see :doc:`CMake`.
The CMake options you need to add are:
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* ``-DCMAKE_CROSSCOMPILING=True``
* ``-DCMAKE_INSTALL_PREFIX=<install-dir>``
* ``-DLLVM_TABLEGEN=<path-to-host-bin>/llvm-tblgen``
If you're compiling with GCC, you can use architecture options for your target,
and the compiler driver will detect everything that it needs:
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* ``-DCMAKE_CXX_FLAGS='-march=armv7-a -mcpu=cortex-a9 -mfloat-abi=hard'``
However, if you're using Clang, the driver might not be up-to-date with your
specific Linux distribution, version or GCC layout, so you'll need to fudge.
In addition to the ones above, you'll also need:
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* ``'-target arm-linux-gnueabihf'`` or whatever is the triple of your cross GCC.
* ``'--sysroot=/usr/arm-linux-gnueabihf'``, ``'--sysroot=/opt/gcc/arm-linux-gnueabihf'``
or whatever is the location of your GCC's sysroot (where /lib, /bin etc are).