
The "S|s|single" option is handled by systemd (starting rescue.target). And the rescue target basically removes the need for a special debug shell. (Also, there is "systemd.crash_shell=1" for starting a shell if systemd crashes.)
The "S|s|single" option is handled by systemd (starting rescue.target). And the rescue target basically removes the need for a special debug shell. (Also, there is "systemd.crash_shell=1" for starting a shell if systemd crashes.)