As more boards adopt support for the EFI CapsuleUpdate mechanism, there is a growing issue of being able to target updates to them properly. The current mechanism of hardcoding UUIDs for each board at compile time is unsustainable, and maintaining lists of GUIDs is similarly cumbersome.
In this series, I propose that we adopt v5 GUIDs, these are generated by using a well-known salt GUID as well as board specific information (like the model/revision), these are hashed together and the result is truncated to form a new UUID. The well-known salt GUID can be specific to the architecture (SoC vendor), or OEM. It is defined in the board defconfig so that vendors can easily bring their own. Specifically, the following fields are used to generate a GUID for a particular fw_image: * namespace salt * board compatible (usually the first entry in the dt root compatible array). * fw_image name (the string identifying the specific image, especially relevant for board that can update multiple images). == Usage == Boards can integrate dynamic UUID support as follows: 1. Adjust Kconfig to depend on EFI_CAPSULE_DYNAMIC_UUIDS if EFI_HAVE_CAPSULE_SUPPORT. 2. Skip setting the fw_images image_type_id property. 3. Generate a UUID and set CONFIG_EFI_CAPSULE_NAMESPACE_UUID in your defconfig. == Limitations == * Changing GUIDs The primary limitation with this approach is that if any of the source fields change, so will the GUID for the board. It is therefore pretty important to ensure that GUID changes are caught during development. * Supporting multiple boards with a single image This now requires having an entry with the GUID for every board which might lead to larger UpdateCapsule images. == Tooling == This series introduces a new tool: genguid. This can be used to generate the same GUIDs that the board would at runtime. This series follows a related discussion started by Ilias: https://lore.kernel.org/u-boot/cac_iwjjnha4gmf897mqyzndbgjfg8k4kwgstxwuy72wkyli...@mail.gmail.com/ --- Changes in v3: - Add manpage for genguid - Add dedicated CONFIG_TOOLS_GENGUID option - Minor code fixes addressing v2 feedback - Link to v2: https://lore.kernel.org/r/20240529-b4-dynamic-uuid-v2-0-c26f31057...@linaro.org Changes in v2: - Move namespace UUID to be defined in defconfig - Add tests and tooling - Only use the first board compatible to generate UUID. - Link to v1: https://lore.kernel.org/r/20240426-b4-dynamic-uuid-v1-0-e8154e00e...@linaro.org --- Caleb Connolly (7): lib: uuid: add UUID v5 support efi: add a helper to generate dynamic UUIDs doc: uefi: document dynamic UUID generation sandbox: switch to dynamic UUIDs lib: uuid: supporting building as part of host tools tools: add genguid tool test: lib/uuid: add unit tests for dynamic UUIDs arch/Kconfig | 1 + board/sandbox/sandbox.c | 16 --- configs/sandbox_defconfig | 1 + configs/sandbox_flattree_defconfig | 1 + doc/develop/uefi/uefi.rst | 31 +++++ doc/genguid.1 | 52 +++++++ include/sandbox_efi_capsule.h | 6 +- include/uuid.h | 21 ++- lib/Kconfig | 8 ++ lib/efi_loader/Kconfig | 23 +++ lib/efi_loader/efi_capsule.c | 1 + lib/efi_loader/efi_firmware.c | 66 +++++++++ lib/uuid.c | 81 +++++++++-- test/lib/uuid.c | 88 ++++++++++++ .../test_efi_capsule/test_capsule_firmware_fit.py | 2 +- .../test_efi_capsule/test_capsule_firmware_raw.py | 8 +- .../test_capsule_firmware_signed_fit.py | 2 +- .../test_capsule_firmware_signed_raw.py | 4 +- test/py/tests/test_efi_capsule/version.dts | 6 +- tools/Kconfig | 7 + tools/Makefile | 3 + tools/binman/etype/efi_capsule.py | 2 +- tools/binman/ftest.py | 2 +- tools/genguid.c | 154 +++++++++++++++++++++ 24 files changed, 538 insertions(+), 48 deletions(-) --- change-id: 20240422-b4-dynamic-uuid-1a5ab1486c27 base-commit: 2e682a4a406fc81ef32e05c28542cc8067f1e15f // Caleb (they/them)
