[U-Boot] Quick guide to Kconfig

[Hans de Goede]

Hi,

On 07/31/2014 06:51 AM, Masahiro Yamada wrote:
> Hi all,
> 
> 
> 
> The mainline has switched to Kconfig.
> 
> Please make sure to use "make <board>_defconfig"
> instead of "make <board>_config".
> 
> 
> 
> [1] Board Configuration
> 
>      make  <board_name>_defconfig
> 
> 
> 
> [2] Modify configuration
> 
> 
>  make config,  make menuconfig,  make nconfig, ... etc.
> 
> 
>  For SPL,
>    make spl/config,  make spl/menuconfig,  make spl/nconfig, ... etc.

I'm a bit confused here, a single "make" will build both the SPL +
the regular u-boot binary, so why 2 separate menuconfig commands for them ?

To be a bit more specific, currently for sunxi for some boards
(the ones most used by devs) we have both Foo_defconfig and Foo_FEL_defconfig
with the latter one being identical to the first one, except that it not only
defines SPL (all our builds use SPL) but also SPL_FEL, this changes some
compile time settings as well as leads to using a different linker script
for the SPL. The end result is a SPL binary which can be loaded through the
"FEL" allwinner usb firmware loading / update mechanism, rather then written
to a sdcard as our regular builds.

Rather then doubling the amount of defconfigs we have to allow using FEL
on any sunxi board, I would like to remove the Foo_FEL_defconfig files
and make it possible to do a FEL build by doing something like this:

make Foo_defconfig
make menuconfig
<select FEL>
make

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).

Perhaps you can give me some hints on how I can best implement the above ?

Thanks & Regards,

Hans