SMP 68k (Re: New pmap module for m68k)

[Romain Dolbeau <romain%dolbeau.org@localhost>]

Le jeu. 13 nov. 2025 à 10:05, Romain Dolbeau <romain%dolbeau.org@localhost> a écrit :
> I'd love to see this happen, but building hardware for it is a bit of
> a pain. Having emulation working as a starting point would be great
> (for buildhost and test SW before creating HW).

Well, barely a year later and the world has changed a lot for this
kind of stuff - whether we like it or not- because of LLMs (I'm not
using the i-word to describe it).

```
NetBSD/virt68k (virt68k) (constty)

login: root
Oct 19 14:54:44 virt68k login: ROOT LOGIN (root) on tty constty
Last login: Mon Oct 19 11:52:23 2026 on constty
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    2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013,
    2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023,
    2024, 2025, 2026
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 11.0 (GENERIC.MP) #15: Sun Oct 18 12:50:46 CEST 2026

Welcome to NetBWe recommend that you create a non-root account and use
su(1) for root access.
virt68k# sysctl hw.ncpu
hw.ncpu = 8
virt68k# sysctl hw.model
hw.model = Qemu 11.1.2: MC68040+MMU+FPU, 4k+4k on-chip physical I/D caches
virt68k#
```

Took claude code a day to get a first version (of both qemu & netbsd),
and about another one to "optimize" the pmap code, moving away from
one big lock and making "make -j" relatively efficient to self-host a
full kernel rebuild. Whether that would translate to actual hardware
is a wide open question. But now that software is much less of an
issue, I need to get around to actually building my SMP MC680x0
homegrown... (which is basically two CPUs and a big FPGA to handle
everything else)

I don't think AI-generated code is welcome in NetBSD, so I'll stop
here, but if anyone wants to discuss this off-list they're welcome.

Cordially,

-- 
Romain Dolbeau