Re: powerpc FPU emulation fails for single precision arithmetic (Was: kernel panic on ibm4xx-based powerpc box with DDB)

[Simon Burge <simonb%NetBSD.org@localhost>]

Rin Okuyama wrote:

> By the way, I'd also like to fix port-powerpc/51368:
> 
>    http://gnats.netbsd.org/51368
> 
> FPU emulation for ppc gives wrong results for single precision
> arithmetic. As described in the PR, I found the fix from FreeBSD:
> 
> ====
>    https://svnweb.freebsd.org/base?view=revision&revision=258250
> 
>    Make single precision floating point arithmetic actually work -- I think
>    it never did -- and fix an obvious missing line. Floating point emulation
>    on Book-E still needs some work but this gets it basically functional on
>    soft-FPU systems (hard FPU for Book-E is not yet implemented).
> 
>    MFC after:	1 week
> ====
> 
> With this fix, single precision calculations get sane on ibm4xx and
> booke as far as I checked.

How exactly does single precision fail without this fix?  I haven't
looked, but is there any simple single precision IEEE test suite that
shows this?

I'm all for the fix BTW :)

Cheers,
Simon.