There are 3 parts to the complete FreeCalypso software suite which are built
independently of each other:

* The tools that run on a GNU/Linux PC or other host system are the most
  straightforward: there is a top level Makefile (named Makefile.hosttools if
  you looking at a development source snapshot, will be renamed to just
  Makefile in packaged releases of the host tools) that coordinates building
  and installing all of them.

* The gsm-fw tree, which will eventually become our main GSM firmware, needs to
  be built with a GNU cross-compiler toolchain for ARM7.  This firmware can be
  built for several different target devices and with different feature
  configurations, hence there is no singular build for it - it's more like the
  Linux kernel in terms of its build configuration management.

* We also have a few utilities which need to be compiled to run on Calypso
  targets, but which are not part of gsm-fw; they are gathered in the
  target-utils tree.  They are built with the same GNU toolchain for ARM7 as
  gsm-fw, but don't have any fancy configuration system.

Building and installing FreeCalypso host tools
==============================================

If you are working with a packaged FC host tools release, just run 'make', then
'make install' as root.  If you are working with a development source snapshot,
do 'make -f Makefile.hosttools' instead.

The "standard" install directories are /usr/local/bin for binaries and
/usr/local/share/freecalypso for helper files.  If you need to change these
paths to something else, you'll need to edit a bunch of individual component
Makefiles, and possibly also some source files like loadtools/defpath.c -
sorry, FreeCalypso is not GNU and does not use autotools.

Building and installing the ARM7 toolchain
==========================================

The current "official" GNU ARM toolchain for FreeCalypso consists of
binutils-2.21.1, gcc-4.5.4 and newlib-2.0.0 with a specific set of patches and
build configuration options.  Build it as follows:

1. Download these 3 source tarballs for the standard GNU+newlib components:

   binutils-2.21.1a.tar.bz2
   gcc-core-4.5.4.tar.bz2
   newlib-2.0.0.tar.gz

2. Run the build+install.sh script in the toolchain directory.  Read the
   comments in the script first for the usage instructions.

The toolchain thus built will need to be in your PATH before you can compile
gsm-fw or target-utils.

Please note: the toolchain that is prescribed for FreeCalypso as above is
*believed* to be equivalent to the one used by OsmocomBB, but there are no
guarantees.  Use any other toolchain at your own risk.

Compiling target-utils
======================

Running 'make' in the target-utils tree with the ARM7 toolchain present in your
PATH will result in compalstage and loadagent being built; these are the two
components needed in order to use FreeCalypso loadtools.  Run 'make install' to
install these target binaries in /usr/local/share/freecalypso, which is where
loadtools will look for them.

Run 'make all' in target-utils to build some other components that aren't
really needed.