Please read this if you considering unlocking the boot loader or rooting your phone.
Please note that you may void the warranty of your phone and/or any warranty from your operator if you unlock the boot loader. You should only unlock the boot loader of your phone if you are an advanced user with good knowledge of the technology and risks involved.
For more information go here http://unlockbootloader.sonymobile.com/
Please also note
The Sony Xperia support team will not be able provide any support, related to unlocking the boot loader or rooting your phone.
We also recommend you to read the below blogposts.
Sony Xperia support team
2012-06-05 08:44 AM
you can try this. I already tried it and found it useful.http://www.androidust.com/single-click-root-for-xp
2012-06-06 10:11 AM
It's simple. Flash ftf with 4.0.3 kernel (not full firmware!), root with Doomlord script and flash 4.0.4 kernel again. Proper ftf's are as always on xda.