[U-Boot] [PATCH v2 01/19] Makefile: prepare for using Kbuild-style Makefile

[Masahiro Yamada]

Hello Simon



> > +# Tentative step for Kbuild-style makefiles coexist with conventional
> > U-Boot style makefiles
> > +#  U-Boot conventional sub makefiles always include some other makefiles.
> > +#  So, the build system searches a line beginning with "include" before
> > entering into the sub makefile
> > +#  in order to distinguish which style it is.
> >
> 
> Would looking for obj- be better or worse?

At first I thought of this but I was kind of worried
whether all makefiles should forcibly have obj-y or obj-.

arch/arm/cpu/armv7/tegra114/
arch/arm/cpu/armv7/tegra30/
directories have no source files but only a Makefile.

After all, I simply added
obj- :=
line in them, so I think your suggestion will work.

If you prefer to search obj-, I will consider to change at version 3.

In any case, this ugly grep switch is tentative.
I want to refactor all makefiles and delete this switch
as soon as possible.



> an indent might help here, and below.

I will fix at v3.



> > +               fi
> >
> >  $(LIBS):       depend $(SUBDIR_TOOLS)
> > -               $(MAKE) -C $(dir $(subst $(obj),,$@))
> > +               if grep -q "^include" $(dir $(subst $(obj),,$@))Makefile;
> > then \
> >
> 
> This check seems to appear a lot - could it become a $(call ...) perhaps?


I did not care so much about this part becuase it is temporary.
But re-writing it shortly with $(call ...) is not difficult.
I will try at v3.
Thanks for your advice.




> Re testing, I used:
> 
> $ ./tools/buildman/buildman -b try-kbuild -k
> 
> and confirmed that the binaries do change, for example, with cm41xx:
> 
> $ wc ...
>    1348    5418  123176
> try-kbuild/01_of_20_g0c5274e6_Prepare-v2013.04-rc4/cm41xx/u-boot.bin
>    1348    5417  123188
> try-kbuild/02_of_20_gd3068182_Makefile--prepare-fo/cm41xx/u-boot.bin
> 
> The change may well be harmless though.

It is probably because of include/generated/version_autogenerated.h

The length of PLAIN_VERSION and U_BOOT_VERSION changes
because the output `git describe` command is used for here.

Actually I gave it a try.


For master branch (Prepare v2013.04-rc4), I got:

#define PLAIN_VERSION "2013.10-rc4"
#define U_BOOT_VERSION "U-Boot 2013.10-rc4"
#define CC_VERSION_STRING "arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3"
#define LD_VERSION_STRING "GNU ld (GNU Binutils for Ubuntu) 2.23.2"


For try-kbuild branch (Makefile: prepare for using Kbuild-style Makefile)
I got:

#define PLAIN_VERSION "2013.10-rc4-00001-gc31a399"
#define U_BOOT_VERSION "U-Boot 2013.10-rc4-00001-gc31a399"
#define CC_VERSION_STRING "arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3"
#define LD_VERSION_STRING "GNU ld (GNU Binutils for Ubuntu) 2.23.2"


For the list of things you should take into account to get identical
output files, please refer the thread of version1 of this series:
[U-Boot] [PATCH 00/19] First step towards Kbuild: Use Kbuild style makefiles
Message-Id: <20130917093533.738A.AA925319 at jp.panasonic.com>


> (2) Git commit hash
> 
> Git commit hash is contained in include/generated/version_autogenerated.h.
> So, I also modified include/version.h not to include it as follows:
> 
>      #ifndef DO_DEPS_ONLY
>     -#include "generated/version_autogenerated.h"
>     +/* #include "generated/version_autogenerated.h" */
>     +#define PLAIN_VERSION "__DUMMY__"
>     +#define U_BOOT_VERSION "__DUMMY__"
>     +#define CC_VERSION_STRING "__DUMMY__"
>     +#define LD_VERSION_STRING "__DUMMY__"
>      #endif

This is what I did when I compared md5sum.
After applying above as a prerequisite commit,
I tried 'tools/buildman/buildman -b try-kbuild -k' again
and I got the same size for cm41xx/u-boot.bin


If you compare the size of u-boot.bin,
please take care of the order of object files too.

I also mentioned this in the thread of v1.





> It would be nice to add a feature to buildman to compare binaries. Of
> course we would need to add a Makefile option to disable the timestamp
> embedding first, since all binaries are different because of that.

Sounds a good idea.
I will take a look when I have time.



Best Regards
Masahiro Yamada