ABI choice for MIPS on debian lenny?

[Laurent GUERBY <laurent@guerby.net>]

Hi,

On debian lenny I'm playing with GCC trunk (4.4) to build a tri-ABI
compiler on a lemote netbook (running gnewsense kernel and lenny
userspace).

My understanding is that lenny userspace is -mabi=32 (o32) and
GCC and libc support abi=32,n32,64, the kernel being 64.

n32 seems to be more performant than 32, do you know why
it is not used by default? Is it unsupported on some hardware?

For reference GCC discussion:
http://gcc.gnu.org/ml/gcc/2009-02/msg00413.html

Thanks in advance,

Laurent