1===================================================================
2How To Build On ARM
3===================================================================
4
5Introduction
6============
7
8This document contains information about building/testing LLVM and
9Clang on an ARM machine.
10
11This document is *NOT* tailored to help you cross-compile LLVM/Clang
12to ARM on another architecture, for example an x86_64 machine. To find
13out more about cross-compiling, please check :doc:`HowToCrossCompileLLVM`.
14
15Notes On Building LLVM/Clang on ARM
16=====================================
17Here are some notes on building/testing LLVM/Clang on ARM. Note that
18ARM encompasses a wide variety of CPUs; this advice is primarily based
19on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips.
20
21#. If you are building LLVM/Clang on an ARM board with 1G of memory or less,
22   please use ``gold`` rather then GNU ``ld``.
23   Building LLVM/Clang with ``--enable-optimized``
24   is prefered since it consumes less memory. Otherwise, the building
25   process will very likely fail due to insufficient memory. In any
26   case it is probably a good idea to set up a swap partition.
27
28#. If you want to run ``make
29   check-all`` after building LLVM/Clang, to avoid false alarms (eg, ARCMT
30   failure) please use at least the following configuration:
31
32   .. code-block:: bash
33
34     $ ../$LLVM_SRC_DIR/configure --with-abi=aapcs-vfp
35
36#. The most popular linaro/ubuntu OS's for ARM boards, eg, the
37   Pandaboard, have become hard-float platforms. The following set
38   of configuration options appears to be a good choice for this
39   platform:
40
41   .. code-block:: bash
42
43     ./configure --build=armv7l-unknown-linux-gnueabihf \
44     --host=armv7l-unknown-linux-gnueabihf \
45     --target=armv7l-unknown-linux-gnueabihf --with-cpu=cortex-a9 \
46     --with-float=hard --with-abi=aapcs-vfp --with-fpu=neon \
47     --enable-targets=arm --enable-optimized --enable-assertions
48