CODEWITHSUNDEEP
c++cgcclinker
Martin
Martin

Reputation: 9369

How to force linkage to non installed libraries during cross compilation

My situation with g++ is the following. I build a shared library called libplugin.so, which is loaded at run-time by an application. This libplugin.so links to some other shared libraries, with the -no-as-needed linker option, and to a static library.

Since libplugin.so itself does not use any of the symbols in the listed libraries, -no-as-needed is required to make the dynamic loader load all the required libraries - which are really referenced by the static library only - when the plugin is loaded at run-time. On my x86 building machine, all the libraries listed as -no-as-needed are installed in the system. So, the library is built fine there and the program is also ok.

Now I am trying to cross compile for ARM, but there are some problems, because the linker cannot find the libraries indicated as -no-as-needed in the system when building libplugin.so. The linked cannot find the libraries because they (deliberately) are not installed. I prefer not to install them.

So here is my question. As libplugin.so does not directly reference the libraries passed to -no-as-needed in any way, is there a way to "force" the linker to build libplugin.so although the ARM libraries passed to -no-as-needed do not exist in my x86 building system?

Below is an example:

arm-linux-gnueabihf-g++ -o libplugin.so module1.o module2.o -L./libstatic.a -Wl,--no-as-needed -lX11 -lXext -shared -s -fPIC
arm-linux-gnueabihf-ld: cannot find -lX11

Upvotes: 1

Views: 227

Answers (1)

nos
nos

Reputation: 229088

Afaik you can't easily do that. But since your library doesn't use anything in the shared libraries you want to link to , you should be able to trick the linker by creating a dummy libX11 library and link to that:

arm-linux-gnueabihf-gcc -x c -shared -o libX11.so -Wl,-soname,libX11.so.6 /dev/null

This will create a rather empty libX11.so that you can link to. The important part is the soname of this library, which must match the soname of the real library - you can figure that out with e.g.

readelf -a /lib/libX11.so |grep soname

Upvotes: 1

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