[U-Boot] [PATCH 00/16] Add macros to ease our life with independent CONFIGs between U-Boot and SPL

[Scott Wood <scottwood@freescale.com>]

On Sun, 2015-07-26 at 17:26 +0900, Masahiro Yamada wrote:
> Refer to Simon's question, too:
> http://lists.denx.de/pipermail/u-boot/2015-July/219598.html
> 
> Since U-boot introduced SPL (not since Kconfig),
> enabling features for U-boot and SPL independently is always a PITA.
> 
>  - decide if each feature should be supported for SPL or not
>  - Add CONFIG_SPL_FRED_SUPPORT into Makefile.spl
>  - Add #undef include/config_uncmd_spl.h to disable features
>    we do not want to support on SPL
>  - Add "ifdef CONFIG_SPL_BUILD ... endif" here and there to adjust things
>  - Add "#ifdef CONFIG_SPL_BUILD ... #endif" here and there to fix things up
> 
> Things are getting more and more crappy.
> 
> When U-boot switched to Kconfig, first I introduced separate .config
> (.config, spl/.config, tpl/.config) to clean up them.
> But it turned out to be a pain.
> 
> So, I believe the current single .config is much better.
> But I also admit we need something systematic to subdue our PITA.

We had something systematic -- separate .configs, which could have been used 
to get rid of the CONFIG_SPL_FRED_SUPPORT stuff -- that you reverted (which 
was the only reason the uncmd stuff ever existed).

Yet somehow this is "much better". :-(

> One possibility is to support "spl-y" in makefiles.
> (This idea is cribbed from barebox.)
> 
>   obj-$(CONFIG_FOO) += foo.o
>   spl-$(CONFIG_SPL_FOO) += foo.o
> 
> is cleaner than
> 
>   ifdef CONFIG_SPL_BUILD
>     obj-$(CONFIG_SPL_FOO) += foo.o
>   else
>     obj-$(CONFIG_FOO) += foo.o
>   endif
> 
> It is a nice improvement in makefile side.
> But we still need to do something with C files.
> 
> Another option is something like
>    CONFIG_FOO=yyn  (yes for U-boot, yes for SPL, no for TPL)
> 
> To achieve this, I think a big operation is needed in Kconfig core.
> I cannot do that.
> (Of course, Patches are welcome if someone else can do that.)
> 
> So, I was thinking of something different.
> 
> My idea was inspired by IS_ENABLED() macro in include/linux/kconfig.h.
> 
> Linux defines different macros for built-in and module,
> and it is possible to write
>    #if IS_ENABLED(CONFIG_FOO)
>            ...
>    #endif
> 
>  instead of
> 
>    #if defined(CONFIG_FOO) || defined(CONFIG_FOO_MODULE)
>            ...
>    #endif
> 
> So, I'd like to propose new macros to write code like
> 
>    #if CONFIG_IS_ENABLED(FOO)
>             ...
>    #endif
> 
>  instead of
> 
>    #if (!defined(CONFIG_SPL_BUILD) && defined(CONFIG_FOO)) || \
>          (defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_FOO))
>              ...
>    #endif

With separate .config this is just:

#ifdef CONFIG_FOO
        ...
#endif

-Scott