AVAILABLE CONFIGURATIONS
^^^^^^^^^^^^^^^^^^^^^^^^

arm-defconfig
	Builds an ARM toolchain using gcc 3.4.5

arm920t-defconfig-4.2.4
arm926t-defconfig-4.2.4
	Builds an ARM toolchain using gcc 4.2.4.  This configuration
	builds both gcc and g++.  There are two versions: one for 
	arm920t (armv4t) and arm926t (arv5t) because of differences
	in the way that soft floating is handled in these two architectures.

	NOTE: At present, there are issues with some of the binutils
	programs (arm-elf-objcopy in particular) that cause Floating
	point exceptions when trying to build NuttX.  This is probably
	due to improperly positioned sections and can probably fixed
	by changing the architectures .ldscript file.

bfin-defconfig-4.2.4
	Builds an Blackfin toolchain using gcc 4.2.4

h8300_config
	Builds an H8/300 toolchain using gcc 3.4.5

m68hc11-config
	Builds an hc11 toolchain using gcc 3.4.5

m68k-config
	Builds an M68K toolchain using gcc 3.4.5

sh-defconfig
	Builds an SH-1/2 toolchain using gcc 3.4.5

GENERAL BUILD STEPS
^^^^^^^^^^^^^^^^^^^

1. CD to the correct directory.

   Change to the directory just above the NuttX installation.  If <nuttx-dir> is
   where NuttX is installed, then cd to <nuttx-dir>/..

2. Get and Install the buildroot Module

   a. Using a release tarball:

     cd <nuttx-dir>/..
     Download the appropriate buildroot package.
     unpack the buildroot package
     rename the directory to buildroot

   b. Using CVS
   
     Check out the misc/buildroot module. CVS checkout instructions:

        cvs -d:pserver:anonymous@nuttx.cvs.sourceforge.net:/cvsroot/nuttx login
        cvs -z3 -d:pserver:anonymous@nuttx.cvs.sourceforge.net:/cvsroot/nuttx co -P misc/buildroot

     Move the buildroot Source Tree and create the archive directory

        mv misc/buildroot .

   Make the archive directory:
  
     mkdir archive

   The <nuttx-dir>/../buildroot is where the toolchain is built;
   The <nuttx-dir>/../archive directory is where toolchain sources will be downloaded.

3. Make sure that NuttX is configured

     cd <nuttx-dir>/tools
     ./configure.sh <nuttx-configuration>
     
4. Configure and Make the buildroot

     cd buildroot
     cp configs/<config-file> .config
     make oldconfig
     make

   This will download the large source packages for the toolchain and build the toolchain.
   The resulting binaries will be under buildroot/build_<arch>.  There will also be a
   large build directory called something like toolchain_build_<arch>; this directory
   can be removed once the build completes successfully.

   Where <config-file> is one of the configuration files listed above and <arch> is an
   archtecture name.  Examples: build_m32c, build_arm_nofpu, etc.

Cygwin GCC BUILD NOTES
^^^^^^^^^^^^^^^^^^^^^^
   On Cygwin, the buildroot 'make' command will fail with an error like:

   "...
      build/genchecksum cc1-dummy > cc1-checksum.c
      opening cc1-dummy: No such file or directory
   ..."

   This is caused because on Cygwin, host executables will be generated with the extension .exe
   and, apparently, the make variable "exeext" is set incorrectly.  A work around after the
   above occurs is:

      cd toolchain_build_<arch>/gcc-4.2.4-build/gcc	# Go to the directory where error occurred
      mv cc1-dummy.exe cc1-dummy			# Rename the executable without .exe
      rm cc1-checksum.c					# Get rid of the bad generated file

   Then resume the buildroot make:

      cd -						# Back to the buildroot make directory
      make						# Restart the build

   If you build g++, you will see another similar error:

   ...
      build/genchecksum cc1plus-dummy > cc1plus-checksum.c
      opening cc1plus-dummy: No such file or directory
   ...

   The fix is similar:

      cd toolchain_build_<arch>/gcc-4.2.4-build/gcc	# Go to the directory where error occurred
      mv cc1plus-dummy.exe cc1plus-dummy		# Rename the executable without .exe
      rm cc1plus-checksum.c				# Get rid of the bad generated file

   Then resume the buildroot make:

      cd -						# Back to the buildroot make directory
      make						# Restart the build