On Mon, Mar 6, 2017 at 5:59 PM, Clem Cole <clemc@ccc.com> wrote:

But at that time, LCC was putting things in AIX, Ultrix, Tru64, HP/UX, DG/UX, Prime-ux, Intel, AT&T and a host of others. It was kinda neat setting everyone's dirty laundry though.. you learned a lot.

I left out Solaris and SunOS too.

And BTW: Being lucky enough to have hacked on the kernel of almost all of the majors at one time or another, I've been asked an interesting question. Which was the best to work on.. they were all different is the best answer, I give.

But the fact is that DG was a source licensee but they did a full kernel rewrite starting I want to say in the late 1980s, early 1990's to build a scalable SMP. It was probably the easiest of all the kernels I ever got to hack on. Very clean, well documented and the locks were easy to understand. We did a study for DG to TNC into it, be they never pulled the trigger. We quoted it faster than any other port, because our experience had been that everything we had done on DG/UX had gone so smoothly. But we'll never know. They died shortly after the study was finished, which was a shame. I've sometimes wonder what happened to that IP.

It would be interesting to compare it to OSF/1, which was probably the other very cool kernel I hacked on extensively for both Intel and later DEC of course. DG/UX was not quite as modern as Mach from a standpoint of things likes "ports" or being a uKernel - but as a pure well documented and easy to understand SMP UNIX kernel it was hard to beat.

I did do a little work with Chorus and still have the doc set, but never worked with enough to have an opinion of how good it was. It showed promise and I know the UI/AT&T guys had hoped to go there at some point.

Larry's described Solarius pretty well and my experience match his, but I always thought that the locks were madness IMO - so easy to get wrong. SunOS was a lot simpler and as Larry has said was pretty elegant for what was there.

HP/UX was pretty darn bullet proof. The HP folks worked on fault tolerance got rid of panics more than other other UNIX we say, which was pretty amazing, but it was not the easiest kernel to mess with. We did manage to splice the vproc layer and TNC in it and we had a lot of fun with process migration. Its too bad that never shipped. Again, I've wonder about that IP too.

Clem