New port m32r-linux

[Nick Clifton]

Hi Kazuhiro,

> I am preparing porting of m32r-linux target GNU tools.
>
> At the first, I think that it needs new relocations (R_M32R_GOT24,
> R_M32R_26_PLTREL, R_M32R_GOT24 .. .etc).  Now we have only m32r-elf
> target.  Would you tell me the process of porting new targets if
> there are any policies?

Important things to bare in mind when creating a new port:

  * Make sure that it doe snot break other ports.  In particular check
    that native toolchains still build/work correctly after your
    changes.

  * Make sure that a toolchain configured with --enable-targets=all
    --enable-64-bit-bfd will build and run.

  * Ideally the m32r-linux port should be compatible with the m32r-elf
    port.  If this is not possible, (eg because of ABI differences)
    then you must make sure that you have a way to distinguish binary
    files from the two ports.  Typical methods used by other
    toolchains include bits in the e_flags[] field of the ELF header
    and a special .note section.

> Do we need to keep the compatibility of m32r-linux relocations with
> m32r-elf?  I want to change relocation type form REL to RELA for
> porting linux form now.

It is possible to support both REL and RELA relocs in the same target,
although it can be complicated.  One method would be to create a new
set of relocs which map onto the current set, but which are their RELA
equivalents.  (eg R_M32R_16_RELA would be the RELA equivalent of
R_M32R_16).  You could code the linker so that it would be able to
handle both sets of reloc numbers and so retain compatibility with the
current m32r-elf files.

Cheers
        Nick