below...

On Thu, Dec 1, 2016 at 3:13 PM, Paul Ruizendaal <pnr@planet.nl> wrote:

Clem,

Many thanks for your informative post!

Most welcome.

> Assuming I can read the tape, I know I do have a copy of 4.1a distribution on 9-track.
That is great news. Let me know once you had a chance to look at it. I am in no hurry, so whenever you have time, even if that is months from now.

My queue keeps getting bigger. I need to retire so I have time for my home projects ;-)

> Diomidis is correct, 4.1a use Joy/Cooper/Leffler reimplementation of of the BBN stack, not the original BBN stack.
I suspected as much, but I am happy to hear it confirmed. I've been told on several occasions that 4.1a contained the original BBN stack.

Truth is the basic stuff will be pretty similar. The big thing they share is mbuf code and how basic IP/TCP state machines. The primary changes will be that it's not using open/nami and started to get rid of the ioctl hacks IIRC. It's been a long time since I looked at those stacks.

The original BBN release was >>tuned<< for 4.1BSD but was based on their "portable" IP/TCP release. So it's what was used for the HP3000 and few other systems that DARPA wanted IP stacks. Again this is more obvious when you look at the mbuf stuff. Rob needed a specific OS kernel independent way of handling memory, so he wrote his own handler and then spliced the few things it needed into the local kernel.

Joy kept that code for a long time, although in later and later versions of the BSD stack (i.e. by NET2) the mbuf code has been rehashed by many and deviated from Rob's stuff in many ways.

> The BBN stack (Gurwitz et al) was for 4.1 (and other UNIX and non-Unix systems). I do not believe I have a copy of that tape. Rob or maybe Eric Cooper might.
>
> How Sam added the code into the UCB SCCS, I never knew (you can ask him directly, he is still findable these days). Eric Cooper took the basic BBN distribution and put it on the UCB 4.1 systems around campus >>before<< Joy started the sockets work i.e. the installation was done by installing 4.1, then taking the BBN tape and installing it as is.

I can confirm all this. I do have several copies of the BBN tapes from '81 and '82, they survived in Kirk McKusick's archive.

You mean on his CD's - if so can you send me a path. I'll try to peak at them. I have the CD's at home, although not online.

They indeed contain material that is 'copied over' a clean 4 or 4.1 build tree. The first complete BBN beta is from May 1981 and Joy started on his network code in October 1981.

FYI: I don't remember it as a beta, but you might be right. I thought it was the official distribution. BTW it supported the BBN 1822 interface and the Xerox 3Mbit boards with the Xerox taps on the Vax. I wrote a 3Com driver for it and Sam and I hacked up an InterLan and DEC drivers when we finally got 10M cable. We had had a single (3Mbit) Xerox cable that went through Cory and over to the 5th floor of Evan and then hit its limit. But at 3Mbit, it was a huge step of from the Berk-Net (9600 baud serial over DZ-11 ports).

3Com, DEC and InterLan all were working on Unibus ethernet board at different stages of readiness. 3Com must have been shipping for about 18-24 mons by then, because I had used them on Tektronix (I was their first customer) but UCB was using the Xerox gear when we started. DEC had donated some of their gear to the CAD team, so we had those board before Joy/Sam did in Evans. Since I had one "pure DEC" system of our 3 780s in the CAD group (most of the Vaxen at UCB had non-DEC gear), I was often an early "test system" for Sam.

> BTW: about 3 years later, the BBN2 stack comes out from Rob and team and it is actually even more interesting; because it now uses the sockets interface (not the Chaosnet/UofI nami trick), and adds a number of both performance enhancements (Van Jacobson's work, etc.) as well as a more complete implementation of the IP stack. I >>might<< have a copy of that tape squirreled away; but I'll have to look.

I think this might be the material that appears in the BSD source tree in 1985, right?

I don't remember/know if it ever got put directly into the BSD tree. Rob released it independent of the BSD kit and you needed and BBN license to get it. It was what we used at Stellar, because it was easier to make parallel and we were adding it into a more System V then BSD-ish kernel (the Stellar box was a 4 "core" system in its CPU).

There was definitely some bad blood at the time. BBN had the contract to support IP/TCP not UCB. So the stacks did diverge. Most (commercial) people used the BSD 4.2 ( and later NET2) implementation because they got it from UCB and did not get the separate BBN license. Arpanet contractors got the BBN2 code automatically, but I don't think many of folks installed it unless they needed some feature that BBN had that UCB did not. The National Labs are likely to have picked it up; but not all of the Universities.

Van Jacobson's work is ~1988, I think, but I could well be mistaken.

Van was at LBL (up the hill as we used to say). He started with the BSD 4.2 code, but he was talking with Rob pretty regularly. I know by the time we did Stellar, IIRC: both Van and Rob were part of the DARPA advisors committee (predecessor to the IETF). I do remember when we were at Stellar, Van and Rob were talking because we were doing the threading/parallel lock stuff and I'm pretty sure Rob traded some of our work for something Van was doing at the time.

I think the main performance improvement between the 1982 and the 1985 version was a switch from a kernel thread model to a software interrupt model, but as yet I haven't grasped why this is better and my assumption may be incorrect.

I should know, but frankly do not remember. I suspect if I started to stare at the code, some of those bits will refill the cache in my brain. IIRC it was related to the amount of state that needed to be saved/switched. In the thread model, I believe you need the complete context, but in the Interrupt model and are sharing whatever context the kernel has at the time of the interrupt.

Clem