Re: Preliminary results - was: Re: Question on BIGGEST_ALIGNMENT in GCC on NetBSD/m68k

[John Paul Adrian Glaubitz <glaubitz%physik.fu-berlin.de@localhost>]

Hi Kolbjørn,

On Tue, 2026-01-06 at 14:40 +0100, John Paul Adrian Glaubitz wrote:
> Hi Kolbjørn,
> 
> On Tue, 2026-01-06 at 14:34 +0100, Kolbjørn Barmen wrote:
> > On Mon, 16 Jun 2025, John Paul Adrian Glaubitz wrote:
> > 
> > > To summarize:
> > > 
> > > - the ELF header provides provides the e_ident and e_flags fields which could be
> > >   used for identifying a Linux/m68k system using the 4 bytes alignment ABI
> > > - MIPS uses e_flags for differentiating its ABIs
> > > - PA-RISC sets e_ident to 0x03 (Linux) while every other arch uses 0x00 (SysV ABI)
> > > - qemu-user needs to be patched to deal with the changed alignment (include/user/abitypes.h)
> > > - the kernel needs to be patched to deal with the changed alignment (arch/m68k/kernel/signal.c)
> > 
> > 
> > Does this patch exist somewhere? I ask because I am migrating to
> > 32bit-aligned userland (https://www.gentoo.org/downloads/#m68k) and the
> > gcc provided fails building kernel, stopping at arch/m68k/kernel/signal.c
> 
> I haven't created that patch yet as my work on this effort is currently paused. However, it should
> be straight-forward to update the asserts in the kernel code.
> 
> According to Geert, Arnd Bergmann made some changes to the kernel uapi that would allow the kernel
> to be built with either alignment. Not sure what the current state of things is.
> 
> Let's CC Arnd to find out.

FWIW, please feel free to amend this page [1] in the Debian Wiki if you stumble across any problems.

Adrian

> [1] https://wiki.debian.org/M68k/Alignment

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