Over-the-air programming

Recent XDAndroid releases (since Version FRX03) have been made available both as a full system image as well as as a patch against an older release. The advantage of the patch is that it is much smaller than a full system image, which is usually nearly 70 MB.

The XDAndroid patch-form release enlists Android's standard update mechanism: a file called "update.zip" gets deposited in a particular location in the device's filesystem, Android notices the file at the next boot time, applies the update, deletes update.zip, and reboots the phone.

In the case of phones running an (unmolested) Android release provisioned by a mobile network operator (MNO), the MNO pushes update.zip to the device automatically and wirelessly (see over-the-air programming, or OTA), and Android applies the update at the discretion of the user. 

For XDAndroid, update.zip must be downloaded manually and copied to the "andboot" directory (or equivalent) on the SD card. Note that XDAndroid update releases are named, e.g. "update-FRX03.zip" and must be renamed to "update.zip" to engage Android's update system.