[Sony Xperia S, Acro S, Ion] -Harsh-:
I see people asking everywhere how to root xperia s with locked bootloaders.. There's a lot of confusion in new users regarding rooting and I also faced the same when i first started reading this forum. So i finally thought a complete guide integrating everything on how to root a phone on LOCKED bootloader.

For unlocked ones, you can simply get root with CWM by flashing a custom kernel. You can get the details over here : http://xdaforums.com/showthread.php?p=23181182#post23181182

And various custom kernels can be found in our android development thread !!

For noobs, first of all for understanding what rooting is : (As on wiki)

Rooting is a process allowing users of smartphones, tablets, and other devices running the Android operating system to attain privileged control (known as "root access") within Android's subsystem. Rooting is often performed with the goal of overcoming limitations that carriers and hardware manufacturers put on some devices, resulting in the ability to alter or replace system applications and settings, run specialized apps that require administrator-level permissions, or perform other operations that are otherwise inaccessible to a normal Android user. Rooting is analogous to jailbreaking devices running the Apple iOS operating system or the Sony PlayStation 3. On Android, rooting can also facilitate the complete removal and replacement of the device's operating system, usually with a more recent release of its current operating system.

As Android was derived from the Linux kernel, rooting an Android device is similar in practice to accessing administrative permissions on Linux or any other Unix-like operating system such as FreeBSD or OS X.

Read this thread by Doomlord for all details : http://xdaforums.com/showthread.php?t=1526866

Now on to rooting..

Currently the method used for rooting with locked BL is for GB only (you cannot flash a pre-rooted image with locked BL).. SO if you are on ICS and not rooted, you first need to flash to GB and if you are on GB then follow the guide.

First of all, detail guide on HOW to flash is given by gtrab here : http://xdaforums.com/showthread.php?t=1725078

You can flash GB in the same way he said using the GB firmware LT26_6.0.A.3.75_UK Generic from here : http://xdaforums.com/showthread.php?t=1599303

After you have flashed GB finally start the rooting.

Video guide : http://www.youtube.com/watch?v=EHJFVdhPM6k

Sharaz22's guide which the video uses : http://xdaforums.com/showthread.php?t=1742992

Alternate

way to ROOT from GB : Go here (it's pretty easy)

http://xdaforums.com/showthread.php?t=1754429

Just download, flash to GB if you are on ICS and start run.bat and follow the instructions :highfive:

Once you are on rooted ICS, and thinking of flashing to different ICS (latest 6.1.A.2.45) preserving root it can be found HERE :

http://xdaforums.com/showthread.php?t=1856287&highlight=preserving+root+on+ics

Make sure you follow all the instructions given by these dev's before you start flashing your device.

Also, you can never brick your device on LOCKED bootloaders so don't worry !!

As everyone says DO THIS AT YOUR OWN RISK :p

I or anyone of these experts above are not responsible if you burn your phone or PC/laptop ;)

Enjoy !!

Thanks all the experts for giving these guides.. Will keep this post updated with new rooting developments !!

If you feel I've helped you hit the Thanks button !!