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libatomic linking needed for some archs (arm, ppc) #3546
Description
Describe the bug
Some archs require linking to libatomic, otherwise build fails to link with undefined ___atomic_fetch_add_8 etc.
Regression Issue
- Select this option if this issue appears to be a regression.
Expected Behavior
On platforms without hardware support for 8-byte atomics, libatomic should be used.
Current Behavior
[ 7%] Linking CXX shared library libaws-cpp-sdk-core.dylib
cd /opt/local/var/macports/build/aws-sdk-cpp-14f15bf3/work/build/src/aws-cpp-sdk-core && /opt/local/bin/cmake -E cmake_link_script CMakeFiles/aws-cpp-sdk-core.dir/link.txt --verbose=ON
Undefined symbols for architecture ppc:
"___atomic_fetch_add_8", referenced from:
Aws::Utils::Threading::ReaderWriterLock::UnlockWriter() in ub_core.cpp.o
Aws::Utils::Threading::ReaderWriterLock::LockReader() in ub_core.cpp.o
Aws::Utils::Threading::ReaderWriterLock::LockWriter() in ub_core.cpp.o
"___atomic_fetch_sub_8", referenced from:
Aws::Utils::Threading::ReaderWriterLock::UnlockReader() in ub_core.cpp.o
Aws::Utils::Threading::ReaderWriterLock::LockWriter() in ub_core.cpp.o
"___atomic_load_8", referenced from:
Aws::Client::AWSAuthSigner::GetClockSkewOffset() const in ub_core.cpp.o
"___atomic_store_8", referenced from:
Aws::Client::AWSAuthSigner::SetClockSkew(std::chrono::duration<long long, std::ratio<1ll, 1000ll> > const&) in ub_core.cpp.o
__ZN3Aws6Client13AWSAuthSignerC4Ev in ub_core.cpp.o
ld: symbol(s) not found for architecture ppc
collect2: error: ld returned 1 exit status
Reproduction Steps
Run the build on an affected platform.
Possible Solution
Add a configure test to CMakeLists for support of 8-byte atomics.
Additional Information/Context
Relevant for some 32-bit archs: arm, ppc, possibly mips.
AWS CPP SDK version used
1.11.649
Compiler and Version used
gcc 14.3.0
Operating System and version
macOS 10.6.8
Activity
sbaluja commentedon Sep 17, 2025
Curious about your current toolchain, the sdk requires libcurl and a libcrypto (openssl/aws-lc) dependency, how are you getting those? are you building them yourself or getting them via other means?
barracuda156 commentedon Sep 17, 2025
@sbaluja I build everything from source, but largely using MacPorts’ ports – and adding mine when something is missing in upstream or needs extra fixes/tweaks. Specifically curl and openssl are from MacPorts. All AWS libs’ ports are mine (loosely based off FreeBSD ones with Darwin-specific fixes).
kai-ion commentedon Sep 23, 2026
Converting this to a Discussion. It's an improvements we plan to pursue over time rather than one actionable change with a near-term milestone, so a Discussion better fits collecting the specifics and design input.