Update the ARM README.

README.arm.md

@@ -20,8 +20,9 @@ This is the list of known issues on ARM:
 We recommend using at least Ubuntu 14.04 and gcc 4.8, which is part of the
 standard `build-essentials`.
 
-One can install other system libraries instead of building them,
-should the build be troublesome, by adding the following lines in `Make.user`:
+In case the build is failing on one of the dependent libraries, one
+can install various system libraries instead of building them, by
+adding the following lines in `Make.user`:
 
 ````
 override USE_SYSTEM_BLAS=1
@@ -36,9 +37,9 @@ override USE_SYSTEM_ARPACK=1
 The following command will install all the necessary libraries on Ubuntu.
 
 ````
-sudo apt-get install libblas3gf liblapack3gf libfftw3-dev libgmp3-dev \
+sudo apt-get install libblas3gf liblapack3gf libarpack2 libfftw3-dev libgmp3-dev \
  libmpfr-dev libblas-dev liblapack-dev cmake gcc-4.8 \
- g++-4.8 gfortran libgfortran3 m4 libedit-dev libarpack2
+ g++-4.8 gfortran libgfortran3 m4 libedit-dev
 ````
 
 Note that OpenBLAS only supports ARMv7. For older ARM variants, using the reference BLAS
@@ -49,24 +50,38 @@ may be the simplest thing to do.
 If you run into issues building LLVM, see these notes:
 [http:https://llvm.org/docs/HowToBuildOnARM.html](http:https://llvm.org/docs/HowToBuildOnARM.html)
 
-# Raspberry Pi
+## Raspberry Pi
 
-The Raspberry Pi ARM CPU type is not detected by LLVM.
-Before starting the build, it is recommended to do `export JULIA_CPU_TARGET=arm1176jzf-s`
-at the shell to tune the generated code for your CPU architecture.
+Note: Raspberry Pi is ARMv6, which is not well supported at the moment. However it is
+possible to get a working Julia build.
 
-# Raspberry Pi 2
+The Raspberry Pi ARM CPU type is not detected by LLVM. Before
+starting the build, it is recommended to explicitly set the CPU target
+at the shell with the following, which should produce a working build.
 
-In the case of Raspberry Pi 2, in case the default build fails, download LLVM binaries from the LLVM website.
+````
+export JULIA_CPU_TARGET=arm1176jzf-s
+````
+
+It is also preferable to use various system provided dependencies on
+ARMv6 as described in the Build Dependencies section above.
+
+## Raspberry Pi 2
 
-1. Download the [LLVM 3.6.1 binaries for ARMv7a] (http:https://llvm.org/releases/3.6.1/clang+llvm-3.6.1-armv7a-linux-gnueabihf.tar.xz) and extract them in a local directory.
+For Raspberry Pi 2, which is ARMv7, the default build should work. In
+the case of Raspberry Pi 2, in case the default build fails, download
+LLVM binaries from the LLVM website.
+
+1. Download the [LLVM 3.7.0 binaries for ARMv7a] (http:https://llvm.org/releases/3.7.0/clang+llvm-3.7.0-armv7a-linux-gnueabihf.tar.xz) and extract them in a local directory.
 2. For each file in the extracted `bin`, `include`, and `lib` subdirectories, create symlinks from the corresponding directory under `/usr/local`.
-3. Add the following to `Make.user`:
+3. Add the following to `Make.user` and then build:
 ```
 override USE_SYSTEM_LLVM=1
 ```
 
-# Chromebook
+Please do let us know if you had to download a pre-built LLVM in [#10235](https://github.com/JuliaLang/julia/issues/10235).
+
+## Chromebook
 
 On Chromebooks, you have to first install Crouton. If you do not have
 an Ubuntu chroot running on your Chromebook using Crouton, you can do
@@ -78,3 +93,8 @@ so by following these tutorials.
 These tutorials will end up installing Ubuntu 12.04, and you have to
 upgrade to Ubuntu 14.04, or install Ubuntu 14.04 from scratch by
 finding appropriate `crouton` help.
+
+## Scaleway cloud hosted ARM servers
+
+On the current [Scaleway](http:https://scaleway.com) ARM servers, the Julia
+build works out of the box.