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I'm trying to build a package on lauchpad. For it to build I need to set a static path using the LDADD variable in automake:

relay_LDADD = /usr/lib/x86_64-linux-gnu/libm.so /usr/lib/x86_64-linux-gnu/libX11.so.6 $(RELAY_LIBS)

This compiles on the 64 bit build but fails on the 32 bit build. I tried using PKG_CHECK_MODULES but it says 

No package 'm' found
No package 'X11' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

I know it not a non standard path since launchpad is doing the building? How can I get this to work?

The build failed without the libraries specified even though the package specifies them in the build-requires.

kagronick
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1 Answers1

4

You have tried to outwit the buid-system, and it has outwitted you.

It's generally a bad idea to hard-code paths.

Debian (and ubuntu is just a derivative), has started to ship binaries (like libraries) in architecture-dependent directories, to allow installations for multiple architectures on a single system.

These libraries are installed into /usr/lib/<host-triplet>, where <host-triplet> depends on the architecture; e.g. x86_64-linux-gnu is the amd64 architecture for systems with a linux and the gnu tools. a 32bit system would typically have a host-triplet of i386-linux-gnu.

Since you are hard-coding the library path to a 64bit location( /usr/lib/x86_64-linux-gnu/libm.so) this fails on all systems but 64bit/linux/gnu.

Instead you should just tell the linker to link against the m library (libm), resp the X11 library (libX11). Let the linker care for the correct architecture to pick:

relay_LDADD = -lm -lX11 $(RELAY_LIBS)

In general, if you want to link against a library foo, that provides a library-file libfoo.so you would use -lfoo (stripping away the leading lib and the trailing .so).

However, sometimes this is not enough; in those cases your library might use pkg-config to provide the full CFLAGS and LDFLAGS needed to compile/link against this library.

e.g. if I want to use libquicktime:

 $ pkg-config --cflags libquicktime
 -I/usr/include/lqt
 $ pkg-config --libs libquicktime
 -lquicktime -lpthread -lm -lz -ldl

So I would use something like:

  myprog_CFLAGS += $(shell pkg-config --cflags libquicktime)
  myprog_LDADD += $(shell pkg-config --libs libquicktime)

That would work in any GNU(?) Makefile (not related to autotools). In an autotools project, you would probably move the pkg-config check into configure, using the m4-macro PKG_CHECK_MODULES

umläute
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