Controlling Power-on Self-Test (POST)

The Power-on Testing variables are:

• diag-switch?

• diag-device

• diag-file

• diag-level

Setting diag-switch? to true causes the function diagnostic-mode? to return true. When diagnostic-mode? returns true, the system:

• Performs more thorough self tests during any subsequent power-on or system reset process.

• May display additional status messages (the details are implementation dependent).

• Uses different configuration variables for booting. (For more details on the effects on the boot process, see Chapter 2, Booting and Testing Your System)

Most systems have a factory default of false for the diag-switch? variable. To set diag-switch? to true, type:

ok setenv diag-switch? true 
ok

Some systems have a hardware diagnostic switch that also cause diagnostic-mode? to return true. Such systems run the full tests at power-on and system reset if either the hardware switch is set or diag-switch? is true.

Some implementations enable you to force diag-switch? to true by using an implementation-dependent key sequence during power-on. Check your system's documentation for details, or see Appendix C, Troubleshooting Guide."

To set diag-switch? to false, type:

ok setenv diag-switch? false 
ok

When not in diagnostic mode, the system does not announce the diagnostic tests as they are performed (unless a test fails) and may perform fewer tests.