+Command line options
+====================
+
+You can suffix the script call with the following variable parameters:
+
+TARGET=
+-------
+
+By default the target is arm-none-eabi, you may want to use a different target, for example arm-elf. Use that option on your own risk it may brake things.
+
+PREFIX=
+-------
+
+By default the installation prefix is "$(HOME)/sat" you can change it to "/usr" then the binaries will be installed into "/usr/bin" and the toolchain specific
+files in "/usr/arm-none-eabi" assuming you did not change the TARGET variable.
+
+DARWIN_OPT_PATH=
+----------------
+
+When compiling on Mac OS X the build script has to know where MacPorts or Fink
+is installed. The default value is "/opt/local".
+
+SUDO=
+-----
+
+By default this variable is empty. If you need root rights for the install
+step you may set this variable to "sudo".
+
+ $ ./summon-arm-toolchain SUDO=sudo
+
+This will prefix all make install steps with the sudo command asking for
+your root password.
+
+QUIET=
+------
+
+By default set to 0. To decrease console output (may increase compile speed
+in some cases) you can set this variable to 1.
+
+USE_LINARO=
+-----------
+
+By default set to 1. To disable the usage of the Linaro GCC and use of the
+vanilla GCC instead set to 0.
+
+OOCD_EN=
+--------
+
+By default set to 1. To disable compilation of OpenOCD JTAG programming
+software set to 0.
+
+LIBSTM32_EN=
+------------
+
+By default set to 0. To enable compilation of the non-free libstm32 library
+set to 1.
+
+LIBOPENSTM32_EN=
+----------------
+
+By default set to 1. To disable compilation of the open source libopenstm32
+library set to 0.
+
+DEFAULT_TO_CORTEX_M3=
+---------------------
+
+By default set to 0. To enable compilation of binutils and GCC to generate code
+for the Cortex-M3 ARM architecture by default set to 0. Tests have shown that
+using these options is not very reliable and is discouraged. It is more
+reliable to add the necessary options to your build environment instead.
+
+CPUS=
+-----
+
+Overrides the autodetection of CPU cores on the host machine. This option
+is translated into the -j$CPUS+1 option to the make command when running
+the script.
+
+Example:
+--------
+
+ $ ./summon-arm-toolchain LIBSTM32_EN=1 CPUS=5
+
+This will run the script with libstm32 enabled and with 5 CPUs on your host
+machine resulting in calling all make commands with -j6.
+