What are the general thoughts of people regarding 64-bit support on MIPS 
platforms?   Are there others which are interested in this?  Obviously
this breaks compatibility with the old mips platforms like pmax,
but any new hardware out there could potentially support it.

Looking from the ABI standpoint, there're things like the n32 calling
sequence which SGI uses. This supports an LP32 programming model,
but allows programs to pass long long's in registers.
Such a scheme would allow people to take advantage of the 64 bit
registers for things like multi-precision arithmetic, but retain
much of the compactness of a 32-bit programming model.

Right now I have some preliminary changes which keep the same calling
sequences (i.e. o32), but I've modified the interrupt structures to 
save/restore all 64 bits of the registers.  This allows people to
use leaf routines with 64-bit instructions.

Is this of interest to others here?  If so, I'd like to try to 
coordinate how things should be organized in the source tree. . .