|The redundant docomo system software normally cannot be disabled|
BackgroundDoing this is trivial. The needed files are available through XDA Developers. I did this on the original SO-04E firmware (4.1.2, build 10.1.1.D.0.179). To date, the SO-04E has received two OTA updates, this method is compatible with the first update (build 10.1.1.D.2.26), but not yet with the second update (build 10.1.1.D.2.31), though support should be coming soon. The developer of these rooting scripts only needs the build.prop and kernel.sin files from a new build to add support, and those have already been submitted.
If you are currently running a supported build (confirm build in Settings > About Phone) then use Root Keeper to preserve root privileges when upgrading to the latest version by OTA. However, if you use the Sony desktop update tool, you will lose root, and root keeper is not compatible with Andorid 4.3 (though this has not yet been announced for the SO-04E).
Exploit patched in Android 4.2It has been reported that for the Xperia Z, this no longer works on 4.2. The process becomes much more complicated, so if you plan to root your Xperia, do it before the update to 4.2 rolls out, then use Root Keeper. 4.2 has been announced for the Xperia Z, and we can only assume that this exploit will also be fixed for the Xperia A.
Rooting StepsStep 1: Down and unzip the "DooMLoRD Easy Rooting Toolkit" from XDA. All dependencies are included.
Step 2: From Settings, make sure you have turned on 1) USB Debugging in Developer Options and 2) installing apps from unknown sources in Security.
Step 3: connect the phone by USB, navigate to the folder you unzipped, and execute the appropriate script for your environment, e.g., on a mac,
(On mac, do this by typing
sh runme_mac.sh. You may need to give the script execute permission (I didn't), but if so, type
chmod +x runme_mac.sh.)
After RootInstall Titanium Backup and disable all the redundant Docomo junk, but be careful that you don't disable the software update, or some of the other docomo stuff needed to receive OTA updates. DO NOT UNINSTALL THE DOCOMO SYSTEM APPS. It appears that the OTA checks for system applications, but I'm not sure if it checks for all or just those required for the update. I had disabled everything and got the following error when attempting to OTA update.
At first, I thought this was because I had disabled some of the cryptically-named system software, like "docomo service" or "docomo device manager", (as shown below) that was needed to handle the OTA update file. However, after reenabling these, the OTA still resulted in the same "insufficient internal storage space" error. I then reenabled all Docomo apps, and the OTA still failed. So I rebooted. Then it worked, but I am left unable to determine exactly what fixed it, the reboot, or reenabling everything.
These are the Docomo apps that I have left enabled. "docomo" is the docomo account used for sp-mode stuff. Perhaps we'll experiment and figure out just which of these are actually needed.