CODEWITHSUNDEEP
linuxgccshared-librariesstatic-librariesmusl
bge0
bge0

Reputation: 921

musl fails to link libc.a into shared library

I have a C99 shared library that I want to link in a few statically static libraries (via --whole-archive). Note: All the static libs are built with -fPIC

I also would like to build a universal linux binary and thus have decided to use musl. When I try to link in the static libc.a from musl I get the following error:

# Building shared library tgt/Linux-x86_64/mylib/lib/mylib.so
/root/mylib/./tgt/Linux-x86_64/libmusl/bin/musl-gcc -Wl,-whole-archive -L./tgt/Linux-x86_64/libmusl/lib -L./tgt/Linux-x86_64/libz/lib -L./tgt/Linux-x86_64/libssl/lib -L./tgt/Linux-x86_64/libsasl/lib -L./tgt/Linux-x86_64/librdkafka/lib -L./tgt/Linux-x86_64/libcurl/lib -L./tgt/Linux-x86_64/libgjalloc/lib -L./tgt/Linux-x86_64/libavro/lib -L./tgt/Linux-x86_64/libunwind/lib -l:libc.a -l:libpthread.a -l:libz.a -l:libssl.a -l:libcrypto.a -l:libsasl2.a -l:libm.a -l:librt.a -l:libcrypt.a -l:libunwind-x86_64.a -l:librdkafka.a -l:libcurl.a -l:libgjalloc.a -l:libavro.a -Wl,-no-whole-archive -shared -fPIC -o tgt/Linux-x86_64/mylib/lib/mylib.so ./tgt/Linux-x86_64/mylib/obj/myfile.o ./tgt/Linux-x86_64/mylib/obj/myotherfile.o ./tgt/Linux-x86_64/mylib/obj/cJSON.o
/usr/bin/ld: ./tgt/Linux-x86_64/libmusl/lib/libc.a(exit.lo): relocation R_X86_64_PC32 against undefined hidden symbol `__fini_array_start' can not be used when making a shared object
/usr/bin/ld: final link failed: Bad value
collect2: error: ld returned 1 exit status
make: *** [tgt/Linux-x86_64/mylib/lib/mylib.so] Error 1

My musl build looks like:

cd mystatic_libs_build_dir/musl; \
./configure CFLAGS='-fPIC' \
--enable-shared \
--enable-static \
--prefix=/root/mylib/tgt/Linux-x86_64/libmusl; \
make; make install;
# libmusl is available

Upvotes: 1

Views: 2330

Answers (2)

user144765
user144765

Reputation: 133

Recompile musl as long as your own code with CFLAGS="-fPIC -Wa,-mrelax-relocations=no" (your binutils version must be >=2.27).

Upvotes: 0

user1976
user1976

Reputation: 383

exit.lo will be written in assembler which is why your CFLAGS='-fPIC' is not having the effect you intend. This is either 1. a bug in 'musl' or 2. intentional and they do not support statically linking into .so's.

I would assume that it is unintentional and file a bug against 'musl'

You could also edit the asm yourself if you need a fix quickly.

Finally you might be able to configure musl to build with no asm?

Slightly off topic, but other options for a universal binary are:

  1. Simply linking against glibc on the oldest version of Linux that you support.
  2. Rather than struggling with a dependency on 'musl', simply use the Linux kernel api's directly.

Upvotes: 1

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