[U-Boot] Compile v2017.03 on a system where Python 3 is default

[Stefan Agner]

On 2017-03-30 10:54, Jelle van der Waa wrote:
> On 03/28/17 at 05:30pm, Stefan Agner wrote:
>> Hi,
>>
>> When I try to compile U-Boot on my Arch Linux system I get the following
> 
> Python 3 needs some more TLC, I've been hacking on making binman work
> out of the box with Python 3 (and retaining Python 2 compatibility). But
> haven't been able to get it working yet. [1]
> 
> [1] https://github.com/jelly/u-boot/commits/binman_py3

Hm, not sure but I think my issue is not related to that. binman asks
for Python 2 by default using shebang:

11:48 $ head tools/binman/binman
#!/usr/bin/env python2
...

And the way we call binman respects shebang:
# binman                                                                
                                                                   
#
---------------------------------------------------------------------------
                                                              
quiet_cmd_binman = BINMAN  $@                                           
                                                                   
cmd_binman = $(srctree)/tools/binman/binman -d u-boot.dtb -O . \        
                                                                   
                -I . -I $(srctree)/board/$(BOARDDIR) $< 

I do have Python 2 installed, so binman gets executed with Python 2 and
works well here...

Its just that "python" symlinks to python3, which seems to be an issue
for ./lib/libfdt/setup.py.

In the ./lib/libfdt/setup.py case the Makefile calls that script as an
argument to the explicitly called python interpreter:

11:56 $ grep -C 2 -e setup.py tools/Makefile

tools/_libfdt.so: $(patsubst %.o,%.c,$(LIBFDT_OBJS)) tools/libfdt_wrap.c
        LDFLAGS="$(HOSTLDFLAGS)" CFLAGS= python
$(srctree)/lib/libfdt/setup.py \
                "$(_hostc_flags)" $^
        mv _libfdt.so $@


Anyway, it seems that ./lib/libfdt/setup.py actually works fine with
Python 3 when using the --force argument, which is what we want in that
case, imho... So this fix resolves the issue for me:
https://patchwork.ozlabs.org/patch/744927/


--
Stefan

> 
>> error:
>>
>> LDFLAGS="" python ./lib/libfdt/setup.py \
>>         "-Wall -Wstrict-prototypes -O2 -fomit-frame-pointer    -include
>> ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include
>> -I./lib/libfdt -I./tools -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES
>> -D_GNU_SOURCE " lib/libfdt/fdt.c lib/libfdt/fdt_ro.c lib/libfdt/fdt_rw.c
>> lib/libfdt/fdt_strerror.c lib/libfdt/fdt_wip.c lib/libfdt/fdt_region.c
>> lib/libfdt/fdt_sw.c tools/libfdt_wrap.c
>> mv _libfdt.so tools/_libfdt.so
>> mv: cannot stat '_libfdt.so': No such file or directory
>> make[1]: *** [tools/Makefile:124: tools/_libfdt.so] Error 1
>> make: *** [Makefile:1229: tools] Error 2
>>
>>
>> As far as I can tell the issue is that python defaults on my system to
>> python 3:
>> $ python --version
>> Python 3.6.0
>>
>> I can fix the issue by explicitly ask for python2, not sure if that is
>> the proper way to fix this though:
>>
>> diff --git a/tools/Makefile b/tools/Makefile
>> index 1c840d7ae2..c5e422edf9 100644
>> --- a/tools/Makefile
>> +++ b/tools/Makefile
>> @@ -120,7 +120,7 @@ _libfdt.so-sharedobjs += $(LIBFDT_OBJS)
>>  libfdt:
>>
>>  tools/_libfdt.so: $(patsubst %.o,%.c,$(LIBFDT_OBJS))
>> tools/libfdt_wrap.c
>> -       LDFLAGS="$(HOSTLDFLAGS)" python $(srctree)/lib/libfdt/setup.py \
>> +       LDFLAGS="$(HOSTLDFLAGS)" python2 $(srctree)/lib/libfdt/setup.py
>> \
>>                 "$(_hostc_flags)" $^
>>         mv _libfdt.so $@
>>
>>
>> It works, but with warnings:
>> LDFLAGS="" python2 ./lib/libfdt/setup.py \
>>         "-Wall -Wstrict-prototypes -O2 -fomit-frame-pointer    -include
>> ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include
>> -I./lib/libfdt -I./tools -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES
>> -D_GNU_SOURCE " lib/libfdt/fdt.c lib/libfdt/fdt_ro.c lib/libfdt/fdt_rw.c
>> lib/libfdt/fdt_strerror.c lib/libfdt/fdt_wip.c lib/libfdt/fdt_region.c
>> lib/libfdt/fdt_sw.c tools/libfdt_wrap.c
>> In file included from /usr/include/python2.7/Python.h:8:0,
>>                  from tools/libfdt_wrap.c:149:
>> /usr/include/python2.7/pyconfig.h:1190:0: warning: "_POSIX_C_SOURCE"
>> redefined
>>  #define _POSIX_C_SOURCE 200112L
>>
>> In file included from /usr/include/stdint.h:25:0,
>>                  from
>> /usr/lib/gcc/x86_64-pc-linux-gnu/6.3.1/include/stdint.h:9,
>>                  from ././include/compiler.h:19,
>>                  from ././include/libfdt_env.h:12,
>>                  from <command-line>:0:
>> /usr/include/features.h:225:0: note: this is the location of the
>> previous definition
>>  # define _POSIX_C_SOURCE 200809L
>>
>> In file included from /usr/include/python2.7/Python.h:8:0,
>>                  from tools/libfdt_wrap.c:149:
>> /usr/include/python2.7/pyconfig.h:1212:0: warning: "_XOPEN_SOURCE"
>> redefined
>>  #define _XOPEN_SOURCE 600
>>
>> In file included from /usr/include/stdint.h:25:0,
>>                  from
>> /usr/lib/gcc/x86_64-pc-linux-gnu/6.3.1/include/stdint.h:9,
>>                  from ././include/compiler.h:19,
>>                  from ././include/libfdt_env.h:12,
>>                  from <command-line>:0:
>> /usr/include/features.h:166:0: note: this is the location of the
>> previous definition
>>  # define _XOPEN_SOURCE 700
>>
>> mv _libfdt.so tools/_libfdt.so
>>   HOSTCC  tools/proftool
>> ...
>>
>>
>> --
>> Stefan
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