Re: -mfloat-abi=softfp

[Martin Guy <martinwguy@gmail.com>]

On 4/19/10, ng@piments.com <ng@piments.com> wrote:
> On 04/18/10 20:58, Martin Guy wrote:
> > On 4/18/10, ng@piments.com<ng@piments.com>  wrote:
> > >  I am experimenting with building a toolchain with maverick enabled
> based on
> > > patching gcc according to Martin Guy's patch set.
> > > http://martinwguy.co.uk/martin/crunch/
> > >
> > >  He suggests using -mfpu=maverick -mfloat-abi=softfp
> > probably be called LIBCFLAGS or something like that;
>
>   CT_LIBC_GLIBC_EXTRA_CFLAGS:
>   Extra target CFLAGS to use when building.
>
>  I've added the following to the latter option only :
>  -mfpu=maverick -mfloat-abi=softfp
>
>  Does that look like the correct place to put this?

That sounds like the one. There must also be -mcpu=ep9312, otherwise
the assembler fails to recognize the maverick asm instructions, even
though it is told -mfpu=maverick.

I tried building native glibc to get faster sin/cos etc but found that
it went into an infinite loop on certain values of sin(). However,
that was with an unmodified glibc source.
There are patches to put Maverick hacks into glibc, to do with
endianness, rounding modes, the FPU control word and more.

One is large: martinwguy.co.uk/crunch/glibc-crunch.patch
Another is very small and looks half-finished but may be worth investigating
martinwguy.co.uk/crunch/glibc-crunch2.patch

If you have any joy with these let me know.

Good luck!

   M

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