SMP support for 680[34]0 ?

Hello,

Am I correct in my belief that there's currently no support for
shared-memory multiprocessing in any of the 68k port?
And that there is in fact no supported systems with an SMP option?
(conflating symmetric multiprocessing & the shared memory paradigm as
they are now more or less synonymous).

The only port that mentions SMP seems to be luna68k (for the Luna-II),
and more as a rumor than a fact.

I can only find traces of a couple of 68040 SMP systems (from Arix and
Concurrent Computer Corp), but very light on details, though some
probably shipped to customers. Proprietary OS, unclear as to the level
of support (processes, threads, ...).
They also appear in a press article mentioning issues with Motorola's
SMP implementation in the 68040 and the need to disable write-back in
the internal caches, which isn't reassuring.

For the '030, it seems it was mostly non-shared memory (so
distributed) implementations, mostly in the scientific literature.

Does anyone knows about SMP 680[34]0 boxes supporting a UNIX(-like) OS ?

I've read the 68040UM a lot recently (for the
<https://github.com/rdolbeau/QuadraFPGA>), and thinking about building
a dual-68040 box with a FPGA supplying all the I/O, but I'm not sure
about being able to properly support something like the NetBSD kernel.
I'm wondering whether anyone has thoughts about SMP/68k from a kernel
point of view.

Cordially,

-- 
Romain Dolbeau