[TUHS] Do you have any historical UNIX computers?

[Dan Cross]

On Wed, Jun 11, 2025 at 10:22 AM Warner Losh <imp at bsdimp.com> wrote:
> On Wed, Jun 11, 2025 at 9:56 AM Dan Cross <crossd at gmail.com> wrote:
> > [snip]
> > I don't know when exactly it came around.  It was definitely in 4.1.4,
> > and I'm also certain it was in 4.1.3/4.1.3_U1.
> >
> > If Wikipedia can be trusted, it says that MP support came in 4.1.2,
> > for the SPARCserver 600MP systems.  It looks like it only supported up
> > to 4 CPUs.
>
> There's #ifdef MUlTIPROCESSOR in the 4.1.3 and 4.1.4 trees that
> leaked. But it looks like they only work for sun4m machines have real
> defines...
>
> I'd been told at the time, over lunch, that even those code bases
> didn't have MP support, but it may have been SMP support was
> lacking...

I could definitely imagine someone saying something like, "well, it's
not _true_ multiprocessor support" since it really does appear that
the kernel was restricted to running on one CPU at a time.

However, it seems like the LWP support in those versions allows a
single process to run across multiple CPUs, so there's that.

        - Dan C.