[U-Boot] [PATCH] libfdt: fix build with Python 3

[Stefano Babic]

Hi Stefan,

On 03/04/2017 18:41, Stefan Agner wrote:
> Hi Stefano,
> 
> On 2017-04-03 03:30, Stefano Babic wrote:
>> Hi Stefan,
>>
>> On 29/03/2017 21:41, Stefan Agner wrote:
>>> From: Stefan Agner <stefan.agner at toradex.com>
>>>
>>> For some reason Python 3 seems to think it does not need to build
>>> the library. Using the --force parameter makes sure that the library
>>> gets built always. This is especially important since we move the
>>> library in the next step of the Makefile, hence forcing a rebuild
>>> every time the higher level Makefile triggers a rebuild is required
>>> to make sure the library is always there.
>>>
>>> Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>>> ---
>>>
>>>  lib/libfdt/setup.py | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/lib/libfdt/setup.py b/lib/libfdt/setup.py
>>> index 62e7bcc1ac..845a0c2b10 100644
>>> --- a/lib/libfdt/setup.py
>>> +++ b/lib/libfdt/setup.py
>>> @@ -27,7 +27,7 @@ libfdt_module = Extension(
>>>      extra_compile_args =  cflags
>>>  )
>>>
>>> -sys.argv = [progname, '--quiet', 'build_ext', '--inplace']
>>> +sys.argv = [progname, '--quiet', 'build_ext', '--inplace', '--force']
>>>
>>>  setup (name = 'libfdt',
>>>         version = '0.1',
>>>
>>
>> It looks to me we have a genaral problem about which python is called.
>> In fact, I am getting another issue when I build 2017.03 in Yocto. The
>> headers like "Python.h" are taken from the distro, and not from the
>> Yocto's buildsystem (nativepython), that makes them available.
>>
>> It can be easy tested removing the package "libpython" from the host. A
>> "bitbake u-boot", when u-boot 2017.03 is available, fails because no
>> headers are found - but they are all available in Yocto's toolchain.
>>
>> We set the "PYTHON" variable in the makefile, but this is not used
>> consistent, as far as I see, because in some files as setup.py,
>> "/usr/bin/env python" points to the python installed on distro - adding
> 
> Not sure whether that conclusion is correct.  

Quite. I forget to mention...

> As far as I can see we call
> setup.py in tools/Makefile using python explicitly:

Exactly. This makes PYTHON workless.

> 
> 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 $@
> 
> So we are not using /usr/bin/env in this case.
> 

No, but we are using "python" that can be taken just from PATH and not
from the PYTHON variable.

> Not sure though whether a call to "python" is different in that case
> from using "/usr/bin/env python"

I am not sure, too, but I am expecting that shebangs is not evaluated
because python is already running. But this breaks when I build in
Yocto, because I cannot override with "PYTHON=nativepython" the default
interpreter.

Regards,
Stefano


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