[Sony Xperia P, U, Sola, Go] idbx:
I have followed the beginners guide as follows:

Check your phone software/firmware number by going to settings>about phone>build number

If you are on any GB firmware use flashtool guide in second post

If you are on ICS firmware (6.1.B.0.544 or 6.1.B.0.550 or 6.1.B.0.559) ,then

Download Rooting tool by Bin4ry from here

Extract it using 7zip/Winrar etc.

Double click the RunMe.bat and select 1. i.e normal phone option

Backup and restore app will open

Select RootMe.tar and click on restore

Follow instructions and bongo you are rooted

If you are on ICS firmware version (6.1.1.B.1.54 or 6.1.1.B.1.75), then

Download flashtool from official flashtool website

Install it on your PC using onscreen instructions.It will create a folder "Flashtool" in your drive(C\Flastool)

Now go to C\Flastool\drivers\flastool-drivers.exe and click on it and install it after marking/checking "xperia p,xperia u,xperia sola drivers" which is below there on the list

Download the file from here-

Now copy the files "Xperia P LT22_6.1.1.B.1.54_Kernel.ftf" , "Xperia P LT22_6.1.B.0.599_Kernel.ftf" and "Xperia P LT22_6.1.1.B.0.75_Kernel.ft and paste them in "C\Flastool\Firmwares" in PC.

Now keep "Root_with_Restore_by_Bin4ry-XP" folder in the dekstop as it is.

Now for your SXP.Go to 'settings>developer options>USB Debugging">'mark/check this option

Open flashtool from PC.

Click on the "flash" icon of the flashtool which is on the left side of the iconic tab(below the 'file' option-it's like a lightning sign).a window will be opened Mode Selector.Check "FlashMode" and press "ok" button.

You will see "Xperia P LT22 version 6.1.B.0.599" on the options.single click on that .uncheck "exclude kernel" (on the right side) and check "no final verification" and press the "ok" button.

A window will be opened saying to connect your device.switch off your phone for 30 secs.now connect the USB cable to PC(not on your device).now press down the vol.down button and hold it while connecting the USB to your phone.[now the flashtool will start flashing.but if you are doing for the first time sometimes the drivers are not able to detect the drivers of your phone and the phone starts charging in a normal way instead of flashing.don't worry.Disconnect the USB from phone only.wait for 10-20 secs.repeat from step v again and then connect your device while pressing vol.down button.the flashtool will detect your device and start flashing.)

You will be able to see percentage below.after it is finished it will be written there.disconnect USB cable from your phone only after watching it.

Restart your phone.

Go to your dekstop on PC.open the "Root_with_Restore_by_Bin4ry-XP" folder.

Click on "RunMe.bat" .a commend promt window will open on your PC.

now write only "1" (Normal Phone) in the "Make a choice" section

it should be like this.

Make a choice : 1 [Hit enter then]

It will promt to connect your device in debugging mode.Connect the USB to your phone with debugging mode turned on.now the Command Promt Window will do its work and it will say to you to open your "backup and restore" app.

Get your phone in your hand.open "app drawer>back up & restore" and hit the "restore" button.

The phone will be restarted in a while.

now you will see "super user" or "superSU" app on your app drawer.that means your phone is ROOTED successfully.

Restart your device again.(just for being safe)

Phone is rooted but the kernel is of previous version 6.1.B.0.599.So we have to reflash "6.1.1.B.1.54_Kernel.ftf" or 6.1.1.B.1.75_Kernel.ftf to the phone using Flashtool again.

Open flastool.watch step v and do the same.but select the "Xperia P LT22 version 6.1.1.B.1.54" or "6.1.1.B.1.75_Kernel.ftf"option instead of the previous ".599".now check and uncheck as the same before and flash your device pressing "ok" button.

Disconnect the phone.FINISHED.

Enjoy Rooting

Completed successfully. Installed clockwork mod like this:

Download the zip package from this thread

Extract the folder using zip/winrar

Connect your phone to the pc with USB debugging on

Click on install.bat

Completed successfully.

However I am now stuck trying to flash a boot.img file using fastboot over adb. It tells me that I do not have root privileges despite the fact this all worked and I have SuperSU installed on my phone. Does anyone have any advice?

For reference I am trying to install this: http://xdaforums.com/showthread.php?t=2130986 using the locked bootloader version.