[PATCH v6 7/8] doc: uefi: add firmware versioning documentation

[Takahiro Akashi]

On Fri, May 19, 2023 at 07:32:13PM +0900, Masahisa Kojima wrote:
> This commit describes the procedure to add the firmware version
> into the capsule file.
> 
> Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> ---
> Newly created in v6
> 
>  doc/develop/uefi/uefi.rst | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst
> index ffe25ca231..efab0fc7b1 100644
> --- a/doc/develop/uefi/uefi.rst
> +++ b/doc/develop/uefi/uefi.rst
> @@ -510,6 +510,35 @@ where signature.dts looks like::
>              };
>      };
>  
> +Enabling Firmware Versioning
> +****************************
> +
> +The UEFI specification does not define the firmware versioning mechanism.
> +EDK II reference implementation inserts the FMP Payload Header right before
> +the payload. It coutains the fw_version and lowest supported version,
> +EDK II reference implementation uses these information to implement the
> +firmware versioning and anti-rollback protection, the firmware version and
> +lowest supported version is stored into EFI non-volatile variable.
> +
> +In U-Boot, the firmware versioning is implemented utilizing
> +the FMP Payload Header same as EDK II reference implementation,
> +reads the FMP Payload Header and stores the firmware version into
> +"FmpStateXXXX" EFI non-volatile variable. XXXX indicates the image index,
> +since FMP protocol handles multiple image indexes.

I suggested that you should use "FmState" with the firmware's own guid
as a vendor guid of the variable.
In theory, UEFI may have different FMP drivers, then "index id" may
have the same value for different firmwares.

> +
> +1. Run the following command to add firmware version into the capsule file

Anyhow, you'd better clearly mention that an user needs to specify
"--fw-version" option and what happens (or not happen) if the option
is not there.
I think all the text here can be simply merged in "Creating a capsule file".

-Takahiro Akashi


> +.. code-block:: console
> +
> +    $ mkeficapsule --monotonic-count 1 \
> +      --private-key CRT.key \
> +      --certificate CRT.crt \
> +      --index 1 --instance 0 \
> +      --fw-version 5 \
> +      [--fit | --raw | --guid <guid-string] \
> +      <image_blob> <capsule_file_name>
> +
>  Executing the boot manager
>  ~~~~~~~~~~~~~~~~~~~~~~~~~~
>  
> -- 
> 2.17.1
>