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v IPL parameters
– IPL mode
– Switch setting
– Power control status
– Power-on cause
v System vital product data (VPD)
v Time of day
Abnormal ending
The service processor ends an IPL when a condition is detected that prevents the
base machine from doing work. If an IPL stops, an SRC appears on the control
panel, and the System Attention light goes on. The SRC indicates the failing
condition.
Licensed Internal Code (LIC) initialization
Functions performed
The following list is a high-level description of the functions that are performed by
Licensed Internal Code during an IPL:
1. Licensed Internal Code sets the internal processing unit registers and arrays
necessary to run Licensed Internal Code.
2. When initialization is complete, Licensed Internal Code signals the service
processor of the event.
3. Licensed Internal Code enters the disabled state (task dispatcher is disabled).
Once the service processor starts the processing unit, the earlier constructed
queue is made ready. The Licensed Internal Code then does its normal
work-time functions.
See “IPL status SRCs” on page 201 for information that is displayed on the control
panel during an IPL.
Abnormal ending
Licensed Internal Code ends an IPL when a condition is detected that prevents the
machine from doing work. The service processor sends the correct SRC to the
control panel.
Conditions that cause Licensed Internal Code initialization to fail are:
v Licensed Internal Code hangs (loops or waits), causing a Licensed Internal Code
initialization time-out. The processor gives control to the service processor
which, in turn, ends the IPL.
v Licensed Internal Code that is not compatible with the control storage.
Some of the Licensed Internal Code is in main storage in an area that is known
as the Licensed Internal Code overlay area. If this code is not compatible with
resident code in control storage, the IPL might end during the Licensed Internal
Code initialization phase.
v Bad data on file.
If bad data is not detected when read from the file but is detected by the
Licensed Internal Code initialization routine, the IPL ends with an SRC. If bad
data is on the file, use the Main storage dump manager option from the Start a
Service Tool display under DST to save the main storage dump to removable
media. You must install the Licensed Internal Code again to correct this problem.
If the system does not complete an IPL after initializing the Licensed Internal
Code again, the Licensed Internal Code tape is bad.
Chapter 7. Initial Program Load (IPL) Information 219