Develop Bugs

[Q]What exactly is TA partition and when does it change?

Hello everyone, I did my best to help a few people in Q&A section, but now, I have a few questions myself, all of them, regarding mysterious TA partition.
My C1905 came out of the box with branded 15.1.C.2.8 firmware. One of the first things I did after rooting the device was backing up my TA partition, knowing that I will sooner or later unlock the bootloader. However, I then cross-flashed unbranded C2005 15.2.A.2.5 firmware. My questions are:
1)Do I need to backup TA partition again on a new firmware to be able to relock my bootloader without changing it? Does the TA partition vary between firmwares?
2)Will changing my firmware again to official 4.2.2 for C1905 (which should be released within 2 months) require my to back it up again? Is the C2005's TA partition different than C1905's?
3)Just out of curiousity, what exactly does the TA partition contain? From what I've read, it stores unique "DRM keys", but that doesn't tell me much. Are these keys linked with any hardware (like - for comparison - Samsung's "EFS" folder stores IMEI, MAC adress product code etc and without it, phone has very limited capabilities), or is it just more like "locked bootloader certificate"?
I just want to clear that up, thanks in advance for answering.

3) TA partition contains DRM(Digital Rights Management ) keys, as you said, and other bootloader and hardware related information.
As for the relocking part the problem is the DRM keys...If you read some of the wiki article i linked then you will understand how they are being used in order to prevent locking the bootloader again.
Some software requires those to run, Ex:Bravia Engine2(we dont have that in our phones, but if we had and unlocked the bootloader we wouldn't be able to use it).
1),2)No, you have unlocked your bootloader and your DRM keys are gone, you have them only in your back up. If you want to relock then you will restore your backup while in stock rom-kernel.

stamatis said:
1),2)No, you have unlocked your bootloader and your DRM keys are gone, you have them only in your back up. If you want to relock then you will restore your backup while in stock rom-kernel.
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I think you didn't fully understand the first question. Can I backup TA of my current firmware and then use that back up to relock bootloater WITHOUT changing it back to the stock 15.1.C.2.8? Or do I HAVE to roll back to stock firmware and only then I will be able to relock it? Or maybe I can use the stock backup on any firmware, because TA doesn't change? In other words, can I relock the bootloader on other ROM than stock?

WoJtOn said:
I think you didn't fully understand the first question. Can I backup TA of my current firmware and then use that back up to relock bootloater WITHOUT changing it back to the stock 15.1.C.2.8? Or do I HAVE to roll back to stock firmware and only then I will be able to relock it? Or maybe I can use the stock backup on any firmware, because TA doesn't change? In other words, can I relock the bootloader on other ROM than stock?
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I think i answered:laugh: haha.
It is recommended to be on stock. I wouldn't try it with custom rom due to the possibility of hard brick.

Going back to stock, no backup

Hey, I'm about to sell my phone, so I need to get it to its factory state. Prefably so that the guy that buys it could send it over for repairs if needed.
And so I did not backup the TA partition. From what I've read that means no relocking the bootloader. Fine.
But how do I go back to the original 4.1.2 sony-branded system?
I'm currently on CM11. Can I just use Sony Companion to perform the update, is it safe? What steps should I undertake?

As far as I know, Sony Update Service won't work with unlocked bootloader (I may be wrong), however, you just need Flashtool and a FTF from the latest stock firmware for Xperia M single SIM (currently at 15.1.C.2.8)

Sorry mate but you can't lock your bootloader without DRM keys(TA PARTITION BACKUP).
You can flash stock ROM using FTF flashtool and but i cant relock your bootloader but you will get stock rom back.
Warranty is void now!!

Sh!t. That's not good.
Thank you guys for answers!

One more thing.
Is it possible to receive OTA updates after I unlocked bootloader and flashed the stock firmware with flashtool?

No once bootloader is unlocked it bricks the device doing ota updates
Sent from my C1905 using xda premium

Sh!tness. So I guess I'm stuck with the phone forever.
Thanks!

Further info for future Xperia phones you may buy: when you unlock your bootloader your DRM keys get wiped, without them, OTA updates, Mobile Bravia Engine (in models that have them -- not the case for Xperia M), Track ID, Download Music Info and SensME (alongside some other proprietary apps/features) will not work, even if you flash stock firmware again.
Before unlocking your bootloader it's always recommended to do a TA backup first, so, if you need, you can relock your bootloader to get your DRM keys back and make proprietary Sony apps/features working again. Since you didn't backup your TA partition before unlocking, you are out of luck now and there is no way of relocking your bootloader.
Also, DO NOT EVER TRY restoring a TA backup from another device (even if it's exactly the same model), TA partition contain some unique info and flashing a TA backup from another device will permanently hard brick your phone...

Well that's a very comprehensive answer! Thanks!

Is it possible to upgrade the bootloader and radio on a RELOCKED device with TWRP?

Yeah, it's locked with a TWRP on it.
Now the data partition is unencrypted. I want to upgrade the bootloader, but it says it should be first unlocked.
Will unlocking cause destruction to all my data? If so, can I upgrade the bootloader?
P.S. My data is 20GB. I don't want to make a backup at the moment, if not necessary.

First of all: Yes, unlocking your bootloader will erase your data. Make a backup before you do.
Second of all: Is there a reason you want to do this? Your phone should continue to work fine if you're not on the newest bootloader or radio. Over the course of a year, I had updated mine from 6.0.1 to 7.0 to 7.1 without ever updating the bootloader and radio. It will work fine with an older version.
Third of all: As a curiosity, you have TWRP installed to the /recovery, but will it actually boot TWRP with the locked bootloader? I didn't think it would...

It's booting. I don't know why. I'll post a video if you want. BTW, if I bricked my device with the bootloader locked, is there any chance to re-flash it to stock?

I believe so. Instead of Pwr+VolDown to get into the bootloader, you can do Pwr+VolUp to get into recovery, and I think you can sideload the stock firmware. Don't quote me on that, tho, as I could be mistaken. Never had to do it myself, as I've always been unlocked and used Fastboot.

You may run into problems if you need to flash the factory images as you'd have to unlock the bootloader first so if there were any problems and you were unable to unlock it, you would not be able to flash them. My advice would be to unlock it and leave it that way as long as your device is modified.

[Q] Encrypted data

Hi guys,
I just got Xperia M from my friend to install on it some custom ROM and etc. but there is encrypted data and I cant do nothing with it.
I tried repairing software with Xperia Companion, but I get UEUpdateFailed UE_2005 error and cant get past it. I tried also to enter recovery, but there's no recovery. Dont know what to do, cuz I need to check if I can unlock it.
Thanks in advance

Hi,
I can't figure out what exactly is giving you trouble, so you might want to be a little more specific. So I don't know if this is helpful for you, but:
First, there is no stock recovery on the Xperia M. As long as you don't flash a recovery on it, there is none. So you won't be able to enter that.
Next thing, Xperia Companion is a software to update or repair the stock ROM. So you won't be able to flash a custom ROM with that.
Just backup the data (if the data is encrypted and still needed, you didn't say what exactly is encrypted) and use flashtool to flash a ROM.
I'm not sure what you mean with checking if you can unlock it. The encryption? The boot loader? SIM lock? If you can unlock the boot loader (and SIM lock status too) you can check with the service number, so no need to flash it for that. Or is the device not even starting up because of the encryption?

So I dont really know if I can unlock bootloader of that phone cuz I need to "you should confirm that it is possible to unlock the boot loader of your device by checking the service menu. In your device, open the dialler and enter *#*#7378423#*#* to access the service menu" but I cant cuz of encrypted data. When phone boots up it ask me for password, but I dont know it. When I tried to use repair function to flash stock software and then the encryption would be gone it gived me error mentioned before. I dont know any recoveries or Roms that I can flash on locked bootloader. Any sugestions ? I want to flash newest Lineage OS at the end.

Is it possible that the boot loader is already unlocked? PC Companion is not working with unlocked boot loader.
You can also use flash tool to check if the boot loader is unlocked or not.

how to check that in flashtool ?

You switch off your phone, hold the volume down key, connect the usb cable, then it should be recognized in flash tool. Then you click on the lock. It should tell you the state of your boot loader somewhere there.

Question How to relock bootloader?

Hello! I got a problem with my OnePlus 11, as I checked the playback settings on netflix, my widevine says it is L3. Is there anyway to fix this and bring it back to L1? I seriously don't know what happened.

Hello,
The post at this moment just under yours has a part called "Return your phone to unlock and unroot : Step 2 - Relock the bootloader".
Beware and be sure of what you are doing though. With this phone, relocking the bootloader while having any modified system partition (as init_boot for exemple) means a hard brick.

_Johnito_ said:
Hello,
The post at this moment just under yours has a part called "Return your phone to unlock and unroot : Step 2 - Relock the bootloader".
Beware and be sure of what you are doing though. With this phone, relocking the bootloader while having any modified system partition (as init_boot for exemple) means a hard brick.
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Is it safe? What do you mean by modified system partition?