Hi there, So, intrepid me (not really) I upgrade my Stretch to 9.4 and (re)booted this morning without success (boot hangs at or with the line "sp5100_tco I/0 address 0x0cd6 already in use").
Now, I'm impatient by nature, and after five or ten minutes staring at the "sp5100" line I rebooted into recovery mode, whereupon a fsck was performed. At which point I entered the "systemctl default" command and the machine booted up fine into my LXDE desktop. I blacklisted the 'sp5100_tco module.' Apparently there is a conflict between that module and the i2c_piix4 module. It appears I can have one or the other but not both at the same time. I'm unclear about the implications of my blacklisting sp5100 but after having done so I rebooted successfully with no hangs. BTW, I've had the sp5100 warning message at boot ever since I converted to systemd. But with only a ten second delay or so. Not sufficient to try my patience. So here I am without a watchdog. -- Bah, the latest news, the latest news is not the last. Samuel Beckett