Tpm0 warning on boot is cosmetic
You can safely ignore the Tpm0 warning when connected to a console on a 150 Airwall Gateway.
If you have a console connected to your 150 Airwall Gateway you might see a warning about tpm0:
"tpm tpm0: A TPM error (256) occurred continue selftest"
Solution
This is a benign error and does not indicate a problem with the unit.