Android boot process

(This is a stub)
Android's boot up process is summarized below:

Stage	Steps	Comments
Boot-loader	-	Location: bootable\bootloader\legacy\usbloader
	init.S	Initializes stacks, zeros the BSS segment, call _main() in main.c
	main.c	Initializes hardware (clocks, board, keypad, console), creates Linux tags
		Displays "USB FastBoot". Boot from flash, or loops while usb_poll() awaits host PC connection
Linux kernel	-	Sets up the system, loads drivers, and starts running the first process init
The init process	Setup file system	Create and mount directories like /dev, /proc, /sys
	Execute init.rc	This is the boot-up script, commands are using Android-specific syntax, see readme.txt
	Setup console
	Display "A N D R O I D"	This is just a text msg written to /dev/tty0
	Zygote	Zygot process in init.rc brings up Dalvik Java VM and starts the system server
	bootanimation	Shows the animation during boot-up
Framework	….	….

References

• General Android boot process
  • http://www.androidenea.com/2009/06/android-boot-process-from-power-on.html
  • http://bloggervarun.wordpress.com/2010/01/25/embedded-linux-boot-process/

• Boot of Linux on Embedded Devices
  • Linux U-boot: http://www.denx.de/wiki/view/DULG/UBoot
  • OMAP bring-up: http://elinux.org/Android_on_OMAP
  • eLinux boot time: http://elinux.org/Boot_Time#Measuring_Boot-up_Time

• The Android boot image: boot.img
  • Unpack, re-pack boot image: http://android-dls.com/wiki/index.php?title=HOWTO:_Unpack%2C_Edit%2C_and_Re-Pack_Boot_Images#Background