Re: Intermediate step for new arch for lc040 compatibility

[Nat Sloss <nathanialsloss%yahoo.com.au@localhost>]

On Mon, 28 Apr 2025 14:23:51 Izumi Tsutsui wrote:
> > > This would not affect the default built binaries for any m68k port,
> > > but can be used by people to build a custom distribution with the
> > > workaround for defective LC040 chips?
> > 
> > That's correct.  It does not affect the existing m68k ports.
> 
> You wrote on source-changes-d@:
>  https://mail-index.netbsd.org/source-changes-d/2025/04/13/msg014466.html
> 
> > >  pros: less overhead than "FPU_EMULATE" on kernel side
> > >  cons: requires to define proper MACHINE_ARCH (m68ksf etc.) and prepare
> > >  
> > >        two set binaries (at least for mac68k) like evbarm-earmv6{,hf}
> > >        etc. by updating build.sh and release binary sets in
> > >        src/distrib etc.
> > 
> > Soft float did not work and was not an option on m68k - I even and was
> > questioned for it adding missing source defines for libm :(
> > 
> > Why not have a build with -lcfix turned on say m68k-something or other?
> 
> My question is "Why don't you try to make soft-float work on m68k"
> if special (non-default) binaries are necessary for XC68LC040?
> 
> What's the actual problem on it?

These are the reported failures and test results from a soft float 
installation:

http://ftp.netbsd.org/pub/NetBSD/misc/nat/lc040-atf-softfloat.report
http://ftp.netbsd.org/pub/NetBSD/misc/nat/lc040-atf-softfloat.out

As opposed to 14 failures with this change (same for mc68030 with fp emulation 
and a full '040 in quemu).

And the only other concern with soft-float is abi incompatibiity if running the 
binaries on a hard float system (I don't even know if that's possibile).

At least with this change the binaries produced by an -mlcfix toolchain can run 
on any existing m68k system without special requirements.

Then efforts can be unified fixing the libm/tests and or fp emulation for all 
m68k cpus.

That's my rationale...


Best regards,

Nat

> 
> ---
> Izumi Tsutsui