I an trying to edit /ueventd.rc to add the line
"/dev/ttymxc0 0666 root root"
allowing normal users access to the com port.
I have remounted the rootfs as read write and pushed the updated file however after cycling power the changes are gone.
Any help would be appreciated.
The root is a RAM file system so all changes are lost at reboot. To make permanent changes you need to modify the contents of uramdisk.img and put that onto the boot device, which has to be done from a host development system.