Hello Sughosh, Thanks for the documentation. See comments on few typos found (with help of my editor) and suggestions.
Best regards, Etienne On Thu, 15 Sept 2022 at 10:16, Sughosh Ganu <sughosh.g...@linaro.org> wrote: > > Add documentattion for the FWU Multi Bank Update feature. The document s/documentattion/documentation/ > describes the steps needed for setting up the platform for the > feature, as well as steps for enabling the feature on the platform. > > Signed-off-by: Sughosh Ganu <sughosh.g...@linaro.org> > --- > Changes since V9: None > > doc/develop/uefi/fwu_updates.rst | 165 +++++++++++++++++++++++++++++++ > doc/develop/uefi/index.rst | 1 + > doc/develop/uefi/uefi.rst | 2 + > 3 files changed, 168 insertions(+) > create mode 100644 doc/develop/uefi/fwu_updates.rst > > diff --git a/doc/develop/uefi/fwu_updates.rst > b/doc/develop/uefi/fwu_updates.rst > new file mode 100644 > index 0000000000..fad3fbb3a8 > --- /dev/null > +++ b/doc/develop/uefi/fwu_updates.rst > @@ -0,0 +1,165 @@ > +.. SPDX-License-Identifier: GPL-2.0+ > +.. Copyright (c) 2022 Linaro Limited > + > +FWU Multi Bank Updates in U-Boot > +================================ > + > +The FWU Multi Bank Update feature implements the firmware update > +mechanism described in the PSA Firmware Update for A-profile Arm > +Architecture specification [1]. Certain aspects of the Dependable > +Boot specification [2] are also implemented. The feature provides a > +mechanism to have multiple banks of updatable firmware images and for > +updating the firmware images on the non-booted bank. On a successful > +update, the platform boots from the updated bank on subsequent > +boot. The UEFI capsule-on-disk update feature is used for performing > +the actual updates of the updatable firmware images. > + > +The bookkeeping of the updatable images is done through a structure > +called metadata. Currently, the FWU metadata supports identification > +of images based on image GUIDs stored on a GPT partitioned storage > +media. There are plans to extend the metadata structure for non GPT > +partitioned devices as well. > + > +Accessing the FWU metadata is done through generic API's which are > +defined in a driver which complies with the U-Boot's driver model. A > +new uclass UCLASS_FWU_MDATA has been added for accessing the FWU > +metadata. Individual drivers can be added based on the type of storage > +media, and it's partitioning method. Details of the storage device s/it's/its/ > +containing the FWU metadata partitions are specified through a U-Boot > +specific device tree property `fwu-mdata-store`. Please refer to > +U-Boot `doc <doc/device-tree-bindings/firmware/fwu-mdata-gpt.yaml>`__ > +for the device tree bindings. > + > +Enabling the FWU Multi Bank Update feature > +------------------------------------------ > + > +The feature can be enabled by specifying the following configs:: > + > + CONFIG_EFI_CAPSULE_ON_DISK=y > + CONFIG_EFI_CAPSULE_FIRMWARE_MANAGEMENT=y > + CONFIG_EFI_CAPSULE_FIRMWARE=y CONFIG_EFI_CAPSULE_FIRMWARE is not needed. Selected by the above. > + CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y > + > + CONFIG_FWU_MULTI_BANK_UPDATE=y > + CONFIG_CMD_FWU_METADATA=y > + CONFIG_DM_FWU_MDATA=y Note also in efi_setup.c, CONFIG_FWU_MULTI_BANK_UPDATE enforces capsules are not checked at 1st EFI command. This means we need CONFIG_EFI_CAPSULE_ON_DISK_EARLY=y, if I'm right. > + CONFIG_FWU_MDATA_GPT_BLK=y > + CONFIG_FWU_NUM_BANKS=<val> > + CONFIG_FWU_NUM_IMAGES_PER_BANK=<val> > + > +in the .config file > + > +The first group of configuration settings enable the UEFI > +capsule-on-disk update functionality. The second group of configs > +enable the FWU Multi Bank Update functionality. Please refer to the > +section :ref:`uefi_capsule_update_ref` for more details on generation > +of the UEFI capsule. > + > +Setting up the device for GPT partitioned storage > +------------------------------------------------- > + > +Before enabling the functionality in U-Boot, a GPT partitioned storage > +device is required. Assuming a GPT partitioned storage device, the > +storage media needs to be partitioned with the correct number of > +partitions, given the number of banks and number of images per bank > +that the platform is going to support. Each updatable firmware image > +will be stored on an separate partition. In addition, the two copies s/an/a/ > +of the FWU metadata will be stored on two separate partitions. > + > +As an example, a platform supporting two banks with each bank > +containing three images would need to have 2 * 3 = 6 partitions plus > +the two metadata partitions, or 8 partitions. In addition the storage > +media can have additional partitions of non-updatable images, like the > +EFI System Partition(ESP), a partition for the root file system > +etc. An example list of images on the storage medium would be > + > +* FWU metadata 1 > +* U-Boot 1 > +* OP-TEE 1 > +* FWU metadata 2 > +* OP-TEE 2 > +* U-Boot 2 > +* ESP > +* rootfs > + > +When generating the partitions, a few aspects need to be taken care > +of. Each GPT partition entry in the GPT header has two GUIDs:: > + > +* PartitionTypeGUID > +* UniquePartitionGUID > + > +The PartitionTypeGUID value should correspond to the > +``image_type_uuid`` field of the FWU metadata. This field is used to > +identify a given type of updatable firmware image, e.g. U-Boot, > +OP-TEE, FIP etc. This GUID should also be used for specifying the > +`--guid` parameter when generating the capsule. > + > +The UniquePartitionGUID value should correspond to the ``image_uuid`` > +field in the FWU metadata. This GUID is used to identify images of a > +given image type in different banks. > + > +Similarly, the FWU specifications defines the GUID value to be used 'FWU specifications define' or 'FWU specifications define'. > +for the metadata partitions. This would be the PartitionTypeGUID for > +the metadata partitions. > + > +When generating the metadata, the ``image_type_uuid`` and the > +``image_uuid`` values should match the *PartitionTypeGUID* and the > +*UniquePartitionGUID* values respectively. > + > +Performing the Update > +--------------------- > + > +Once the storage media has been partitioned and populated with the > +metadata partitions, the UEFI capsule-on-disk update functionality can > +be used for performing the update. Refer to the section > +:ref:`uefi_capsule_update_ref` for details on how the update can be > +invoked. > + > +On a successful update, the FWU metadata gets updated to reflect the > +bank from which the platform would be booting on subsequent boot. > + > +Based on the value of bit15 of the Flags member of the capsule header, > +the updated images would either be accepted by the U-Boot's UEFI > +implementation, or by the Operating System. If the Operating System is > +accepting the firmware images, it does so by generating an empty > +*accept* capsule. The Operating System can also reject the updated > +firmware by generating a *revert* capsule. The empty capsule can be > +applied by using the exact same procedure used for performing the > +capsule-on-disk update. > + > +The task of accepting the different firmware images, post an update > +may be done by multiple, separate components in the Operating > +System. To help identify the firmware image that is being accepted, > +the accept capsule passes the image GUID of the firmware image being > +accepted. The relevant code in U-Boot then sets the Accept bit of the > +corresponding firmware image for which the accept capsule was > +found. Only when all the firmware components in a bank have been > +accepted does the platform transition to the regular state from trial > +state. nit: for clarity, I found you should rephrase as "from ... to ...": '... does the platform transition from trial state to regular state.' > + > +The revert capsule on the other hand does not pass any image GUID, > +since reverting any image of the bank has the same result of the > +platform booting from the other bank on subsequent boot. > + > +Generating an empty capsule > +--------------------------- > + > +The empty capsule can be generated using the mkeficapsule utility. To > +build the tool, enable:: > + > + CONFIG_TOOLS_MKEFICAPSULE=y > + > +Run the following commands to generate the accept/revert capsules:: > + > +.. code-block:: bash > + > + $ ./tools/mkeficapsule \ > + [--fw-accept --guid <image guid>] | \ > + [--fw-revert] \ > + <capsule_file_name> Maybe examples as: + $ ./tools/mkeficapsule --guid <image guid> <image> <capsule_file_name> + $ ./tools/mkeficapsule --fw-accept --guid <image guid> + $ ./tools/mkeficapsule --fw-revert > + > +Links > +----- > + > +* [1] https://developer.arm.com/documentation/den0118/a/ - FWU Specification > +* [2] > https://git.codelinaro.org/linaro/dependable-boot/mbfw/uploads/6f7ddfe3be24e18d4319e108a758d02e/mbfw.pdf > - Dependable Boot Specification > diff --git a/doc/develop/uefi/index.rst b/doc/develop/uefi/index.rst > index 7e65dbc5d5..e26b1fbe05 100644 > --- a/doc/develop/uefi/index.rst > +++ b/doc/develop/uefi/index.rst > @@ -13,3 +13,4 @@ can be run an UEFI payload. > uefi.rst > u-boot_on_efi.rst > iscsi.rst > + fwu_updates.rst > diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst > index 941e427093..536b278dd9 100644 > --- a/doc/develop/uefi/uefi.rst > +++ b/doc/develop/uefi/uefi.rst > @@ -277,6 +277,8 @@ Enable ``CONFIG_OPTEE``, ``CONFIG_CMD_OPTEE_RPMB`` and > ``CONFIG_EFI_MM_COMM_TEE` > > [1] https://optee.readthedocs.io/en/latest/building/efi_vars/stmm.html > > +.. _uefi_capsule_update_ref: > + > Enabling UEFI Capsule Update feature > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > -- > 2.34.1 >