From 868e74bdce7a2c49d60e2ef56a077b0aa7f2ba08 Mon Sep 17 00:00:00 2001 From: Renato Golin Date: Fri, 15 Nov 2013 08:42:14 +0000 Subject: Adding some info about stability of ARM boards Patch by Mikael Lyngvig git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194794 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/HowToBuildOnARM.rst | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) (limited to 'docs/HowToBuildOnARM.rst') diff --git a/docs/HowToBuildOnARM.rst b/docs/HowToBuildOnARM.rst index b58dfac..f2edaef 100644 --- a/docs/HowToBuildOnARM.rst +++ b/docs/HowToBuildOnARM.rst @@ -25,15 +25,15 @@ on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips. process will very likely fail due to insufficient memory. In any case it is probably a good idea to set up a swap partition. -#. If you want to run ``make - check-all`` after building LLVM/Clang, to avoid false alarms (eg, ARCMT - failure) please use at least the following configuration: +#. 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: .. code-block:: bash $ ../$LLVM_SRC_DIR/configure --with-abi=aapcs-vfp -#. The most popular linaro/ubuntu OS's for ARM boards, eg, the +#. 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: @@ -45,3 +45,25 @@ on the ARMv6 and ARMv7 architectures and may be inapplicable to older chips. --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 + +#. ARM development boards can be unstable and you may experience that cores + are disappearing, caches being flushed on every big.LITTLE switch, and + other similar issues. To help ease the effect of this, set the Linux + scheduler to "performance" on **all** cores using this little script: + + .. code-block:: bash + + # The code below requires the package 'cpufrequtils' to be installed. + for ((cpu=0; cpu<`grep -c proc /proc/cpuinfo`; cpu++)); do + sudo cpufreq-set -c $cpu -g performance + done + +#. 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 + should consider to buy a fast USB stick. On systems with a fast eMMC, + that's a good option too. + +#. 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. -- cgit v1.1