@lduboeuf Your instructions for Xenial worked perfectly.

It was necessary to:
sudo touch /userdata/.writable_image
sudo touch /userdata/.writable_device_image
and reboot.

I can see that creating those two files means that the /dev/loop0 device is mounted read/write at boot time which means it is already writable when the ofono.override file is bind mounted.

BTW, can you point me at the documentation about those two files?

@lduboeuf I'll give it a go and report back later today. Thanks.

I am working on an application that uses dbus to access ofonod and I'd like to configure ofonod to output debugging information to gain insight.

I though I'd be able to edit the file /etc/init/ofono.override and add the "-d" option to the exec directive.

I tried remounting the / filesystem as read/write but I realised that the ofono.override file is itself a bind mount and is still read only. Then I had a go at editing the file in recovery mode by setting up suitable loop devices and mounts but that didn't end well - the phone no longer boots into ubuntu and I need to start with a fresh installation!

Is there a way to edit ofono.override without fouling things up?

BTW I'm running Ubuntu Touch on a Nexus 5.