| Measured Boot using a Discrete TPM (PoC) |
| ======================================== |
| |
| Measured Boot is the process of cryptographically measuring the code and |
| critical data used at boot time, for example using a TPM, so that the |
| security state can be attested later. |
| |
| The current implementation of the driver included in |TF-A| supports several |
| backends and each has a different means to store the measurements. |
| This section focuses on the Discrete TPM backend, which stores measurements |
| in a PCR within the TPM. This backend can be paired with the `TCG event log`_ |
| to provide attestation of the measurements stored in the event log. See |
| details in :ref:`Measured Boot Design`. |
| |
| This section provides instructions to setup and build a proof of concept (PoC) |
| that showcases the use of Measured Boot with a Discrete TPM interface. |
| |
| .. note:: |
| The instructions given in this document are meant to build a PoC to |
| show how Measured Boot on TF-A can interact with a Discrete TPM interface. |
| This PoC is platform specific, and uses a SPI based Discrete TPM, the |
| Raspberry Pi communicates with the TPM via a GPIO pin bit-banged SPI interface. |
| For other platforms, different may be required to interface with the hardware |
| (e.g., different hardware communication protocols) and different TPM interfaces |
| (e.g., |FIFO| vs |CRB|). |
| |
| Components |
| ~~~~~~~~~~ |
| |
| - **Platform**: The PoC is developed on the Raspberry Pi 3 (rpi3), due to quick |
| driver development and the availability of GPIO pins to interface with a TPM |
| expansion module. Measured boot capabilities using the TCG Event Log are |
| ported to the Raspberry Pi 3 platform inside TF-A. This PoC specifically uses |
| the Raspberry Pi 3 Model B V1.2, but this PoC is compatible with other |
| Raspberry Pi 3 models. |
| |
| - **Discrete TPM**: The TPM chip selected is a breakout board compatible with |
| the Raspberry Pi 3 GPIO pins. This PoC uses a |SPI| based LetsTrust TPM |
| breakout board equipped with a Infineon Optiga™ SLB 9670 TPM 2.0 chip. Link |
| to device: https://thepihut.com/products/letstrust-tpm-for-raspberry-pi |
| |
| .. note:: |
| If you have another TPM breakout board that uses the same |
| Infineon Optiga™ SLB 9670 TPM 2.0 SPI based chip, it will also work. |
| Ensure that the correct GPIO pins are utilized on the Raspberry Pi 3 to |
| avoid communication issues, and possible hardware failures. |
| |
| - **TF-A TPM Drivers**: To interface with a physical (Discrete) TPM chip in |
| TF-A, the PoC uses TF-A drivers that provide the command, interface, link, |
| and platform layers required to send and receive data to and from the TPM. |
| The drivers are located in TFA, and not in a |SP|, so that they may be used |
| in early stages such as BL2, and in some cases, BL1. The design of the TPM |
| Drivers is documented here: :ref:`Discrete TPM drivers`. |
| |
| - **U-boot BL33**: This PoC showcases measured boot up to BL33, and for |
| simplicity uses a U-boot image for BL33, so that the image is measured and |
| loaded. Currently U-boot does not have Discrete TPM support for the |
| Raspberry Pi 3 platform so the boot flow ends here. |
| |
| |
| Building the PoC for the Raspberry Pi 3 |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| **Build instructions for U-Boot.bin for Raspberry Pi 3.** |
| |
| First, the build requires a BL33 firmware image that can be packaged and measured |
| by TF-A. |
| |
| U-boot can be built for the Raspberry Pi 3, but there are some changes to be made |
| to allow the build to succeed. First Clone U-boot and enter the repo. |
| |
| .. code:: shell |
| |
| git clone https://github.com/u-boot/u-boot.git |
| cd u-boot |
| |
| Now to switch to a specific tag ``v2024.04`` for testing purposes, and then build |
| the defconfig labelled ``rpi_3_b_plus_defconfig``. |
| |
| .. code:: shell |
| |
| git checkout tags/v2024.04 -b tfa_dtpm_poc |
| make CROSS_COMPILE=aarch64-linux-gnu- rpi_3_b_plus_defconfig |
| |
| Lastly open the ``.config`` and change ``CONFIG_TEXT_BASE`` and |
| ``CONFIG_SYS_UBOOT_START`` to ``0x11000000`` to match the BL33 starting point. |
| |
| .. code:: shell |
| |
| vim .config |
| CONFIG_TEXT_BASE=0x11000000 |
| CONFIG_SYS_UBOOT_START=0x11000000 |
| |
| To build the u-boot binary, use the following command. |
| |
| .. code:: shell |
| |
| make CROSS_COMPILE=aarch64-linux-gnu- -j$(nproc) |
| |
| **Build TF-A for Raspberry Pi 3 with Discrete TPM and Measured Boot.** |
| |
| Copy over the ``u-boot.bin`` file over to your TF-A working directory. |
| |
| .. code:: shell |
| |
| cp /path/to/u-boot/build/u-boot.bin /path/to/tfa/u-boot.bin |
| |
| TF-A build command: |
| |
| .. code:: shell |
| |
| CROSS_COMPILE=aarch64-linux-gnu- \ |
| make PLAT=rpi3 \ |
| RPI3_PRELOADED_DTB_BASE=0x200000 \ |
| BL33=u-boot.bin \ |
| SUPPORT_VFP=1 \ |
| DEBUG=0 \ |
| MEASURED_BOOT=1 \ |
| DISCRETE_TPM=1 \ |
| MBOOT_TPM_HASH_ALG=sha256 \ |
| TPM_INTERFACE=FIFO_SPI \ |
| MBEDTLS_DIR=/path/to/mbedtls/repo \ |
| LOG_LEVEL=40 \ |
| fip all |
| |
| This build command is similar to the one provided in the TF-A Raspberry Pi 3 |
| platform port, To learn more about the platform and its build options, visit |
| :ref:`Raspberry Pi 3`. |
| |
| - ``RPI3_PRELOADED_DTB_BASE`` is given a different address to accommodate the |
| larger BL1 and BL2 firmware sizes, this is to accommodate the TPM drivers |
| that are packaged in BL1 and BL2 for this PoC. |
| - ``BL33`` is the non trusted firmware, in this case the U-Boot binary built |
| earlier. |
| - ``SUPPORT_VFP`` is enabled, allows Vector Floating Point operations in EL3. |
| - ``MEASURED_BOOT`` is enabled to allow the Measured Boot flow. |
| - ``DISCRETE_TPM=1`` enables the build of Discrete TPM drivers. |
| - ``MBOOT_TPM_HASH_ALG=sha256`` sets the hash algorithm to sha256, this is |
| the only algorithm supported by both TF-A Measured Boot and the SLB 9670 |
| TPM 2.0. |
| - ``TPM_INTERFACE=FIFO_SPI`` specifies the use of the FIFO SPI interface. |
| - ``MBEDTLS_DIR`` is the path to your local mbedtls repo. |
| - ``LOG_LEVEL=40`` ensures that eventlog is printed at the end of BL1 and BL2. |
| |
| |
| **Hardware Setup:** |
| |
| - **TPM Connection**: Connect the LetsTrust TPM board to GPIO pins 17 - 26 on |
| the 40-pin GPIO header on the Raspberry Pi board. The 2x5 header of the TPM |
| module must be aligned to the pins in a specific orientation, match the 3v3 |
| and RST pins from the TPM board to pins 17 and 18 respectively on the |
| Raspberry Pi 3 header. See `rpi3 pinout`_. |
| |
| - **Serial Console**: Establish a serial connection to the Raspberry Pi 3 to |
| view serial output during the boot sequence. The GND, TXD, and RXD pins, |
| which are labelled 6, 8, and 10 on the Raspberry Pi 3 header respectively, |
| are the required pins to establish a serial connection. The recommended way |
| to connect to the board from another system is to use a USB to serial TTL |
| cable to output the serial console in a easy manner. |
| |
| - **SD Card Setup**: Format a SD Card as ``FAT32`` with a default Raspbian |
| installation that is similar to the default Raspberry Pi 3 boot partition, |
| this partition will utilize the default files installed in the root |
| directory with Rasbian such as: |
| |
| :: |
| |
| bcm2710-rpi3-b.dtb |
| bootcode.bin |
| config.txt |
| fixup.dat |
| start.elf |
| |
| Open ``config.txt`` and overwrite the file with the following lines: |
| |
| :: |
| |
| arm_64bit=1 |
| disable_commandline_tags=2 |
| enable_uart=1 |
| armstub=armstub8.bin |
| device_tree_address=0x200000 |
| device_tree_end=0x210000 |
| |
| These configurations are required to enable uart, enable 64bit mode, |
| use the build TF binary, and the modified rpi3 device tree address |
| and size. |
| |
| Copy ``armstub8.bin`` from the TF-A build path to the root folder of the |
| SD card. |
| |
| The SD Card is now ready to be booted. |
| |
| Running the PoC for the Raspberry Pi 3 |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| Insert the SD Card into the Raspberry Pi 3 SD card port and boot the system. |
| |
| To access the serial console output from the Raspberry Pi 3 you can either: |
| |
| - Follow `instructions`_ to use PuTTY to connect to Raspberry Pi 3 serial console. |
| |
| - Use the linux ``screen`` command: |
| |
| .. code:: shell |
| |
| screen /dev/ttyUSB0 115200 |
| |
| Once booted the output from the serial console will look like this: |
| |
| .. code:: shell |
| |
| Raspberry Pi Bootcode |
| |
| Read File: config.txt, 153 |
| |
| Read File: start.elf, 2975040 (bytes) |
| |
| Read File: fixup.dat, 7265 (bytes) |
| |
| MESS:00:00:01.170422:0: brfs: File read: /mfs/sd/config.txt |
| MESS:00:00:01.174630:0: brfs: File read: 153 bytes |
| MESS:00:00:01.211473:0: HDMI0:EDID error reading EDID block 0 attempt 0 |
| MESS:00:00:01.217639:0: HDMI0:EDID error reading EDID block 0 attempt 1 |
| MESS:00:00:01.223977:0: HDMI0:EDID error reading EDID block 0 attempt 2 |
| MESS:00:00:01.230313:0: HDMI0:EDID error reading EDID block 0 attempt 3 |
| MESS:00:00:01.236650:0: HDMI0:EDID error reading EDID block 0 attempt 4 |
| MESS:00:00:01.242987:0: HDMI0:EDID error reading EDID block 0 attempt 5 |
| MESS:00:00:01.249324:0: HDMI0:EDID error reading EDID block 0 attempt 6 |
| MESS:00:00:01.255660:0: HDMI0:EDID error reading EDID block 0 attempt 7 |
| MESS:00:00:01.261997:0: HDMI0:EDID error reading EDID block 0 attempt 8 |
| MESS:00:00:01.268334:0: HDMI0:EDID error reading EDID block 0 attempt 9 |
| MESS:00:00:01.274429:0: HDMI0:EDID giving up on reading EDID block 0 |
| MESS:00:00:01.282647:0: brfs: File read: /mfs/sd/config.txt |
| MESS:00:00:01.286929:0: gpioman: gpioman_get_pin_num: pin LEDS_PWR_OK not defined |
| MESS:00:00:01.487295:0: gpioman: gpioman_get_pin_num: pin DISPLAY_DSI_PORT not defined |
| MESS:00:00:01.494853:0: gpioman: gpioman_get_pin_num: pin LEDS_PWR_OK not defined |
| MESS:00:00:01.500763:0: *** Restart logging |
| MESS:00:00:01.504638:0: brfs: File read: 153 bytes |
| MESS:00:00:01.510139:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 0 |
| MESS:00:00:01.517254:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 1 |
| MESS:00:00:01.524112:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 2 |
| MESS:00:00:01.530970:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 3 |
| MESS:00:00:01.537826:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 4 |
| MESS:00:00:01.544685:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 5 |
| MESS:00:00:01.551543:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 6 |
| MESS:00:00:01.558399:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 7 |
| MESS:00:00:01.565258:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 8 |
| MESS:00:00:01.572116:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 9 |
| MESS:00:00:01.578730:0: hdmi: HDMI0:EDID giving up on reading EDID block 0 |
| MESS:00:00:01.584634:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 0 |
| MESS:00:00:01.592427:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 1 |
| MESS:00:00:01.599286:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 2 |
| MESS:00:00:01.606142:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 3 |
| MESS:00:00:01.613001:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 4 |
| MESS:00:00:01.619858:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 5 |
| MESS:00:00:01.626717:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 6 |
| MESS:00:00:01.633575:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 7 |
| MESS:00:00:01.640431:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 8 |
| MESS:00:00:01.647288:0: hdmi: HDMI0:EDID error reading EDID block 0 attempt 9 |
| MESS:00:00:01.653905:0: hdmi: HDMI0:EDID giving up on reading EDID block 0 |
| MESS:00:00:01.659769:0: hdmi: HDMI:hdmi_get_state is deprecated, use hdmi_get_display_state instead |
| MESS:00:00:01.668264:0: HDMI0: hdmi_pixel_encoding: 162000000 |
| MESS:00:00:01.673988:0: vec: vec_middleware_power_on: vec_base: 0x7e806000 rev-id 0x00002708 @ vec: 0x7e806100 @ 0x00000420 enc: 0x7e806060 @ 0x00000220 cgmsae: 0x7e80605c @ 0x00000000 |
| MESS:00:00:01.880234:0: dtb_file 'bcm2710-rpi-3-b.dtb' |
| MESS:00:00:01.889713:0: brfs: File read: /mfs/sd/bcm2710-rpi-3-b.dtb |
| MESS:00:00:01.894375:0: Loaded 'bcm2710-rpi-3-b.dtb' to 0x200000 size 0x7cb2 |
| MESS:00:00:01.915761:0: brfs: File read: 31922 bytes |
| MESS:00:00:02.007202:0: brfs: File read: /mfs/sd/config.txt |
| MESS:00:00:02.017277:0: brfs: File read: 153 bytes |
| MESS:00:00:02.020772:0: Failed to open command line file 'cmdline.txt' |
| MESS:00:00:02.042302:0: gpioman: gpioman_get_pin_num: pin EMMC_ENABLE not defined |
| MESS:00:00:02.398066:0: kernel= |
| MESS:00:00:02.455255:0: brfs: File read: /mfs/sd/armstub8.bin |
| MESS:00:00:02.459284:0: Loaded 'armstub8.bin' to 0x0 size 0xdbe74 |
| MESS:00:00:02.465109:0: No compatible kernel found |
| MESS:00:00:02.469610:0: Device tree loaded to 0x200000 (size 0x823f) |
| MESS:00:00:02.476805:0: uart: Set PL011 baud rate to 103448.300000 Hz |
| MESS:00:00:02.483381:0: uart: Baud rate change done... |
| MESS:00:00:02.486793:0: uart: Baud rateNOTICE: Booting Trusted Firmware |
| NOTICE: BL1: v2.11.0(release):v2.11.0-187-g0cb1ddc9c-dirty |
| NOTICE: BL1: Built : 10:57:10, Jul 9 2024 |
| INFO: BL1: RAM 0x100ee000 - 0x100f9000 |
| INFO: Using crypto library 'mbed TLS' |
| NOTICE: TPM Chip: vendor-id 0xd1, device-id 0x0, revision-id: 0x16 |
| NOTICE: rpi3: Detected: Raspberry Pi 3 Model B (1GB, Sony, UK) [0x00a02082] |
| INFO: BL1: Loading BL2 |
| INFO: Loading image id=1 at address 0x100b4000 |
| INFO: Image id=1 loaded: 0x100b4000 - 0x100c0281 |
| INFO: TCG_EfiSpecIDEvent: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 3 |
| INFO: Digest : 00 |
| INFO: : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| INFO: : 00 00 00 |
| INFO: EventSize : 33 |
| INFO: Signature : Spec ID Event03 |
| INFO: PlatformClass : 0 |
| INFO: SpecVersion : 2.0.2 |
| INFO: UintnSize : 1 |
| INFO: NumberOfAlgorithms : 1 |
| INFO: DigestSizes : |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: DigestSize : 32 |
| INFO: VendorInfoSize : 0 |
| INFO: PCR_Event2: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 3 |
| INFO: Digests Count : 1 |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: Digest : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| INFO: : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| INFO: EventSize : 17 |
| INFO: Signature : StartupLocality |
| INFO: StartupLocality : 0 |
| INFO: PCR_Event2: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 1 |
| INFO: Digests Count : 1 |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: Digest : 55 11 51 d8 8b 7f 41 d3 18 16 f2 e8 80 bf 80 fa |
| INFO: : b4 03 6d 96 4c a0 0a 98 45 cf 25 2f 1e a9 09 3e |
| INFO: EventSize : 5 |
| INFO: Event : BL_2 |
| NOTICE: BL1: Booting BL2 |
| INFO: Entry point address = 0x100b4000 |
| INFO: SPSR = 0x3c5 |
| NOTICE: BL2: v2.11.0(release):v2.11.0-187-g0cb1ddc9c-dirty |
| NOTICE: BL2: Built : 10:56:39, Jul 9 2024 |
| INFO: Using crypto library 'mbed TLS' |
| NOTICE: TPM Chip: vendor-id 0xd1, device-id 0x0, revision-id: 0x16 |
| INFO: BL2: Doing platform setup |
| INFO: BL2: Loading image id 3 |
| INFO: Loading image id=3 at address 0x100e0000 |
| INFO: Image id=3 loaded: 0x100e0000 - 0x100e706b |
| INFO: BL2: Loading image id 5 |
| INFO: Loading image id=5 at address 0x11000000 |
| INFO: Image id=5 loaded: 0x11000000 - 0x110a8ad8 |
| INFO: TCG_EfiSpecIDEvent: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 3 |
| INFO: Digest : 00 |
| INFO: : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| INFO: : 00 00 00 |
| INFO: EventSize : 33 |
| INFO: Signature : Spec ID Event03 |
| INFO: PlatformClass : 0 |
| INFO: SpecVersion : 2.0.2 |
| INFO: UintnSize : 1 |
| INFO: NumberOfAlgorithms : 1 |
| INFO: DigestSizes : |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: DigestSize : 32 |
| INFO: VendorInfoSize : 0 |
| INFO: PCR_Event2: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 3 |
| INFO: Digests Count : 1 |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: Digest : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| INFO: : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| INFO: EventSize : 17 |
| INFO: Signature : StartupLocality |
| INFO: StartupLocality : 0 |
| INFO: PCR_Event2: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 1 |
| INFO: Digests Count : 1 |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: Digest : 55 11 51 d8 8b 7f 41 d3 18 16 f2 e8 80 bf 80 fa |
| INFO: : b4 03 6d 96 4c a0 0a 98 45 cf 25 2f 1e a9 09 3e |
| INFO: EventSize : 5 |
| INFO: Event : BL_2 |
| INFO: PCR_Event2: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 1 |
| INFO: Digests Count : 1 |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: Digest : f3 00 5c ed a2 12 8b 76 b7 82 da c5 28 c3 02 52 |
| INFO: : 19 e4 3a 82 f2 3c ab 1e 0d 78 84 9c b5 fe e2 4f |
| INFO: EventSize : 14 |
| INFO: Event : SECURE_RT_EL3 |
| INFO: PCR_Event2: |
| INFO: PCRIndex : 0 |
| INFO: EventType : 1 |
| INFO: Digests Count : 1 |
| INFO: #0 AlgorithmId : SHA256 |
| INFO: Digest : 90 28 81 42 12 b7 9b ca aa 0c 40 76 33 5a 69 71 |
| INFO: : b6 19 2b 90 f2 d2 69 b8 de 8e 6d 05 4d c2 73 f9 |
| INFO: EventSize : 6 |
| INFO: Event : BL_33 |
| NOTICE: BL1: Booting BL31 |
| INFO: Entry point address = 0x100e0000 |
| INFO: SPSR = 0x3cd |
| NOTICE: BL31: v2.11.0(release):v2.11.0-187-g0cb1ddc9c-dirty |
| NOTICE: BL31: Built : 10:56:58, Jul 9 2024 |
| INFO: rpi3: Checking DTB... |
| INFO: rpi3: Reserved 0x10000000 - 0x10100000 in DTB |
| INFO: BL31: Initializing runtime services |
| INFO: BL31: Preparing for EL3 exit to normal world |
| INFO: Entry point address = 0x11000000 |
| INFO: SPSR = 0x3c9 |
| |
| |
| U-Boot 2024.04-g84314330-dirty (Apr 23 2024 - 15:41:54 -0500) |
| |
| DRAM: 948 MiB |
| RPI 3 Model B (0xa02082) |
| Core: 68 devices, 14 uclasses, devicetree: embed |
| MMC: mmc@7e202000: 0, mmc@7e300000: 1 |
| Loading Environment from FAT... OK |
| In: serial,usbkbd |
| Out: serial,vidconsole |
| Err: serial,vidconsole |
| Net: No ethernet found. |
| starting USB... |
| Bus usb@7e980000: USB DWC2 |
| scanning bus usb@7e980000 for devices... |
| Error: smsc95xx_eth No valid MAC address found. |
| 2 USB Device(s) found |
| scanning usb for storage devices... 0 Storage Device(s) found |
| Hit any key to stop autoboot: 2 1 0 |
| Card did not respond to voltage select! : -110 |
| No EFI system partition |
| No EFI system partition |
| Failed to persist EFI variables |
| No EFI system partition |
| Failed to persist EFI variables |
| No EFI system partition |
| Failed to persist EFI variables |
| Missing TPMv2 device for EFI_TCG_PROTOCOL |
| ** Booting bootflow '<NULL>' with efi_mgr |
| Loading Boot0000 'mmc 0' failed |
| EFI boot manager: Cannot load any image |
| Boot failed (err=-14) |
| Card did not respond to voltage select! : -110 |
| No ethernet found. |
| No ethernet found. |
| U-Boot> |
| |
| |
| Next steps for Discrete TPM and Measured Boot development |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| In order to automatically validate the workings of the Discrete TPM, the creation |
| of test cases that compare the eventlog image hashes with what is stored in PCR0 |
| are a great way to test the core functionality of the Discrete TPM in Measured Boot. |
| |
| Development of Discrete TPM drivers such as a reference FIFO |I2C|, MMIO, and CRB |
| drivers has not started, these drivers will allow a larger number of platform |
| to use a Discrete TPM in TF-A. |
| |
| *Copyright (c) 2025, Arm Limited. All rights reserved.* |
| |
| .. _TCG event log: https://trustedcomputinggroup.org/resource/tcg-efi-platform-specification/ |
| .. _rpi3 pinout: https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#gpio |
| .. _instructions: https://www.circuitbasics.com/use-putty-to-access-the-raspberry-pi-terminal-from-a-computer/ |
| .. _workaround: https://github.com/mhomran/u-boot-rpi3-b-plus |