How can I install missing perl modules on an embedded system? - perl

Question

I'm running Linux on an embedded system, specifically Yocto Linux on a Cyclone V FPGA. I'm able to use Perl in its most basic form, but I'm unable to load any Perl modules. For example, when trying to use the GetOpt::Long module, I get the following error
root#socfpga_cyclone5:/mnt/sdcard# ./test.pl
Can't locate Getopt/Long.pm in #INC (#INC contains:
/etc/perl
/usr/lib/perl/site_perl/5.14.2/
/usr/lib/perl/site_perl/5.14.2
/usr/lib/perl/vendor_perl/5.14.2/
/usr/lib/perl/vendor_perl/5.14.2
/usr/lib/perl/5.14.2/
/usr/lib/perl/5.14.2
/usr/local/lib/site_perl
/usr/lib/perl/5.14.2
.) at ./test.pl line 3.
BEGIN failed--compilation aborted at ./test.pl line 3.
Does anybody know how I can go about installing these modules? Do the modules depend on hardware architecture at all? Is it reasonable to just copy and paste the .pm files somewhere from some source (and where would I be able to find and download these .pm files)?

Answer 1

I know your question is more than two years old, but it's a good question and I'm sad that nobody has answered it.
The perl ecosystem is very large, and the disk footprint of a full-featured perl installation is a problem on embedded systems. For that reason only a minimal system is installed when you add perl to your image. Other perl modules are available as bitbake packages.
Most of the time you can figure out what packages a recipe offers from the recipe, but the perl recipe is very complicated. The easiest way to find out what packages are built by the perl recipe is to build it (bitbake perl) and then look in the packages-split directory, which you will find in your bitbake work directory. For my system (cortex A8) that looks something like this:
$ ls -1 /poky/build/tmp/work/cortexa8hf-vfp-neon-poky-linux-gnueabi/perl/5.20.0-r1/packages-split
perl
perl-dbg
perl-dev
perl-doc
perl-lib
perl-lib.shlibdeps
perl-misc
perl-misc.shlibdeps
perl-module-anydbm-file
perl-module-app-cpan
perl-module-app-prove
perl-module-app-prove-state
(...)
If the module you want is listed, just add it to IMAGE_INSTALL like this:
IMAGE_INSTALL += "\
perl \
perl-module-base \
perl-module-bytes \
perl-module-data-dumper \
perl-module-digest-md5 \
perl-module-file-spec \
perl-module-file-spec-functions \
perl-module-findbin \
perl-module-getopt-long \
(...)"
If you want a module that isn't already being build, you will need to make your own recipe for it using the cpan class. See the examples in poky/meta/recipes-extended/perl and /poky/meta/recipes-lsb4/perl.
Editorializing, I've not been very happy with using perl on embedded systems. The biggest issue is the deferral of dependency resolution until runtime. It's too easy to mess this up and end up with Can't locate foobar.pm in #INC errors.

Answer 2

Have a look at this thread: https://lists.yoctoproject.org/pipermail/yocto/2013-July/015198.html
It sounds like perl modules have been packaged by whatever other thing needed first, but someone is working on making them available separately.
Some modules could be installed by just copying; others require a compiler or other build steps first. You are best off using whatever tools the yocto project provides.