Recompile with -fPIC Gentoo

Question

I'm new to Gentoo and trying to install a 3D modelling program called TexGen (http://texgen.sourceforge.net/index.php/Main_Page) using CMake, and I keep getting the error:

relocation R_X86_64_32 against `.rodata' can not be used when making a shared object; recompile with -fPIC

This occurs during the step:

[ 80%] Linking CXX shared module ../_Renderer.so

I've looked all over and tried setting the -fPIC flag in the cmake options file, but there's no change in the result. As I said I'm quite new (in the order of a few weeks) to Linux and Gentoo and any help would be greatly appreciated.

you've only been using linux for a few weeks yet you've delved straight into gentoo? oh boy. — 2ARSJcdocuyVu7LfjUnB, May 17 '16 at 04:49
@MitchWeaver the lab I'm working at only uses gentoo so it's an adventure — aviator333, May 17 '16 at 13:15
If you're getting this error from an official package I'd suggest you to report it to bugs.gentoo.org, if not then forums.gentoo.org, which is a better equipped platform for novices. — rindeal, May 20 '16 at 18:40

score 0 · Answer 1 · answered Jun 17 '16 at 19:27

Actually Gentoo has a eclass(es) to build CMake based projects (see /usr/portage/cmake*.eclass). And AFAIK, it replace package options with yours (to be precise, it adds a new configuration type), configured in /etc/portage/make.conf (or /etc/paludis/bashrc if you use paludis). So, I not wondered that "hacking" CMakeLists.txt in the package ebuild do not help.

So, easiest way is to add that option to your Gentoo settings instead. Personaly I use this way to build boost library in my system (yep, I need boost's static libraries to be linked into dynamic one in some of my projects). And yes, I'm using paludis, but emerge probably has similar feature (a way to set per package compiler options).

The other way, instead of "hacking" compiler options directly (via CMAKE_<LANG>_FLAGS), take a look to CMAKE_POSITION_INDEPENDENT_CODE -- it'll add a proper compiler option for you, and probably eclass' manipulations with cache wouldn't affect this setting.

score 0 · Answer 2 · answered Jul 04 '20 at 08:01

I got it to work (for installing ffmpeg) by simply reinstalling the whole thing from the beginning with all instances of $ ./configure replaced by $ ./configure --enable-shared (first make sure to delete all the folders and files including the .so files from the previous attempt).

Apparently this works because https://stackoverflow.com/a/13812368/10593190.

Recompile with -fPIC Gentoo

2 Answers2