Starting opensm on a system on which opensm worked fine in the past fails. The
following is reported:
# systemctl start opensm.service                      
Job for opensm.service failed because the control process exited with error
code.
See "systemctl status opensm.service" and "journalctl -xe" for details.
# systemctl status opensm.service | cat
* opensm.service - Starts the OpenSM InfiniBand fabric Subnet Manager
     Loaded: loaded (/usr/lib/systemd/system/opensm.service; disabled; vendor
preset: disabled)
     Active: failed (Result: exit-code) since Sat 2020-10-31 17:32:52 PDT; 3min
13s ago
       Docs: man:opensm
    Process: 5985 ExecStart=/usr/lib/opensm-launch (code=exited,
status=203/EXEC)

Oct 31 17:32:52 asus systemd[1]: Starting Starts the OpenSM InfiniBand fabric
Subnet Manager...
Oct 31 17:32:52 asus systemd[5985]: opensm.service: Failed to execute command:
No such file or directory
Oct 31 17:32:52 asus systemd[5985]: opensm.service: Failed at step EXEC
spawning /usr/lib/opensm-launch: No such file or directory
Oct 31 17:32:52 asus systemd[1]: opensm.service: Control process exited,
code=exited, status=203/EXEC
Oct 31 17:32:52 asus systemd[1]: opensm.service: Failed with result
'exit-code'.
Oct 31 17:32:52 asus systemd[1]: Failed to start Starts the OpenSM InfiniBand
fabric Subnet Manager.


Changing ExecStart=/usr/lib/opensm-launch into ExecStart=/usr/sbin/opensm in
/usr/lib/systemd/system/opensm.service seems sufficient to make opensm work
again.