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Adding some info about stability of ARM boards

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Patch by Mikael Lyngvig

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194794 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Renato Golin 2013-11-15 08:42:14 +00:00
parent 42cb3abadd
commit 868e74bdce
1 changed files with 26 additions and 4 deletions
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30
docs/HowToBuildOnARM.rst
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@ -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.