Re: floating point emulation broken

[Paul Koning <paul_koning%dell.com@localhost>]

On Oct 20, 2010, at 9:31 PM, Toru Nishimura wrote:

> Manuel Bouyer said;
> 
>> the in-kernel floating point emulation seems seriously broken.
>> ...
>> anyone familiar with mips floating point ?
> 
> fp.S was inherited from pre-NetBSD project and the maintainance has
> been in abandoned state for many years.  The assembler implementation
> is unlikely fixable, better to replace with fresh code with softfloat mathlib,
> as well as xfer between 32x 64bit FP number and 64bit GP for MIPS64.
> matt@ has some progress in insn emul, I suppose.

I agree.  fp.S emulates MIPS-2 float, which means that it doesn't do any good 
for anything compiled to a newer target.

In our case here, we dropped it 3-4 years ago and switched to a NOFLOAT kernel 
with soft-float in userland.  For an embedded system that's a much cleaner 
solution and it avoids having to fight with the compiler when you want a newer 
integer instruction set.

        paul