Kontron AM4204 - Manual (Page 60)

45 AM4204
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5.1.6 Watchdog
The complete startup and execution process is guarded using external watchdog timers implemented by the
hardware management subsystem IPMC. There are 4 distinct watchdog timers running during
• boot initialization and early boot monitor execution
• boot monitor execution and preparation for OS loading
• OS execution and initialization
The watchdog timers will trigger a specific action when expired. The action is dependent on previous resets
and on watchdog type.
The standard IPMI watchdog as implemented by the Wind River Linux IPMI driver supports different actions
on watchdog timer expiry and a configurable watchdog pre-timeout.
This pre-timeout period is configurable from 1 second up. The pre-timeout allows application software to
take actions just before the watchdog bites and causes a reset or error-halt-state. The pre-timeout action can
either be configured to trigger a Linux kernel panic, where appropriate panic-handlers can collect data, or to
inform a user-space application of the pre-timeout event.
The watchdog can be disabled for debug reasons by an appropriate jumper setting (consult the Quick
Reference Sheet).
5.1.7 MMC Firmware Code
MMC firmware code is organized into boot code and operational code, both of which are stored in a flash
module. Upon an MMC reset, the MMC executes the boot code and performs the following:
• Self test to verify the status of its hardware and memory.
• Calculates a checksum of the operational code.
Upon successful verification of the operational code checksum, the firmware will jump to the operational
code.
5.1.8 Updating MMC Firmware
Updating the MMC is possible in 4 different ways depending on the operating system running on the module.
Those are:
• using ipmitool from the Linux shell
• using kex-flashimage from the Linux shell
• using an IPMI over LAN (IOL) session
• using the ‘download ipmifw’ command from a AT8404 carrier