[Buildroot] perl XS modules

[Arne Caspari]

François, 

Thank you very much for coming back to me. It is highly appreciated. 

I did not know about the scancpan-Script - this would have saved me a
ton of work, literally since I just ported a package with very very
many module dependencies (the Logitech Media Server) to buildroot. Ah
well...

I finally found the issue with the perl XS packages though: The perl
MakeMaker module fails to generate a correct Makefile but instead
messes up the configuration with the host-perl one. I kind of fixed the
issue for me in a very hackish way by modifying the generated Makefile
with the following script: 

define PERL_XML_PARSER_BUILD_CMDS
	sed "s~/usr/bin/gcc~$(TARGET_CC) -Os~" -i $(@D)/Makefile
	sed "s~/usr/bin/gcc~$(TARGET_CC) -Os~" -i $(@D)/Expat/Makefile
	sed "s~x86_64~$(KERNEL_ARCH)~" -i $(@D)/Expat/Makefile
	sed "s~host/usr/lib~staging/usr/lib~" -i $(@D)/Expat/Makefile
	$(MAKE) $(@D)/Makefile -C $(@D)
endef

The module loads correctly afterwards. Unfortunately I do not have any
experience with perl or the MakeMaker module to come up with a less
insane fix.


/Arne

Am Tue, 12 Jul 2016 10:00:41 +0200
schrieb François Perrad <fperrad at gmail.com>:

> The BR package libxml-parser-perl is a very specific host package
> which works only with the the system perl.
> (The reason is : this packge is heavy used, and we don't want the
> cost|time of the host-perl build)
> 
> All Perl modules (XS or Pure Perl) use the naming scheme :
> perl-module-name.
> For example, the wrapper for libxml2 is perl-xml-libxml.
> All these packages use the BR infrastructure perl-package.
> 
> If you want a target package perl-xml-parser (XML expat wrapper),
> start by running:
>    $ support/script/scancpan XML-Parser
> which creates a decent template.
> After add manually, the specific part required by the expat C library.
> (And obviously, read
> https://buildroot.org/downloads/manual/manual.html#_infrastructure_for_perl_cpan_packages
> )
> 
> François
> 
> 2016-07-08 17:40 GMT+02:00 Thomas Petazzoni <
> thomas.petazzoni at free-electrons.com>:
> 
> > Hello,
> >
> > François, could you have a look at the below question, that is Perl
> > and cross-compilation related?
> >
> > Thanks!
> >
> > Thomas
> >
> > On Fri, 8 Jul 2016 09:59:10 +0200, Arne Caspari wrote:  
> > > Hi all,
> > >
> > > I try to build the libxml-parser-perl package for an ARM target.
> > > Unfortunately the compiled perl module fails to load with the
> > > following error message:
> > >
> > > loadable library and perl binaries are mismatched
> > >
> > > After some digging I found that the module needs to be compiled
> > > with the same toolchain and compiler defines as the perl binary
> > > in order to be ABI compatible. Forcing the defines to be exactly
> > > the same as the ones used for the perl binary did not fix the
> > > issue so I believe it must be a problem with the toolchain.
> > >
> > > I get it right, buildroot builds the host-perl package with the
> > > GCC installed on the build system. In my case this is GCC Version
> > > 6.1 while the toolchain in buildroot uses 4.9.3. If I get the
> > > build procedure right, the ABI for perl is then configured for
> > > the 6.1 toolchain while module builds will use the toolchain
> > > provided by buildroot which is ABI incompatible.
> > >
> > > Is there a way to make buildroot build an initial toolchain to
> > > build the host packages with? Did anybody ever successfully build
> > > perlXS modules?
> > >
> > > Thanks,
> > >
> > > /Arne
> > > _______________________________________________
> > > buildroot mailing list
> > > buildroot at busybox.net
> > > http://lists.busybox.net/mailman/listinfo/buildroot  
> >
> >
> >
> > --
> > Thomas Petazzoni, CTO, Free Electrons
> > Embedded Linux, Kernel and Android engineering
> > http://free-electrons.com
> >