--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/Compiling	Tue Jun 24 00:16:04 2014 +0000
@@ -0,0 +1,67 @@
+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.