Linux x86-64 support is currently limited to the hl2dm branch. The existing x86 build remains the default.

Build with:

cd src
bash ./Build.sh hl2dm x86_64

The preserved 32-bit build remains available as:

cd src
bash ./Build.sh hl2dm x86

The build accepts SOURCEPYTHON_SDK as a CMake cache path when the HL2SDK is outside src/hl2sdk/hl2dm.

Architecture-specific dependencies are kept beside, rather than in place of, the existing x86 dependencies:

thirdparty/python_linux64/
thirdparty/boost/lib/linux64/
thirdparty/dyncall/lib/linux64/
thirdparty/DynamicHooks/lib/linux64/
thirdparty/AsmJit/lib/linux64/

The tested dependency baseline is CPython 3.13.2, Boost 1.87, the current HL2DM branch of AlliedModders HL2SDK, and a DynamicHooks build containing the Linux System V AMD64 backend.

The packaged runtime uses Python3/plat-linux64. Native optional packages in the standard library are loaded from Python3/lib-dynload-linux64, leaving the existing x86 Python3/lib-dynload directory untouched. Native optional packages in the shared site-packages directory must be rebuilt for x86-64; 32-bit extension modules cannot be imported by the x86-64 runtime.

Post-hook callbacks that need function arguments must select the preserved entry-register snapshot through CHook::SetUsePreRegisters. The legacy m_bUsePreRegisters member remains available to the x86 backend, but it is not the invocation-local selector used by the reentrant x86-64 backend.

The upstream x86 CPython _ctypes module still declares libffi.so.7 as a runtime dependency. Distributions that no longer provide that SONAME must supply it separately for 32-bit deployments. This legacy dependency is not used by the x86-64 _ctypes module and was not introduced by this port.