[Buildroot] [PATCH 3/3] python3: Compile host-python3 statically

[Frederik Peter Aalund]

I noticed that while the host-python executable doesn't have an rpath
value, it does have a runpath value:

  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library:
[libpython3.5m.so.1.0]
 0x0000000000000001 (NEEDED)             Shared library: [libpthread.so.0]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x000000000000001d (RUNPATH)            Library runpath:
[/projects/RedPitaya/OS/buildroot/buildroot/output/host/usr/lib]
 0x000000000000000c (INIT)               0x4008c0

Turns out that I had LD_LIBRARY_PATH defined which overrides runpath
(though not rpath). After undefining LD_LIBRARY_PATH, everything worked.
Sorry for the confusion.

*Frederik Aalund*
Chief Information Officer, Co-owner

SBT Aqua
Copenhagen, Denmark
Mobile: +45 30340086
fpa at sbtaqua.com
sbtaqua.com

On Tue, 20 Sep 2016 at 15:57 Frederik Peter Aalund <fpa at sbtaqua.com> wrote:

> Hi Thomas
>
> Thanks again for reviewing. It appears that the host-python3 executable
> doesn't have an rpath entry. This would indeed explain the weird behaviour.
>
> I looked at the build log and found that "-Wl,-rpath" is indeed correctly
> passed on:
> -Wl,-rpath,/projects/RedPitaya/OS/buildroot/buildroot/output/host/usr/lib
>
> This is reflected in the resulting Makefile:
> CONFIGURE_LDFLAGS=
>  -L/projects/RedPitaya/OS/buildroot/buildroot/output/host/lib
> -L/projects/RedPitaya/OS/buildroot/buildroot/output/host/usr/lib
> -Wl,-rpath,/projects/RedPitaya/OS/buildroot/buildroot/output/host/usr/lib
> -Wl,--enable-new-dtags
>
> So I don't know how it can be that the rpath is not set in the final
> binary. Do you also see this problem?
>
> Thanks again.
>
> *Frederik Aalund*
> Chief Information Officer, Co-owner
>
> SBT Aqua
> Copenhagen, Denmark
> Mobile: +45 30340086
> fpa at sbtaqua.com
> sbtaqua.com
>
> On Fri, 16 Sep 2016 at 19:08 Thomas Petazzoni <
> thomas.petazzoni at free-electrons.com> wrote:
>
>> Hello,
>>
>> Please wrap the text in your commit messages to a reasonable line width
>> (72 characters).
>>
>> On Fri, 16 Sep 2016 15:30:31 +0200, Frederik Aalund wrote:
>> > The previous behaviour was to compile host-python3 with
>> `--enable-shared` as is done for the target python installation. The
>> problem is that if the host *already* has a python installation, then
>> host-python3 will be called with the system `libpython3.5.so`. So even
>> though the $(HOST_DIR) python executable is called, the system .so is used.
>>
>> This should not be the case. All host binaries we build are built with
>> -Wl,-rpath,$(HOST_DIR)/usr/lib, which means that they should look up
>> libraries in $(HOST_DIR)/usr/lib *before* looking at /usr/lib.
>>
>> Can you double check what "readelf -a output/host/usr/bin/python" says
>> about this? readelf should show you this rpath encoded into the Python
>> binary. If that's not the case, then this is the problem.
>>
>> Best regards,
>>
>> Thomas
>> --
>> Thomas Petazzoni, CTO, Free Electrons
>> Embedded Linux and Kernel engineering
>> http://free-electrons.com
>>
>
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