@JerryChang, Yes it make sense not to truncate the original raw file. But same also did not worked while I trucate the sparse img file from 12GB to 16GB.
My use case is as follows :
- I want to clone a image to multiple devices with a fix rootfs partition (16GB).
- Remaining space I want to create two additional partitions to mount at /data and /opt of different sizes for user specific contents.
- Later I want to set rootfs partition to ro-mode for which I am following this thread and it seems with #R32.1 overlay works with some modification on kernerl module (Though this step comes later as I am stuck right now with the 1 and 2 step).
Any alternate way you would like to recommend would be very helpful?