filesystemsandroid-sourceddext4

The image dumped by dd are different with the origin image in Android

I have an Android device, which has enabled dynamic partition. The system/system_ext/product are dynamic partition of super partition.

I flash super.img to the device, then use dd to dump the system to system.dump.img. I also extract system.img from the super.img by lpunpack.

But the system.img are different with system.dump.img, the size and md5sum are different. And the dumpe2fs output are the same. The two images can be mount locally, and the content are the same.

So why the system.img are different with system.dump.img.

Solution

  • Android verified boot will append the verity metadata, and the hash tree to the end of the system image. And dd will not dump this appended part.