Re: [GSoC] the AMD64 port

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

    I'll add my response to Simon's, we basically say the same thing :-)

:I'm a student interested in doing the AMD64 port as a Google Summer of 
:Code project.
:I would like to have some questions answered, in order to be able to 
:make an informed decision.
:  1. Does porting require messing with the source code of gcc/binutils/gdb?

    This might need a little work.  64 bit world builds will generate
    a 64 bit cross compiler which the 64 bit kernel build should use (when
    building on a 32 bit platform), but currently our libraries in /usr/lib
    use a single path for 32 or 64 bit libs so we can't build a compiler that
    supports both.

    This means you should be able to work on a 64 bit kernel without messing
    with the compiler sources, though we might need to do a few small
    cleanups.

    I think it would be beneficial for our 2.0 release to actually go through
    the pain of moving our 32 bit libraries into a i386 or amd64 subdirectory,
    with the original directory turned into a softlink, or something like
    that so we would be able to have both targets on the same architecture.
    That's probably a mini-project in of itself.

:  2. Do I need to have an AMD64 machine with more than 4 GB RAM to be 
:able to fully test my work?

    No, any 64 bit capable machine will do.

:  3. Would I be required to get 32-bit binaries working on 64-bit 
:kernels or would being able to run 64-bit binaries suffice?

    No, 64 bit binaries will suffice.  32 bit support is desired, it makes
    things easier, but not required.

:  4. Is SMP part of the equation?

    Yes, but UP could be done first.  SMP mechanics for 64 bit platforms
    are virtually identical as those for 32 bit platforms.

:  5. In general, is there a fixed list of things that should be done, or 
:am I free to choose based on my interests/abilitity?

    You are definitely free to choose.  Really, just getting past basic
    booting would be major milestone!

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>