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Diffstat (limited to 'doc/develop/uefi/uefi.rst')
| -rw-r--r-- | doc/develop/uefi/uefi.rst | 68 |
1 files changed, 67 insertions, 1 deletions
diff --git a/doc/develop/uefi/uefi.rst b/doc/develop/uefi/uefi.rst index ffe25ca231..6626ceec52 100644 --- a/doc/develop/uefi/uefi.rst +++ b/doc/develop/uefi/uefi.rst @@ -318,6 +318,33 @@ Run the following command --guid <image GUID> \ <capsule_file_name> +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. + +To add the fw_version into the FMP Payload Header, +add --fw-version option in mkeficapsule tool. + +.. code-block:: console + + $ mkeficapsule \ + --index <index> --instance 0 \ + --guid <image GUID> \ + --fw-version 5 \ + <capsule_file_name> + +If the --fw-version option is not set, FMP Payload Header is not inserted +and fw_version is set as 0. + Performing the update ********************* @@ -330,7 +357,7 @@ bit in OsIndications variable with => setenv -e -nv -bs -rt -v OsIndications =0x0000000000000004 -Since U-boot doesn't currently support SetVariable at runtime, its value +Since U-Boot doesn't currently support SetVariable at runtime, its value 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. @@ -510,6 +537,45 @@ where signature.dts looks like:: }; }; +Anti-rollback Protection +************************ + +Anti-rollback prevents unintentional installation of outdated firmware. +To enable anti-rollback, you must add the lowest-supported-version property +to dtb and specify --fw-version when creating a capsule file with the +mkeficapsule tool. +When executing capsule update, U-Boot checks if fw_version is greater than +or equal to lowest-supported-version. If fw_version is less than +lowest-supported-version, the update will fail. +For example, if lowest-supported-version is set to 7 and you run capsule +update using a capsule file with --fw-version of 5, the update will fail. +When the --fw-version in the capsule file is updated, lowest-supported-version +in the dtb might be updated accordingly. + +To insert the lowest supported version into a dtb + +.. code-block:: console + + $ dtc -@ -I dts -O dtb -o version.dtbo version.dts + $ fdtoverlay -i orig.dtb -o new.dtb -v version.dtbo + +where version.dts looks like:: + + /dts-v1/; + /plugin/; + &{/} { + firmware-version { + image1 { + image-type-id = "09D7CF52-0720-4710-91D1-08469B7FE9C8"; + image-index = <1>; + lowest-supported-version = <3>; + }; + }; + }; + +The properties of image-type-id and image-index must match the value +defined in the efi_fw_image array as image_type_id and image_index. + Executing the boot manager ~~~~~~~~~~~~~~~~~~~~~~~~~~ |