[HECnet] SIMH VAX Project

[Johnny Billquist]

On 06/30/11 16:51, Mark Benson wrote:
On 30 Jun 2011, at 14:40, Johnny Billquist<bqt at softjar.se>   wrote:

. However, most people just find it overly complex to manage compared to DECnet IV, without any tangible benefits.

I will need to look at reconfiguring my Alpha I think. Contemplating changing the disks around in it anyway so might try and get it right on re-install.

Changing from DECnet-PLUS to DECnet IV is actually simple. You just uninstall one product, and install the other one.
(And then you need to configure it, of course...)

As for the "problems" with NetBSD, I think I saw that you figured out that simh needs to be run as root for it to work. That should be pretty obvious, since it would be a big security problem if everyone was allowed to sniff the ethernet cables at will. Also, it is "ra0" and not "/dev/ra0". Ethernet device names are not paths that exist in the file system. It should be obvious if you actually do an ls on /dev... There isn't any /dev/ra0 (well, unless you happen to run a VAX with NetBSD, in which case there would be a /dev/ra0[a-h] for a disk drive.

NetBSD's /dev is very confusing - a whole lot of nodes exist for hardware that isn't there (as far as I can see).

It's the traditional Unix way. :-)
Linux have moved into having a hierarchy, and sometimes also creating and deleting entries dynamically. As do some other Unix variants.
In NetBSD, they are created for the "just in case" scenario. And it's very flat. Actually much easier to understand and manage, if you ask me.
Any entries you don't need, you can just delete them.
There is a MAKEDEV script in /dev which can recreate them for you, if you ever need to. Or you can do it by hand, of course...

I was clutching at straws. :)

Nothing wrong with that. :-)

Yes, both simh and the machine itself can share the same ethernet port, with the possible problem of talking between those two entities. But from other machines, there will not be any problems (this is not an aspect of the pcap library, but actually a thing related to the Berkley packet filter (bpf) which pcap use, and also to the underlying ethernet driver and possibly the hardware itself).

However, there is in general a bigger problem with simh, NetBSD and DECnet, in that DECnet expects to be able to change the MAC address of the ethernet interface

SIMH uses a separate MAC address that is specified in the bootstrap configuration. I'd imagine (I don't know for sure) that DECNet's MAC control would alter this value, not require altering the hardware embedded MAC of the NIC. The two instances appear to outside Ethernet devices as separate entities as far as I can tell.

Hmm. I haven't checked, but I guess it just puts the ethernet interface in promiscuous mode, and does all the packet matching itself then.
That should work just fine, for the cost of some extra cpu cycles.

As for compiling, yes, the pcap library have to be around already at compile time, or the compilation will fail (obviously). Not withstanding shared libraries and all that, the header files, which are also installed along with the pcap library itself, are needed for compilation. And at link time, the library is checked for some information at that time also. That said, libpcap is a standard component of NetBSD, and there is no need to install another version from pkgsrc.

It may have pulled it in as a dependancy via pkgsrc. I know it compiled and installed 4 packages.

If you build simh from pkgsrc, then yes. simh have a depencency on libpcap >= 0.6
I'm somewhat intruiged that they actually made it dependant on libpcap from pkgsrc instead of using the system libpcap. But that is another problem, for another day... :-)

Well, not really. Linux and Unix are written by different people, but they are based on the same basic design. VMS and WNT was designed by the same person, but not designed in the same way.

Anyone using one Unix system will feel pretty much at home with any other Unix system. Yes, some details differs, but almost everything will be the same, down to using the same shell, similary file system layout, and so on... Try that between VMS and WNT if you dare... :-)

It was only a joke. ;) ;)

Actually, I'm using yet another OS written by Dave Cutler every day, and that is RSX... :-) (And it wasn't just designed by him, his name is all over the sources...)

I hostnamed my new Windows PC 'cutler' - I needed a name and as it's running a spiritual successor of NT I thought it was appropriate ;)

:-)

	Johnny