SMBIOS tables

The System Management BIOS (SMBIOS) table is used to deliver management information from the firmware to the operating system. The content is standardized in [1].

In Linux you can use the dmidecode command to view the contents of the SMBIOS table.

When booting via UEFI the SMBIOS table is transferred as an UEFI configuration table to the operating system.

To generate SMBIOS tables in U-Boot, the CONFIG_GENERATE_SMBIOS_TABLE option must be enabled. The easiest way to provide the values to use is via the device tree. For details see smbios.txt.

See also the smbios command.

Programming Interface

Developers can access SMBIOS information programmatically:

Functions

  • smbios_locate() - Locate and parse SMBIOS tables

  • smbios_get_header() - Get a specific SMBIOS table by type

  • smbios_string() - Extract strings from SMBIOS tables

Example code:

const struct smbios_type1 *sys;
struct smbios_info info;
int ret;

ret = smbios_locate(gd_smbios_start(), &info);
if (ret)
    return ret;

sys = smbios_get_header(&info, SMBIOS_SYSTEM_INFORMATION);
if (sys) {
    const char *manufacturer = smbios_string(&sys->hdr, sys->manufacturer);

    printf("Manufacturer: %s\n", manufacturer);
}

Board-specific Implementation

Boards can provide custom SMBIOS data by implementing board-specific functions:

  • smbios_update_version() - Update version strings

  • smbios_system_serial() - Provide system serial number

  • smbios_system_uuid() - Provide system UUID

  • smbios_system_sku() - Provide SKU number

  • smbios_baseboard_serial() - Provide baseboard serial number

These functions are called during SMBIOS table generation if defined.

Troubleshooting

Common issues and solutions:

Tables not generated

Ensure CONFIG_SMBIOS is enabled and memory allocation is sufficient

Missing information

Check that board-specific functions are implemented or default configuration values are set

Incorrect data

Verify environment variables and board-specific function implementations

Memory layout issues

Check memory map and ensure SMBIOS tables don’t conflict with other data