r/R36H

So I have two R36H devices, and both SD cards have 10gb of "free space" that I'd like to utilize. Opening the card in Linux shows me several partitions: Boot (117mb FAT) Root (7gb EXT4) Easyrom (87gb exfat) and then Freespace (10gb).

Now, I have cloned the SD card from the manufacturer and copied it to my own reliable 128gb cards, but I cannot figure out how to put that extra 10gb of free space into the "Easyrom" partition. Resizing the partition does not work whether the card is mounted or not.