Re: Tuple and changes for m68k with -malign-int

Hi Geert,

On Mon, 2025-05-19 at 09:42 +0200, Geert Uytterhoeven wrote:
> > AmigaOS doesn't use ELF though, it uses COFF. And Amiga Unix, which uses
> > ELF, has a default alignment of 4 bytes as specified by the AT&T ABI.
> 
> Initially Linux didn't use ELF either, but a.out.

Yes, the same applies for NetBSD. This also becomes obvious that the
NetBSD header on m68k is called "netbsd-elf.h", instead of just "netbsd.h".

> SunOS4 (based on BSD) did use 2-byte alignment on m68k, so I am still
> surprised NetBSD didn't follow suit.

When NetBSD still used a.out, it actually used 2 bytes alignment. They
switched over when they switched from a.out to ELF, see:

https://wiki.debian.org/M68k/Alignment

> SunOS5 (based on SVR4) no longer supported m68k.

True. I would now be really interested to find out what my Sony NEWS
machines use on m68k. According to Wikipedia, it's based on SVR4, so
I assume it uses ELF with 4 bytes alignment, see:

https://en.wikipedia.org/wiki/UNIX_System_V#SVR4

There is also an Atari Unix which I would like to test as well.

> I expect (the history of) the gcc sources would tell you more about
> the default alignment on other (legacy UNIX) OSes supporting m68k...

Good idea. I will do that. My assumption is that on Linux, GCC developers
actually just forgot to switch alignment from 2 to 4 bytes with the switch
to ELF unlike NetBSD.

Adrian

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