Re: MPS signals and Emacs

[Eli Zaretskii <eliz@gnu.org>]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: eggert@cs.ucla.edu,  eller.helmut@gmail.com,  emacs-devel@gnu.org
> Date: Mon, 22 Apr 2024 11:02:56 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> An example in Emacs is the control stack marking.
> >
> > Is that just one example, or is that the _only_ example?  If the
> > former, what other examples of ambiguous references are there in
> > Emacs?
> 
> I think I've also seen at least one other example, but I forget where
> that was (maybe specpdl, or bytecode?). I think the function called
> is mark_mem or so.

So any Lisp object referenced from the C stack or from byte-code will
not be copied by MPS?  What are the implications of that for Emacs?
AFAIU, the current GC considers any such object as live, marks it, and
doesn't collect it as garbage during the sweep step, but being unable
to copy such an object means something very different for a copying
GC, doesn't it?  Because AFAIU live objects _are_ copied.