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Booting
Table 5-31 displays the normal boot process, as reflected in changes to front panel LED states.
Table 5-31 Normal Boot Process LED States
System Power StateDiagnostic
Panel
PowerExternal
Health
Internal
Health
System
Health
Step
No ac power to the system.OffOffOffOffOff1
System is shut down, but ac
power and standby power are
active.
OffSteady
amber
OffOffOff2
System power rails are on when
power switch is toggled.
OffSteady
green
OffOffOff3
System power rails are on; BMC
drives External Health LED.
OffSteady
green
Steady greenOffOff4
System is booting firmware
(has passed BOOT_START in
firmware).
OffSteady
green
Steady greenSteady
green
Off5
System has finished booting
firmware and an OS is either
booting or running.
OffSteady
green
Steady greenSteady
green
Steady
green
6
NOTE: In the normal boot process even though the BMC is running while the system is shut
down (Power LED is steady amber), it does not drive the External Health LED to steady green
until +12VDC power from the bulk power supplies is applied.
The following steps describe the system boot process. Step numbers provided correspond to the
steps in Table 5-31:
3) System power switch turns on bulk power supplies and fans, and releases RESET on all CPUs
simultaneously, when toggled on.
5) Initial CPU firmware code fetch is PAL code from EEPROM in PDH, retrieved 4 bytes at a
time by DMDC in Zx2 (No shared memory or I/O devices are available at this time; they are not
initially configured).
5) Firmware code stack is initially in BBRAM in PDH, retrieved 4 byes at a time, through PDH
and DMD buses.
5) PAL code configures all CPUs.
5) SAL code configures all platform CEC chips, including shared memory and all responding
I/O devices.
5) Firmware code and stack are relocated to shared memory after all x4DIMM ranks in shared
memory are configured and tested.
5) EFI Shell launches from shared memory, and cache lines are retrieved 128 bytes at a time by
MEMC in Zx2.
6) The OS loader launches using the EFI device driver.
6) The OS boots and starts its own device drivers.
6) The OS can use runtime PAL and SAL calls, and ACPI features. These abstraction layers enable
platform independence.
Booting 173