Re: NetBSD/vax vm for github testing

[Anders Magnusson <ragge%tethuvudet.se@localhost>]

    Den 2025-01-09 kl. 01:15, skrev Thor Lancelot Simon:
> On Mon, Jan 06, 2025 at 07:29:32PM +0000, John Klos wrote:
> > > However it takes 24 minutes even to build ancient small emacs-18.59.
> > > simh emulating microvax3900 on my i5-4570 NetBSD/amd64 took ~70 hours
> > > to build perl 5.38.2 (from pkgsrc-2023Q4) so it won't finish in
> > > 6 hour github CI limit.
> > >         
> > I suppose because additional cores can't be thrown at simh, this is a
> > difficult limit.
> >       
> I didn't realize simh had no multiprocessor support (does NetBSD/vax?).
> One answer might be distcc if additional VMs could be brought up in
> the same network environment.
>     
    I wrote multiprocessor support for NetBSD/vax many years ago; but not many vax machines can have multiple CPUs.
It did work on VAX8250, which was just over one VUPS (which is extremely slow today).

Also, emulating multiprocessor support in general using a multiprocessor machine is extremely difficult, since you need to synchronise the CPUs so that they emulate at exactly the same speed.  

-- Ragge