[U-Boot] Quick guide to Kconfig

[Ian Campbell]

On Thu, 2014-07-31 at 16:38 +0200, Hans de Goede wrote:
> make Foo_defconfig
> make menuconfig
> <select FEL>
> make

I was hoping that I might eventually be able to do something like
	make Foo_defconfig CONFIG_SPL_FEL=y
or perhaps
	make Foo_defconfig S:CONFIG_SPL_FEL=y
and have it DTRT(tm).

> I was planning on taking a shot at this, but the different make menuconfig
> and make spl/menuconfigs have me somewhat confused (I've a decent knowledge of
> Kconfig from my kernel work).

I think part of the problem is that right now we are at "Phase I" of the
switch to Kconfig, which is where the board.cfg settings have moved as a
string into CONFIG_SYS_EXTRA_OPTIONS. I suppose "Phase II" is that the
various maintainers implement proper Kconfig options for their platforms
and transition the individual settings over to it. Eventually
CONFIG_SYS_EXTRA_OPTIONS goes away.

Eventually (sooner rather than later, I think) we will want to have a
first-class Kconfig setting for CONFIG_SPL_FEL and then things like
"make spl/menuconfig" would let you enable FEL, I think/hope.

Apologies if I've misunderstood something and am therefore talking
nonsense ;-)

Ian.