docs/fingerprint: Instructions on verifying firmware and biod install

Documentation that describes how to verify that biod and the FPMCU
firmware get installed to the rootfs for a given Chrome OS board.

BRANCH=none
BUG=none
TEST=view in gitiles

Change-Id: I757c6a0bf0f43f6248430dd3f8248783f9b55d23
Signed-off-by: Tom Hughes <tomhughes@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2020513
Commit-Queue: Craig Hesling <hesling@chromium.org>
Reviewed-by: Craig Hesling <hesling@chromium.org>

1 files changed, 40 insertions, 1 deletions

diff --git a/docs/fingerprint/fingerprint.md b/docs/fingerprint/fingerprint.md
index 8cf55d4888..b92559acf6 100644
--- a/docs/fingerprint/fingerprint.md
+++ b/docs/fingerprint/fingerprint.md
@@ -326,6 +326,20 @@ 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-<BOARD> biod
+```
+
+```bash
+(chroot) $ ls /build/<BOARD>/usr/bin/biod
+/build/<BOARD>/usr/bin/biod
+```
+
 ### Update FPMCU_FIRMWARE
 
 `FPMCU_FIRMWARE` should be set to the set of fingerprint firmware that should be
@@ -336,7 +350,7 @@ built and installed for the [Chrome OS board].
 
 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
+[`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`.
 
@@ -346,6 +360,29 @@ 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-<BOARD> chromeos-firmware-fpmcu
+```
+
+```bash
+(chroot) $ ls /build/<BOARD>/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
@@ -408,5 +445,7 @@ detail.
 [`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/+/refs/heads/master/chromeos-base/chromeos-firmware-fpmcu/chromeos-firmware-fpmcu-9999.ebuild
 [firmware ebuild]: https://chrome-internal.googlesource.com/chromeos/overlays/chromeos-overlay/+/refs/heads/master/chromeos-base/chromeos-firmware-fpmcu/chromeos-firmware-fpmcu-9999.ebuild#40
 [`chromeos-fpmcu-release*` ebuilds]: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/master/sys-firmware
+[internal manifest]: https://chromium.googlesource.com/chromiumos/docs/+/master/developer_guide.md#get-the-source-code