Linker error for atomic functions on aarch64-linux #201254
Description
Describe the bug
When using some atomic functions on aarch64 linux fails during the linking phase when using the -z defs linker option (as observed while trying to compile bobcat on aarch64-linux):
/nix/store/1g5g7vzlcprmg1d6864fs5r4nf1h5b5j-binutils-2.39/bin/ld: /build/test.o: in function `foo(int)':
zzfr0vqndwngbh5b2skgdgl90aqqrpwl-test.cpp:(.text+0x2c): undefined reference to `__aarch64_ldadd4_acq_rel'
collect2: error: ld returned 1 exit status
Steps To Reproduce
Steps to reproduce the behavior:
- save the following nix code into
fail.nix - on an aarch64 Linux system, run
nix-build -I nixpkgs=PATH_TO_NIXPKGS fail.nix
{ pkgs ? import <nixpkgs> {} }:
pkgs.gcc10Stdenv.mkDerivation {
name = "link failure on aarch64";
version = "0.1";
dontUnpack = true;
src = pkgs.writeText "test.cpp" ''
#include <atomic>
int foo(int i) {
std::atomic<int> f(i);
return f.fetch_add(3);
}
'';
buildPhase = ''
g++ --std=c++20 -c $src -o $TMP/test.o
g++ --std=c++20 -shared -Wl,-z,defs $TMP/test.o -o libtest.so
'';
}Expected behavior
Linking should succeed.
Additional context
According to https://bugzilla.redhat.com/show_bug.cgi?id=1830472
On aarch64 -moutline-atomics has been turned on by default, and those symbols are solely in libgcc.a, not in libgcc_s.so.*.
Indeed libgcc_s.so from gcc-lib is a linker script:
$ cat /nix/store/q2nal9l25ff4zvd99l2ifjnpaw1ij21n-gcc-10.4.0-lib/lib/libgcc_s.so
/* GNU ld script
Use the shared library, but some functions are only in
the static library. */
GROUP ( libgcc_s.so.1 -lgcc )Adding the -v flag to the invocation of g++ one can observe this call to collect2:
/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/libexec/gcc/aarch64-unknown-linux-gnu/10.4.0/collect2 \
-plugin \
/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/libexec/gcc/aarch64-unknown-linux-gnu/10.4.0/liblto_plugin.so \
-plugin-opt=/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/libexec/gcc/aarch64-unknown-linux-gnu/10.4.0/lto-wrapper \
-plugin-opt=-fresolution=/run/user/1000/ccYTLoAU.res \
-plugin-opt=-pass-through=-lgcc_s \
-plugin-opt=-pass-through=-lc \
-plugin-opt=-pass-through=-lgcc_s \
--eh-frame-hdr \
-shared \
-X \
-EL \
-maarch64linux \
-o \
libtest.so \
/nix/store/g14swv4f0rg83naqj87g1mjmyvrmrxmf-glibc-2.35-163/lib/crti.o \
/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/lib/gcc/aarch64-unknown-linux-gnu/10.4.0/crtbeginS.o \
-L/nix/store/dwk83gbvz3dfzm7kk18lrphsbjn8qxq0-libmilter-8.15.2/lib \
-L/nix/store/bl0wv9qaj5ws3d1j9hl983qlpghx334f-libxcb-1.14/lib \
-L/nix/store/0gx2fkm4ndif74l9vaw2gi8ffm8vqp84-libX11-1.8.1/lib \
-L/nix/store/l95ixfjbvi6wj1il5a062b8sprcc1m3a-openssl-3.0.7/lib \
-L/nix/store/c51zf8aa3zna0qzjbyl2ac3j2q9nns27-ncurses-6.3-p20220507/lib \
-L/nix/store/cbdlrdy51iiszglwyq96q8dk3yg725hs-readline-6.3p08/lib \
-L/nix/store/94qlip4nc7c8kwvrrwav3sc008maxwhk-util-linux-2.38.1-lib/lib \
-L/nix/store/dwk83gbvz3dfzm7kk18lrphsbjn8qxq0-libmilter-8.15.2/lib \
-L/nix/store/bl0wv9qaj5ws3d1j9hl983qlpghx334f-libxcb-1.14/lib \
-L/nix/store/0gx2fkm4ndif74l9vaw2gi8ffm8vqp84-libX11-1.8.1/lib \
-L/nix/store/l95ixfjbvi6wj1il5a062b8sprcc1m3a-openssl-3.0.7/lib \
-L/nix/store/c51zf8aa3zna0qzjbyl2ac3j2q9nns27-ncurses-6.3-p20220507/lib \
-L/nix/store/cbdlrdy51iiszglwyq96q8dk3yg725hs-readline-6.3p08/lib \
-L/nix/store/94qlip4nc7c8kwvrrwav3sc008maxwhk-util-linux-2.38.1-lib/lib \
-L/nix/store/g14swv4f0rg83naqj87g1mjmyvrmrxmf-glibc-2.35-163/lib \
-L/nix/store/vqlcm9k500r8wsnam86rlan95yxnalxa-gcc-10.4.0-lib/lib \
-L/nix/store/g14swv4f0rg83naqj87g1mjmyvrmrxmf-glibc-2.35-163/lib \
-L/nix/store/vqlcm9k500r8wsnam86rlan95yxnalxa-gcc-10.4.0-lib/lib \
-L/nix/store/zk5rgbk1nrcy6r6fafamfqnnsc59z9n8-gcc-wrapper-10.4.0/bin \
-L/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/lib/gcc/aarch64-unknown-linux-gnu/10.4.0 \
-L/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/lib/gcc/aarch64-unknown-linux-gnu/10.4.0/../../../../lib64 \
-L/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/lib/gcc/aarch64-unknown-linux-gnu/10.4.0/../../.. \
-dynamic-linker=/nix/store/g14swv4f0rg83naqj87g1mjmyvrmrxmf-glibc-2.35-163/lib/ld-linux-aarch64.so.1 \
-z \
defs \
test.o \
-rpath \
/nix/store/bspxp2j6ggc7v5an4s3qky6k6h6fw5gj-bobcat-5.10.01/lib \
-lstdc++ \
-lm \
-lgcc_s \
-lc \
-lgcc_s \
/nix/store/rvjj7j3hl1zm3xgy9vh8wck5r7cqp0py-gcc-10.4.0/lib/gcc/aarch64-unknown-linux-gnu/10.4.0/crtendS.o \
/nix/store/g14swv4f0rg83naqj87g1mjmyvrmrxmf-glibc-2.35-163/lib/crtn.o \
Removing the glibc lib directory from the library path (ie. removing -L/nix/store/g14swv4f0rg83naqj87g1mjmyvrmrxmf-glibc-2.35-163/lib), makes this call successful.
The root cause is that glibc contains a libgcc_so.1 library in its lib folder:
$ file /nix/store/xl52bf8jch51zzh84rszxn0hpbxadll4-glibc-2.35-163/lib/libgcc_s.so
/nix/store/xl52bf8jch51zzh84rszxn0hpbxadll4-glibc-2.35-163/lib/libgcc_s.so: symbolic link to libgcc_s.so.1This is found before the right one from gcc, and this breaks linking when it would just work if libgcc_so.1 would be the proper linker script.
Why does glibc contain the libgcc_s.so library?
Notify maintainers
Metadata
Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.
[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
- system: `"aarch64-linux"`
- host os: `Linux 5.15.74-v8+, Debian GNU/Linux, 11 (bullseye), nobuild`
- multi-user?: `no`
- sandbox: `yes`
- version: `nix-env (Nix) 2.11.1`
- channels(claudio): `"nixpkgs"`
- nixpkgs: `/home/claudio/.nix-defexpr/channels/nixpkgs`