SMBIOS support in U-Boot

U-Boot supports generating and using SMBIOS (System Management BIOS) tables, which provide standardized hardware and firmware information to the operating system and applications.

Overview

SMBIOS is a standard developed by the Desktop Management Task Force (DMTF) that defines a way for firmware to present hardware information to software running on the system. The information is organized into typed data structures called SMBIOS tables or structures.

SMBIOS Generation in U-Boot

U-Boot can automatically generate SMBIOS tables based on configuration and hardware detection. The tables are created during the boot process and made available to the operating system.

See also the developer documentation: SMBIOS tables.

Configuration

SMBIOS support is enabled through several Kconfig options:

CONFIG_SMBIOS - Enable SMBIOS table generation
CONFIG_SMBIOS_PARSER - Enable SMBIOS table parsing support
CONFIG_CMD_SMBIOS - Enable the smbios command

Providing Values

SMBIOS field values can be provided through two mechanisms, in order of precedence:

Sysinfo Driver: A sysinfo driver (UCLASS_SYSINFO) can provide dynamic values at runtime through predefined sysinfo IDs.
Device Tree Properties: Static values can be defined in device tree nodes corresponding to each SMBIOS table type.

Device Tree Configuration

SMBIOS values can be specified in device tree nodes, but only when a sysinfo driver is present. The ‘smbios’ node must be a subnode of the sysinfo device in the device tree.

The following smbios subnodes and properties are supported:

BIOS Information (smbios/bios):

version - BIOS version string

System Information (smbios/system):

manufacturer - System manufacturer
product - Product name
version - System version
serial - Serial number
sku - SKU number
family - Product family
wakeup-type - System wakeup type (numeric)

Baseboard Information (smbios/baseboard):

manufacturer - Baseboard manufacturer
product - Baseboard product name
version - Baseboard version
serial - Baseboard serial number
asset-tag - Asset tag number
feature-flags - Feature flags (numeric)
chassis-location - Location in chassis

Chassis Information (smbios/chassis):

manufacturer - Chassis manufacturer
version - Chassis version
serial - Chassis serial number
asset-tag - Chassis asset tag
sku - Chassis SKU number

Processor Information (smbios/processor):

manufacturer - CPU manufacturer
version - Processor version/model
socket-design - Socket designation

Cache Information (smbios/cache):

socket-design - Socket designation

Example device tree configuration:

sysinfo {
    compatible = "sandbox,sysinfo-sandbox";

    smbios {
        system {
            manufacturer = "Example Corp";
            product = "Example Board";
            version = "1.0";
            serial = "123456789";
            sku = "EXAMPLE-SKU-001";
            family = "Example Family";
        };

        baseboard {
            manufacturer = "Example Corp";
            product = "Example Baseboard";
            version = "Rev A";
            serial = "BB123456789";
        };
    };
};

The device tree values serve as defaults and will be overridden by any values provided by a sysinfo driver.

SMBIOS Table Types

U-Boot generates several standard SMBIOS table types:

Type 0: BIOS Information: Contains BIOS vendor, version, release date, and characteristics
Type 1: System Information: Contains system manufacturer, product name, version, serial number, UUID, SKU number, and family
Type 2: Baseboard Information: Contains motherboard/baseboard manufacturer, product name, version, and serial number
Type 3: System Enclosure: Contains chassis information including type, manufacturer, version, and serial number
Type 4: Processor Information: Contains CPU information including family, manufacturer, version, and characteristics
Type 16: Physical Memory Array: Describes the physical memory configuration
Type 17: Memory Device: Describes individual memory modules
Type 19: Memory Array Mapped Address: Maps physical memory arrays to system addresses
Type 32: System Boot Information: Contains boot status information

Using SMBIOS Tables

Generated SMBIOS tables are typically placed in memory where the operating system can find them. The location varies by architecture:

x86: Tables placed in conventional memory below 1MB
ARM/AArch64: Tables passed via device tree or ACPI

The smbios command

U-Boot provides the smbios command to display SMBIOS information.

Example:

smbios           # Show all tables