From abe916ea5c1deeb54829baecd8d0a5448d26ded0 Mon Sep 17 00:00:00 2001 From: Renato Golin Date: Fri, 6 Nov 2015 18:39:34 +0000 Subject: [PATCH] [Docs] Change ARM build info to CMake git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252329 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/HowToBuildOnARM.rst | 56 ++++++++++++++++++++++++++-------------- 1 file changed, 36 insertions(+), 20 deletions(-) diff --git a/docs/HowToBuildOnARM.rst b/docs/HowToBuildOnARM.rst index 6579d36a72a..356c846d82b 100644 --- a/docs/HowToBuildOnARM.rst +++ b/docs/HowToBuildOnARM.rst @@ -18,33 +18,44 @@ Here are some notes on building/testing LLVM/Clang on ARM. Note that ARM encompasses a wide variety of CPUs; this advice is primarily based on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips. -#. If you are building LLVM/Clang on an ARM board with 1G of memory or less, - please use ``gold`` rather then GNU ``ld``. - Building LLVM/Clang with ``--enable-optimized`` - is preferred since it consumes less memory. Otherwise, the building - process will very likely fail due to insufficient memory. In any - case it is probably a good idea to set up a swap partition. +#. The most popular Linaro/Ubuntu OS's for ARM boards, e.g., the + Pandaboard, have become hard-float platforms. There are a number of + choices when using CMake. Autoconf usage is deprecated as of 3.8. -#. If you want to run ``make check-all`` after building LLVM/Clang, to avoid - false alarms (e.g., ARCMT failure) please use at least the following - configuration: + Building LLVM/Clang in ``Relese`` mode is preferred since it consumes + a lot less memory. Otherwise, the building process will very likely + fail due to insufficient memory. It's also a lot quicker to only build + the relevant back-ends (ARM and AArch64), since it's very unlikely that + you'll use an ARM board to cross-compile to other arches. If you're + running Compiler-RT tests, also include the x86 back-end, or some tests + will fail. .. code-block:: bash - $ ../$LLVM_SRC_DIR/configure --with-abi=aapcs-vfp + cmake $LLVM_SRC_DIR -DCMAKE_BUILD_TYPE=Release \ + -DLLVM_TARGETS_TO_BUILD="ARM;X86;AArch64" -#. The most popular Linaro/Ubuntu OS's for ARM boards, e.g., the - Pandaboard, have become hard-float platforms. The following set - of configuration options appears to be a good choice for this - platform: + Other options you can use are: + + .. code-block:: bash + + Use Ninja instead of Make: "-G Ninja" + Build with assertions on: "-DLLVM_ENABLE_ASSERTIONS=True" + Force Python2: "-DPYTHON_EXECUTABLE=/usr/bin/python2" + Local (non-sudo) install path: "-DCMAKE_INSTALL_PREFIX=$HOME/llvm/instal" + CPU flags: "DCMAKE_C_FLAGS=-mcpu=cortex-a15" (same for CXX_FLAGS) + + After that, just typing ``make -jN`` or ``ninja`` will build everything. + ``make -jN check-all`` or ``ninja check-all`` will run all compiler tests. For + running the test suite, please refer to :doc:`TestingGuide`. + +#. If you are building LLVM/Clang on an ARM board with 1G of memory or less, + please use ``gold`` rather then GNU ``ld``. In any case it is probably a good + idea to set up a swap partition, too. .. code-block:: bash - ../$LLVM_SRC_DIR/configure --build=armv7l-unknown-linux-gnueabihf \ - --host=armv7l-unknown-linux-gnueabihf \ - --target=armv7l-unknown-linux-gnueabihf --with-cpu=cortex-a9 \ - --with-float=hard --with-abi=aapcs-vfp --with-fpu=neon \ - --enable-targets=arm --enable-optimized --enable-assertions + $ sudo ln -sf /usr/bin/ld /usr/bin/ld.gold #. ARM development boards can be unstable and you may experience that cores are disappearing, caches being flushed on every big.LITTLE switch, and @@ -58,6 +69,10 @@ on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips. sudo cpufreq-set -c $cpu -g performance done + Remember to turn that off after the build, or you may risk burning your + CPU. Most modern kernels don't need that, so only use it if you have + problems. + #. Running the build on SD cards is ok, but they are more prone to failures than good quality USB sticks, and those are more prone to failures than external hard-drives (those are also a lot faster). So, at least, you @@ -66,4 +81,5 @@ on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips. #. Make sure you have a decent power supply (dozens of dollars worth) that can provide *at least* 4 amperes, this is especially important if you use USB - devices with your board. + devices with your board. Externally powered USB/SATA harddrives are even + better than having a good power supply. -- 2.34.1