Assume my platform is vanilla (non-embedded) x86-64 Linux using GNU build toolchain (GCC, etc.).
To specify $ORIGIN in RPATH, I know about the linker option: -Wl,-rpath,'$$ORIGIN'.
Today, I discovered another option: -Wl,-z,origin.
Should I always include -Wl,-z,origin when using -Wl,-rpath,'$$ORIGIN'?
Official GNU ld docs, say:
Marks the object may contain $ORIGIN.
Related, but different: https://stackoverflow.com/questions/33853271/what-are-the-recommended-gnu-linker-options-to-specify-rpath
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Answer
I know about the linker option:
-Wl,-rpath,'$$ORIGIN'
You know wrong: above option will not do what you want. The option you want is -Wl,-rpath='$ORIGIN'. The difference:
echo "int main() { }" | gcc -xc - -Wl,-rpath,'$$ORIGIN' &&
readelf -d a.out | grep ORIGIN
0x000000000000000f (RPATH) Library rpath: [$$ORIGIN]
echo "int main() { }" | gcc -xc - -Wl,-rpath='$ORIGIN' &&
readelf -d a.out | grep ORIGIN
0x000000000000000f (RPATH) Library rpath: [$ORIGIN]
Should I always include
-Wl,-z,origin
The -Wl,-z,origin sets DF_ORIGIN in FLAGS_1 dynamic entry.
As of current GLIBC trunk, nothing looks at the value of that flag, so if you target GLIBC (most Linux programs do), the answer is: it doesn’t matter one bit whether you use -z origin or not.
The answer may be different for other libc implementations. However, Solaris libc (where the whole $ORIGIN is coming from) also does not appear to require the DF_ORIGIN to be set, so it’s probably a safe bet to ignore this completely.