Re: Question on BIGGEST_ALIGNMENT in GCC on NetBSD/m68k

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Adrian,

On Wed, 18 Jun 2025 at 14:27, John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
> On Wed, 2025-06-18 at 22:21 +1000, Greg Ungerer wrote:
> > > Could you please elaborate this a bit more, please?
> > >
> > > Coldfire is handled as a separate target via TARGET_COLDFIRE in GCC, so we
> > > would certainly be able to toggle the alignment settings independent of
> > > what's done on classic m68k.
> >
> > The net out is that it is the same gcc compiler, m68k-linux-gcc.
> > ColdFire just needs specific code generation via command line switches,
> > like -m5200 (or -m5206e or -m5307 or -mcfv4e, etc). This is the same way
> > you would specify 680x0 level - m68020, -m68030, etc.
>
> Yes, but there is a TARGET_COLDFIRE macro as I mentioned above which could
> be used to trigger which alignment to use by default. I don't see how that
> would complicate things.
>
> > The bulk of the instruction set is the same. Asm code will look totally
> > familiar to anyone who knows m68k :-)   One notable difference is that
> > there is a more limited set addressing modes for some instructions.
>
> True, but you won't be able to run any classic m68k binaries on ColdFire
> and the other way around, are you?

IIIRC if you use a proper subset of the user mode instructions, you
can create binaries that run on both.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds