Android Bootup Process

• Bootloader
  • See if a key is pressed (Fastboot / Recovery / Normal)
  • Kernel (usually with an initrd) is loaded into RAM, generally from the boot partition
• Kernel
  • Core kernel initialization
    • Memory and I/O areas are setup
    • Interrupts are started
    • Process Table is initialized
  • Driver initialization
  • Kernel daemons (threads) are started
  • Root filesystem is mounted
  • The first user-space process is started (/init)
• init
  • Reads and processes init.rc and init.<machine>.rc
  • Dalvik / ART VM is started (Zygote)
  • Several daemons are started
    • rild (Radio Interface Link Daemon)
    • vold (Volume Daemon - media volumes, not audio)
  • system_server starts
• System Server
  • Initializes several core services
    • A library is loaded to initialize interfaces to native services
    • Then Java-based core services are initialilzed in ServerThread::run() in SystemServer.java
• The Activity Manager starts core applications (which are Dalvik applications)
  • com.android.phone - Phone app
  • android.process.acore - System UI and a few core apps
• Other processes are also started by /init
  • adb
  • mediaserver
  • dbus-daemon
  • akmd