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The Recovery Image
==================
Quick turn-around testing
-------------------------
* Devices using recovery-as-boot (e.g. Pixels, which set BOARD\_USES\_RECOVERY\_AS\_BOOT)
# After setting up environment and lunch.
m -j bootimage
adb reboot bootloader
# Pixel devices don't support booting into recovery mode with `fastboot boot`.
fastboot flash boot
# Manually choose `Recovery mode` from bootloader menu.
* Devices with a separate recovery image (e.g. Nexus)
# After setting up environment and lunch.
mm -j && m ramdisk-nodeps && m recoveryimage-nodeps
adb reboot bootloader
# To boot into the new recovery image without flashing the recovery partition:
fastboot boot $ANDROID_PRODUCT_OUT/recovery.img
Running the tests
-----------------
# After setting up environment and lunch.
mmma -j bootable/recovery
# Running the tests on device (under normal boot).
adb root
adb sync data
# 32-bit device
adb shell /data/nativetest/recovery_unit_test/recovery_unit_test
# Or 64-bit device
adb shell /data/nativetest64/recovery_unit_test/recovery_unit_test
Running the manual tests
------------------------
`recovery-refresh` and `recovery-persist` executables exist only on systems without
/cache partition. And we need to follow special steps to run tests for them.
- Execute the test on an A/B device first. The test should fail but it will log
some contents to pmsg.
- Reboot the device immediately and run the test again. The test should save the
contents of pmsg buffer into /data/misc/recovery/inject.txt. Test will pass if
this file has expected contents.
Using `adb` under recovery
--------------------------
When running recovery image from debuggable builds (i.e. `-eng` or `-userdebug` build variants, or
`ro.debuggable=1` in `/prop.default`), `adbd` service is enabled and started by default, which
allows `adb` communication. A device should be listed under `adb devices`, either in `recovery` or
`sideload` state.
$ adb devices
List of devices attached
1234567890abcdef recovery
Although `/system/bin/adbd` is built from the same code base as the one in the normal boot, only a
subset of `adb` commands are meaningful under recovery, such as `adb root`, `adb shell`, `adb push`,
`adb pull` etc. Since Android Q, `adb shell` no longer requires manually mounting `/system` from
recovery menu.
## Troubleshooting
### `adb devices` doesn't show the device.
$ adb devices
List of devices attached
* Ensure `adbd` is built and running.
By default, `adbd` is always included into recovery image, as `/system/bin/adbd`. `init` starts
`adbd` service automatically only in debuggable builds. This behavior is controlled by the recovery
specific `/init.rc`, whose source code is at `bootable/recovery/etc/init.rc`.
The best way to confirm a running `adbd` is by checking the serial output, which shows a service
start log as below.
[ 18.961986] c1 1 init: starting service 'adbd'...
* Ensure USB gadget has been enabled.
If `adbd` service has been started but device not shown under `adb devices`, use `lsusb(8)` (on
host) to check if the device is visible to the host.
`bootable/recovery/etc/init.rc` disables Android USB gadget (via sysfs) as part of the `fs` action
trigger, and will only re-enable it in debuggable builds (the `on property` rule will always run
_after_ `on fs`).
on fs
write /sys/class/android_usb/android0/enable 0
# Always start adbd on userdebug and eng builds
on property:ro.debuggable=1
write /sys/class/android_usb/android0/enable 1
start adbd
If device is using [configfs](https://www.kernel.org/doc/Documentation/usb/gadget_configfs.txt),
check if configfs has been properly set up in init rc scripts. See the [example
configuration](https://android.googlesource.com/device/google/wahoo/+/master/init.recovery.hardware.rc)
for Pixel 2 devices. Note that the flag set via sysfs (i.e. the one above) is no-op when using
configfs.
### `adb devices` shows the device, but in `unauthorized` state.
$ adb devices
List of devices attached
1234567890abcdef unauthorized
recovery image doesn't honor the USB debugging toggle and the authorizations added under normal boot
(because such authorization data stays in /data, which recovery doesn't mount), nor does it support
authorizing a host device under recovery. We can use one of the following options instead.
* **Option 1 (Recommended):** Authorize a host device with adb vendor keys.
For debuggable builds, an RSA keypair can be used to authorize a host device that has the private
key. The public key, defined via `PRODUCT_ADB_KEYS`, will be copied to `/adb_keys`. When starting
the host-side `adbd`, make sure the filename (or the directory) of the matching private key has been
added to `$ADB_VENDOR_KEYS`.
$ export ADB_VENDOR_KEYS=/path/to/adb/private/key
$ adb kill-server
$ adb devices
`-user` builds filter out `PRODUCT_ADB_KEYS`, so no `/adb_keys` will be included there.
Note that this mechanism applies to both of normal boot and recovery modes.
* **Option 2:** Allow `adbd` to connect without authentication.
* `adbd` is compiled with `ALLOW_ADBD_NO_AUTH` (only on debuggable builds).
* `ro.adb.secure` has a value of `0`.
Both of the two conditions need to be satisfied. Although `ro.adb.secure` is a runtime property, its
value is set at build time (written into `/prop.default`). It defaults to `1` on `-user` builds, and
`0` for other build variants. The value is overridable via `PRODUCT_DEFAULT_PROPERTY_OVERRIDES`.
Localization of the background texts
------------------------------------
The recovery image supports localization of several background texts, e.g. installing, error,
factory reset warnings, etc. For devices using `xxhdpi` and `xxxhdpi`, the build system generates
these localization images dynamically since android-10 when building the recovery image. While
the static images under res-*dpi/images/ is used for other display resolutions and as a
backup.
Check the invocation of the image_generator tool in the [makefile]. And the detailed usage of the
image_generator is documented [here](./tools/image_generator/README.md).
[makefile]: https://android.googlesource.com/platform/build/+/refs/heads/master/core/Makefile#1800
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