Re: Intermediate step for new arch for lc040 compatibility

John Klos <[email protected]> Sat, 3 May 2025 18:20:59 +0000 (UTC)
Newsgroups gmane.os.netbsd.ports.m68k
Message-ID <[email protected]>
Hi,

> However, this is only for those *using hard-float binaries*. And
> that's where I'm confused. While I do see why one would want to run a
> standard distribution on XC68LC040, why hard-float? It makes a lot
> more sense to me to just run a soft-float distribution on any FPU-less
> system. And it will be faster, as the FP emulation code doesn't need
> the overhead of the F-traps.

I can see why each solution is imperfect, and I agree that it'd make more 
sense to run soft-float on systems without FPUs, particularly ones with 
buggy instruction trapping.

> I must confess I don't even know if there's a soft-float variant of
> NetBSD/m68k (all my systems running NetBSD have FPU for now, though
> I'm considering a home-made one with a FPU-less MC68040V), but for me
> it would make a lot more sense to use that (and add it if it's
> missing) rather than a XC68LC040-specific variant. Sure a bunch of Mac
> LC475 shipped with those, but ultimately it's probably easier and more
> convenient to either upgrade them to full '040 or bug-free MC68LC040,
> or to run soft-float on them.

There was this ages ago:

https://jmmv.dev/2004/09/netbsdmac68k-soft-float-support.html

Plus, here's NetBSD 5.0.1 from 2012:

https://mac68k.org/mac68k-softfloat/

It might not be a lot of work to get soft-float working 100%.

John