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.
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AOSP offers the following options for storing configuration information on a
device:
System properties
Hardware abstraction layer (HAL) properties
System config XML files
Resource overlays (static and runtime)
System properties
System properties are string key/value pairs stored in the build.prop
global dictionary. System properties are system-wide resources that are easy to
use and have a low performance overhead. When using system properties, you don't
need to use interprocess communication (IPC) even if a system property is shared
across multiple processes. However, system properties are similar to global
variables and can be harmful when misused. The misuse of system properties can
result in issues such as security vulnerabilities and apps becoming inaccessible
to users. Before using system properties to store configuration information,
consider the other configuration options.
When the source of truth for a configuration is from a hardware component on a
device, the HAL for the hardware must provide the information for that
component. Define a new HAL method in the existing HAL for accessing the
configuration. For further information on developing a HAL, see
AIDL for HALs.
System config XML files
When the configuration data is static but complicated (structured), consider
using XML or other such formats for the configuration data. Ensure that the
file schema remains stable. For XML files, you can use
xsd_config
to keep the schema stable, and to take advantage of an autogenerated XML
parser.
Resource overlay
You can use resource overlays to customize a product. There are two types of
resource overlays:
Runtime resource overlay (RRO) is used to change the resource values
of a target package at runtime. For example, an app installed on the system
image might change its behavior based upon the value of a resource. Rather than
hardcoding the resource value at build time, an RRO installed on a different
partition can change the values of the app's resources at runtime. For more
information on RROs, see
Change the value of an app's resources at runtime.
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Last updated 2025-06-12 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-06-12 UTC."],[],[],null,["# Configuration overview\n\nAOSP offers the following options for storing configuration information on a\ndevice:\n\n- System properties\n- Hardware abstraction layer (HAL) properties\n- System config XML files\n- Resource overlays (static and runtime)\n\nSystem properties\n-----------------\n\n*System properties* are string key/value pairs stored in the `build.prop`\nglobal dictionary. System properties are system-wide resources that are easy to\nuse and have a low performance overhead. When using system properties, you don't\nneed to use interprocess communication (IPC) even if a system property is shared\nacross multiple processes. However, system properties are similar to global\nvariables and can be harmful when misused. The misuse of system properties can\nresult in issues such as security vulnerabilities and apps becoming inaccessible\nto users. Before using system properties to store configuration information,\nconsider the other configuration options.\n\nFor further information on system properties, see\n[Add system properties](/docs/core/architecture/configuration/add-system-properties)\n| **Note:** Previous to Android 10, AOSP used a ConfigStore HAL to store system properties. ConfigStore HAL is deprecated and should no longer be used. For information on the ConfigStore HAL, refer to [ConfigStore HAL](/docs/core/architecture/configuration/archive).\n\nHAL properties\n--------------\n\nWhen the source of truth for a configuration is from a hardware component on a\ndevice, the HAL for the hardware must provide the information for that\ncomponent. Define a new HAL method in the existing HAL for accessing the\nconfiguration. For further information on developing a HAL, see\n[AIDL for HALs](/docs/core/architecture/aidl/aidl-hals).\n| **Note:** Don't configure the HAL to use system properties as a side-channel communication mechanism for HALs.\n\nSystem config XML files\n-----------------------\n\nWhen the configuration data is static but complicated (structured), consider\nusing XML or other such formats for the configuration data. Ensure that the\nfile schema remains stable. For XML files, you can use\n[`xsd_config`](/docs/core/architecture/config-file-schema-api#config-build-rule)\nto keep the schema stable, and to take advantage of an autogenerated XML\nparser.\n\nResource overlay\n----------------\n\nYou can use resource overlays to customize a product. There are two types of\nresource overlays:\n\n- *Standard resource overlay* used to customize a product at build time. Foris\n information on standard resource overlays, see\n [Customizing the build with resource overlays](/docs/setup/create/new-device#use-resource-overlays).\n\n- *Runtime resource overlay (RRO)* is used to change the resource values\n of a target package at runtime. For example, an app installed on the system\n image might change its behavior based upon the value of a resource. Rather than\n hardcoding the resource value at build time, an RRO installed on a different\n partition can change the values of the app's resources at runtime. For more\n information on RROs, see\n [Change the value of an app's resources at runtime](/docs/core/runtime/rros)."]]
