# Fingerprint Firmware (FPMCU) [TOC] *** note NOTE: The build commands assume you are in the `~/trunk/src/platform/ec` directory inside the chroot. *** *** note WARNING: When switching branches in the EC codebase, you probably want to nuke the `build` directory or at least the board you're working on: `rm -rf build/` or `make clobber` to prevent compilation errors. *** ## Software The main source code for fingerprint sensor functionality lives in the [`common/fpsensor`] directory. The driver code for specific sensors lives in the [`driver/fingerprint`] directory. ## Hardware {#hardware} The following "boards" (specified by the `BOARD` environment variable when building the EC code) are for fingerprint: MCU | Sensor | Firmware (EC "board") | Dev Board | Nucleo Board ---------------------- | ---------- | ---------------------------------------------- | -------------------------------------------- | ------------ [STM32H743] \(Cortex-M7) | [FPC 1145] | `dartmonkey`
(aka `nocturne_fp`, `nami_fp`) | [Icetower v0.2]
(Previously Dragontalon) | [Nucleo H743ZI2] [STM32F412] \(Cortex-M4) | [FPC 1025] | `bloonchipper`
(aka `hatch_fp`) | [Dragonclaw v0.2] | [Nucleo F412ZG] ### Sensor Template Sizes Sensor | Fingerprint Template Size ---------- | -------------------------------- [FPC 1145] | [~48 KB][FPC 1145 Template Size] [FPC 1025] | [~5 KB][FPC 1025 Template Size] ### Determining Hardware {#chromeos-config-fingerprint} If you have access to a shell on your Chromebook, you can use [Chrome OS Config] to determine the FPMCU that it contains: ```bash (dut) $ cros_config /fingerprint board ``` Alternatively, if you have a Chromium OS build, you can use [Chrome OS Config] in the chroot to determine the FPMCU: ```bash (chroot) $ cros_config_host -c /build//usr/share/chromeos-config/yaml/config.yaml -m get /fingerprint board ``` *** note **NOTE**: If you get an empty response when running these commands, the [Chrome OS Config] properties for fingerprint may not have been set up yet. See the [section on updating Chrome OS Config](#update-chromeos-config). *** ## Building FPMCU Firmware Locally ### See `Makefile` target options ```bash (chroot) ~/trunk/src/platform/ec $ make help ``` ### Build Replace `` in the command below with the fingerprint MCU that you are targeting (e.g., `nocturne_fp`, `dartmonkey`, `bloonchipper`). ```bash (chroot) ~/trunk/src/platform/ec $ make BOARD= -j ``` ### Verbose Build output Use `V=1` to see the complete compiler output (all flags). ```bash (chroot) ~/trunk/src/platform/ec $ make V=1 BOARD=nocturne_fp -j ``` ## Building all EC firmware (before "repo upload") Before uploading a change to Gerrit via `repo upload`, you'll need to build *all* the boards in the EC codebase to make sure your changes do not break any others. *** note NOTE: If you forget to do this, do not worry. `repo upload` will warn you and prevent you from uploading. *** ```bash (chroot) ~/trunk/src/platform/ec $ make buildall -j ``` ## Building and running unit tests See the [Unit Tests] documentation for details on how to [run the unit tests]. ## Build ectool ```bash (chroot) ~/trunk/src/platform/ec $ make BOARD=nocturne_fp utils-host -j ``` ## Build and run the `host_command` fuzz test ```bash (chroot) ~/trunk/src/platform/ec $ make run-host_command_fuzz ``` ## Logs [`timberslide`] is a simple daemon that collects logs from the FPMCU and writes them to disk. [`timberslide`] reads from sysfs, where the kernel driver [periodically dumps the FPMCU console output][cros_ec_debugfs]. [`timberslide`] writes the resulting logs to `/var/log/cros_fp.log`. There are multiple instances of [`timberslide`] that run; one for each MCU running the EC codebase. ### Starting timberslide ```bash (dut)$ start timberslide LOG_PATH=/sys/kernel/debug/cros_fp/console_log ``` ### Stopping timberslide ```bash (dut)$ stop timberslide LOG_PATH=/sys/kernel/debug/cros_fp/console_log ``` ### Manually running timberslide ```bash (dut)$ timberslide --device_log=/sys/kernel/debug/cros_fp/console_log ``` ### Reading logs from kernel If [`timberslide`] is not running you can just `cat` the logs directly from the kernel: ```bash (dut)$ cat /sys/kernel/debug/cros_fp/console_log ``` ## Production Updates (Auto-Update) ### `fp_updater.sh` and `bio_fw_updater` *** note **NOTE**: The auto-update process requires a working version of the firmware running on the FPMCU. See [Fingerprint Factory Requirements] for details on flashing in the factory. *** [`fp_updater.sh`] and [`bio_fw_updater`] are wrappers around [`flashrom`] and require already-functioning RO firmware running on the FPMCU. It’s meant to be used in production to update the RW firmware. `fp_updater.sh` was used prior to M77; `bio_fw_updater` replaces it. It's also possible to use the updater to update the RO firmware if you disable *both* HW and SW write protect, which we use for updating development devices that do not have write protect enabled (dogfood devices, EVT, etc.) In production, only the RW portion of the firmware can be updated (unless the user disables [hardware write protection]). ## Factory / RMA / Development Updates {#factory-rma-dev-updates} ### `flash_fp_mcu` *** note **NOTE**: This tool is really just for us to use during development or during the RMA flow (must go through finalization again in that case). We never update RO in the field (can’t by design). See [Fingerprint Factory Requirements] for details on flashing in the factory. *** [`flash_fp_mcu`] enables spidev and toggles some GPIOs to put the FPMCU (STM32) into bootloader mode. At that point it uses [`stm32mon`] to rewrite the entire flash (both RO and RW). The FPMCU can only be put into bootloader mode when [hardware write protection] is disabled, which means [`flash_fp_mcu`] can only be used when [hardware write protection] is disabled. [`flash_fp_mcu`] is available in the [Chromium OS test image]. ### `stm32mon` [`stm32mon`] is a tool used to send commands to the STM32 bootloader. We use it for development (through [`flash_fp_mcu`]) to erase and flash the entire chip. [`stm32mon`] is available in the [Chromium OS test image]. ## Keys The `RO` section of the fingerprint firmware contains the public portion of the key used to sign the RW firmware. The RO firmware uses the public key to validate the signature of the RW firmware before jumping to it. It is not possible to update the public key stored in the RO firmware once a device has been shipped (i.e., once [hardware write protection] is enabled). Different keys are used to sign the firmware during development and production. The `dev` key is used for local builds and development and is not private; it is called `dev_key.pem` and located in the "board" directory for the given FPMCU (e.g., [`board/nocturne_fp/dev_key.pem`]). After doing a build, the `ec.bin` in the `build` directory (e.g., `build/nocturne_fp/ec.bin`) will be signed with the `dev` key. The two other types of keys are `premp` and `mp`, which stand for "pre-mass production" and "mass production", respectively. Both the `premp` and `mp` keys are only available to the buildbots as part of the official build. The `premp` is typically used during bringup of new hardware to validate the signing flow of the buildbots, while the `mp` key is used for PVT and production devices. Switching keys is only possible when the `RO` firmware is not write protected, since the public portion of the keypair is stored in the `RO` firmware. ### Generate Key For testing, you can generate a new key by using the following openssl command: ```bash openssl genrsa -3 -out board/$BOARD/dev_key.pem 3072 ``` ### Resources * https://sites.google.com/a/google.com/chromeos/resources/engineering/releng/signer-documentation * https://sites.google.com/a/google.com/chromeos/paygen---payload * https://b.corp.google.com/issues/77882970 ## Signing [`futility`] is used to sign EC firmware. There’s a wrapper script around it for signing called [`sign_official_build.sh`]. ### Key ID The output of `futility show` will show a `Public Key File` and `Signature` section, each of which have an `ID` field. This ID lets you match the key to the signature in case there is more than one. [It’s just a sha1sum of the public key,][vboot_key_id] so it lets you [uniquely identify the key being used][vb2_public_key]. If you have the key (e.g., in PEM format), you can compute the `ID` with the `futility show` command: ```bash (chroot) $ futility show ./path/to/key.pem ``` #### Example If you are building the `hatch_fp` "board" on your local machine (which signs the resulting `ec.bin` with the `dev` key, you can check the `ID` with: ```bash (chroot)$ futility show board/hatch_fp/dev_key.pem ``` ``` Private Key file: board/hatch_fp/dev_key.pem Key length: 3072 Key sha1sum: 61382804da86b4156d666cc9a976088f8b647d44 ``` ```bash (chroot)$ futility show build/hatch_fp/ec.bin ``` ``` Public Key file: build/hatch_fp/ec.bin Vboot API: 2.1 Desc: "" Signature Algorithm: 7 RSA3072EXP3 Hash Algorithm: 2 SHA256 Version: 0x00000001 ID: 61382804da86b4156d666cc9a976088f8b647d44 Signature: build/hatch_fp/ec.bin Vboot API: 2.1 Desc: "" Signature Algorithm: 7 RSA3072EXP3 Hash Algorithm: 2 SHA256 Total size: 0x1b8 (440) ID: 61382804da86b4156d666cc9a976088f8b647d44 Data size: 0x2864c (165452) Signature verification succeeded. ``` ### Showing Key ID (fingerprint) for running FW [Asked on chromeos-chatty-firmware][chatty-firmware-q] about adding an EC command to show the Key ID (fingerprint) from the RO version. This would make it a lot easier during both development and testing. ## Power See [Measuring Power] for instructions on how to measure power with the fingerprint development boards. ### Dragonclaw v0.2 ```bash (chroot) $ dut-control -t 60 pp3300_dx_mcu_mv pp3300_dx_fp_mv pp1800_dx_fp_mv pp3300_dx_mcu_mw pp3300_dx_fp_mw pp1800_dx_fp_mw ``` **Firmware Version**: `bloonchipper_v2.0.4277-9f652bb3-RO_v2.0.7314-3dfc5ff6-RW.bin` #### MCU is idle ``` (chroot) $ dut-control fpmcu_slp_alt:off ``` ``` @@ NAME COUNT AVERAGE STDDEV MAX MIN @@ sample_msecs 113 533.56 40.91 658.52 447.06 @@ pp1800_dx_fp_mv 113 1800.00 0.00 1800.00 1800.00 @@ pp1800_dx_fp_mw 113 0.00 0.00 0.00 0.00 @@ pp3300_dx_fp_mv 113 3280.00 0.00 3280.00 3280.00 @@ pp3300_dx_fp_mw 113 0.01 0.05 0.26 0.00 @@ pp3300_dx_mcu_mv 113 3280.00 0.00 3280.00 3280.00 @@ pp3300_dx_mcu_mw 113 24.67 0.00 24.67 24.67 ``` #### MCU in low power mode (suspend) ``` (chroot) $ dut-control fpmcu_slp_alt:on ``` ``` @@ NAME COUNT AVERAGE STDDEV MAX MIN @@ sample_msecs 115 526.56 36.79 607.60 426.58 @@ pp1800_dx_fp_mv 115 1800.00 0.00 1800.00 1800.00 @@ pp1800_dx_fp_mw 115 0.00 0.00 0.00 0.00 @@ pp3300_dx_fp_mv 115 3287.30 2.25 3288.00 3280.00 @@ pp3300_dx_fp_mw 115 0.00 0.02 0.26 0.00 @@ pp3300_dx_mcu_mv 115 3280.97 2.62 3288.00 3280.00 @@ pp3300_dx_mcu_mw 115 4.02 0.64 10.76 3.94 ``` ### Icetower v0.1 *** note **NOTE**: Icetower v0.1 has a hardware bug in the INA connections, so you cannot measure the 1.8V fingerprint sensor rail. See http://b/178098140. Additionally, before https://crrev.com/c/2689101, the sleep GPIOs were not configured correctly, so the change needs to be cherry-picked in order to measure releases before that point. *** ```bash (chroot) $ dut-control -t 60 pp3300_dx_mcu_mv pp3300_dx_fp_mv pp3300_dx_mcu_mw pp3300_dx_fp_mw ``` **Firmware Version**: `dartmonkey_v2.0.2887-311310808-RO_v2.0.7304-441100b93-RW.bin` #### MCU is idle ``` (chroot) $ dut-control fpmcu_slp_alt:off ``` ``` @@ NAME COUNT AVERAGE STDDEV MAX MIN @@ sample_msecs 178 337.13 20.91 404.32 289.82 @@ pp3300_dx_fp_mv 178 3256.00 0.00 3256.00 3256.00 @@ pp3300_dx_fp_mw 178 0.00 0.00 0.00 0.00 @@ pp3300_dx_mcu_mv 178 3248.00 0.00 3248.00 3248.00 @@ pp3300_dx_mcu_mw 178 45.17 0.09 45.21 44.95 ``` #### MCU in low power mode (suspend) ``` (chroot) $ dut-control fpmcu_slp_alt:on ``` ``` @@ NAME COUNT AVERAGE STDDEV MAX MIN @@ sample_msecs 174 345.60 31.93 457.62 283.00 @@ pp3300_dx_fp_mv 174 3264.00 0.00 3264.00 3264.00 @@ pp3300_dx_fp_mw 174 0.00 0.00 0.00 0.00 @@ pp3300_dx_mcu_mv 174 3260.69 3.94 3264.00 3256.00 @@ pp3300_dx_mcu_mw 174 5.47 0.10 5.48 4.17 ``` ## Chrome OS Build (portage / ebuild) In order to use the fingerprint sensor with a given [Chrome OS board], a few things need to be configured for the [Chrome OS board]. ### Enable biod USE flag The biod [`USE` flag] needs to be enabled for the [Chrome OS board]. This `USE` flag [determines whether the `biod` daemon is built and installed][biod chromium-os]. To enable the `USE` flag, update the `make.defaults` for the [Chrome OS board]. See the [`make.defaults` for the Hatch board][hatch make.defaults] as an example. #### Verifying biod is installed in the rootfs After enabling the `biod` [`USE` flag] and building the `biod` package for your target [Chrome OS board], the `biod` binary should be in the build directory: ```bash (chroot) $ emerge- biod ``` ```bash (chroot) $ ls /build//usr/bin/biod /build//usr/bin/biod ``` ### Update FPMCU_FIRMWARE `FPMCU_FIRMWARE` should be set to the set of fingerprint firmware that should be built and installed for the [Chrome OS board]. `FPMCU_FIRMWARE` is a [`USE_EXPAND` variable][`USE` flag], [defined in the base `make.defaults`][FPMCU_FIRMWARE make.defaults]. The `biod` ebuild uses the resulting [`USE` flags] to [determine which FPMCU release firmware to build][biod release firmware] and the [`chromeos-firmware-fpmcu` ebuild] uses the resulting [`USE` flags] to [determine which firmware to install][firmware ebuild] to the rootfs in `/opt/google/biod/fw`. Possible values for `FPMCU_FIRMWARE` can be found by looking at the `FIRMWARE_EC_BOARD` values in the [`chromeos-fpmcu-release*` ebuilds], which correspond to the [FPMCU hardware](#hardware). See the [Hatch baseboard `make.defaults`] for an example. #### Verifying FPMCU firmware is installed in the rootfs Once you have added the `FPMCU_FIRMWARE` flag and rebuilt the [`chromeos-firmware-fpmcu` ebuild], the firmware will show up in the the chroot: *** note **NOTE**: This requires access to the [internal manifest]. *** ```bash (chroot) $ emerge- chromeos-firmware-fpmcu ``` ```bash (chroot) $ ls /build//opt/google/biod/fw bloonchipper_v2.0.2626-3c315108.bin dartmonkey_v2.0.2887-311310808.bin ``` The above output assumes you selected the `bloonchipper` and `dartmonkey` firmware by setting `FPMCU_FIRMWARE="bloonchipper dartmonkey"`. The actual version numbers displayed will not necessarily match since the firmware is constantly updated. ### Update Chrome OS Config {#update-chromeos-config} With "unibuild", the same OS image (build) for a given [Chrome OS board] is used across multiple devices. Often there will be some devices that have a fingerprint sensor, some that do not, and even different sensors for the same board. Determining what fingerprint hardware is on a given [Chrome OS board] is thus done at runtime, using [Chrome OS Config]. The `fingerprint` config needs to be in the `model.yaml` for the given [Chrome OS board]. The [Chrome OS Config fingerprint] section describes the attributes for the `fingerprint` config in more detail. The [`ec_extras` attribute] needs to be set to the list of fingerprint firmware that should be built as part of the build. See the [`model.yaml` for the Hatch board][hatch model.yaml] as an example. Instead of crafting the `model.yaml` by hand, newer boards are moving to the [Chrome OS Project Configuration] model, where the config is generated using [Starlark]. The common [`create_fingerprint`] function can be used across models to configure the fingerprint settings. See the [Morphius `config.star`] for an example of how to call `create_fingerprint`. After you modify a `config.star` file you will need to [regenerate the config]. If you need to change many projects (e.g., modifying [`create_fingerprint`]), you can use the [`CLFactory`] tool. Once you have updated the config, you can test your changes by [running `cros_config`](#chromeos-config-fingerprint). The Chrome OS Config documentation has a [section on testing properties] that describes this in more detail. ### SKUs The fingerprint sensor may only be included on certain SKUs for a given device. The fingerprint code uses [Chrome OS Config] to determine whether a device has a fingerprint sensor or not. For each SKU, there is an associated [fingerprint config][Chrome OS Config fingerprint]. [Chrome OS Config] determines the [SKU information][Chrome OS Config SKU] (and thus the [fingerprint config][Chrome OS Config fingerprint]) from [CBI Info]. The SKU for a given device can be found by viewing `chrome://system/#platform_identity_sku`. [`common/fpsensor`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/common/fpsensor/ [`driver/fingerprint`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/driver/fingerprint [`nocturne_fp`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/nocturne_fp/ [`nami_fp`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/nami_fp/ [`hatch_fp`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/hatch_fp/ [`bloonchipper`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/bloonchipper/ [`dartmonkey`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/dartmonkey/ [hardware write protection]: ../write_protection.md [`flash_fp_mcu`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/util/flash_fp_mcu [`stm32mon`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/e1f3f89e7ea7945adddd0c2e6838f5e59856cff2/util/stm32mon.c#14 [`futility`]: https://chromium.googlesource.com/chromiumos/platform/vboot_reference/+/HEAD/futility/ [`sign_official_build.sh`]: https://chromium.googlesource.com/chromiumos/platform/vboot_reference/+/HEAD/scripts/image_signing/sign_official_build.sh [vboot_key_id]: https://chromium.googlesource.com/chromiumos/platform/vboot_reference/+/e7db36856ce418552637d1981c173d22dfe5bf39/firmware/2lib/include/2id.h#5 [vb2_public_key]: https://chromium.googlesource.com/chromiumos/platform/vboot_reference/+/e7db36856ce418552637d1981c173d22dfe5bf39/firmware/2lib/include/2rsa.h#14 [chatty-firmware-q]: https://groups.google.com/a/google.com/d/msg/chromeos-chatty-firmware/ZSg423wsFPg/26UbdGwjFQAJ [`fp_updater.sh`]: http://go/cros-fp-updater-nocturne-source [`bio_fw_updater`]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/biod/tools [`flashrom`]: https://chromium.googlesource.com/chromiumos/third_party/flashrom/ [STM32F412]: https://www.st.com/resource/en/reference_manual/dm00180369.pdf [STM32H743]: https://www.st.com/resource/en/reference_manual/dm00314099.pdf [`board/nocturne_fp/dev_key.pem`]: https://chromium.googlesource.com/chromiumos/platform/ec/+/HEAD/board/nocturne_fp/dev_key.pem [`timberslide`]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/timberslide [cros_ec_debugfs]: https://chromium.googlesource.com/chromiumos/third_party/kernel/+/9db44685934a2e4bc9180ea2de87a6c429672395/drivers/platform/chrome/cros_ec_debugfs.c [Fingerprint Factory Requirements]: ./fingerprint-factory-requirements.md [Chromium OS test image]: https://chromium.googlesource.com/chromiumos/platform/factory/+/HEAD/README.md#building-test-image [Chrome OS Config]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/chromeos-config/README.md [Chrome OS Config fingerprint]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/chromeos-config/README.md#fingerprint [section on testing properties]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/chromeos-config/README.md#adding-and-testing-new-properties [Chrome OS board]: https://chromium.googlesource.com/chromiumos/docs/+/HEAD/developer_guide.md#Select-a-board [biod chromium-os]: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/4ea72b588af3394cb9fd1c330dcf726472183dfd/virtual/target-chromium-os/target-chromium-os-1.ebuild#154 [hatch make.defaults]: https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/2f075f0e7ce09d3eb460f3c529da463a6201276c/overlay-hatch/profiles/base/make.defaults#22 [Hatch baseboard `make.defaults`]: https://chrome-internal.googlesource.com/chromeos/overlays/baseboard-hatch-private/+/HEAD/profiles/base/make.defaults#17 [hatch model.yaml]: https://chrome-internal.googlesource.com/chromeos/overlays/overlay-hatch-private/+/HEAD/chromeos-base/chromeos-config-bsp-hatch-private/files/model.yaml [`ec_extras` attribute]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/chromeos-config/README.md#build_targets [FPMCU_FIRMWARE make.defaults]: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/4ea72b588af3394cb9fd1c330dcf726472183dfd/profiles/base/make.defaults#157 [`USE` flag]: https://devmanual.gentoo.org/general-concepts/use-flags/index.html [`USE` flags]: https://devmanual.gentoo.org/general-concepts/use-flags/index.html [biod release firmware]: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/4ea72b588af3394cb9fd1c330dcf726472183dfd/chromeos-base/biod/biod-9999.ebuild#49 [`chromeos-firmware-fpmcu` ebuild]: https://chrome-internal.googlesource.com/chromeos/overlays/chromeos-overlay/+/HEAD/chromeos-base/chromeos-firmware-fpmcu/chromeos-firmware-fpmcu-9999.ebuild [firmware ebuild]: https://chrome-internal.googlesource.com/chromeos/overlays/chromeos-overlay/+/HEAD/chromeos-base/chromeos-firmware-fpmcu/chromeos-firmware-fpmcu-9999.ebuild#40 [`chromeos-fpmcu-release*` ebuilds]: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/HEAD/sys-firmware [internal manifest]: https://chromium.googlesource.com/chromiumos/docs/+/HEAD/developer_guide.md#get-the-source-code [Unit Tests]: ../unit_tests.md [run the unit tests]: ../unit_tests.md#running [Measuring Power]: ./fingerprint-dev-for-partners.md#measure-power [dragonclaw]: ./fingerprint-dev-for-partners.md#fpmcu-dev-board [FPC 1145]: ../../driver/fingerprint/fpc/libfp/fpc1145_private.h [FPC 1025]: ../../driver/fingerprint/fpc/bep/fpc1025_private.h [FPC 1145 Template Size]: https://chromium.googlesource.com/chromiumos/platform/ec/+/127521b109be8aac352e80e319e46ed123360408/driver/fingerprint/fpc/libfp/fpc1145_private.h#46 [FPC 1025 Template Size]: https://chromium.googlesource.com/chromiumos/platform/ec/+/127521b109be8aac352e80e319e46ed123360408/driver/fingerprint/fpc/bep/fpc1025_private.h#44 [Dragonclaw v0.2]: ./fingerprint-dev-for-partners.md#fpmcu-dev-board [Icetower v0.2]: ./fingerprint-dev-for-partners.md#fpmcu-dev-board [Nucleo F412ZG]: https://www.digikey.com/en/products/detail/stmicroelectronics/NUCLEO-F412ZG/6137573 [Nucleo H743ZI2]: https://www.digikey.com/en/products/detail/stmicroelectronics/NUCLEO-H743ZI2/10130892 [CBI Info]: https://chromium.googlesource.com/chromiumos/docs/+/HEAD/design_docs/cros_board_info.md [Chrome OS Config SKU]: https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/chromeos-config/README.md#identity [Chrome OS Project Configuration]: https://chromium.googlesource.com/chromiumos/config/+/HEAD/README.md [Starlark]: https://docs.bazel.build/versions/master/skylark/language.html [`create_fingerprint`]: https://chromium.googlesource.com/chromiumos/config/+/e1fa0d7f56eb3dd6e9378e4326de086ada46b7d3/util/hw_topology.star#444 [Morphius `config.star`]: https://chrome-internal.googlesource.com/chromeos/project/zork/morphius/+/593b657a776ed6b320c826916adc9cd845faf709/config.star#85 [regenerate the config]: https://chromium.googlesource.com/chromiumos/config/+/HEAD/README.md#making-configuration-changes-for-your-project [`CLFactory`]: https://chromium.googlesource.com/chromiumos/config/+/HEAD/README.md#making-bulk-changes-across-repos