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Diffstat (limited to 'Documentation/drivers')
| -rw-r--r-- | Documentation/drivers/cbfs_smbios.md | 65 | ||||
| -rw-r--r-- | Documentation/drivers/index.md | 1 |
2 files changed, 66 insertions, 0 deletions
diff --git a/Documentation/drivers/cbfs_smbios.md b/Documentation/drivers/cbfs_smbios.md new file mode 100644 index 0000000000..54b7ca4179 --- /dev/null +++ b/Documentation/drivers/cbfs_smbios.md @@ -0,0 +1,65 @@ +# CBFS SMBIOS hooks + +The document describes the coreboot options how to make CBFS files populate +platform-unique SMBIOS data. + +## SMBIOS System UUID + +The [DMTF SMBIOS specification] defines a field in the type 1 System +Information Structure called System UUID. It is a 16 bytes value compliant with +[RFC4122] and assumed to be unique per platform. Certain mainboard ports have +SMBIOS hooks to generate the UUID from external data, e.g. Lenovo Thinkpads +(see DRIVER_LENOVO_SERIALS). This driver aims to provide an option to populate +the UUID from CBFS for boards that can't generate the UUID from any source. + +### Usage + +In the coreboot configuration menu (`make menuconfig`) go to `Generic Drivers` +and select an option `System UUID in CBFS`. The Kconfig system will enable +`DRIVERS_GENERIC_CBFS_UUID` and the relevant code parts will be compiled into +coreboot image. + +After the coreboot build for your board completes, use the cbfstool to include +the file containing the UUID: + +```shell +./build/cbfstool build/coreboot.rom add -n system_uuid -t raw -f /path/to/uuid_file.txt +``` + +Where `uuid_file.txt` is the unterminated string representation of the SMBIOS +type 1 UUID, e.g. `4c4c4544-0051-3410-8051-b5c04f375931`. If you use vboot with +1 or 2 RW partitions you will have to specify the RW regions where the file is +going to be added too. By default the RW CBFS partitions are truncated, so the +files would probably not fit, one needs to expand them first. + +```shell +./build/cbfstool build/coreboot.rom expand -r FW_MAIN_A +./build/cbfstool build/coreboot.rom add -n system_uuid -t raw \ + -f /path/to/uuid_file.txt -r FW_MAIN_A +./build/cbfstool build/coreboot.rom truncate -r FW_MAIN_A + +./build/cbfstool build/coreboot.rom expand -r FW_MAIN_B +./build/cbfstool build/coreboot.rom add -n system_uuid -t raw \ + -f /path/to/uuid_file.txt -r FW_MAIN_B +./build/cbfstool build/coreboot.rom truncate -r FW_MAIN_B +``` + +By default cbfstool adds files to COREBOOT region only, so when vboot is +enabled and the platform is booting from RW partition, the file would not be +picked up by the driver. + +One may retrieve the UUID from running system (if it exists) using the +following command: + +```shell +echo -n `sudo dmidecode -s system-uuid` > uuid_file.txt +``` + +The above command ensures the file does not end with whitespaces like LF and/or +CR. The above command will not add any whitespaces. But the driver will handle +situations where up to 2 additional bytes like CR and LF will be included in +the file. Any more than that will make the driver fail to populate UUID in +SMBIOS. + +[DMTF SMBIOS specification]: https://www.dmtf.org/standards/smbios +[RFC4122]: https://www.ietf.org/rfc/rfc4122.txt diff --git a/Documentation/drivers/index.md b/Documentation/drivers/index.md index ac9b0141cb..95c1e312a0 100644 --- a/Documentation/drivers/index.md +++ b/Documentation/drivers/index.md @@ -14,3 +14,4 @@ Some of the drivers currently available include: * [SMMSTOREv2](smmstorev2.md) * [SoundWire](soundwire.md) * [USB4 Retimer](retimer.md) +* [CBFS SMBIOS hooks](cbfs_smbios.md) |