Server Management Functional Specifications; Bmc Internal Timestamp Clock; System Event Log (Sel) - AIC SB402-CP2 User Manual

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4.2 Server Management Functional Specifications

The BMC maintains an internal timestamp clock that is used by various BMC subsystems for time

stamping SEL entries. As part of BMC initialization after AC power is applied or the BMC is reset,

the BMC initializes this internal clock to the value retrieved from the SSB component‟s RTC by a

SMBus* slave read operation. This is the system RTC and runs on battery power as well, so it

maintains the current time even when there is no AC supplied to the system.

4.2.1.1 System Clock Synchronization

The BIOS must send the Set SEL Time command with the current system time to the BMC during

system Power-on Self-Test (POST). Synchronization during very early POST is preferred, so that

any SEL entries recorded during system boot can be accurately time stamped.

Additionally, during sleep state transitions other than S0, the BIOS will synchronize the time.

If the time is modified through an OS interface, then the BMC‟s time is not synchronized until the

next system reboot.

The BMC implements the system event log as specified in the Intelligent Platform Management

Interface Specification, Version 2.0. The SEL is accessible regardless of the system power state

through the BMC's in-band and out-of-band interfaces.

The BMC allocates 95231 bytes (approximately 93 KB) of non-volatile storage space to store

system events. The SEL timestamps may not be in order. Up to 3,639 SEL records can be stored

at a time. Any command that results in an overflow of the SEL beyond the allocated space is

rejected with an "Out of Space" IPMI completion code (C4h).

4.2.2.1 Sensor Data Record (SDR) Repository

The BMC implements the sensor data record (SDR) repository as specified in the Intelligent

Platform Management Interface Specification, Version 2.0. The SDR is accessible through the

BMC‟s in-band and out-of-band interfaces regardless of the system power state. The BMC

allocates 65,519 bytes of non-volatile storage space for the SDR.

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