[Info-vax] [XDM] Can't open display

[chris]

On 1/11/23 17:43, JKB wrote:
> 	Hello,
> 
> 	I have posted here few days ago a question about xdm. I have
> 	reinstall DECW$ from scratch on OpenVMS 7.3 (VAX).
> 
> 	On a Unix workstation, I launch
> 	Xephyr -query fermat :1
> 
> 	and this server tries a connection to fermat (VAX) as
> 	SYS$SPECIFIC:[TCPIP$XDM.WORK] contains three new files after each
> 	connection:
> 
> $ dir
> 
> Directory SYS$SPECIFIC:[TCPIP$XDM.WORK]
> 
> HILBERT_1.COM;1     HILBERT_1.ERR;1     HILBERT_1.OUT;1
> 
> 	If I understand, DECW$ tries to start @HILBERT_1.COM;1 and writes
> 	errors in HILBERT_1.ERR;1
> 
> $ type HILBERT_1.ERR
> [17E 1673458252] xdm error: server open failed for hilbert:1, giving up
> $ type HILBERT_1.OUT
> $ type HILBERT_1.COM
> $ @SYS$COMMON:[SYSEXE]TCPIP$XDM_XSESSION.COM hilbert:1
> 
> 	I have tried to start
> $ @SYS$COMMON:[SYSEXE]TCPIP$XDM_XSESSION.COM hilbert:1
> 
> 	and this command returns:
> p1 = HILBERT:1
> p2 =
> Executing SYS$MANAGER:SYLOGIN
> 
> 
> Executing run sys$system:decw$wsinit
> 
> Can't open display
> 
> Executing run sys$system:decw$session
> 
> X Toolkit Error: Can't open display: _WSA4:
> 
> Fatal error detected, image exiting -- final message:
> no safety display could be opened
> : non-translatable vms error code: 0xE4A, vms message:
> %system-e-unsupported, unsupported operation or function
> 
> Connection closed by foreign host.
> 
> 	Why "Can't open display" ?
> 
> 	Help will be welcome,
> 
> 	JKB
> 

The message is clear. On unix at least, that usually means that the X
server can't find a valid display device hw to connect to. The
xorg.conf file defines the screen and display device, right
down to the hardware pci bus node id. The device bus is often probed
and autoconfigured at os install, so you get a desktop login at
reboot, on modern systems. Won't work without a valid display
adapter and the correct device driver installed and loaded. All that
needs to be verified.

Manually, you would call X to autoconfigure, with the command line
X --configure. That would generate a file named xorg.conf.new, which
would then copy to /etc/X11/xorg.conf, or similar. For all X errors,
there should be an X log file called Xorg.0.log, for a single display.
Note that X won't work without a running network, as it needs the
loopback device for the underlying xdmcp protocol...

On VMS, all that may be hidden under the hood, but it must be there
in some form or another...

Chris