Re: Question on BIGGEST_ALIGNMENT in GCC on NetBSD/m68k

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

Hi Eero,

On Fri, 13 Jun 2025 at 21:29, Eero Tamminen <oak@helsinkinet.fi> wrote:
> On 13.6.2025 17.53, John Paul Adrian Glaubitz wrote:
> > On Fri, 2025-06-13 at 17:15 +0300, Eero Tamminen wrote:
> >> Wouldn't next upgrade completely break user's Debian system so it needs
> >> complete re-install?
> >
> > You would need to extract the glibc package manually from my tests. After that,
> > upgrading the system should be possible.
>
> I think quite a bit more binaries than just Glibc are needed for Debian
> upgrade tooling to work, but OK.
>
> As to other potential issues...
>
> I assume there are no m68k port packages with closed source executable
> code (FW) [1], like the other architectures (esp. x86) have & need, and
> that any code intended to work also on non-m68k platform, should be fine
> with 4-byte alignment.
>
> But what about m68k specific C/C++ and assembly code that may hard-code
> 2-byte alignment assumptions; is there any tooling to detect (potential)
> alignment issues in those?

This is one of my worries, too.
The Debian package archive is much larger than the NetBSD one...

> Or is the plan just to rely on packages' self-tests to reveal issues,
> and then track them down from there?
>
>
> [1] Are sources for "bootstra.tos" & "amiboot" anywhere, in case they
> need updates:
> https://wiki.debian.org/M68k/Installing
> https://people.debian.org/~wouter/d-i/images/20130502-06:51/tools/atari/
> https://people.debian.org/~wouter/d-i/images/20130502-06:51/tools/amiga/
> ?

https://github.com/geertu/m68kboot

I don't expect any changes would be needed for the bootstraps.
FWIW, include/uapi/linux/zorro.h already has __packed for the various
AmigaOS structs, as that was needed for APUS (support for which was
removed from the kernel a long time ago).

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