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comparison docs/HowToBuildOnARM.rst @ 0:95c75e76d11b
LLVM 3.4
| author | Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> |
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| date | Thu, 12 Dec 2013 13:56:28 +0900 |
| parents | |
| children | afa8332a0e37 |
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| 1 =================================================================== | |
| 2 How To Build On ARM | |
| 3 =================================================================== | |
| 4 | |
| 5 Introduction | |
| 6 ============ | |
| 7 | |
| 8 This document contains information about building/testing LLVM and | |
| 9 Clang on an ARM machine. | |
| 10 | |
| 11 This document is *NOT* tailored to help you cross-compile LLVM/Clang | |
| 12 to ARM on another architecture, for example an x86_64 machine. To find | |
| 13 out more about cross-compiling, please check :doc:`HowToCrossCompileLLVM`. | |
| 14 | |
| 15 Notes On Building LLVM/Clang on ARM | |
| 16 ===================================== | |
| 17 Here are some notes on building/testing LLVM/Clang on ARM. Note that | |
| 18 ARM encompasses a wide variety of CPUs; this advice is primarily based | |
| 19 on 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 preferred 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 check-all`` after building LLVM/Clang, to avoid | |
| 29 false alarms (e.g., ARCMT failure) please use at least the following | |
| 30 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, e.g., 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 | |
| 49 #. ARM development boards can be unstable and you may experience that cores | |
| 50 are disappearing, caches being flushed on every big.LITTLE switch, and | |
| 51 other similar issues. To help ease the effect of this, set the Linux | |
| 52 scheduler to "performance" on **all** cores using this little script: | |
| 53 | |
| 54 .. code-block:: bash | |
| 55 | |
| 56 # The code below requires the package 'cpufrequtils' to be installed. | |
| 57 for ((cpu=0; cpu<`grep -c proc /proc/cpuinfo`; cpu++)); do | |
| 58 sudo cpufreq-set -c $cpu -g performance | |
| 59 done | |
| 60 | |
| 61 #. Running the build on SD cards is ok, but they are more prone to failures | |
| 62 than good quality USB sticks, and those are more prone to failures than | |
| 63 external hard-drives (those are also a lot faster). So, at least, you | |
| 64 should consider to buy a fast USB stick. On systems with a fast eMMC, | |
| 65 that's a good option too. | |
| 66 | |
| 67 #. Make sure you have a decent power supply (dozens of dollars worth) that can | |
| 68 provide *at least* 4 amperes, this is especially important if you use USB | |
| 69 devices with your board. |