, it feel like
> somewhat of an abuse ..

Why?  It uses the Kconfig language itself to specify additional
constraints on the final configuration.  Seems to be the essence of
elegance to me.  :-)

g.