==== SPMC ==== This document describes the SPMC (S-EL1) implementation for OP-TEE. More information on the SPMC can be found in the FF-A specification can be found in the `FF-A spec `_. .. toctree:: :numbered: SPMC Responsibilities ===================== The SPMC is a critical component in the FF-A flow. Some of its major responsibilities are: - Initialisation and run-time management of the SPs: The SPMC component is responsible for initialisation of the Secure Partitions (loading the image, setting up the stack, heap, ...). - Routing messages between endpoints: The SPMC is responsible for passing FF-A messages from normal world to SPs and back. It also responsible for passing FF-A messages between SPs. - Memory management: The SPMC is responsible for the memory management of the SPs. Memory can be shared between SPs and between a SP to the normal world. This document describes OP-TEE as a S-EL1 SPMC. Secure Partitions ================= Secure Partitions (SPs) are the endpoints used in the FF-A protocol. When OP-TEE is used as a SPMC SPs run primarily inside S-EL0. OP-TEE will use FF-A for it transport layer when the OP-TEE ``CFG_CORE_FFA=y`` configuration flag is enabled. The SPMC will expose the OP-TEE core, privileged mode, as an secure endpoint itself. This is used to handle all GlobalPlaform programming mode operations. All GlobalPlatform messages are encapsulated inside FF-A messages. The OP-TEE endpoint will unpack the messages and afterwards handle them as standard OP-TEE calls. This is needed as TF-A (S-EL3) does only allow FF-A messages to be passed to the secure world when the SPMD is enabled. SPs run from the initial boot of the system until power down and don't have any built-in session management compared to GPD TEE TAs. The only means of communicating with the outside world is through messages defined in the FF-A specification. The context of a SP is saved between executions. The `Trusted Service `_ repository includes the libsp libary which export all needed functions to build a S-EL0 SP. It also includes many examples of how to create and implement a SP. Secure Partition formats ======================== OP-TEE specific ELF format -------------------------- OP-TEE uses an ELF format for its :ref:`trusted_applications`. It has an OP-TEE specific section which contains a header structure for describing the Trusted Application. A very similar format can be used for Secure Partitions. The same ELF format allows OP-TEE to use the built-in ELF loader (``ldelf``) with all its features like handling relocations or ASLR. In this case a different section is used for the header structure to distinguish between Trusted Applications and Secure Partitions. SPMC agnostic flat binary format -------------------------------- This simple binary format aims for maximum portability between SPMC implementations by removing the dependency on an ELF loader and implementation specific metadata in the SP image. The SPMC can simply copy the binary into the memory and start running it. The relocations, the stack setup and any further initialization steps should be handled by the startup code of the secure partition. The access rights for different sections of the binary can be configured either by adding load relative memory regions to the SP manifest or by using the ``FFA_MEM_PERM_SET`` interface in the startup code. SPMC Program Flow ================= SP images are either embedded into the OP-TEE image or loaded from the FIP by BL2. This makes it possible to start SPs during boot, before the rich OS is available in the normal world. Starting SPs ------------ SPs are loaded and started as the last step in OP-TEE's initialisation process. This is done by adding ``sp_init_all()`` to the ``boot_final`` initcall level. .. uml:: :width: 800 autoactivate on thread_optee_smc_a64.s -> boot_final boot_final -> secure_partition.c: sp_init_all() loop for each SP secure_partition.c -> secure_partition.c: sp_init_uuid() return end return return autoactivate off thread_optee_smc_a64.s -> thread_optee_smc_a64.s: thread_ffa_msg_wait() thread_optee_smc_a64.s -> thread_optee_smc_a64.s: ffa_msg_loop() autoactivate off thread_optee_smc_a64.s -> SPMD: SMC :``sp_init_all()``: Initialise all SPs which have been added by the ``SP_PATHS`` compiler option and run them :``thread_ffa_msg_wait()``: All SPs are loaded and started. A ``FFA_MSG_WAIT`` message is sent to the Normal World. Each ELF format SP is loaded into the system using ``ldelf`` and started. This is based around the same process as loading the early TAs. For each binary format SP a simpler method is used to copy the binary into a suitable memory area. All SPs are run after they are loaded and run until a ``FFA_MSG_WAIT`` is sent by the SP. .. uml:: autoactivate on secure_partition.c -> secure_partition.c: sp_init_uuid() secure_partition.c -> secure_partition.c: sp_open_session() secure_partition.c -> secure_partition.c: find_sp() return secure_partition.c -> secure_partition.c: sp_create_session() return alt OP-TEE specific ELF format secure_partition.c -> secure_partition.c:ldelf_load_ldelf() return secure_partition.c -> secure_partition.c:ldlelf_init_with_ldelf() return else SPMC agnostic flat binary format secure_partition.c -> secure_partition.c:load_binary_sp() return end secure_partition.c -> secure_partition.c: sp_init_set_registers() return return secure_partition.c -> secure_partition.c: enter_sp() return secure_partition.c -> secure_partition.c: sp_msg_handler() return return :``init_with_ldelf()``: Load the OP-TEE specific ELF format SP :``load_binary_sp()``: Load the SPMC agnostic flat binary format SP :``sp_init_info()``: Initialise the ``struct ffa_init_info``. The ``struct ffa_init_info`` is passed to the SP during it first run. :``sp_init_set_registers()``: Initialise the registers of the SP :``sp_msg_handler()``: Handle the SPs FF-A message Once all SPs are loaded and started we return to the SPMD and the Normal World is booted. SP message handling ------------------- The SPMC is split into 2 main message handlers: :``thread_spmc_msg_recv()`` thread_spmc.c: Used to handle message coming from the Normal World. :``sp_msg_handler()`` spmc_sp_handler.c: Used to handle message where the source or the destination is a SP. When a ``FFA_MSG_SEND_DIRECT_REQ`` message is received by the SPMC from the Normal World, a new thread is started. The FF-A message is passed to the thread and it will call the ``sp_msg_handler()`` function. Whenever the SPMC (``sp_msg_handler()``) receives a message not intended for one of the SPs, it will exit the thread and return to the Normal World passing the FF-A message. Currently only a ``FFA_MSG_SEND_DIRECT_REQ`` can be passed from the Normal World to a SP. .. uml:: :width: 800 skinparam backgroundcolor transparent participant "None-secure world" as None_secure_world box "S-EL3" participant SPMD end box box "S-EL1" participant thread_spmc participant spmc_sp_handler end box box "S-EL0" participant SP end box autoactivate on None_secure_world -> SPMD: FFA_MSG_SEND_DIRECT_REQ \n SMC SPMD -> thread_spmc: thread_spmc_msg_recv() \n ERET thread_spmc -> spmc_sp_handler : spmc_sp_start_thread() == thread == spmc_sp_handler -> spmc_sp_handler : sp_msg_handler() loop FF-A dst != NSW spmc_sp_handler -> spmc_sp_handler: ffa_handle_sp_direct_req() spmc_sp_handler -> spmc_sp_handler: enter_sp() spmc_sp_handler -> spmc_sp_handler: sp_enter_invoke_cmd() autoactivate off spmc_sp_handler -> SP: __thread_enter_user_mode() \n ERET activate SP SP -> spmc_sp_handler : (FF-A message) sp_handle_svc() \n SVC deactivate SP activate spmc_sp_handler spmc_sp_handler -> spmc_sp_handler: Store SP context spmc_sp_handler -> spmc_sp_handler: return to sp_enter_invoke_cmd() deactivate spmc_sp_handler spmc_sp_handler -> spmc_sp_handler: Retrieve FF-A message from SP context return return return end return == End of thread == return return \n SMC return FFA_MSG_SEND_DIRECT_RESP \n ERET Every message received by the SPMC from the Normal World is handled in the ``thread_spmc_msg_recv()`` function. When entering a SP we need to be running in a OP-TEE thread. This is needed to be able to push the TS session (We push the TS session to get access to the SP memory). Currently the only possibility to enter a SP from the Normal world is via a ``FFA_MSG_SEND_DIRECT_REQ``. Whenever we receive a ``FFA_MSG_SEND_DIRECT_REQ`` message which doesn't have OP-TEE as the endpoint-id, we start a thread and forward the FF-A message to the ``sp_msg_handler()``. The ``sp_msg_handler()`` is responsible for all messages coming or going to/from a SP. It runs in a while loop and will handle every message until it comes across a messages which is not intended for the secure world. After a message is handled by the SPMC or when it needs to be forwarded to a SP, ``sp_enter()`` is called. ``sp_enter()`` will copy the FF-A arguments and resume the SP. When the SPMC needs to have access to the SPs memory, it will call ``ts_push_current_session()`` to gain access and ``ts_pop_current_session()`` to release the access. Running and exiting SPs ----------------------- The SPMC resumes/starts the SP by calling the ``sp_enter()``. This will set up the SP context and jump into S-EL0. Whenever the SP performs a system call it will end up in ``sp_handle_svc()``. ``sp_handle_svc()`` stores the current context of the SP and makes sure that we don't return to S-EL0 but instead returns to S-EL1 back to ``sp_enter()``. ``sp_enter()`` will pass the FF-A registers (x0-x7) to ``spmc_sp_msg_handler()``. This will process the FF-A message. RxTx buffer managment --------------------- RxTx buffers are used by the SPMC to exchange information between an endpoint and the SPMC. The rxtx_buf struct is used by the SPMC for abstracting buffer management. Every SP has a ``struct rxtx_buf`` wich will be passed to every function that needs access to the rxtx buffer. A separate ``struct rxtx_buf`` is defined for the Normal World, which gives access to the Normal World buffers. FF-A compliance =============== .. |ffa_fs| replace:: :octicon:`check-circle-fill` .. |ffa_ps| replace:: :octicon:`check-circle` .. |ffa_ns| replace:: :octicon:`x` .. |ffa_na| replace:: :octicon:`horizontal-rule` Legend ------ * |ffa_fs| Fully supported * |ffa_ps| Partially implemented * |ffa_ns| Not supported * |ffa_na| Does not apply for the FF-A instance or version Partition boot protocol ----------------------- Only FF-A v1.0 partition boot protocol is supported by the SPMC. Supported partition manifest fields ----------------------------------- +--------------------------------+-----------+-----------+-----------+ | Field | Mandatory | FF-A v1.0 | FF-A v1.1 | +================================+===========+===========+===========+ | FF-A version | Yes | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | UUID | Yes | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Partition ID | No | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Auxiliary IDs | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Name (description) | No | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Number of execution contexts | Yes | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Run-time EL | Yes | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Execution state | Yes | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Load address | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Entry point offset | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Translation granule | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Boot order | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | RX/TX information | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Messaging method | Yes | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Primary scheduler implemented | No | |ffa_na| | |ffa_na| | +--------------------------------+-----------+-----------+-----------+ | Run-time model | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Tuples | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | **Memory regions** | +--------------------------------+-----------+-----------+-----------+ | Base address | No | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Load address relative offset | No | |ffa_na| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Page count | Yes | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Attributes | Yes | |ffa_ps| | |ffa_ps| | +--------------------------------+-----------+-----------+-----------+ | Name | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Stream & SMMU IDs | No | |ffa_na| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Stream ID access permissions | No | |ffa_na| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | **Device regions** | +--------------------------------+-----------+-----------+-----------+ | Physical base address | Yes | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Page count | Yes | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Attributes | Yes | |ffa_fs| | |ffa_fs| | +--------------------------------+-----------+-----------+-----------+ | Interrupts | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | SMMU IDs | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Stream IDs | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Exclusive access and ownership | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ | Name | No | |ffa_ns| | |ffa_ns| | +--------------------------------+-----------+-----------+-----------+ Limitations ^^^^^^^^^^^ * The values of mandatory but not supported fields are ignored by the SP loader. This means all values are accepted but the SPMC might behave differently than expected. * Memory region attributes doesn't support shareability and cacheability flags. Supported FF-A interfaces ------------------------- The table below describes the implementation level of each FF-A interface on different FF-A instances. The two instances are between OP-TEE SPMC and the SPMC and between OP-TEE SPMC and its S-EL0 secure partitions. The FF-A specification uses 'Secure Phyisical' and 'Secure Virtual' terms for these instances. +--------------------------+-----------------------+-----------------------+ | | OP-TEE <-> SPMD | OP-TEE <-> S-EL0 SPs | | Interface +-----------+-----------+-----------+-----------+ | | FF-A v1.0 | FF-A v1.1 | FF-A v1.0 | FF-A v1.1 | +==========================+===========+===========+===========+===========+ | FFA_ERROR | |ffa_fs| | |ffa_ps| | |ffa_fs| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_SUCCESS | |ffa_fs| | |ffa_fs| | |ffa_ps| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_INTERRUPT | |ffa_ps| | |ffa_ps| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_VERSION | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_FEATURES | |ffa_ps| | |ffa_ns| | |ffa_ps| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_RX_ACQUIRE | |ffa_na| | |ffa_ns| | |ffa_na| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_RX_RELEASE | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_RXTX_MAP | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_RXTX_UNMAP | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_PARTITION_INFO_GET | |ffa_fs| | |ffa_ns| | |ffa_fs| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_ID_GET | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_SPM_ID_GET | |ffa_na| | |ffa_ns| | |ffa_na| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MSG_WAIT | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_YIELD | |ffa_na| | |ffa_ns| | |ffa_na| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_RUN | |ffa_ns| | |ffa_ns| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_NORMAL_WORLD_RESUME | |ffa_ns| | |ffa_ns| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MSG_SEND | |ffa_na| | |ffa_na| | |ffa_na| | |ffa_na| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MSG_SEND2 | |ffa_na| | |ffa_ns| | |ffa_na| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MSG_SEND_DIRECT_REQ | |ffa_fs| | |ffa_ps| | |ffa_fs| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MSG_SEND_DIRECT_RESP | |ffa_fs| | |ffa_ps| | |ffa_fs| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MSG_POLL | |ffa_na| | |ffa_na| | |ffa_na| | |ffa_na| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_DONATE | |ffa_ns| | |ffa_ns| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_LEND | |ffa_ns| | |ffa_ns| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_SHARE | |ffa_ps| | |ffa_ps| | |ffa_ps| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_RETRIEVE_REQ | |ffa_ps| | |ffa_ps| | |ffa_ps| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_RETRIEVE_RESP | |ffa_ps| | |ffa_ps| | |ffa_ps| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_RELINQUISH | |ffa_ps| | |ffa_ps| | |ffa_ps| | |ffa_ps| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_RECLAIM | |ffa_fs| | |ffa_fs| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_PERM_GET | |ffa_na| | |ffa_na| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_PERM_SET | |ffa_na| | |ffa_na| | |ffa_fs| | |ffa_fs| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_FRAG_RX | |ffa_fs| | |ffa_fs| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_FRAG_TX | |ffa_fs| | |ffa_fs| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_OP_PAUSE | |ffa_ns| | |ffa_ns| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ | FFA_MEM_OP_RESUME | |ffa_ns| | |ffa_ns| | |ffa_ns| | |ffa_ns| | +--------------------------+-----------+-----------+-----------+-----------+ Limitations ^^^^^^^^^^^ * FF-A v1.1 error code ``NO_DATA`` is not supported. * ``FFA_SUCCESS`` is not supported as a response to an ``FFA_MSG_SEND_DIRECT_REQ`` message. * Non-secure interrupts are not forwarded to the normal world via ``FFA_INTERRUPT``. * Interrupts cannot be forwarded to S-EL0 secure partitions. * Only ``FFA_RXTX_MAP`` feature query is supported by the ``FFA_FEATURES`` interface. ``FFA_MEM_DONATE``, ``FFA_MEM_LEND``, ``FFA_MEM_SHARE`` and ``FFA_MEM_RETRIEVE_REQ`` feature query is not implemented. * FF-A v1.1 ``Flags`` field in ``FFA_MSG_SEND_DIRECT_REQ`` and ``FFA_MSG_SEND_DIRECT_RESP`` calls is not supported. * Transferring memory transaction descriptors in a buffer distinct from the TX buffer is not supported by the secure virtual instance. * Transferring fragmented memory transaction descriptors is not supported by the secure virtual instance. * The only supported 'Memory region attributes descriptor' value is normal memory, write-back cacheability and inner shareable. All other values are denied on the secure physical instance. The secure virtual instance's implementation ignores the value of this descriptor but uses the same attributes for the region. * The NS flag support in not implemented for 'Memory region attributes descriptor'. * Only read-write non-executable value can be used in the 'Memory access permissions descriptor' at the secure phyisical instance. * The ``Flags`` field of ``FFA_MEM_RELINQUISH`` is ignored. * The secure phyisical instanced doesn't implemented the receiving of ``FFA_MEM_RELINQUISH``. * Time slicing of memory management operations is not supported. Configuration ============= SPMC config options --------------------------- To configure OP-TEE as a S-EL1 SPMC with Secure Partition support, the following flags should be set for optee_os: - ``CFG_CORE_SEL1_SPMC=y`` - ``CFG_SECURE_PARTITION=y`` - ``CFG_DT=y`` - ``CFG_MAP_EXT_DT_SECURE=y`` Furthermore TF-A should be configured as the SPMD, expecting a S-EL1 SPMC: - ``SPD=spmd`` - ``SPMD_SPM_AT_SEL2=0`` - ``ARM_SPMC_MANIFEST_DTS=`` SP loading mechanism --------------------- OP-TEE SPMC supports two methods for finding and loading the SP executable images. Currently only ELF executables are supported. In the build repo the loading method can be selected with the SP_PACKAGING_METHOD option. Embedded SP ^^^^^^^^^^^ In this case the early TA mechanism of optee_os is reused: the SP ELF files are embedded into the main OP-TEE binary. Each ELF should start with a specific section (.sp_head) containing a struct which describes the SP (UUID, stack size, etc.). The images can be added to optee_os using the ``SP_PATHS`` config option, the build repo will set this up automatically when ``SP_PACKAGING_METHOD=embedded`` is selected. The images passed in ``SP_PATHS`` are processed by ``ts_bin_to_c.py`` in optee_os and linked into the main binary. At runtime the ``for_each_secure_partition()`` macro can iterate through these images, so a particular SP can be found by UUID and then loaded. The SP manifest file `[1]`_ used by the SPMC to setup SPs is also handled by ``ts_bin_to_c.py``, it will be concatenated to the end of the SP ELF. FIP SP ^^^^^^ In this case the SP ELF files and the corresponding SP manifest DTs are encapsulated into SP packages and packed into the FIP. The goal of providing this alternative flow is to make updating SPs easier (independent of the main OP-TEE binary) and to get aligned with Hafnium (S-EL2 SPMC). For more information about the FIP, please refer to the TF-A documentation `[2]`_. The SP packaging process and the package format is provided by TF-A, detailed description is available at `[3]`_. In the build repo this method can be selected by ``SP_PACKAGING_METHOD=fip``, it covers all the necessary setup automatically. In case of using another buildsystem, the following steps should be implemented: - TF-A config ``SP_LAYOUT_FILE``: provide a JSON file which describes the SPs (path to SP executable and corresponding DT, example `[4]`_). The TF-A buildsystem will create the SP packages (using sptool) based on this and pack them into the FIP. - TF-A config ``ARM_BL2_SP_LIST_DTS``: provide a DT snippet which describes the SPs' UUIDs and load addresses (example: `[5]`_). This will be injected into the SP list in ``TB_FW_CONFIG`` DT of TF-A, and BL2 will load the SP packages based on this. Note that BL2 doesn't automatically load all images from the FIP: it's necessary to explicitly define them in ``TB_FW_CONFIG`` (using this injected snippet or manually editing the DT). - TF-A config ``ARM_SPMC_MANIFEST_DTS``: provide the SPMC manifest (example: `[6]`_). This DT is passed to the SPMC as a boot argument (in the TF-A naming convention this is the ``TOS_FW_CONFIG``). It should contain the list of SP packages and their load addresses in the ``compatible = "arm,sp_pkg"`` node. At boot optee_os will parse the SP package load addresses from the SPMC manifest and find the SP packages already loaded by BL2. Iterating through the SP packages, based on the SP package header in each package it will map the SP executable image and the corresponding manifest DT and collect these to the ``fip_sp_list`` list. Later when initialising the SPs, the ``for_each_fip_sp`` macro is used to iterate this list and load the executables, just like for the embedded SP case. .. _[1]: [1] https://trustedfirmware-a.readthedocs.io/en/v2.6/components/ffa-manifest-binding.html .. _[2]: [2] https://trustedfirmware-a.readthedocs.io/en/v2.6/design/firmware-design.html#firmware-image-package-fip .. _[3]: [3] https://trustedfirmware-a.readthedocs.io/en/v2.6/components/secure-partition-manager.html#secure-partition-packages .. _[4]: [4] https://trustedfirmware-a.readthedocs.io/en/v2.6/components/secure-partition-manager.html#describing-secure-partitions .. _[5]: [5] https://github.com/OP-TEE/build/blob/master/fvp/bl2_sp_list.dtsi .. _[6]: [6] https://github.com/OP-TEE/build/blob/master/fvp/spmc_manifest.dts