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The docs/ANDROID-QEMUD.TXT document describes how clients running in the
emulated system can communicate with the emulator through the 'qemud'
multiplexing daemon.
This document lists all services officially provided by the emulator to
clients. Each service is identified by a unique name. There is no provision
for versioning. Instead, if you need new features, create a new service
with a slightly different name and modify clients to use it in the system
"gsm" service:
The GSM service provides a communication channel where GSM/GPRS AT commands
can be exchanged between the emulated system and an emulated modem.
The messages consist in un-framed character messages as they appear in a
regular AT command channel (i.e. terminated by \r\n most of the time).
There can be only 1 client talking to the modem, since the AT command
protocol does not allow for anything more complex.
Implementation: android-qemu1-glue/telephony/modem_driver.c
Since: SDK 1.0
"gps" service:
The GPS service is used to broadcast NMEA 0183 sentences containing fix
information to all clients. The service doesn't listen to clients at all.
All sentences are un-framed and end with a \n character.
Implementation: android/gps.c
Since: SDK 1.0
"hw-control" / "control" service:
This service is named "control" in 1.0 and 1.1, and "hw-control"
in 1.5 and later releases of the SDK.
This service is used to allow the emulated system to control various aspects
of hardware emulation. The corresponding clients are in
hardware/libhardware_legacy in the Android source tree.
All messages use the optional framing described in ANDROID-QEMUD.TXT.
Only one client can talk with the service at any one time, but clients
quickly connect/disconnect to the service anyway.
Supported messages are:
1/ Client sends "power:light:brightness:<lightname>:<val>", where
<lightname> is the name of a light and <val> is an decimal value
between 0 (off) and 255 (brightest). Valid values for 'light' are:
Currently, only 'lcd_backlight' is supported by the emulator.
Note that the brightness value doesn't scale linearly on physical
2/ Client sends "set_led_state:<color-rgb>:<on-ms>:<off-ms>" where
<color-rgb> is an 8-hexchar value describing an xRGB color, and
<on-ms> and <off-ms> are decimal values expressing timeout in
This is used to modify the color of the notification LED on the
emulated phone as well as provide on/off timeouts for flashing.
Currently unsupported by the emulator.
3/ Client sends "vibrator:<timeout>", where <timeout> is a decimal value.
used to enable vibrator emulation for <timeout> milli-seconds.
Currently unsupported by the emulator.
Implementation: android/hw-control.cpp
Since: SDK 1.0
"sensors" service:
This service is used for sensor emulation. All messages are framed and the
protocol is the following:
1/ Clients initially sends "list-sensors" and receives a single string
containing a decimal mask value. The value is a set of bit-flags
indicating which sensors are provided by the hardware emulation. The
bit flags are defined as:
bit 0: accelerometer
bit 1: compass
bit 2: orientation
bit 3: temperature
2/ Client sends "set-delay:<delay-ms>", where <delay-ms> is a decimal
string, to set the minimum delay in milliseconds between sensor event
reports it wants to receive.
3/ Client sends "wake", the service must immediately send back "wake" as
an answer. This is used to simplify parts of the client emulation.
4/ Client sends "set:<sensor-name>:<flag>", where <sensor-name> is the
name of one of the emulated sensors, and <flag> is either "0" or "1".
This is used to enable or disable the report of data from a given
emulated sensor hardware.
the list of valid <sensor-name> values is the following:
acceleration : for the accelerometer
magnetic-field : for the compass
orientation : for the orientation sensor
temperature : for the temperature sensor
5/ If at least one of the emulated sensors has been enabled with
"set:<name>:1", then the service should broadcast periodically the
state of sensors.
this is done by broadcasting a series of framed messages that look
Note that each line, corresponds to an independent framed message.
Each line, except the last one, is optional and should only be
produced if the corresponding sensor reporting has been enabled
through "set:<name>:1".
<x>, <y>, <z>, <azimuth>, <pitch>, <roll> and <celsius> are floating
point values written as strings with the "%g" printf formatting option.
The last 'sync' message is required to end the broadcast and contains
the current VM clock time in micro-seconds. The client will adjust it
internally to only care about differences between sensor broadcasts.
If reporting is disabled for all sensors, no broadcast message needs
to be sent back to clients.
Implementation: android/hw-sensors.cpp
Since: SDK 1.5 (cupcake)
"boot-properties" service:
WARNING: These properties don't get set until init starts a service in
class "core" called "qemu-props". Other init services in class "core"
include servicemanager and vold. If those processes read the property
(they probably don't right now), there is a small chance it has not been set yet.
Also, init services are started asynchronously, so there is no guarantee that
services started just after qemu-props will not run before qemu-props, and may
not see the new properties. This hasn't been an issue, but should probably
be cleaned up.
This service is used to set system properties in the emulated system at
boot time. It is invoked by the 'qemu-props' helper program that is invoked
by /system/etc/init.goldfish.rc. All messages are framed and the protocol
is the following:
1/ Clients sends the 'list' command
2/ Service answers by listing all system properties to set. One per
message with the following format:
Note that <property-value> is not zero-terminated.
3/ After sending all the properties, the service force-closes the
Implementation: android/boot-properties.c
Since: SDK 1.XXX (donut)