Kontron AM4301 - Manual (Page 18)

6 AM4301
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2.4 Hardware Management Overview
The AMC Carrier communicates with the Module Management Controller (MMC) using the IPMB_L channel.
The memory subsystem of the MMC consists of an integrated flash memory to hold the MMC operation code
and integrated RAM for data. The field replacement unit (FRU) inventory information is stored in the
nonvolatile memory on an EEPROM connected via a local I2C interface to the MMC microcontroller. It is
possible to store up to 4 KBytes within the FRU inventory information. Event generation over IPMB-L bus to
reach the AMC Carrier that forward it to the ShMc ensure that 'post-mortem' logging information is available
even if the power of the AMC is disabled.
The onboard DC voltages and temperature are monitored by the MMC microcontroller device. The MMC will
send an event to the Carrier AMC if any of the thresholds are exceeded.
To increase the reliability of the AM4301 SBC management subsystem, an external watchdog supervisor only
for the MMC is implemented. The MMC must strobe the external watchdog at two-second intervals to ensure
continuity of operation of the board's management subsystem. If the MMC ceases to strobe the watchdog
supervisor, the watchdog isolates the MMC from the IPMBs and resets the MMC. The watchdog supervisor
does not reset the payload power and the restart of the MMC will not affect the payload and will restore the
previous Module Hot Swap state. The watchdog timeout expires after six seconds if strobes are not
generated. The external watchdog supervisor is not configurable and must not be confused with the IPMI
v1.5 watchdog timer commands.
This external watchdog of the MMC is implemented in a second microcontroller. This microcontroller is
responsible to monitor the MMC and to manage MMC fail safe firmware upgrade process. The name of this
second microcontroller is the Firmware Upgrade Manager (FWUM). The FWUM can handle two Firmware code
that are stored in two external SEPROM memories. If a failure occurs during firmware upgrade, the FWUM will
automatically rollback to the redundant MMC firmware image.
2.4.1 Sensor Data Record (SDR)
Every sensor on the baseboard is associated with a Sensor Data Record (SDR). Sensor Data Records contain
information about the sensors identification such as sensor type, sensor name, sensor unit. SDR also
contain the configuration of a specific sensor such as threshold/hystheresis, event generation capabilities
that specifies sensor behaviour. Some fields of the sensor SDR are configurable through IPMI v1.5 command
and are set to built-in initial value. Finally one field wich is the sensor owner must reflect the module
addresses that allow the AMC Carrier to identify the owner of the SDR when it is scanned from the module
management controller and merged within the AMC Carrier Device SDR repository.
From IPMI prespective, the AM4301 management controller is set up as a satellite management controller
(SMC). It does support sensor devices, and use the IPMI static sensor population feature of IPMI v1.5 to
merge the hot swaped AMC sensor with the carrier board sensors population. The usual way the AMC Carrier is
informed about an AMC insertion is through the AMC Module Hot Swap sensor and a radial presence line on
the AMC connector. All SDRs can be queried using Device SDR commands to the firmware. Module sensors
that have been implemented are listed below.