I routinely scan dmesg for certain keywords that might indicate potential problems
in my Knoppix LiveUSB. I use the following simple bash program for this:
knoppix@Microknoppix:~$ alias | grep dmx
alias dmx='for j in  { warn fail error corrupt }; do dmesg | grep -i $j; done'
Applying this scan to Knoppix 7.7.0, I get the following report:
knoppix@Microknoppix: ~$ dmx
[    6.278315] UDF-fs: warning (device sda): udf_fill_super: No partition found (2)
[    6.358741] UDF-fs: warning (device sdb): udf_fill_super: No partition found (2)
[    6.474193] UDF-fs: warning (device sdc): udf_fill_super: No partition found (2)
[   11.315379] systemd-udevd[2311]: Process '/usr/sbin/alsactl -E HOME=/var/run/alsa restore 0' failed with exit code 99.
[   14.464064] systemd-udevd[2363]: Process '/usr/sbin/alsactl -E HOME=/var/run/alsa restore 0' failed with exit code 99.
[   17.338552] systemd-logind[2600]: Failed to start user service, ignoring: Unknown unit: user@1000.service
For reference,
knoppix@Microknoppix:~$ dmesg | grep -i starting 
[   10.763121] systemd-udevd[2297]: starting version 228
I am not aware of any actual difficulties in using Knoppix 7.7.0 as a LiveUSB that
these warning or failure messages would seem to presage. I am assuming that these
are merely inconsequential artifacts related to having systsemd 'present but not
being used', whatever that means.