Sez Jay McCauley <mccauley@sgi.com>:  IRIX does not and cannot have a
  coff2elf (actually, it's 'cof2elf') converter.  The COFF (actually,
  ECOFF) to ELF transition was also the transition to the use of
  Expanded Fundamental Types (EFT), an SVR4-ism.  EFT enlarges a number
  of basic data types, finally casting off the last vestiges of the
  PDP-11.  So, structures built in an EFT world would have their
  members at different offsets than they would in a pre-EFT (e.g. IRIX
  4.x) world. The operating system uses the fact that an executable is
  in ELF to trigger the use of EFT-based strucures for input and
  output.  So, even if you had a program like coff2elf, the resulting
  transformed executable would not operate correctly for almost any
  interesting case.  Trivial programs that don't have any system calls
  which pass in structures or get structures back from the OS could
  theoretically work, but these fall into the "uninteresting" class.

  Note that the cof2elf(1) program referred to by the elf(1) manpage in
  IRIX 5.2 does not exist. The elf(1) manpage is wrong.