Starting March 27, 2025, we recommend using android-latest-release instead of aosp-main to build and contribute to AOSP. For more information, see Changes to AOSP.
Custom device development
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This page explains several tasks you might need to perform if you're
setting up a build for your own device.
Create a custom flash configuration
Fastboot instructions are defined in an artifact called fastboot-info.txt. If
you build multiple targets, you'll have multiple fastboot-info.txt files in
the $OUT_DIR. And, $ANDROID_PRODUCT_OUT points to the
most current target you built. This page list the tasks for fastboot to execute
and can be regenerated using m fastboot_info. You can introduce custom
flashing logic by modifying the fastboot-info.txt file.
The fastboot-info.txt file supports these commands:
flash %s: Flashes a given partition. Optional arguments include
--slot-other,filename_path, and--apply-vbmeta`.update-super: Updates the super partition.if-wipe: Conditionally runs some other component if a wipe is specified.erase %s: Erases a given partition (can only be used in conjunction
with if-wipe -> eg. if-wipe erase cache).
Determine flash lock state
If you're building a custom flashboot daemon (flashbootd) for a device, you need
to be able to obtain bootloader and bootloader lock state. The
getFlashLockState() @SystemApi transmits the bootloader
state and the PersistentDataBlockManager.getFlashLockState() system
API returns the bootloader's lock status on compliant devices.
| Return value |
Conditions |
FLASH_LOCK_UNKNOWN |
Returned only by devices upgrading to Android 7.x or higher that didn't
previously support the bootloader changes required to get the flash lock
status if they supported flashing lock/unlock capability.
- New devices running Android 7.x or higher must be in either a
FLASH_LOCK_LOCKED or FLASH_LOCK_UNLOCKED state.
- Devices upgrading to Android 7.x or higher that don't support flashing
unlock/lock capability should return a
FLASH_LOCK_LOCKED state.
|
FLASH_LOCK_LOCKED |
Returned by any device that doesn't support flashing
lock/unlock (that is, the device is always locked), or any device that supports
flashing lock/unlock and is in the locked state. |
FLASH_LOCK_UNLOCKED |
Returned by any device that supports flashing lock/unlock and is
in the unlocked state. |
Manufacturers should test the values returned by devices with locked and
unlocked bootloaders. For example, AOSP
contains a reference implementation that returns a value based on the
ro.boot.flash.locked boot property. Example code is located in the
following directories:
frameworks/base/services/core/java/com/android/server/PersistentDataBlockService.javaframeworks/base/core/java/android/service/persistentdata/PersistentDataBlockManager.java
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-08-29 UTC.
[null,null,["Last updated 2025-08-29 UTC."],[],[],null,["# Custom device development\n\nThis page explains several tasks you might need to perform if you're\nsetting up a build for your own device.\n\nCreate a custom flash configuration\n-----------------------------------\n\nFastboot instructions are defined in an artifact called `fastboot-info.txt`. If\nyou build multiple targets, you'll have multiple `fastboot-info.txt` files in\nthe \u003cvar translate=\"no\"\u003e$OUT_DIR\u003c/var\u003e. And, `$ANDROID_PRODUCT_OUT` points to the\nmost current target you built. This page list the tasks for fastboot to execute\nand can be regenerated using `m fastboot_info`. You can introduce custom\nflashing logic by modifying the `fastboot-info.txt` file.\n\nThe `fastboot-info.txt` file supports these commands:\n\n- `flash %s`: Flashes a given partition. Optional arguments include `--slot-other,`\u003cvar translate=\"no\"\u003efilename_path\u003c/var\u003e`, and`--apply-vbmeta\\`.\n- `update-super`: Updates the super partition.\n- `if-wipe`: Conditionally runs some other component if a wipe is specified.\n- `erase %s`: Erases a given partition (can only be used in conjunction with `if-wipe` -\\\u003e eg. `if-wipe erase cache`).\n\nDetermine flash lock state\n--------------------------\n\nIf you're building a custom flashboot daemon (flashbootd) for a device, you need\nto be able to obtain bootloader and bootloader lock state. The\n`getFlashLockState()` `@SystemApi` transmits the bootloader\nstate and the `PersistentDataBlockManager.getFlashLockState()` system\nAPI returns the bootloader's lock status on compliant devices.\n\n| Return value | Conditions |\n|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| `FLASH_LOCK_UNKNOWN` | Returned only by devices upgrading to Android 7.x or higher that didn't previously support the bootloader changes required to get the flash lock status if they supported flashing lock/unlock capability. - New devices running Android 7.x or higher must be in either a `FLASH_LOCK_LOCKED` or `FLASH_LOCK_UNLOCKED` state. - Devices upgrading to Android 7.x or higher that don't support flashing unlock/lock capability should return a `FLASH_LOCK_LOCKED` state. |\n| `FLASH_LOCK_LOCKED` | Returned by any device that doesn't support flashing lock/unlock (that is, the device is always locked), or any device that supports flashing lock/unlock and is in the locked state. |\n| `FLASH_LOCK_UNLOCKED` | Returned by any device that supports flashing lock/unlock and is in the unlocked state. |\n\nManufacturers should test the values returned by devices with locked and\nunlocked bootloaders. For example, AOSP\ncontains a reference implementation that returns a value based on the\n`ro.boot.flash.locked` boot property. Example code is located in the\nfollowing directories:\n\n- `frameworks/base/services/core/java/com/android/server/PersistentDataBlockService.java`\n- `frameworks/base/core/java/android/service/persistentdata/PersistentDataBlockManager.java`"]]
