Remote BIOS Configuration

Overview

The biosconfig_manager service enables users to view and modify the BIOS setup configuration parameters remotely through the Baseboard Management Controller (BMC) at any host state. Changes to these parameters will take effect upon the next system reboot or immediately, depending on the host firmware.

For more details, please refer to design document.

Features

• Remote management of BIOS settings.
• Immediate updates or scheduled changes upon reboot.
• Reset BIOS Settings support through the dbus.
• ChangePassword support to change the BIOS setup password.

RBC Manager Interface

The Manager interface exposes methods and properties to Get & Set BIOS attributes via dbus and its documented here

Object Path

/xyz/openbmc_project/BIOSConfig/Manager

Methods

• SetAttribute Sets a specific BIOS attribute to a new value.
• GetAttribute Retrieves the current and pending values of a BIOS attribute.

Properties

• ResetBIOSSettings To reset the BIOS settings based on the Reset Flag.
• BaseBIOSTable Captures the entire BIOS table (collective information of all the BIOS attributes and their properties)

Signature of BaseBIOSTable

The BaseBIOSTable property in the RBC Manager Interface is a complex dictionary that defines the structure of BIOS attributes. Its type signature is as follows:

dict[string, struct[
    enum[self.AttributeType],
    boolean,
    string,
    string,
    string,
    variant[int64, string],
    variant[int64, string],
    array[struct[enum[self.BoundType], variant[int64, string], string]]
]]

This structure consists of:

• Attribute Name (string): The name of the BIOS attribute.
• Attribute Type (enum): The type of the BIOS attribute (e.g., String, Integer).
• Read-only Status (boolean): Whether the attribute is read-only.
• Display Name (string): The human-readable name of the attribute.
• Description (string): A description of what the attribute does.
• Menu Path (string): The BIOS menu path where this attribute can be found.
• Current Value (variant[int64, string]): The current value of the attribute.
• Default Value (variant[int64, string]): The default value of the attribute.
• Options (array of structs): The available options or bounds for this attribute.

Examples

Here is an example json structure of a String attribute with attributeName DrdFreqLimit & its various properties in BaseBIOSTable signature.

{
  "DdrFreqLimit": {
    "attributeType": "xyz.openbmc_project.BIOSConfig.Manager.AttributeType.String",
    "readonlyStatus": false,
    "displayname": "Memory Operating Speed Selection",
    "description": "Force specific Memory Operating Speed or use Auto setting.",
    "menuPath": "Advanced/Memory Configuration/Memory Operating Speed Selection",
    "current": "0x00",
    "default": "0x0B",
    "options": [
      { "optionstring": "auto", "optionvalue": "enum0" },
      { "optionstring": "2133", "optionvalue": "enum1" },
      { "optionstring": "2400", "optionvalue": "enum2" },
      { "optionstring": "2664", "optionvalue": "enum3" },
      { "optionstring": "2933", "optionvalue": "enum4" }
    ]
  }
}

Here is another example json structure of a Integer attribute with attribute with name BIOSSerialDebugLevel & its various properties in BaseBIOSTable signature.

{
  "BIOSSerialDebugLevel": {
    "attributeType": "xyz.openbmc_project.BIOSConfig.Manager.AttributeType.Integer",
    "readonlyStatus": false,
    "displayname": "BIOS Serial Debug level",
    "description": "BIOS Serial Debug level during system boot.",
    "menuPath": "Advanced/Debug Feature Selection",
    "current": "0x00",
    "default": "0x01",
    "options": [
      { "optionstring": "MinBound", "optionvalue": 0 },
      { "optionstring": "MaxBound", "optionvalue": 4 },
      { "optionstring": "ScalarIncrement", "optionvalue": 1 }
    ]
  }
}

Initialization of BaseBIOSTable

When the bios-settings-mgr daemon starts, it initializes with an empty BaseBIOSTable. It is the responsibility of provider daemons, such as PLDM or IPMI, to populate this table by fetching or defining the BIOS settings. These provider daemons are expected to gather the necessary BIOS attributes and values from their respective sources (ex: bmc, system firmware) and then initialize the BaseBIOSTable property with those settings.

BIOS with PLDM as Communication Protocol

For systems that use the PLDM (Platform Level Data Model) protocol between BMC & Host, OEM vendors can define their own BIOS attributes in the form of JSON files. The PLDM daemon parses these files and initializes the BaseBIOSTable property accordingly. This allows for flexible and custom BIOS configuration options based on the vendor's specifications.

For more details , refer to the BIOS Support in PLDM.

BIOS with IPMI as Communication Protocol

For systems that use the Intelligent Platform Management Interface protocol between BMC & Host, BIOS attributes are gathered from BIOS as an xml file & BaseBIOSTable would then be initialized with the attributes data from the parsed xml file.

For more details, refer to the code BIOS Support in IPMI.

RBC Password Interface

Object Path

xyz.openbmc_project.BIOSConfig.Password

Methods

• ChangePassword
  Used to change the BIOS setup password.

Properties

• PasswordInitialized Used to indicate whether the BIOS password-related details have been received.