Enabling systemd Debug Shell During Boot

To diagnose systemd related boot issues, you can enable early shell access during boot.

Perform the following steps to enable early shell access:

1. Restart the Photon OS machine or the virtual machine running Photon OS.

   When the Photon OS splash screen appears, as it restarts, type the letter e quickly.

2. Append systemd.debug-shell=1 to the kernel command line.

   Optionally, to change logging level to debug, you can append systemd.log_level=debug.

3. Press F10 to proceed with the boot.

4. Press Alt+Ctrl+F9 to switch to tty9 to access the debug shell.