gcc编译时rpath选项不生效问题

问题

笔者在尝试编译qemu时，需要指定qemu在运行时用指定路径下的spice库，尝试使用-wl,-rpath=<link_path>选项，但是编译出来的程序总是自动链接到系统自带的spice库上。

解决方案

通过检索，找到一下链接：https://stackoverflow.com/questions/47117443/dynamic-linking-with-rpath-not-working-under-ubuntu-17-10；他似乎遇到和我一样的问题。

原文答案如下：
What likely happened is that your updated linker emits DT_RUNPATH dynamic tag, where the old linker emitted DT_RPATH. (It’s also possible that your old linker was GNU-ld, and the new one is Gold.)

The DT_RUNPATH is preferred as more correct, and affects search path of the binary itself, but not of any of the dependent libraries.

The DT_RPATH has global effect, similar to adding the directory to LD_LIBRARY_PATH environment variable.

You can verify this with: readelf -d a.out | grep 'R.*PATH'.

If you do see the RPATH vs. RUNPATH difference, and in fact are using Gold, you can force the “old” behavior with -Wl,--disable-new-dtags (GNU ld also had --disable-new-dtags added to it recently, so it should work for either linker).

总结

通过添加-Wl,--disable-new-dtags选项可以解决。

参考

Dynamic linking with rpath not working under Ubuntu 17.10

RPATH and RUNPATH