kconfig: switch to single .config configuration

When Kconfig for U-boot was examined, one of the biggest issues was
how to support multiple images (Normal, SPL, TPL).  There were
actually two options, "single .config" and "multiple .config".
After some discussions and thought experiments, I chose the latter,
i.e. to create ".config", "spl/.config", "tpl/.config" for Normal,
SPL, TPL, respectively.

It is true that the "multiple .config" strategy provided us the
maximum flexibility and helped to avoid duplicating CONFIGs among
Normal, SPL, TPL, but I have noticed some fatal problems:

[1] It is impossible to share CONFIG options across the images.
  If you change the configuration of Main image, you often have to
  adjust some SPL configurations correspondingly.  Currently, we
  cannot handle the dependencies between them.  It means one of the
  biggest advantages of Kconfig is lost.

[2] It is too painful to change both ".config" and "spl/.config".
  Sunxi guys started to work around this problem by creating a new
  configuration target.  Commit cbdd9a9737cc (sunxi: kconfig: Add
  %_felconfig rule to enable FEL build of sunxi platforms.) added
  "make *_felconfig" to enable CONFIG_SPL_FEL on both images.
  Changing the configuration of multiple images in one command is a
  generic demand.  The current implementation cannot propose any
  good solution about this.

[3] Kconfig files are getting ugly and difficult to understand.
  Commit b724bd7d6349 (dm: Kconfig: Move CONFIG_SYS_MALLOC_F_LEN to
  Kconfig) has sprinkled "if !SPL_BUILD" over the Kconfig files.

[4] The build system got more complicated than it should be.
  To adjust Linux-originated Kconfig to U-Boot, the helper script
  "scripts/multiconfig.sh" was introduced.  Writing a complicated
  text processor is a shell script sometimes caused problems.

Now I believe the "single .config" will serve us better.  With it,
all the problems above would go away.  Instead, we will have to add
some CONFIG_SPL_* (and CONFIG_TPL_*) options such as CONFIG_SPL_DM,
but we will not have much.  Anyway, this is what we do now in
scripts/Makefile.spl.

I admit my mistake with my apology and this commit switches to the
single .config configuration.

It is not so difficult to do that:

 - Remove unnecessary processings from scripts/multiconfig.sh
  This file will remain for a while to support the current defconfig
  format.  It will be removed after more cleanups are done.

 - Adjust some makefiles and Kconfigs

 - Add some entries to include/config_uncmd_spl.h and the new file
   scripts/Makefile.uncmd_spl.  Some CONFIG options that are not
   supported on SPL must be disabled because one .config is shared
   between SPL and U-Boot proper going forward.  I know this is not
   a beautiful solution and I think we can do better, but let's see
   how much we will have to describe them.

 - update doc/README.kconfig

More cleaning up patches will follow this.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/Kconfig b/Kconfig
index 6be33e30e2d3a3d3857e7b8d0a4a8135de04cd81..4cb51c0e5612113ad8331ed38a898929aa1043c7 100644 (file)
--- a/Kconfig
+++ b/Kconfig
@@ -11,9 +11,6 @@ config UBOOTVERSION
 # Allow defaults in arch-specific code to override any given here
 source "arch/Kconfig"
 
-# Allow defaults in arch-specific code to override any given here
-source "arch/Kconfig"
-
 menu "General setup"
 
 config LOCALVERSION

diff --git a/scripts/Makefile.uncmd_spl b/scripts/Makefile.uncmd_spl
index 343c3fc199329ff5146dbc424253537cf3cf2c9f..40035468e76e9c627de1a9eb2281baf0ab789fc4 100644 (file)
--- a/scripts/Makefile.uncmd_spl
+++ b/scripts/Makefile.uncmd_spl
@@ -3,7 +3,6 @@
 # TODO: Invent a better way
 
 ifdef CONFIG_SPL_BUILD
-CONFIG_OF_CONTROL=
 
 ifndef CONFIG_SPL_DM
 CONFIG_DM_SERIAL=
@@ -13,6 +12,4 @@ CONFIG_DM_SPI=
 CONFIG_DM_SPI_FLASH=
 endif
 
-CONFIG_DM_DEVICE_REMOVE=
-
 endif