Platform Initial Program Load - IBM p5 590 System Handbook

Since there are dual service processors per CEC, both service processors must
be updated when firmware updates are applied and activated using the
Apply/Activate command on the HMC.
The system power code image (stored on the BPC part of service processor)
contains the power code for the frames that house the CEC cages, I/O cages,
and clustering switches. The BPC service processor code load not only has the
code load for the BPC service processor itself, but it also has the code for the
DCA, bulk power regulator, fans, and other more granular field replaceable unit
that have firmware to help manage the frame and its power and cooling controls.
The BPC service processor code load also has the firmware for the cluster
switches that may be installed in the frame.
The BPC part of the service processor has a two sided flash, and overall, it is the
same hardware as the CEC service processor. When the concurrent firmware
Install/Activate command from the HMC is initiated, the BPC service
processor reboots as part of the concurrent activate process. The BPC
initialization sequence central electronics complex after the reboot is unique. The
BPC service processor must check the code levels of all the down level devices,
including DCAs, BPRs, fans, cluster switches, and it must load those if they are
different than what is in the active flash side of the BPC. Since the p5-590 and
p5-595 have dual BPC service processors for each frame side, both will be
updated as part of the firmware update process.

7.1.2 Platform initial program load

The main function of the p5-590 and p5-595 service processors is to initiate
platform initial program load (IPL), also referred to as platform boot. The service
processor has a self initialization procedure and then initiates a sequence of
initializing and configuring many components on the CEC backplane.
The service processor has various functional states, which can be queried and
reported to the POWER Hypervisor. Service processor states include, but are not
limited to, standby, reset, power up, power down, and runtime. As part of the IPL
process, the primary service processor will check the state of the backup. The
primary service processor is responsible for reporting the condition of the backup
service processor to the POWER Hypervisor. The primary service processor will
wait for the backup service processor to indicate that it is ready to continue with
the IPL (for a finite time duration). If the backup service processor fails to initialize
in a timely fashion, the primary will report the backup service processor as a
non-functional device to the POWER Hypervisor and will mark it as a GARDed
resource before continuing with the IPL. The backup service processor can later
be integrated into the system.
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Chapter 7. Service processor