init.rc changes to run any script Can be used to start any android application, service
on property:dev.bootcomplete=1
exec - system system -- /system/bin/sh <custom script path>
# exec - system system -- /system/bin/sh /data/local/bootscript/testservice.sh
Script can contains applications start, stop commands
/system/bin/am startservice com.example.android.testservice/.MyService
/system/bin/am stopservice com.example.android.testservice/.MyService
/system/bin/am start/kill/force-stop com.example.android.testservice/.MainActivity
Enter the machine using adb shell
Identify the partition either using
Run cat /proc/partitions OR
parted utility
Dump the partition to a file using dd
dd if=/dev/block/mmcblk0p6 of=/data/kernel_ramfs.img
Extract it to your linux system adb pull /data/kernel_ramfs.img
Run sudo apt-get install abootimg
Run abootimg -i kernel_ramfs.img. It need to show
Android Boot Image Info:
* file name = kernel_ramfs.img
* image size = 16777216 bytes (16.00 MB)
page size = 2048 bytes
* Boot Name = ""
* kernel size = 9797076 bytes (9.34 MB)
ramdisk size = 2017625 bytes (1.92 MB)
* load addresses:
kernel: 0x40008000
ramdisk: 0x41000000
tags: 0x40000100
* empty cmdline
* id = 0x7c37c0d4 0xcefde745 0xe81b85ba 0xf05275ba 0xbe7de0ad 0x00000000 0x00000000 0x00000000
That means you dump the correct kernel+ramfs
abootimg -x kernel_ramfs.img
It will extract zImage and also initrd.img
mkdir initrd
cd initrd
cat ../initrd.img | gunzip | cpio -vid
Modify the ramdisk accordingly (e.g. you modify init.rc or add another additonal files) Then repack accordingly
cd initrd
find . | cpio --create --format='newc' | gzip > ../myinitrd.img
cd ..
abootimg --create myboot.img -f bootimg.cfg -k zImage -r myinitrd.img
Repacking might fail due to size issue, remove unnecessary comments, files from ramdisk image and try again after recreating initrd image.
Enter in fastboot mode
adb reboot-bootloader
sudo fastboot devices -l # To check whether device entered in fastboot mode
sudo fastboot erase boot # Erase existing boot image
sudo fastboot flash boot boot.img # Flash new image
sudo fastboot reboot # To come out from fastboot mode
Verify init.rc for changes Verify dmesg, logcat(Any init.rc script invokation error will come in dmesg)
Another way Download the Extract Tools..!! - https://drive.google.com/file/d/0B4fizJM7V7pPMUNkNzNEV01Sb28/view
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Get boot.img file
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unpack boot.img file ~/Downloads/Extract\ Tolls/unmkbootimg boot.img
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Extract ramdisk (initramfs) gzip -dc initramfs.cpio.gz | cpio -i
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Re-pack ramdisk find . | cpio -o -H newc | gzip > ../initramfs.cpio.gz # From the extracted folder
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Re-pack boot img ~/Downloads/Extract\ Tolls/mkbootimg --kernel kernel.gz --ramdisk ../initramfs.cpio.gz -o new_boot.img
References:
http://droidcore.blogspot.in/2012/12/how-to-edit-initrc-in-android.html