Re: differences between mips64-elf and mips-ecoff ?

[Ian Lance Taylor <ian@zembu.com>]

   From: Ricky Charlet <rcharlet@redcreek.com>
   Date: Fri, 10 Nov 2000 09:54:11 -0700

	   In further reading, I have found out that ecoff was an old (and from
   what I read unsucessful) attempt to develop a binary object encoding
   format which would apply to a large range of processors and become an
   open standard. elf format is more mips specific. 

This is more or less incorrect.

ECOFF (Extended COFF, where COFF means Common Object File Format) was
invented to extend the COFF format to handle some peculiar details
required by the MIPS architecture, such as the GP register.  ECOFF was
used on Digital's Ultrix, and was therefore also used for the Alpha in
the Digital backed OSF/1, later called Digital Unix.  I don't believe
that ECOFF has ever been used for anything other than the MIPS and the
Alpha.

ELF, like COFF before it, was invented by AT&T when it was in charge
of Unix.  ELF was introduced with SVR4 (COFF was introduced with
SVR3).  It is a portable format used by a wide range of processors,
including MIPS.

Although it was necessary to extend COFF to make it support MIPS, ELF
is a more flexible format, and no special extensions were required for
MIPS support.

	   Now I am makeing an infernece here, the rest of this is not something
   I've read. Because ecoff is quite old, and there seems to be no such
   mips64-ecoff target I assume that MIPS III & IV ISA (with the 64 bit
   modes) were defined only in mips elf formats. And therefore mips64-elf
   is the only target which will run a mips chip in 64 bit mode.

As far as I know, nobody has ever produced a mips64 machine which uses
the ECOFF format.

Ian

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