[U-Boot] [RFC PATCH 0/2] Add macros to ease our life with independent CONFIGs between U-Boot and SPL

[Masahiro Yamada]

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.

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

I hope this series will make our life easier.

I know scripts/basic/fixdep.c must be tweaked for generating correct
.cmd files.

But I think this series is enough to show my intention.
Looks nice or not?
Comments are welcome.



Masahiro Yamada (2):
  kbuild: add a makefile macro useful with per-image config options
  linux/kconfig.h: add C macros useful for per-image config options

 include/linux/kconfig.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 scripts/Kbuild.include  |  3 +++
 2 files changed, 51 insertions(+)

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1.9.1