On Wed, 29 May 2024 at 17:49, Caleb Connolly <caleb.conno...@linaro.org> wrote:
> Document how platforms can generate GUIDs at runtime rather than > maintaining a list of UUIDs per-board. > > Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org> > --- > doc/develop/uefi/uefi.rst | 31 +++++++++++++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst > index 0389b269c01b..0b60702c052a 100644 > --- a/doc/develop/uefi/uefi.rst > +++ b/doc/develop/uefi/uefi.rst > @@ -448,8 +448,39 @@ the location of the firmware updates is not a very > secure > practice. Getting this information from the firmware itself is more > secure, assuming the firmware has been verified by a previous stage > boot loader. > > +The image_type_id contains a GUID value which is specific to the image > +and board being updated, that is to say it should uniquely identify the > +board model (and revision if relevant) and image pair. Traditionally, > +these GUIDs are generated manually and hardcoded on a per-board basis, > +however this scheme makes it difficult to scale up to support many > +boards. > + > +To address this, v5 GUIDs can be used to generate board-specific GUIDs > +at runtime, based on a set of persistent identifiable information: > + > +.. code-block:: c > + > + /** > + * efi_capsule_update_info_gen_ids - generate GUIDs for the images > + * > + * Generate the image_type_id for each image in the > update_info.images array > + * using the model and compatible strings from the device tree and > a salt > + * UUID defined at build time. > + * > + * Returns: status code > + */ > + static efi_status_t efi_capsule_update_info_gen_ids(void); > + > +These strings are combined with the fw_image name to generate GUIDs for > +each image. Support for dynamic UUIDs can be enabled by turning on > +CONFIG_EFI_CAPSULE_DYNAMIC_UUIDS, generating a new namespace UUID and > +setting CONFIG_EFI_CAPSULE_NAMESPACE_UUID to it. > + > +The genguid tool can be used to determine the GUIDs for a particular board > +and image. It can be found in the tools directory. > + > The firmware images structure defines the GUID values, image index > values and the name of the images that are to be updated through > the capsule update feature. These values are to be defined as part of > an array. These GUID values would be used by the Firmware Management > > -- > 2.45.0 > > Reviewed-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
