doc: Expand doc on 3rd-party cross compilers

Add documentation for OS X users that want to compile
using an available 3rd-party cross compiler and also
complete the section to describe the existing support
for the GCC ARM Embedded toolchain.

Change-Id: I97d27d46c0048a49029dbe4d66fe141755c226e9
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

2 files changed, 32 insertions, 1 deletions

diff --git a/doc/getting_started/getting_started.rst b/doc/getting_started/getting_started.rst
index b5e97e22b..f13ad2de6 100644
--- a/doc/getting_started/getting_started.rst
+++ b/doc/getting_started/getting_started.rst
@@ -120,11 +120,13 @@ The ELF binaries generated by the build system are named by default
 The build system generates different names for different use cases depending on
 the hardware and boards used.
 
+.. _third_party_x_compilers:
+
 Using Custom and 3rd Party Cross Compilers
 ==========================================
 
 The Zephyr SDK is provided for convenience and ease of use. It provides
-cross-compilers for all ports supported by Zephyr and does not require any extra
+cross-compilers for all ports supported by the Zephyr OS and does not require any extra
 flags when building applications or running tests.
 
 If you have a custom cross-compiler or if you wish to use a vendor provided SDK,
@@ -167,6 +169,21 @@ follow the steps below to build with any custom or 3rd party cross-compilers:
 
 The above will build the sample using the toolchain downloaded from `GCC ARM Embedded`_.
 
+Alternatively, you can use the existing support for GCC ARM Embedded:
+
+   .. code-block:: console
+
+      $ export GCCARMEMB_TOOLCHAIN_PATH="~/gcc-arm-none-eabi-5_3-2016q1/"
+
+      $ export ZEPHYR_GCC_VARIANT=gccarmemb
+
+      $ cd zephyr-project
+
+      $ source zephyr-env.sh
+
+      $ cd $ZEPHYR_BASE/samples/hello_world/microkernel
+
+      $ make BOARD=arduino_due
 
 Running a Sample Application in QEMU
 ====================================
diff --git a/doc/getting_started/installation_mac.rst b/doc/getting_started/installation_mac.rst
index 14fdb3d44..ab44e6798 100644
--- a/doc/getting_started/installation_mac.rst
+++ b/doc/getting_started/installation_mac.rst
@@ -10,6 +10,20 @@ applications on the following Mac OS version:
 
 * Mac OS X 10.11 (El Capitan)
 
+Developing for Zephyr on OS X generally requires you to build the
+toolchain yourself. However, if there is already an OS X toolchain for your
+target architecture you can use it directly.
+
+Using a 3rd Party toolchain
+***************************
+
+If a toolchain is available for the architecture you plan to build for, then
+you can use it as explained in:
+:ref:`third_party_x_compilers`.
+
+An example of an available 3rd party toolchain is GCC ARM Embedded for the
+Cortex-M family of cores.
+
 .. _mac_requirements:
 
 Installing Requirements and Dependencies