[Info-vax] Xephyr and Decwindows problem

[Stephen Hoffman]

On 2015-01-14 12:55:39 +0000, mattiheikinoja at gmail.com said:

> Hello,
> I am novice in VMS world, but I am learning :-)
> I have a simulated Vax VMS 5.5-2 system with UCX. I have managed to 
> start Decwindows session in Xephyr (Ubuntu). Problem is that connection 
> is not staying up. Also display backgroud drops after other 
> applications start.
> When using standard X-server everything shows ok, but it is very slow...
> And also: when Decterm starts, it gives warning about missing font... I 
> think that problem is that Xephyr is asking things that VMS cant 
> answer... So, how I need to configure Xephyr to make it work right?

Welcome.

You're probably approaching this problem using modern expectations 
around how computers and operating systems' user interfaces work, and 
also with a few liabilities lurking for this case  — VMS isn't usually 
used with a graphical interface — and with some very old and very 
limited and rather buggy software — OPenVMS on VAX, and the associated 
and old DECwindows and TCP/IP Services packages — and you're also 
working with what can be some of the least-well-documented and 
sometimes the least stable aspects of emulation — the virtual 
networking.

OpenVMS is a command-line environment.  DECwindows was a user 
interface, but never really became a management or control interface.  
Put another way, you'll quickly need to use the command line for 
various tasks, which means DECwindows and X is a massive weight for 
little payback, since you're going to end up using a DECterm for a 
number of tasks.   The DECwindows version you're using is based on a 
hand-ported version of X Windows — VAX was too slow for a straight X 
port, so there was a whole lot of work performed by OpenVMS engineering 
to get X to run faster on VAX — so there are going to be some oddities 
and differences from standard X, and it's obviously also an ancient 
version of X.   Put another way, might as well start with a 
command-line session, and with software from ~23 years ago means 
sketchy IP support and telnet.  (Unless your goal here is to spend time 
getting sketchy old code to work and to interoperate with newer code, 
then there's more than a few choices available in IP and X and ancient 
OpenVMS that should satisfy your desires.)

If you want to learn about OpenVMS, I'd suggest not starting out with 
as many of these strikes against you.  No DECwindows / X.   If you're 
going to try emulation, then use a recent OpenVMS Alpha V8.4 
configuration with a recent TCP/IP Services version, and (obviously) on 
an Alpha emulator.  And don't start out with an ancient IP stack and 
emulator networking as the first mess (of many) that you're going to 
tangle with.  If you're really stuck on VAX for some unspecified 
reason, then use V7.3 and the then-current X Windows support — that's 
~13 years old, though only slightly less sketchy.

Though you didn't indicate which emulator is in use here, I'd guess 
you're using simh, and simh doesn't implement JIT support when last I 
checked.  The VAX code is always interpreted.   There's an MP version 
around which might be faster.  Some of the other emulators have JIT 
support, which can help with emulation performance.

As for X fonts, look around for previous discussions of DECwindows font 
daemon.  <http://labs.hoffmanlabs.com/node/134>   There'll be other 
discussions of the font daemon.   Some folks will move the fonts 
around, though I don't know what the old VAX licensing allowed for, in 
that area.  (Again, X adds a whole lot more complexity here.)

As for the performance, X is very heavyweight, very network-intensive, 
and the particular emulator can be a performance limit.    Use telnet 
or use an emulated serial line.   Get OpenVMS going (VAX, if you have 
to), then use the console connection into the emulator, or get basic IP 
and the telnet server going, and connect that way.   As for what's 
happening here, you're going to have to dig through the X Windows 
server logs on your Linux box, and through anything that's getting 
logged by the OpenVMS X clients.  Some sort of authentication error 
wouldn't be a surprise, as code as old as the DECwindows you're dealing 
with didn't know to do that.  Current DECwindows has limited support 
for X authentication, and had some nasty bugs with X authentication, 
and you're back almost a quarter century with the code you're working 
with here.)

Good luck with this, though.  You're in the proverbial deep end of the 
VMS pool here, unless somebody has already tried this combination.


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