0. Building requirements
   linux-2.4.21.tar.gz
   diff-2.4.21-rmk1-pxa1-intc3.gz
   gcc-2.96 or above in i386
   tarballs from open source community
   Linux
   2GB free disk space

1. Directory tree
   build.sh:	building script
   patch/:	all patches needed by binutils, glibc, gcc
   source/:	all tarballs: binutils-2.14.90, glibc-2.3.2, gcc-3.3.2, linux-2.4.21

2. How to build toolchain?
   % cp linux-2.4.21.tar.gz ./source
   % cp diff-2.4.21-rmk1-pxa1-intc3.gz ./patch
   % ./build.sh 2>&1 | tee sh.log
   Select 2(arm-linux) when asked 'select a target'. Then press Enter three
   times, wait for about 30 minutes in P4/3GHz,512MB Ram.

3. How to adjust the building script
   1) % vi build.sh
      define DEFAULT_PREFIX as you will, arm-linux/ will be placed into $DEFAULT_PREFIX.
   2) input path when running build.sh. Press Enter, the path in [] will be used.
      a) install path: where will arm-linux/ be placed?
      b) tarball path: where are tarballs located?
      c) patches path: where are patches located?

4. How to debug?
   If error, you may read sh.log to see where error occurs? 
   Make sure you have permissions to the installed directory. 
   Make sure the name of tarballs must be consistent with the variables in build.sh, e.g: if you use binutils-2.14.90.tar.gz, the $BINUTILSDISTO must be binutils-2.14.90.

5. Results
   By default, the toolchain will be placed in /usr/local/arm-linux.
   All tarballs will be unpacked into current directory.
   build-binutils, build-gcc-core, build-gcc, build-glibc and linux-2.4.21 will be created in current directory.

6. How to use toolchain?
   You can use new toolchain by the following ways:
    % export PATH=/usr/local/arm-linux/bin:$PATH
   You can use 'arm-linux-gcc -v' to make sure you are using correct toolchain.