How to add a new target in binutils ?

[Shawn <shaolin dot xie at ia dot ac dot cn>]

Hi, All:
    I'm new to binutils and I want to port a linker  to a new 
architecture. What I need is just a very basic linker , which can link 
static elf object files or static libraries into executables, no 
functionality for shared library or dynamic link.
    I tried the Gold first,  but found it has been bounded to the 
binutils, and can't be compiled separately. so I tried to port the 
bintuils as a whole.
    I have read the "Binutils Porting Guide To A New Target 
Architecture" written by MR.Swami.Reddy@nsc.com, which seems to be very 
helpful for me. But  I 'm stucking in some details now.
    First I want to get a full functional configure& compile system for 
this port,  say "mpu". I begin with reviewing the example port "cr16" in 
the tutorial.   Here is what I have done:
    1.  Download binutils-2.22.tar.gz
    2.  copy follow file and change the name from "cr16" to "mpu"
         a).bfd/cpu-cr16.c
         b).bfd/elf32-cr16.c
         c).gas/config/tc-cr16.c
         d).gas/config/tc-cr16.h
         e).include/elf/cr16.h
         f).include/opcode/cr16.h
         g).ld/emulparams/elf32cr16.sh
         h).ld/emultempl/cr16elf.em
         i).ld/scripttempl/elf32cr16.sc
         j).opcodes/cr16-dis.c
         k).opcodes/cr16-opc.c
    3. add corresponding entry in the following configuration files:
        a) bfd/Makefile.amb
        b) bfd/archures.c
        c)  bfd/bfd-in2.h
        d)  bfd/config.bfd
        e)  bfd/configure.in
        f)  bfd/libbfd.h
        g)  bfd/targets.c
        h)  binutils/readelf.c
        i)  config.sub
        j)  gas/Makefile.am
        k)  gas/configure.tgt
        l)   include/dis-asm.h
        m)  include/elf/common.h
        n)  ld/Makefile.am
        o)  ld/configure.tgt
        p)  opcodes/Makefile.am
        q)  opcodes/configure.in
        r)  opcodes/disassemble.c

     3)configure the script with following command:
        ~/Work/binutils/binutils-mpu-2.22/configure  \
        --prefix=/home/xiesl/Tools/binutils                \
        --target=mpu-elf                                          \
        --enable-maintainer-mode

      4). run make , but error occurs:
        configure: error: *** unknown target vector bfd_elf32_mpu_vec
        make[1]: *** [configure-bfd] error 1
        make[1]:leaving directory `/tmp/build'
        make: *** [all] error 2
===================================
I really hope someone can give me some advice , for porting the linker, 
or this error message. Thanks.

Shawn.