[U-Boot] [PATCH 0/34] Switch over to real Kbuild

[Masahiro Yamada]

Hello Simon


> Further to this one - here is my full buildman output. There are a few
> PPC problems also:

Your close check is highly appreciated.
Thanks!

> 29: Makefile: move more flags to the top Makefile
>    powerpc: +   rainier_nand glacier_nand canyonlands_nand
> sequoia_nand haleakala_nand kilauea_nand acadia_nand bamboo_nand
> 30: Makefile: refactor include path settings
> 31: Makefile: move more stuff to top Makefile
>    powerpc:    rainier_nand glacier_nand canyonlands_nand sequoia_nand
> haleakala_nand kilauea_nand acadia_nand bamboo_nand

It looks like nand_spl boards are
broken at 29 and fixed at 31.

I will fix this problem at v2.


> 34: Kbuild: change out-of-tree building
>    sandbox: +   sandbox
>   blackfin:    bf561-acvilon cm-bf537u
> 35: Kbuild: add dummy obj-y to create built-in.o
> 36: Makefile: rename scripts/Makefile.build to scripts/Makefile.build.tmp
> 37: Kbuild: import more build scripts from Linux v3.12 tag
> 38: Kbuild: use Linux Kernel build scripts
>    sandbox:    sandbox
>   blackfin: +   bf561-acvilon cm-bf537u

Sandbox is broken at 34 and fixed at 38.

I will fix this problem too at v2.


buildman is also reporting something about bf561-acvilon and cm-bf537u.
But as long as I tested, I believe it is unrelated to Kbuild.

Sonic Zhang posted some patches to fix errors/warnings of Blackfin
boards.
Please check this again after u-boot-blackfin/mater is merged.



> > What will happen with the 'FIX ME's that are generated? e.g.:

I mentioned about My Next Plan in this covor letter.
I want to refactor more makefiles lator including such as
"FIX ME" or "TODO" items.

> > +# FIX ME
> > +ifneq ($(filter lib lib/lzma lib/zlib, $(obj)),)
> > +ccflags-y := -O2
> > +endif

I was thinking to do something about this after Kconfig.

Some Blackfin, M68K boards want to compile lib, lib/lzma, lib/zlib
with -O2 option and other sources with -Os option.

I think this feature is WANT, not MUST.

If this feature deserves maintainance,
how about adding new CONFIG macro like this?

config CC_OPTIMIZE_LIBS_FOR_SPEED
	bool "Optimize libraries for speed"
	help
	  Enabling this option will pass "-O2" when compiling C sources
  	   under lib/ directory even if -Os is given to the whole sources.
	  If unsure, say N.


And add the following line to lib/Makefile.

subdir-ccflags-$(CONFIG_OPTIMIZE_LIBS_FOR_SPEED) += -O2



> Have you done any comparison on build times?

Do you mean Kbuild is slower than U-Boot conventional build system?



Best Regards
Masahiro Yamada