Linker error when unit testing: ld: illegal text-r

问题:

In Xcode 4.3.2, building an iPad app, which includes libavutil.a from the ffmpeg distribution, it builds and runs correctly but when I try to run unit tests (Cmd-U) I get the following linker error:

ld: illegal text-relocation to cstring in /myPath/libavutil.a(imgutils.o) from _av_image_check_size in /myPath/libavutil.a(imgutils.o) for architecture armv7 clang: error: linker command failed with exit code 1 (use -v to see invocation)

This is on the device (We can't run it in the simulator currently because we don't have fat binaries for all the libraries we are including).

Why will it build and run correctly normally but not link when running unit tests?

回答1:

The answer, from here.

is to add:

-read_only_relocs suppress

to the linker flags.

The other link explains why. The solution was originally found here.

回答2:

I solved this linker error by enabling Position-Independent Code in the compiler and linker settings in XCode.

回答3:

Just to be specific, the line that specifically worked to fix a similar linking error with ffmpeg for 32bit OSX link using xcode/c++11, was to add -Wl,-read_only_relocs,suppress to the link line. Variations of this didn't work.