[Buildroot] host-python link fails due to missing readline

[Arnout Vandecappelle <arnout@mind.be>]

On 29-01-16 01:08, Jeff Gray wrote:
> Host machine : Ubuntu 12.04.2 x86_64
> Buildroot : 2015.11.1
> Target : arm920t
> Build fail : host-python-2.7.10
> 
> Build stopped with an error during host-python:
> Failed to build these modules:
> readline
> 
> I can see that readline-6.3 has been built for target, but not host. In the log
> file, I see these references to not finding readline as expected in the
> host-python configuration stage:
> checking how to link readline libs... none
> checking for rl_callback_handler_install in -lreadline... no
> checking for rl_pre_input_hook in -lreadline... no
> checking for rl_completion_display_matches_hook in -lreadline... no
> checking for rl_completion_matches in -lreadline... no 
> 
> And then later in the build process, because readline is not there:
> running build_ext
> /usr/lib/libreadline.so: not an ELF file.

 That is just weird... For two reasons:
- it shouldn't try to link with readline to begin with;
- since this is host compilation, /usr/lib/readline.so should be OK.

 What is also weird is that configure can't find readline, but the compilation
doesn't complain about missing header files.

 Can you check from which package /usr/lib/readline.so is coming?
dpkg -S /usr/lib/readline.so

 Does your gcc somehow generate 32bit code? Are you running inside some kind of
container that could affect things?

 It may also be useful to look at the config.log of python.


> 
> Then when trying to build the readline Python extension (shortened for readability):
> building 'readline' extension
> /usr/bin/gcc ... -c /output/build/host-python-2.7.10/Modules/readline.c ...
> (some warnings but nothing serious)
> /usr/bin/gcc -pthread -shared readline.o ... -lreadline -lncurses -lpython2.7 -o
> readline.so
> /usr/bin/ld: skipping incompatible
> /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../lib/libreadline.so when searching
> for -lreadline
> /usr/bin/ld: skipping incompatible /usr/lib/../lib/libreadline.so when searching
> for -lreadline
> /usr/bin/ld: skipping incompatible
> /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../libreadline.so when searching for
> -lreadline
> /usr/bin/ld: skipping incompatible /usr/lib/libreadline.so when searching for
> -lreadline
> /usr/bin/ld: cannot find -lreadline
> collect2: ld returned 1 exit status 
> 
> There is no /output/host/usr/lib/gcc/x86_64/ directory. Should there be one?

 Why do you mention this directory?


 Regards,
 Arnout


> 
> I'm experienced with embedded development, but new to buildroot, so forgive me
> an obvious error. I have searched through the list archives for similar issues,
> but can't find anything since a similar problem that was reported fixed by a
> Python update (the patch which is no longer part of buildroot).
> http://lists.busybox.net/pipermail/buildroot/2014-April/094460.html
> 
> I'm not sure what area to look at for this issue. Should readline be built for
> host before the host-python build? Or is it a config error in host-python
> looking for something that isn't there?
> 
> My .config file is on Google Drive here: https://goo.gl/gLj4rM
> My full build log file (16MB) is here: https://goo.gl/NLDCOj
> 
> 
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-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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