Re: Plan needed for switching m68k to 32-bit alignment

[Thorsten Glaser <tg@debian.org>]

On Fri, 25 Oct 2024, John Paul Adrian Glaubitz wrote:

>as m68k has supported 32-bit alignment through the "-malign-int"
>switch for a long time.

That switch constitutes a fundamental ABI change, even if
the effect is limited.

Question is, do we need a kernel change for this at all?
Is there anything in the kernel/userland interface that
gets affected by this, or do these APIs use sufficient
explicit padding? Has anyone looked at this?

If we know that the answer is no, the plan could look
different from a yes answer, so…

Additionally… has anyone done the simple “enable -malign-int
in GCC, begin rebuilding stuff, first glibc, then others,
see what breaks”? Is there sufficient effect that we cannot
incrementally change over?

(Another question: does -malign-int switch to natural
alignment for all types, i.e. 64 bit for llong and double,
etc. or are we going to have to change GCC first as well
to avoid more surprises?)

bye,
//mirabilos
-- 
Solange man keine schmutzigen Tricks macht, und ich meine *wirklich*
schmutzige Tricks, wie bei einer doppelt verketteten Liste beide
Pointer XORen und in nur einem Word speichern, funktioniert Boehm ganz
hervorragend.		-- Andreas Bogk über boehm-gc in d.a.s.r