On Thu, Mar 31, 2022 at 06:57:50PM +0530, Sughosh Ganu wrote:
> Update the capsule update functionality related documentation to
> refect the additional definitions that need to be made per platform
> for supporting the capsule update feature.
>
> Signed-off-by: Sughosh Ganu
> ---
>
> Changes since V3:
> * Rephrase the commit message to indicate that the doc changes are not
> just limited to adding the GUID values, but other info as well.
> * Elaborate with an example on the relation between the dfu alt number
> and the image index
>
> doc/develop/uefi/uefi.rst | 24 ++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst
> index fe337c88bd..d886635cc3 100644
> --- a/doc/develop/uefi/uefi.rst
> +++ b/doc/develop/uefi/uefi.rst
> @@ -312,8 +312,8 @@ Run the following command
> .. code-block:: console
>
> $ mkeficapsule \
> - --index 1 --instance 0 \
> - [--fit | --raw ] \
> + --index --instance 0 \
> + --guid \
>
>
> Performing the update
> @@ -333,6 +333,26 @@ won't be taken over across the reboot. If this is the
> case, you can skip
> this feature check with the Kconfig option (CONFIG_EFI_IGNORE_OSINDICATIONS)
> set.
>
> +A few things need to be defined in the board file for performing the
> +capsule upadte. The first is defining the function set_dfu_alt_info in
s/upadte/update/
> +the board file. This function sets the environment variable
> +dfu_alt_info. Instead of taking the variable from the environment, the
> +capsule update feature requires that the variable be set through the
I think we should also mention that allowing a user to change the location
of the firmware updates in flash is not a good security practice.
Having that baked in the firmware (as long as a prior stage boot loader
verifies it)
is a better approach.
Thanks
/Ilias
> +board function, since that is more robust. Secondly, define GUID
> +values and image index of the images that are to be updated through
> +the capsule update feature in the board file. Both the values are to
> +be defined as part of the fw_images array. These GUID values would be
> +used by the Firmware Management Protocol(FMP) to populate the image
> +descriptor array and also displayed as part of the ESRT table. The
> +image index values defined in the array should be one greater than the
> +dfu alt number that corresponds to the firmware image. So, if the dfu
> +alt number for an image is 2, the value of image index in the
> +fw_images array for that image should be 3. The dfu alt number can be
> +obtained by running the following command::
> +
> +dfu list
> +
> +
> Finally, the capsule update can be initiated by rebooting the board.
>
> Enabling Capsule Authentication
> --
> 2.25.1
>
