22.2 Debugging under zVM

22.2 Debugging under z/VM

When running Linux under z/VM, the z/VM debugging tools are at your disposal. These include several useful commands such as display and trace.

In order to use these commands, you must be in CP mode. You can usually enter CP mode by pressing the PA1 key. If you want to issue a debug command without halting your virtual machine with the PA1 key, you can prefix the command with #CP; for example:

 #CP TRACE I PSWA 2000 

22.2.1 The trace command

The trace command is used to trace the flow of program execution.

To use this command, you need to create a trace set containing so-called trace traps. A trace trap consists of the trace command and operands. (If you do not specifically name a trace set at the first time you create a trace trap, CP places it in a trace set named INITIAL.)

22.2.2 References

The following books contain more details on the z/VM and VM/ESA commands introduced in this chapter (query, trace, display):

• z/VM CP Command and Utility Reference, SC24-5967

• Virtual Machine/Enterprise Systems Architecture CP Command and Utility Reference, SC24-5773