How to mount AOSP .img files?

Question

I generate *.img by building AOSP.

Like ramdisk.img,boot.img etc.

I want to mount this file

Answer 1

simg2img

Some Android images are compressed by default for some builds. This is the case for example of the HiKey960 build with lunch hikey960-eng, but not for emulator builds e.g. with lunch aosp_x86_64-eng.

You must first usesimg2img to decompress them:

simg2img system.img out.img
sudo losetup --show -f -P out.img
sudo mount /dev/loop0 /mnt/loop0

simg2img lives under ./out/host/linux-x86/bin/simg2img, and gets added automatically to PATH by lunch.

Note however that this is not the case for all the images, e.g. boot.img.

If you skip simg2img, you get the error:

NTFS signature is missing.
Failed to mount '/dev/loop3': Invalid argument
The device '/dev/loop3' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?

when trying to mount.

It appears that the compressed format is something that fastboot can understand.

Also mentioned at: https://stackoverflow.com/a/9675784/895245

Tested in Ubuntu 16.04 host, at branch repo init -b android-8.1.0_r1.