Merge "Move to .md files for even trivial documentation."
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init/README.md
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init/README.md
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Android Init Language
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---------------------
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The Android Init Language consists of five broad classes of statements:
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Actions, Commands, Services, Options, and Imports.
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All of these are line-oriented, consisting of tokens separated by
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whitespace. The c-style backslash escapes may be used to insert
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whitespace into a token. Double quotes may also be used to prevent
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whitespace from breaking text into multiple tokens. The backslash,
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when it is the last character on a line, may be used for line-folding.
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Lines which start with a # (leading whitespace allowed) are comments.
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Actions and Services implicitly declare a new section. All commands
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or options belong to the section most recently declared. Commands
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or options before the first section are ignored.
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Actions and Services have unique names. If a second Action is defined
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with the same name as an existing one, its commands are appended to
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the commands of the existing action. If a second Service is defined
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with the same name as an existing one, it is ignored and an error
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message is logged.
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Init .rc Files
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--------------
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The init language is used in plain text files that take the .rc file
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extension. These are typically multiple of these in multiple
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locations on the system, described below.
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/init.rc is the primary .rc file and is loaded by the init executable
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at the beginning of its execution. It is responsible for the initial
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set up of the system. It imports /init.${ro.hardware}.rc which is the
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primary vendor supplied .rc file.
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During the mount\_all command, the init executable loads all of the
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files contained within the /{system,vendor,odm}/etc/init/ directories.
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These directories are intended for all Actions and Services used after
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file system mounting.
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One may specify paths in the mount\_all command line to have it import
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.rc files at the specified paths instead of the default ones listed above.
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This is primarily for supporting factory mode and other non-standard boot
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modes. The three default paths should be used for the normal boot process.
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The intention of these directories is:
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1. /system/etc/init/ is for core system items such as
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SurfaceFlinger, MediaService, and logcatd.
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2. /vendor/etc/init/ is for SoC vendor items such as actions or
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daemons needed for core SoC functionality.
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3. /odm/etc/init/ is for device manufacturer items such as
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actions or daemons needed for motion sensor or other peripheral
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functionality.
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All services whose binaries reside on the system, vendor, or odm
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partitions should have their service entries placed into a
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corresponding init .rc file, located in the /etc/init/
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directory of the partition where they reside. There is a build
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system macro, LOCAL\_INIT\_RC, that handles this for developers. Each
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init .rc file should additionally contain any actions associated with
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its service.
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An example is the logcatd.rc and Android.mk files located in the
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system/core/logcat directory. The LOCAL\_INIT\_RC macro in the
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Android.mk file places logcatd.rc in /system/etc/init/ during the
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build process. Init loads logcatd.rc during the mount\_all command and
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allows the service to be run and the action to be queued when
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appropriate.
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This break up of init .rc files according to their daemon is preferred
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to the previously used monolithic init .rc files. This approach
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ensures that the only service entries that init reads and the only
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actions that init performs correspond to services whose binaries are in
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fact present on the file system, which was not the case with the
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monolithic init .rc files. This additionally will aid in merge
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conflict resolution when multiple services are added to the system, as
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each one will go into a separate file.
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There are two options "early" and "late" in mount\_all command
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which can be set after optional paths. With "--early" set, the
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init executable will skip mounting entries with "latemount" flag
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and triggering fs encryption state event. With "--late" set,
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init executable will only mount entries with "latemount" flag but skip
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importing rc files. By default, no option is set, and mount\_all will
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process all entries in the given fstab.
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Actions
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-------
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Actions are named sequences of commands. Actions have a trigger which
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is used to determine when the action should occur. When an event
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occurs which matches an action's trigger, that action is added to
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the tail of a to-be-executed queue (unless it is already on the
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queue).
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Each action in the queue is dequeued in sequence and each command in
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that action is executed in sequence. Init handles other activities
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(device creation/destruction, property setting, process restarting)
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"between" the execution of the commands in activities.
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Actions take the form of:
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on <trigger> [&& <trigger>]*
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<command>
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<command>
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<command>
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Services
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--------
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Services are programs which init launches and (optionally) restarts
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when they exit. Services take the form of:
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service <name> <pathname> [ <argument> ]*
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<option>
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<option>
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...
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Options
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-------
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Options are modifiers to services. They affect how and when init
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runs the service.
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`console [<console>]`
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> This service needs a console. The optional second parameter chooses a
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specific console instead of the default. The default "/dev/console" can
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be changed by setting the "androidboot.console" kernel parameter. In
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all cases the leading "/dev/" should be omitted, so "/dev/tty0" would be
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specified as just "console tty0".
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`critical`
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> This is a device-critical service. If it exits more than four times in
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four minutes, the device will reboot into recovery mode.
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`disabled`
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> This service will not automatically start with its class.
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It must be explicitly started by name.
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`setenv <name> <value>`
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|
> Set the environment variable _name_ to _value_ in the launched process.
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`socket <name> <type> <perm> [ <user> [ <group> [ <seclabel> ] ] ]`
|
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> Create a unix domain socket named /dev/socket/_name_ and pass its fd to the
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launched process. _type_ must be "dgram", "stream" or "seqpacket". User and
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group default to 0. 'seclabel' is the SELinux security context for the
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socket. It defaults to the service security context, as specified by
|
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seclabel or computed based on the service executable file security context.
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For native executables see libcutils android\_get\_control\_socket().
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`file <path> <type>`
|
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> Open a file path and pass its fd to the launched process. _type_ must be
|
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"r", "w" or "rw". For native executables see libcutils
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android\_get\_control\_file().
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`user <username>`
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> Change to 'username' before exec'ing this service.
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Currently defaults to root. (??? probably should default to nobody)
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As of Android M, processes should use this option even if they
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require Linux capabilities. Previously, to acquire Linux
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capabilities, a process would need to run as root, request the
|
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|
capabilities, then drop to its desired uid. There is a new
|
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|
mechanism through fs\_config that allows device manufacturers to add
|
||||||
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Linux capabilities to specific binaries on a file system that should
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be used instead. This mechanism is described on
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<http://source.android.com/devices/tech/config/filesystem.html>. When
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using this new mechanism, processes can use the user option to
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select their desired uid without ever running as root.
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As of Android O, processes can also request capabilities directly in their .rc
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files. See the "capabilities" option below.
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`group <groupname> [ <groupname>\* ]`
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> Change to 'groupname' before exec'ing this service. Additional
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groupnames beyond the (required) first one are used to set the
|
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supplemental groups of the process (via setgroups()).
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Currently defaults to root. (??? probably should default to nobody)
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`capabilities <capability> [ <capability>\* ]`
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> Set capabilities when exec'ing this service. 'capability' should be a Linux
|
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capability without the "CAP\_" prefix, like "NET\_ADMIN" or "SETPCAP". See
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http://man7.org/linux/man-pages/man7/capabilities.7.html for a list of Linux
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capabilities.
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`seclabel <seclabel>`
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> Change to 'seclabel' before exec'ing this service.
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Primarily for use by services run from the rootfs, e.g. ueventd, adbd.
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Services on the system partition can instead use policy-defined transitions
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based on their file security context.
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If not specified and no transition is defined in policy, defaults to the init context.
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`oneshot`
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> Do not restart the service when it exits.
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||||||
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`class <name>`
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> Specify a class name for the service. All services in a
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named class may be started or stopped together. A service
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is in the class "default" if one is not specified via the
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class option.
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`onrestart`
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> Execute a Command (see below) when service restarts.
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`writepid <file...>`
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> Write the child's pid to the given files when it forks. Meant for
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cgroup/cpuset usage.
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`priority <priority>`
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> Scheduling priority of the service process. This value has to be in range
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-20 to 19. Default priority is 0. Priority is set via setpriority().
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`namespace <pid|mnt>`
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> Enter a new PID or mount namespace when forking the service.
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||||||
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`oom_score_adjust <value>`
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> Sets the child's /proc/self/oom\_score\_adj to the specified value,
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which must range from -1000 to 1000.
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|
Triggers
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|
--------
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|
Triggers are strings which can be used to match certain kinds of
|
||||||
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events and used to cause an action to occur.
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||||||
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Triggers are subdivided into event triggers and property triggers.
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||||||
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Event triggers are strings triggered by the 'trigger' command or by
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the QueueEventTrigger() function within the init executable. These
|
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take the form of a simple string such as 'boot' or 'late-init'.
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|
||||||
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Property triggers are strings triggered when a named property changes
|
||||||
|
value to a given new value or when a named property changes value to
|
||||||
|
any new value. These take the form of 'property:<name>=<value>' and
|
||||||
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'property:<name>=\*' respectively. Property triggers are additionally
|
||||||
|
evaluated and triggered accordingly during the initial boot phase of
|
||||||
|
init.
|
||||||
|
|
||||||
|
An Action can have multiple property triggers but may only have one
|
||||||
|
event trigger.
|
||||||
|
|
||||||
|
For example:
|
||||||
|
`on boot && property:a=b` defines an action that is only executed when
|
||||||
|
the 'boot' event trigger happens and the property a equals b.
|
||||||
|
|
||||||
|
`on property:a=b && property:c=d` defines an action that is executed
|
||||||
|
at three times:
|
||||||
|
|
||||||
|
1. During initial boot if property a=b and property c=d.
|
||||||
|
2. Any time that property a transitions to value b, while property c already equals d.
|
||||||
|
3. Any time that property c transitions to value d, while property a already equals b.
|
||||||
|
|
||||||
|
|
||||||
|
Commands
|
||||||
|
--------
|
||||||
|
|
||||||
|
`bootchart [start|stop]`
|
||||||
|
> Start/stop bootcharting. These are present in the default init.rc files,
|
||||||
|
but bootcharting is only active if the file /data/bootchart/enabled exists;
|
||||||
|
otherwise bootchart start/stop are no-ops.
|
||||||
|
|
||||||
|
`chmod <octal-mode> <path>`
|
||||||
|
> Change file access permissions.
|
||||||
|
|
||||||
|
`chown <owner> <group> <path>`
|
||||||
|
> Change file owner and group.
|
||||||
|
|
||||||
|
`class_start <serviceclass>`
|
||||||
|
> Start all services of the specified class if they are
|
||||||
|
not already running.
|
||||||
|
|
||||||
|
`class_stop <serviceclass>`
|
||||||
|
> Stop and disable all services of the specified class if they are
|
||||||
|
currently running.
|
||||||
|
|
||||||
|
`class_reset <serviceclass>`
|
||||||
|
> Stop all services of the specified class if they are
|
||||||
|
currently running, without disabling them. They can be restarted
|
||||||
|
later using `class_start`.
|
||||||
|
|
||||||
|
`copy <src> <dst>`
|
||||||
|
> Copies a file. Similar to write, but useful for binary/large
|
||||||
|
amounts of data.
|
||||||
|
|
||||||
|
`domainname <name>`
|
||||||
|
> Set the domain name.
|
||||||
|
|
||||||
|
`enable <servicename>`
|
||||||
|
> Turns a disabled service into an enabled one as if the service did not
|
||||||
|
specify disabled.
|
||||||
|
If the service is supposed to be running, it will be started now.
|
||||||
|
Typically used when the bootloader sets a variable that indicates a specific
|
||||||
|
service should be started when needed. E.g.
|
||||||
|
|
||||||
|
on property:ro.boot.myfancyhardware=1
|
||||||
|
enable my_fancy_service_for_my_fancy_hardware
|
||||||
|
|
||||||
|
`exec [ <seclabel> [ <user> [ <group>\* ] ] ] -- <command> [ <argument>\* ]`
|
||||||
|
> Fork and execute command with the given arguments. The command starts
|
||||||
|
after "--" so that an optional security context, user, and supplementary
|
||||||
|
groups can be provided. No other commands will be run until this one
|
||||||
|
finishes. _seclabel_ can be a - to denote default.
|
||||||
|
|
||||||
|
`export <name> <value>`
|
||||||
|
> Set the environment variable _name_ equal to _value_ in the
|
||||||
|
global environment (which will be inherited by all processes
|
||||||
|
started after this command is executed)
|
||||||
|
|
||||||
|
`hostname <name>`
|
||||||
|
> Set the host name.
|
||||||
|
|
||||||
|
`ifup <interface>`
|
||||||
|
> Bring the network interface _interface_ online.
|
||||||
|
|
||||||
|
`insmod [-f] <path> [<options>]`
|
||||||
|
> Install the module at _path_ with the specified options.
|
||||||
|
-f: force installation of the module even if the version of the running kernel
|
||||||
|
and the version of the kernel for which the module was compiled do not match.
|
||||||
|
|
||||||
|
`load_all_props`
|
||||||
|
> Loads properties from /system, /vendor, et cetera.
|
||||||
|
This is included in the default init.rc.
|
||||||
|
|
||||||
|
`load_persist_props`
|
||||||
|
> Loads persistent properties when /data has been decrypted.
|
||||||
|
This is included in the default init.rc.
|
||||||
|
|
||||||
|
`loglevel <level>`
|
||||||
|
> Sets the kernel log level to level. Properties are expanded within _level_.
|
||||||
|
|
||||||
|
`mkdir <path> [mode] [owner] [group]`
|
||||||
|
> Create a directory at _path_, optionally with the given mode, owner, and
|
||||||
|
group. If not provided, the directory is created with permissions 755 and
|
||||||
|
owned by the root user and root group. If provided, the mode, owner and group
|
||||||
|
will be updated if the directory exists already.
|
||||||
|
|
||||||
|
`mount_all <fstab> [ <path> ]\* [--<option>]`
|
||||||
|
> Calls fs\_mgr\_mount\_all on the given fs\_mgr-format fstab and imports .rc files
|
||||||
|
at the specified paths (e.g., on the partitions just mounted) with optional
|
||||||
|
options "early" and "late".
|
||||||
|
Refer to the section of "Init .rc Files" for detail.
|
||||||
|
|
||||||
|
`mount <type> <device> <dir> [ <flag>\* ] [<options>]`
|
||||||
|
> Attempt to mount the named device at the directory _dir_
|
||||||
|
_flag_s include "ro", "rw", "remount", "noatime", ...
|
||||||
|
_options_ include "barrier=1", "noauto\_da\_alloc", "discard", ... as
|
||||||
|
a comma separated string, eg: barrier=1,noauto\_da\_alloc
|
||||||
|
|
||||||
|
`powerctl`
|
||||||
|
> Internal implementation detail used to respond to changes to the
|
||||||
|
"sys.powerctl" system property, used to implement rebooting.
|
||||||
|
|
||||||
|
`restart <service>`
|
||||||
|
> Like stop, but doesn't disable the service.
|
||||||
|
|
||||||
|
`restorecon <path> [ <path>\* ]`
|
||||||
|
> Restore the file named by _path_ to the security context specified
|
||||||
|
in the file\_contexts configuration.
|
||||||
|
Not required for directories created by the init.rc as these are
|
||||||
|
automatically labeled correctly by init.
|
||||||
|
|
||||||
|
`restorecon_recursive <path> [ <path>\* ]`
|
||||||
|
> Recursively restore the directory tree named by _path_ to the
|
||||||
|
security contexts specified in the file\_contexts configuration.
|
||||||
|
|
||||||
|
`rm <path>`
|
||||||
|
> Calls unlink(2) on the given path. You might want to
|
||||||
|
use "exec -- rm ..." instead (provided the system partition is
|
||||||
|
already mounted).
|
||||||
|
|
||||||
|
`rmdir <path>`
|
||||||
|
> Calls rmdir(2) on the given path.
|
||||||
|
|
||||||
|
`setprop <name> <value>`
|
||||||
|
> Set system property _name_ to _value_. Properties are expanded
|
||||||
|
within _value_.
|
||||||
|
|
||||||
|
`setrlimit <resource> <cur> <max>`
|
||||||
|
> Set the rlimit for a resource.
|
||||||
|
|
||||||
|
`start <service>`
|
||||||
|
> Start a service running if it is not already running.
|
||||||
|
|
||||||
|
`stop <service>`
|
||||||
|
> Stop a service from running if it is currently running.
|
||||||
|
|
||||||
|
`swapon_all <fstab>`
|
||||||
|
> Calls fs\_mgr\_swapon\_all on the given fstab file.
|
||||||
|
|
||||||
|
`symlink <target> <path>`
|
||||||
|
> Create a symbolic link at _path_ with the value _target_
|
||||||
|
|
||||||
|
`sysclktz <mins_west_of_gmt>`
|
||||||
|
> Set the system clock base (0 if system clock ticks in GMT)
|
||||||
|
|
||||||
|
`trigger <event>`
|
||||||
|
> Trigger an event. Used to queue an action from another
|
||||||
|
action.
|
||||||
|
|
||||||
|
`umount <path>`
|
||||||
|
> Unmount the filesystem mounted at that path.
|
||||||
|
|
||||||
|
`verity_load_state`
|
||||||
|
> Internal implementation detail used to load dm-verity state.
|
||||||
|
|
||||||
|
`verity_update_state <mount-point>`
|
||||||
|
> Internal implementation detail used to update dm-verity state and
|
||||||
|
set the partition._mount-point_.verified properties used by adb remount
|
||||||
|
because fs\_mgr can't set them directly itself.
|
||||||
|
|
||||||
|
`wait <path> [ <timeout> ]`
|
||||||
|
> Poll for the existence of the given file and return when found,
|
||||||
|
or the timeout has been reached. If timeout is not specified it
|
||||||
|
currently defaults to five seconds.
|
||||||
|
|
||||||
|
`write <path> <content>`
|
||||||
|
> Open the file at _path_ and write a string to it with write(2).
|
||||||
|
If the file does not exist, it will be created. If it does exist,
|
||||||
|
it will be truncated. Properties are expanded within _content_.
|
||||||
|
|
||||||
|
|
||||||
|
Imports
|
||||||
|
-------
|
||||||
|
The import keyword is not a command, but rather its own section and is
|
||||||
|
handled immediately after the .rc file that contains it has finished
|
||||||
|
being parsed. It takes the below form:
|
||||||
|
|
||||||
|
`import <path>`
|
||||||
|
> Parse an init config file, extending the current configuration.
|
||||||
|
If _path_ is a directory, each file in the directory is parsed as
|
||||||
|
a config file. It is not recursive, nested directories will
|
||||||
|
not be parsed.
|
||||||
|
|
||||||
|
There are only two times where the init executable imports .rc files:
|
||||||
|
|
||||||
|
1. When it imports /init.rc during initial boot
|
||||||
|
2. When it imports /{system,vendor,odm}/etc/init/ or .rc files at specified
|
||||||
|
paths during mount_all
|
||||||
|
|
||||||
|
|
||||||
|
Properties
|
||||||
|
----------
|
||||||
|
Init provides information about the services that it is responsible
|
||||||
|
for via the below properties.
|
||||||
|
|
||||||
|
`init.svc.<name>`
|
||||||
|
> State of a named service ("stopped", "stopping", "running", "restarting")
|
||||||
|
|
||||||
|
|
||||||
|
Boot timing
|
||||||
|
-----------
|
||||||
|
Init records some boot timing information in system properties.
|
||||||
|
|
||||||
|
`ro.boottime.init`
|
||||||
|
> Time after boot in ns (via the CLOCK\_BOOTTIME clock) at which the first
|
||||||
|
stage of init started.
|
||||||
|
|
||||||
|
`ro.boottime.init.selinux`
|
||||||
|
> How long it took the first stage to initialize SELinux.
|
||||||
|
|
||||||
|
`ro.boottime.init.cold_boot_wait`
|
||||||
|
> How long init waited for ueventd's coldboot phase to end.
|
||||||
|
|
||||||
|
`ro.boottime.<service-name>`
|
||||||
|
> Time after boot in ns (via the CLOCK\_BOOTTIME clock) that the service was
|
||||||
|
first started.
|
||||||
|
|
||||||
|
|
||||||
|
Bootcharting
|
||||||
|
------------
|
||||||
|
This version of init contains code to perform "bootcharting": generating log
|
||||||
|
files that can be later processed by the tools provided by <http://www.bootchart.org/>.
|
||||||
|
|
||||||
|
On the emulator, use the -bootchart _timeout_ option to boot with bootcharting
|
||||||
|
activated for _timeout_ seconds.
|
||||||
|
|
||||||
|
On a device:
|
||||||
|
|
||||||
|
adb shell 'touch /data/bootchart/enabled'
|
||||||
|
|
||||||
|
Don't forget to delete this file when you're done collecting data!
|
||||||
|
|
||||||
|
The log files are written to /data/bootchart/. A script is provided to
|
||||||
|
retrieve them and create a bootchart.tgz file that can be used with the
|
||||||
|
bootchart command-line utility:
|
||||||
|
|
||||||
|
sudo apt-get install pybootchartgui
|
||||||
|
# grab-bootchart.sh uses $ANDROID_SERIAL.
|
||||||
|
$ANDROID_BUILD_TOP/system/core/init/grab-bootchart.sh
|
||||||
|
|
||||||
|
One thing to watch for is that the bootchart will show init as if it started
|
||||||
|
running at 0s. You'll have to look at dmesg to work out when the kernel
|
||||||
|
actually started init.
|
||||||
|
|
||||||
|
|
||||||
|
Comparing two bootcharts
|
||||||
|
------------------------
|
||||||
|
A handy script named compare-bootcharts.py can be used to compare the
|
||||||
|
start/end time of selected processes. The aforementioned grab-bootchart.sh
|
||||||
|
will leave a bootchart tarball named bootchart.tgz at /tmp/android-bootchart.
|
||||||
|
If two such barballs are preserved on the host machine under different
|
||||||
|
directories, the script can list the timestamps differences. For example:
|
||||||
|
|
||||||
|
Usage: system/core/init/compare-bootcharts.py _base-bootchart-dir_ _exp-bootchart-dir_
|
||||||
|
|
||||||
|
process: baseline experiment (delta) - Unit is ms (a jiffy is 10 ms on the system)
|
||||||
|
------------------------------------
|
||||||
|
/init: 50 40 (-10)
|
||||||
|
/system/bin/surfaceflinger: 4320 4470 (+150)
|
||||||
|
/system/bin/bootanimation: 6980 6990 (+10)
|
||||||
|
zygote64: 10410 10640 (+230)
|
||||||
|
zygote: 10410 10640 (+230)
|
||||||
|
system_server: 15350 15150 (-200)
|
||||||
|
bootanimation ends at: 33790 31230 (-2560)
|
||||||
|
|
||||||
|
|
||||||
|
Systrace
|
||||||
|
--------
|
||||||
|
Systrace (<http://developer.android.com/tools/help/systrace.html>) can be
|
||||||
|
used for obtaining performance analysis reports during boot
|
||||||
|
time on userdebug or eng builds.
|
||||||
|
|
||||||
|
Here is an example of trace events of "wm" and "am" categories:
|
||||||
|
|
||||||
|
$ANDROID_BUILD_TOP/external/chromium-trace/systrace.py \
|
||||||
|
wm am --boot
|
||||||
|
|
||||||
|
This command will cause the device to reboot. After the device is rebooted and
|
||||||
|
the boot sequence has finished, the trace report is obtained from the device
|
||||||
|
and written as trace.html on the host by hitting Ctrl+C.
|
||||||
|
|
||||||
|
Limitation: recording trace events is started after persistent properties are loaded, so
|
||||||
|
the trace events that are emitted before that are not recorded. Several
|
||||||
|
services such as vold, surfaceflinger, and servicemanager are affected by this
|
||||||
|
limitation since they are started before persistent properties are loaded.
|
||||||
|
Zygote initialization and the processes that are forked from the zygote are not
|
||||||
|
affected.
|
||||||
|
|
||||||
|
|
||||||
|
Debugging init
|
||||||
|
--------------
|
||||||
|
By default, programs executed by init will drop stdout and stderr into
|
||||||
|
/dev/null. To help with debugging, you can execute your program via the
|
||||||
|
Android program logwrapper. This will redirect stdout/stderr into the
|
||||||
|
Android logging system (accessed via logcat).
|
||||||
|
|
||||||
|
For example
|
||||||
|
service akmd /system/bin/logwrapper /sbin/akmd
|
||||||
|
|
||||||
|
For quicker turnaround when working on init itself, use:
|
||||||
|
|
||||||
|
mm -j &&
|
||||||
|
m ramdisk-nodeps &&
|
||||||
|
m bootimage-nodeps &&
|
||||||
|
adb reboot bootloader &&
|
||||||
|
fastboot boot $ANDROID_PRODUCT_OUT/boot.img
|
||||||
|
|
||||||
|
Alternatively, use the emulator:
|
||||||
|
|
||||||
|
emulator -partition-size 1024 \
|
||||||
|
-verbose -show-kernel -no-window
|
||||||
560
init/readme.txt
560
init/readme.txt
|
|
@ -1,560 +0,0 @@
|
||||||
Android Init Language
|
|
||||||
---------------------
|
|
||||||
|
|
||||||
The Android Init Language consists of five broad classes of statements,
|
|
||||||
which are Actions, Commands, Services, Options, and Imports.
|
|
||||||
|
|
||||||
All of these are line-oriented, consisting of tokens separated by
|
|
||||||
whitespace. The c-style backslash escapes may be used to insert
|
|
||||||
whitespace into a token. Double quotes may also be used to prevent
|
|
||||||
whitespace from breaking text into multiple tokens. The backslash,
|
|
||||||
when it is the last character on a line, may be used for line-folding.
|
|
||||||
|
|
||||||
Lines which start with a # (leading whitespace allowed) are comments.
|
|
||||||
|
|
||||||
Actions and Services implicitly declare a new section. All commands
|
|
||||||
or options belong to the section most recently declared. Commands
|
|
||||||
or options before the first section are ignored.
|
|
||||||
|
|
||||||
Actions and Services have unique names. If a second Action is defined
|
|
||||||
with the same name as an existing one, its commands are appended to
|
|
||||||
the commands of the existing action. If a second Service is defined
|
|
||||||
with the same name as an existing one, it is ignored and an error
|
|
||||||
message is logged.
|
|
||||||
|
|
||||||
|
|
||||||
Init .rc Files
|
|
||||||
--------------
|
|
||||||
The init language is used in plaintext files that take the .rc file
|
|
||||||
extension. These are typically multiple of these in multiple
|
|
||||||
locations on the system, described below.
|
|
||||||
|
|
||||||
/init.rc is the primary .rc file and is loaded by the init executable
|
|
||||||
at the beginning of its execution. It is responsible for the initial
|
|
||||||
set up of the system. It imports /init.${ro.hardware}.rc which is the
|
|
||||||
primary vendor supplied .rc file.
|
|
||||||
|
|
||||||
During the mount_all command, the init executable loads all of the
|
|
||||||
files contained within the /{system,vendor,odm}/etc/init/ directories.
|
|
||||||
These directories are intended for all Actions and Services used after
|
|
||||||
file system mounting.
|
|
||||||
|
|
||||||
One may specify paths in the mount_all command line to have it import
|
|
||||||
.rc files at the specified paths instead of the default ones listed above.
|
|
||||||
This is primarily for supporting factory mode and other non-standard boot
|
|
||||||
modes. The three default paths should be used for the normal boot process.
|
|
||||||
|
|
||||||
The intention of these directories is as follows
|
|
||||||
1) /system/etc/init/ is for core system items such as
|
|
||||||
SurfaceFlinger, MediaService, and logcatd.
|
|
||||||
2) /vendor/etc/init/ is for SoC vendor items such as actions or
|
|
||||||
daemons needed for core SoC functionality.
|
|
||||||
3) /odm/etc/init/ is for device manufacturer items such as
|
|
||||||
actions or daemons needed for motion sensor or other peripheral
|
|
||||||
functionality.
|
|
||||||
|
|
||||||
All services whose binaries reside on the system, vendor, or odm
|
|
||||||
partitions should have their service entries placed into a
|
|
||||||
corresponding init .rc file, located in the /etc/init/
|
|
||||||
directory of the partition where they reside. There is a build
|
|
||||||
system macro, LOCAL_INIT_RC, that handles this for developers. Each
|
|
||||||
init .rc file should additionally contain any actions associated with
|
|
||||||
its service.
|
|
||||||
|
|
||||||
An example is the logcatd.rc and Android.mk files located in the
|
|
||||||
system/core/logcat directory. The LOCAL_INIT_RC macro in the
|
|
||||||
Android.mk file places logcatd.rc in /system/etc/init/ during the
|
|
||||||
build process. Init loads logcatd.rc during the mount_all command and
|
|
||||||
allows the service to be run and the action to be queued when
|
|
||||||
appropriate.
|
|
||||||
|
|
||||||
This break up of init .rc files according to their daemon is preferred
|
|
||||||
to the previously used monolithic init .rc files. This approach
|
|
||||||
ensures that the only service entries that init reads and the only
|
|
||||||
actions that init performs correspond to services whose binaries are in
|
|
||||||
fact present on the file system, which was not the case with the
|
|
||||||
monolithic init .rc files. This additionally will aid in merge
|
|
||||||
conflict resolution when multiple services are added to the system, as
|
|
||||||
each one will go into a separate file.
|
|
||||||
|
|
||||||
There are two options "early" and "late" in mount_all command
|
|
||||||
which can be set after optional paths. With "--early" set, the
|
|
||||||
init executable will skip mounting entries with "latemount" flag
|
|
||||||
and triggering fs encryption state event. With "--late" set,
|
|
||||||
init executable will only mount entries with "latemount" flag but skip
|
|
||||||
importing rc files. By default, no option is set, and mount_all will
|
|
||||||
mount_all will process all entries in the given fstab.
|
|
||||||
|
|
||||||
Actions
|
|
||||||
-------
|
|
||||||
Actions are named sequences of commands. Actions have a trigger which
|
|
||||||
is used to determine when the action should occur. When an event
|
|
||||||
occurs which matches an action's trigger, that action is added to
|
|
||||||
the tail of a to-be-executed queue (unless it is already on the
|
|
||||||
queue).
|
|
||||||
|
|
||||||
Each action in the queue is dequeued in sequence and each command in
|
|
||||||
that action is executed in sequence. Init handles other activities
|
|
||||||
(device creation/destruction, property setting, process restarting)
|
|
||||||
"between" the execution of the commands in activities.
|
|
||||||
|
|
||||||
Actions take the form of:
|
|
||||||
|
|
||||||
on <trigger> [&& <trigger>]*
|
|
||||||
<command>
|
|
||||||
<command>
|
|
||||||
<command>
|
|
||||||
|
|
||||||
|
|
||||||
Services
|
|
||||||
--------
|
|
||||||
Services are programs which init launches and (optionally) restarts
|
|
||||||
when they exit. Services take the form of:
|
|
||||||
|
|
||||||
service <name> <pathname> [ <argument> ]*
|
|
||||||
<option>
|
|
||||||
<option>
|
|
||||||
...
|
|
||||||
|
|
||||||
|
|
||||||
Options
|
|
||||||
-------
|
|
||||||
Options are modifiers to services. They affect how and when init
|
|
||||||
runs the service.
|
|
||||||
|
|
||||||
console [<console>]
|
|
||||||
This service needs a console. The optional second parameter chooses a
|
|
||||||
specific console instead of the default. The default "/dev/console" can
|
|
||||||
be changed by setting the "androidboot.console" kernel parameter. In
|
|
||||||
all cases the leading "/dev/" should be omitted, so "/dev/tty0" would be
|
|
||||||
specified as just "console tty0".
|
|
||||||
|
|
||||||
critical
|
|
||||||
This is a device-critical service. If it exits more than four times in
|
|
||||||
four minutes, the device will reboot into recovery mode.
|
|
||||||
|
|
||||||
disabled
|
|
||||||
This service will not automatically start with its class.
|
|
||||||
It must be explicitly started by name.
|
|
||||||
|
|
||||||
setenv <name> <value>
|
|
||||||
Set the environment variable <name> to <value> in the launched process.
|
|
||||||
|
|
||||||
socket <name> <type> <perm> [ <user> [ <group> [ <seclabel> ] ] ]
|
|
||||||
Create a unix domain socket named /dev/socket/<name> and pass its fd to the
|
|
||||||
launched process. <type> must be "dgram", "stream" or "seqpacket". User and
|
|
||||||
group default to 0. 'seclabel' is the SELinux security context for the
|
|
||||||
socket. It defaults to the service security context, as specified by
|
|
||||||
seclabel or computed based on the service executable file security context.
|
|
||||||
For native executables see libcutils android_get_control_socket().
|
|
||||||
|
|
||||||
file <path> <type>
|
|
||||||
Open a file path and pass its fd to the launched process. <type> must be
|
|
||||||
"r", "w" or "rw". For native executables see libcutils
|
|
||||||
android_get_control_file().
|
|
||||||
|
|
||||||
user <username>
|
|
||||||
Change to 'username' before exec'ing this service.
|
|
||||||
Currently defaults to root. (??? probably should default to nobody)
|
|
||||||
As of Android M, processes should use this option even if they
|
|
||||||
require Linux capabilities. Previously, to acquire Linux
|
|
||||||
capabilities, a process would need to run as root, request the
|
|
||||||
capabilities, then drop to its desired uid. There is a new
|
|
||||||
mechanism through fs_config that allows device manufacturers to add
|
|
||||||
Linux capabilities to specific binaries on a file system that should
|
|
||||||
be used instead. This mechanism is described on
|
|
||||||
http://source.android.com/devices/tech/config/filesystem.html. When
|
|
||||||
using this new mechanism, processes can use the user option to
|
|
||||||
select their desired uid without ever running as root.
|
|
||||||
As of Android O, processes can also request capabilities directly in their .rc
|
|
||||||
files. See the "capabilities" option below.
|
|
||||||
|
|
||||||
group <groupname> [ <groupname> ]*
|
|
||||||
Change to 'groupname' before exec'ing this service. Additional
|
|
||||||
groupnames beyond the (required) first one are used to set the
|
|
||||||
supplemental groups of the process (via setgroups()).
|
|
||||||
Currently defaults to root. (??? probably should default to nobody)
|
|
||||||
|
|
||||||
capabilities <capability> [ <capability> ]*
|
|
||||||
Set capabilities when exec'ing this service. 'capability' should be a Linux
|
|
||||||
capability without the "CAP_" prefix, like "NET_ADMIN" or "SETPCAP". See
|
|
||||||
http://man7.org/linux/man-pages/man7/capabilities.7.html for a list of Linux
|
|
||||||
capabilities.
|
|
||||||
|
|
||||||
seclabel <seclabel>
|
|
||||||
Change to 'seclabel' before exec'ing this service.
|
|
||||||
Primarily for use by services run from the rootfs, e.g. ueventd, adbd.
|
|
||||||
Services on the system partition can instead use policy-defined transitions
|
|
||||||
based on their file security context.
|
|
||||||
If not specified and no transition is defined in policy, defaults to the init context.
|
|
||||||
|
|
||||||
oneshot
|
|
||||||
Do not restart the service when it exits.
|
|
||||||
|
|
||||||
class <name>
|
|
||||||
Specify a class name for the service. All services in a
|
|
||||||
named class may be started or stopped together. A service
|
|
||||||
is in the class "default" if one is not specified via the
|
|
||||||
class option.
|
|
||||||
|
|
||||||
onrestart
|
|
||||||
Execute a Command (see below) when service restarts.
|
|
||||||
|
|
||||||
writepid <file...>
|
|
||||||
Write the child's pid to the given files when it forks. Meant for
|
|
||||||
cgroup/cpuset usage.
|
|
||||||
|
|
||||||
priority <priority>
|
|
||||||
Scheduling priority of the service process. This value has to be in range
|
|
||||||
-20 to 19. Default priority is 0. Priority is set via setpriority().
|
|
||||||
|
|
||||||
namespace <pid|mnt>
|
|
||||||
Enter a new PID or mount namespace when forking the service.
|
|
||||||
|
|
||||||
oom_score_adjust <value>
|
|
||||||
Sets the child's /proc/self/oom_score_adj to the specified value,
|
|
||||||
which must range from -1000 to 1000.
|
|
||||||
|
|
||||||
|
|
||||||
Triggers
|
|
||||||
--------
|
|
||||||
Triggers are strings which can be used to match certain kinds of
|
|
||||||
events and used to cause an action to occur.
|
|
||||||
|
|
||||||
Triggers are subdivided into event triggers and property triggers.
|
|
||||||
|
|
||||||
Event triggers are strings triggered by the 'trigger' command or by
|
|
||||||
the QueueEventTrigger() function within the init executable. These
|
|
||||||
take the form of a simple string such as 'boot' or 'late-init'.
|
|
||||||
|
|
||||||
Property triggers are strings triggered when a named property changes
|
|
||||||
value to a given new value or when a named property changes value to
|
|
||||||
any new value. These take the form of 'property:<name>=<value>' and
|
|
||||||
'property:<name>=*' respectively. Property triggers are additionally
|
|
||||||
evaluated and triggered accordingly during the initial boot phase of
|
|
||||||
init.
|
|
||||||
|
|
||||||
An Action can have multiple property triggers but may only have one
|
|
||||||
event trigger.
|
|
||||||
|
|
||||||
For example:
|
|
||||||
'on boot && property:a=b' defines an action that is only executed when
|
|
||||||
the 'boot' event trigger happens and the property a equals b.
|
|
||||||
|
|
||||||
'on property:a=b && property:c=d' defines an action that is executed
|
|
||||||
at three times,
|
|
||||||
1) During initial boot if property a=b and property c=d
|
|
||||||
2) Any time that property a transitions to value b, while property
|
|
||||||
c already equals d.
|
|
||||||
3) Any time that property c transitions to value d, while property
|
|
||||||
a already equals b.
|
|
||||||
|
|
||||||
|
|
||||||
Commands
|
|
||||||
--------
|
|
||||||
|
|
||||||
bootchart [start|stop]
|
|
||||||
Start/stop bootcharting. These are present in the default init.rc files,
|
|
||||||
but bootcharting is only active if the file /data/bootchart/enabled exists;
|
|
||||||
otherwise bootchart start/stop are no-ops.
|
|
||||||
|
|
||||||
chmod <octal-mode> <path>
|
|
||||||
Change file access permissions.
|
|
||||||
|
|
||||||
chown <owner> <group> <path>
|
|
||||||
Change file owner and group.
|
|
||||||
|
|
||||||
class_start <serviceclass>
|
|
||||||
Start all services of the specified class if they are
|
|
||||||
not already running.
|
|
||||||
|
|
||||||
class_stop <serviceclass>
|
|
||||||
Stop and disable all services of the specified class if they are
|
|
||||||
currently running.
|
|
||||||
|
|
||||||
class_reset <serviceclass>
|
|
||||||
Stop all services of the specified class if they are
|
|
||||||
currently running, without disabling them. They can be restarted
|
|
||||||
later using class_start.
|
|
||||||
|
|
||||||
copy <src> <dst>
|
|
||||||
Copies a file. Similar to write, but useful for binary/large
|
|
||||||
amounts of data.
|
|
||||||
|
|
||||||
domainname <name>
|
|
||||||
Set the domain name.
|
|
||||||
|
|
||||||
enable <servicename>
|
|
||||||
Turns a disabled service into an enabled one as if the service did not
|
|
||||||
specify disabled.
|
|
||||||
If the service is supposed to be running, it will be started now.
|
|
||||||
Typically used when the bootloader sets a variable that indicates a specific
|
|
||||||
service should be started when needed. E.g.
|
|
||||||
on property:ro.boot.myfancyhardware=1
|
|
||||||
enable my_fancy_service_for_my_fancy_hardware
|
|
||||||
|
|
||||||
exec [ <seclabel> [ <user> [ <group> ]* ] ] -- <command> [ <argument> ]*
|
|
||||||
Fork and execute command with the given arguments. The command starts
|
|
||||||
after "--" so that an optional security context, user, and supplementary
|
|
||||||
groups can be provided. No other commands will be run until this one
|
|
||||||
finishes. <seclabel> can be a - to denote default.
|
|
||||||
|
|
||||||
export <name> <value>
|
|
||||||
Set the environment variable <name> equal to <value> in the
|
|
||||||
global environment (which will be inherited by all processes
|
|
||||||
started after this command is executed)
|
|
||||||
|
|
||||||
hostname <name>
|
|
||||||
Set the host name.
|
|
||||||
|
|
||||||
ifup <interface>
|
|
||||||
Bring the network interface <interface> online.
|
|
||||||
|
|
||||||
insmod [-f] <path> [<options>]
|
|
||||||
Install the module at <path> with the specified options.
|
|
||||||
-f
|
|
||||||
Force installation of the module even if the version of the running kernel
|
|
||||||
and the version of the kernel for which the module was compiled do not match.
|
|
||||||
|
|
||||||
load_all_props
|
|
||||||
Loads properties from /system, /vendor, et cetera.
|
|
||||||
This is included in the default init.rc.
|
|
||||||
|
|
||||||
load_persist_props
|
|
||||||
Loads persistent properties when /data has been decrypted.
|
|
||||||
This is included in the default init.rc.
|
|
||||||
|
|
||||||
loglevel <level>
|
|
||||||
Sets the kernel log level to level. Properties are expanded within <level>.
|
|
||||||
|
|
||||||
mkdir <path> [mode] [owner] [group]
|
|
||||||
Create a directory at <path>, optionally with the given mode, owner, and
|
|
||||||
group. If not provided, the directory is created with permissions 755 and
|
|
||||||
owned by the root user and root group. If provided, the mode, owner and group
|
|
||||||
will be updated if the directory exists already.
|
|
||||||
|
|
||||||
mount_all <fstab> [ <path> ]* [--<option>]
|
|
||||||
Calls fs_mgr_mount_all on the given fs_mgr-format fstab and imports .rc files
|
|
||||||
at the specified paths (e.g., on the partitions just mounted) with optional
|
|
||||||
options "early" and "late".
|
|
||||||
Refer to the section of "Init .rc Files" for detail.
|
|
||||||
|
|
||||||
mount <type> <device> <dir> [ <flag> ]* [<options>]
|
|
||||||
Attempt to mount the named device at the directory <dir>
|
|
||||||
<flag>s include "ro", "rw", "remount", "noatime", ...
|
|
||||||
<options> include "barrier=1", "noauto_da_alloc", "discard", ... as
|
|
||||||
a comma separated string, eg: barrier=1,noauto_da_alloc
|
|
||||||
|
|
||||||
powerctl
|
|
||||||
Internal implementation detail used to respond to changes to the
|
|
||||||
"sys.powerctl" system property, used to implement rebooting.
|
|
||||||
|
|
||||||
restart <service>
|
|
||||||
Like stop, but doesn't disable the service.
|
|
||||||
|
|
||||||
restorecon <path> [ <path> ]*
|
|
||||||
Restore the file named by <path> to the security context specified
|
|
||||||
in the file_contexts configuration.
|
|
||||||
Not required for directories created by the init.rc as these are
|
|
||||||
automatically labeled correctly by init.
|
|
||||||
|
|
||||||
restorecon_recursive <path> [ <path> ]*
|
|
||||||
Recursively restore the directory tree named by <path> to the
|
|
||||||
security contexts specified in the file_contexts configuration.
|
|
||||||
|
|
||||||
rm <path>
|
|
||||||
Calls unlink(2) on the given path. You might want to
|
|
||||||
use "exec -- rm ..." instead (provided the system partition is
|
|
||||||
already mounted).
|
|
||||||
|
|
||||||
rmdir <path>
|
|
||||||
Calls rmdir(2) on the given path.
|
|
||||||
|
|
||||||
setprop <name> <value>
|
|
||||||
Set system property <name> to <value>. Properties are expanded
|
|
||||||
within <value>.
|
|
||||||
|
|
||||||
setrlimit <resource> <cur> <max>
|
|
||||||
Set the rlimit for a resource.
|
|
||||||
|
|
||||||
start <service>
|
|
||||||
Start a service running if it is not already running.
|
|
||||||
|
|
||||||
stop <service>
|
|
||||||
Stop a service from running if it is currently running.
|
|
||||||
|
|
||||||
swapon_all <fstab>
|
|
||||||
Calls fs_mgr_swapon_all on the given fstab file.
|
|
||||||
|
|
||||||
symlink <target> <path>
|
|
||||||
Create a symbolic link at <path> with the value <target>
|
|
||||||
|
|
||||||
sysclktz <mins_west_of_gmt>
|
|
||||||
Set the system clock base (0 if system clock ticks in GMT)
|
|
||||||
|
|
||||||
trigger <event>
|
|
||||||
Trigger an event. Used to queue an action from another
|
|
||||||
action.
|
|
||||||
|
|
||||||
umount <path>
|
|
||||||
Unmount the filesystem mounted at that path.
|
|
||||||
|
|
||||||
verity_load_state
|
|
||||||
Internal implementation detail used to load dm-verity state.
|
|
||||||
|
|
||||||
verity_update_state <mount_point>
|
|
||||||
Internal implementation detail used to update dm-verity state and
|
|
||||||
set the partition.<mount_point>.verified properties used by adb remount
|
|
||||||
because fs_mgr can't set them directly itself.
|
|
||||||
|
|
||||||
wait <path> [ <timeout> ]
|
|
||||||
Poll for the existence of the given file and return when found,
|
|
||||||
or the timeout has been reached. If timeout is not specified it
|
|
||||||
currently defaults to five seconds.
|
|
||||||
|
|
||||||
write <path> <content>
|
|
||||||
Open the file at <path> and write a string to it with write(2).
|
|
||||||
If the file does not exist, it will be created. If it does exist,
|
|
||||||
it will be truncated. Properties are expanded within <content>.
|
|
||||||
|
|
||||||
|
|
||||||
Imports
|
|
||||||
-------
|
|
||||||
The import keyword is not a command, but rather its own section and is
|
|
||||||
handled immediately after the .rc file that contains it has finished
|
|
||||||
being parsed. It takes the below form:
|
|
||||||
|
|
||||||
import <path>
|
|
||||||
Parse an init config file, extending the current configuration.
|
|
||||||
If <path> is a directory, each file in the directory is parsed as
|
|
||||||
a config file. It is not recursive, nested directories will
|
|
||||||
not be parsed.
|
|
||||||
|
|
||||||
There are only two times where the init executable imports .rc files,
|
|
||||||
1) When it imports /init.rc during initial boot
|
|
||||||
2) When it imports /{system,vendor,odm}/etc/init/ or .rc files at specified
|
|
||||||
paths during mount_all
|
|
||||||
|
|
||||||
|
|
||||||
Properties
|
|
||||||
----------
|
|
||||||
Init provides information about the services that it is responsible
|
|
||||||
for via the below properties.
|
|
||||||
|
|
||||||
init.svc.<name>
|
|
||||||
State of a named service ("stopped", "stopping", "running", "restarting")
|
|
||||||
|
|
||||||
|
|
||||||
Boot timing
|
|
||||||
-----------
|
|
||||||
Init records some boot timing information in system properties.
|
|
||||||
|
|
||||||
ro.boottime.init
|
|
||||||
Time after boot in ns (via the CLOCK_BOOTTIME clock) at which the first
|
|
||||||
stage of init started.
|
|
||||||
|
|
||||||
ro.boottime.init.selinux
|
|
||||||
How long it took the first stage to initialize SELinux.
|
|
||||||
|
|
||||||
ro.boottime.init.cold_boot_wait
|
|
||||||
How long init waited for ueventd's coldboot phase to end.
|
|
||||||
|
|
||||||
ro.boottime.<service-name>
|
|
||||||
Time after boot in ns (via the CLOCK_BOOTTIME clock) that the service was
|
|
||||||
first started.
|
|
||||||
|
|
||||||
|
|
||||||
Bootcharting
|
|
||||||
------------
|
|
||||||
This version of init contains code to perform "bootcharting": generating log
|
|
||||||
files that can be later processed by the tools provided by www.bootchart.org.
|
|
||||||
|
|
||||||
On the emulator, use the -bootchart <timeout> option to boot with bootcharting
|
|
||||||
activated for <timeout> seconds.
|
|
||||||
|
|
||||||
On a device:
|
|
||||||
|
|
||||||
adb shell 'touch /data/bootchart/enabled'
|
|
||||||
|
|
||||||
Don't forget to delete this file when you're done collecting data!
|
|
||||||
|
|
||||||
The log files are written to /data/bootchart/. A script is provided to
|
|
||||||
retrieve them and create a bootchart.tgz file that can be used with the
|
|
||||||
bootchart command-line utility:
|
|
||||||
|
|
||||||
sudo apt-get install pybootchartgui
|
|
||||||
# grab-bootchart.sh uses $ANDROID_SERIAL.
|
|
||||||
$ANDROID_BUILD_TOP/system/core/init/grab-bootchart.sh
|
|
||||||
|
|
||||||
One thing to watch for is that the bootchart will show init as if it started
|
|
||||||
running at 0s. You'll have to look at dmesg to work out when the kernel
|
|
||||||
actually started init.
|
|
||||||
|
|
||||||
|
|
||||||
Comparing two bootcharts
|
|
||||||
------------------------
|
|
||||||
A handy script named compare-bootcharts.py can be used to compare the
|
|
||||||
start/end time of selected processes. The aforementioned grab-bootchart.sh
|
|
||||||
will leave a bootchart tarball named bootchart.tgz at /tmp/android-bootchart.
|
|
||||||
If two such barballs are preserved on the host machine under different
|
|
||||||
directories, the script can list the timestamps differences. For example:
|
|
||||||
|
|
||||||
Usage: system/core/init/compare-bootcharts.py base_bootchart_dir
|
|
||||||
exp_bootchart_dir
|
|
||||||
|
|
||||||
process: baseline experiment (delta)
|
|
||||||
- Unit is ms (a jiffy is 10 ms on the system)
|
|
||||||
------------------------------------
|
|
||||||
/init: 50 40 (-10)
|
|
||||||
/system/bin/surfaceflinger: 4320 4470 (+150)
|
|
||||||
/system/bin/bootanimation: 6980 6990 (+10)
|
|
||||||
zygote64: 10410 10640 (+230)
|
|
||||||
zygote: 10410 10640 (+230)
|
|
||||||
system_server: 15350 15150 (-200)
|
|
||||||
bootanimation ends at: 33790 31230 (-2560)
|
|
||||||
|
|
||||||
|
|
||||||
Systrace
|
|
||||||
--------
|
|
||||||
Systrace [1] can be used for obtaining performance analysis reports during boot
|
|
||||||
time on userdebug or eng builds.
|
|
||||||
Here is an example of trace events of "wm" and "am" categories:
|
|
||||||
|
|
||||||
$ANDROID_BUILD_TOP/external/chromium-trace/systrace.py wm am --boot
|
|
||||||
|
|
||||||
This command will cause the device to reboot. After the device is rebooted and
|
|
||||||
the boot sequence has finished, the trace report is obtained from the device
|
|
||||||
and written as trace.html on the host by hitting Ctrl+C.
|
|
||||||
|
|
||||||
LIMITATION
|
|
||||||
Recording trace events is started after persistent properties are loaded, so
|
|
||||||
the trace events that are emitted before that are not recorded. Several
|
|
||||||
services such as vold, surfaceflinger, and servicemanager are affected by this
|
|
||||||
limitation since they are started before persistent properties are loaded.
|
|
||||||
Zygote initialization and the processes that are forked from the zygote are not
|
|
||||||
affected.
|
|
||||||
|
|
||||||
[1] http://developer.android.com/tools/help/systrace.html
|
|
||||||
|
|
||||||
|
|
||||||
Debugging init
|
|
||||||
--------------
|
|
||||||
By default, programs executed by init will drop stdout and stderr into
|
|
||||||
/dev/null. To help with debugging, you can execute your program via the
|
|
||||||
Android program logwrapper. This will redirect stdout/stderr into the
|
|
||||||
Android logging system (accessed via logcat).
|
|
||||||
|
|
||||||
For example
|
|
||||||
service akmd /system/bin/logwrapper /sbin/akmd
|
|
||||||
|
|
||||||
For quicker turnaround when working on init itself, use:
|
|
||||||
|
|
||||||
mm -j &&
|
|
||||||
m ramdisk-nodeps &&
|
|
||||||
m bootimage-nodeps &&
|
|
||||||
adb reboot bootloader &&
|
|
||||||
fastboot boot $ANDROID_PRODUCT_OUT/boot.img
|
|
||||||
|
|
||||||
Alternatively, use the emulator:
|
|
||||||
|
|
||||||
emulator -partition-size 1024 -verbose -show-kernel -no-window
|
|
||||||
Loading…
Add table
Reference in a new issue