On Fri, 26 Apr 2024 at 17:19, Caleb Connolly <caleb.conno...@linaro.org> wrote: > > Document how platforms can generate GUIDs at runtime rather than > maintaining a list of GUIDs per-board. > > Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org> > --- > doc/develop/uefi/uefi.rst | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst > index 0389b269c01b..52076fb4c106 100644 > --- a/doc/develop/uefi/uefi.rst > +++ b/doc/develop/uefi/uefi.rst > @@ -448,8 +448,43 @@ 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
which is/that is > +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 image_type_id UUIDs > + * for all firmware images based on a platform namespace UUID. > + * > + * @namespace: The arch/platform specific namespace salt. This should > be > + * hardcoded per platform and replaced by vendors. > + * @soc: A string identifying the SoC used on this board. > + * @model: The model string for the board. > + * @compatible: The most specific (first) root compatible string. > + * > + * This can be called by board code to populate the image_type_id > + * UUID fields deterministically based on the board's model. Allowing model, allowing > + * many boards to be supported without the need for a large hardcoded > + * array of fw images. This works using v5 UUIDs. > + */ > + int efi_capsule_update_info_gen_ids(efi_guid_t *namespace, const char > *soc, > + > const char *model, > + > const char *compatible); > + > +These strings are combined with the fw_image name to generate GUIDs for > +each image. This function should be called during board init, before the > +EFI subsystem is initialised. initialized > + > 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 > > -- > 2.44.0 > With these Reviewed-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
