Host Management with OpenBMC

This document describes the host-management interfaces of the OpenBMC object structure, accessible over REST.

Inventory

The system inventory structure is under the /org/openbmc/inventory hierarchy.

In OpenBMC the inventory is represented as a path which is hierarchical to the physical system topology. Items in the inventory are referred to as inventory items and are not necessarily FRUs. If the system contains one chassis, a motherboard, and a CPU on the motherboard, then the path to that inventory item would be:

inventory/system/chassis0/motherboard0/cpu0

The properties associated with an inventory item are specific to that item with the addition of these common properties:

  • version: a code version associated with this item
  • fault: indicates whether this item has reported an error condition (True/False)
  • present: indicates whether this item is present in the system (True/False)

The usual list and enumerate REST queries allow the system inventory structure to be accessed. For example, to enumerate all inventory items and their properties:

curl -b cjar -k https://bmc/org/openbmc/inventory/enumerate

To list the properties of one item:

curl -b cjar -k https://bmc/org/openbmc/inventory/system/chassis/motherboard

Sensors

The system inventory structure is under the /org/openbmc/sensors hierarchy.

This interface allows monitoring of system attributes like temperature or altitude, and are represented similar to the inventory, by object paths under the top-level sensors object name. The path categorizes the sensor and shows what the sensor represents, but does not necessarily represent the physical topology of the system.

For example, all temperature sensors are under sensors/temperature. CPU temperature sensors would be sensors/temperature/cpu[n].

These are the common properties associated all sensors:

  • value: current value of sensor
  • units: units of value
  • warning_upper & warning_lower: upper & lower threshold for a warning error
  • critical_upper & critical_lower: upper & lower threshold for a critical error
  • threshold_state: current threshold state (normal, warning, critical)
  • worst_threshold_state: highest threshold state seen for all time. There is a REST call to reset this state to normal.

Unlike IPMI, there are no "functional" sensors in OpenBMC; functional states are represented in the inventory.

To enumerate all sensors in the system:

curl -c cjar -k https://bmc/org/openbmc/sensors/enumerate

List properties of one inventory item:

curl -c cjar -k https://bmc/org/openbmc/sensors/temperature/ambient

Event Logs

The event log structure is under the /org/openbmc/records/events hierarchy. Each event is a separate object under this structure, referenced by number.

BMC and host firmware on POWER-based servers can report logs to the BMC. Typically, these logs are reported in cases where host firmware cannot start the OS, or cannot reliably log to the OS.

The properties associated with an error log are as follows:

  • Association: a uri to the failing inventory part
  • Message: An English text string indicating the failure
  • Reported By: Firmware region that created the log ('Host', 'BMC')
  • Severity: level of problem (Info, Predictive Error, etc)
  • Development Data: Data dump for use by Development to analyze the failure

To list all reported events:

$ curl -b cjar -k https://bmc/org/openbmc/records/events/
{
  "data": [
    "/org/openbmc/records/events/1",
    "/org/openbmc/records/events/2",
    "/org/openbmc/records/events/3",
  ],
  "message": "200 OK",
  "status": "ok"
}

To read a specific event log:

$ curl -b cjar -k https://bmc/org/openbmc/records/events/1
{
  "data": {
    "association": "/org/openbmc/inventory/system/systemevent",
    "debug_data": [ ... ],
    "message": "A systemevent has experienced a unrecoverable error",
    "reported_by": "Host",
    "severity": "unrecoverable error",
    "time": "2016:05:04 01:43:57"
  },
  "message": "200 OK",
  "status": "ok"
}

To delete an event log (log 1 in his example), call the delete method on the event:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data" : []}' \
    https://bmc/org/openbmc/records/events/1/action/delete

To clear all logs, call the top-level clear method:

curl -b cjar -k -H "Content-Type: application/json" -X POST \
    -d '{"data" : []}' \
    https://bmc/org/openbmc/records/events/action/clear

BIOS boot options

With OpenBMC, the BIOS boot options are stored as dbus properties under the settings/host0 path, in the boot_flags property. Their format adheres to the Boot Options Parameters table specified in the IPMI Specification Document, section 28.13.

Each boot parameter is represented by an individual property, and their hex value is displayed in a string format. For example, a boot flags parameter value of 0x8014000000 would be stored as a 8014000000 string in the settings/host0/boot_flags property.

Host power control

The host can be controlled through the chassis object. It implements a number of actions including powerOn and powerOff. These correspond to the IPMI chassis power on and chassis power off commands.

Assuming you have logged in, the following will issue a POST with an empty data payload that powers the host on:

curl -c cjar -b cjar -k -H "Content-Type: application/json" -X POST \
   -d '{"data": []}'  https://bmc/org/openbmc/control/chassis0/action/powerOn

Other actions available are:

  • setIdentify / clearIdentify
  • powerOff
  • softPowerOff
  • reboot
  • softReboot
  • getPowerState