Add minimal cross-compilation support for Windows and AArch64 Linux #78
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Cross-compiling to AArch64 Linux can be done with a CMake toolchain file, along with setting the correct compiler and include paths in the environment. Cross-compiling from X64 Windows to ARM64 Windows doesn't look at the toolchain at all, because CMake + Visual Studio can already cross-compile. Unfortunately, the Visual Studio CMake generator doesn't set CMAKE_SYSTEM_PROCESSOR, which is what the BoringSSL CMakeLists.txt is looking at to choose the architecture. For now, disable the use of assembly when cross-compiling on Windows (assuming that the Visual Studio generator will be used there).
inikulin
approved these changes
Sep 27, 2022
This was referenced Nov 8, 2022
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boring's cross-compilation support isn't in a great state due to how manually CMake wants to be configured, but this enables at least basic cross-compilation in two cases Signal cares about:Cross-compiling to AArch64 Linux can be done with a CMake toolchain file, along with setting the correct compiler and include paths in the environment (
CC,CXX,CPATH). This is similar to how cross-compiling to x86 works.Cross-compiling from X64 Windows to ARM64 Windows doesn't look at the toolchain at all, because CMake + Visual Studio can already cross-compile. Unfortunately, the Visual Studio CMake generator doesn't set
CMAKE_SYSTEM_PROCESSOR, which is what the BoringSSL CMakeLists.txt is looking at to choose the architecture. For now, disable the use of assembly when cross-compiling on Windows (assuming that the Visual Studio generator will be used there).Recommend reviewing with whitespace disabled. I can also split this into two separate PRs if one of them is less controversial than the other.