[Simh] MicroVax 3900 Networking on a Macbook Air

[Mark Pizzolato - Info Comm]

On Saturday, October 3, 2015 at 6:03 PM, Zachary Kline wrote:
> Thanks for these tips. I’m stuck trying to get SIMH to build with VDE support.
> I just installed it manually, and it ended up in /usr/local.
> SIMH doesn’t seem to see /usr/local/lib as a valid library path. I’ve tried
> “make LPATH=/usr/local/lib:/usr/lib,” but that doesn’t seem to have any
> impact at all.
> I’m trying to follow the makefile logic and finding it a bit dense. It looks like it
> *should* work, but I’m just getting Tun/Tap and PCAP.

Well, the 0readme_ethernet.txt clearly says that on OS X the MacPorts 
net/vde2 should be used.

The deeper point here is that, in general, we support vendor supplied 
package install locations (and configurations) which, if possible, we try to 
determine dynamically from local tools.  The thinking here is that the vendor 
supplied packages have been configured and tested by a very wide audience 
and thus work with many cases, where a personally built package may have 
any number of subtle configuration issues which we're not in the business
of troubleshooting.

Historically /usr/local has always been the default destination for personally 
built packages and as such is exactly why it is avoided since the goal is to 
avoid using personally built packages.

On OS X, some dependent components are provided by Apple, and anything 
else is referenced from where MacPorts drops things.  

Folks who build dependent packages and install them on their own in 
their 'personally preferred' locations get to make 'personal adjustments' 
to the makefile, and they get to deal with things which don't work for 
them but work fine for others.  Real negative experiences have driven this 
philosophy.

In the early simh days, we needed some functionality in libpcap which was 
in the www.tcpdump.org source tree but hadn't made it to any of the vendor 
OS platforms.  This was the only external package any simh simulator needed.   
We forced folks to locally build libpcap and it worked well for many folks 
(especially those who built packages regularly), but there were support issues.  
These support issues got worse as time went on and the set of simh users were 
mostly ones coming back to use the VAX or PDP11 simulators for nostalgic 
reasons of their early school or work days and may not have had any familiarity 
with locally building open source packages.   By the time these support problems 
started the needed functionality was widely distributed in all popular host 
systems, so  things were changed to move to use vendor supplied libpcap and 
the screwy user cases disappeared.  As new functionality has been added to 
simh which have leveraged other external packages, the philosophy of using 
vendor supplied packages has continued to be most successful.

- Mark