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Re: ABI choice for MIPS on debian lenny?

On Fri, 2009-02-27 at 22:07 +0100, Arnaud Patard wrote:
> Laurent GUERBY <laurent@guerby.net> writes:
> > 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, 
> fwiw, it would be also interesting to compare o32 with -march=mips3 with
> n32. I'm not sure that in such kind of case the differences will be
> big. 

Looks like on lenny userspace binaries are compiled for MIPS-I whereas
on Mandriva (gdium) there are MIPS-III. I'll do some testing when
I get my 4.4 tri-ABI compiler working, thanks for the hint.

> > do you know why it is not used by default? 
> I think only irix is using it by default :)
> As regards linux, imho, nobody's using it due to the amount of bugs
> hidden waiting for a fix (this is a guess, maybe there are better
> reason).

Do you know of specific GCC open PR against n32? GCC bugzilla search
for target mips returns only 30 PR most of them are not wrong code.

> > Is it unsupported on some hardware?
> iirc you need mips3 or newer ISA. I'm not sure that there are 64bit
> mips not fitting in this category.

May be debian is targeting hardware < mips3?


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