Tuesday, May 24, 2016

Negative effects of unlocked bootloader


Those who are expecting a little bit more from their devices are familiar with online tool to unlock the bootloader - htev.com. Once erated and flashed token via fastboot gives you possibility to change some of the partitions on device. It sounds grt, but there are some serious disadvantages of it. Some people may say this will result in limited warranty, which it is not true, and I explained that issue here.So, what else to expect with unlocked bootloader?




First of all, not all the partitions will be unlocked. Forget about flashing hboot.img, rata.img or tp.img. Permission to fastboot flashwill be denied. The only method to flash those s is to reboot device in RUU mode (fastboot oem rebootRUU) and flash originally signed firmware.zip (from OTA update) usingfastboot flash zip firmware.zipcommand.
So what can be flashed in fastboot mode? Basically just 3 s - boot.img, recovery.img and system.img. Is it enough to flash custom ROM? Yes. With custom recovery you can flash zips or make nandroid backup. Is it enough to be happy? No.The problematic part is flashing boot.img in custom recovery. It's not possible on S-ON devices, unless your device is supported by 4EXT Recovery with SmartFlash fture. So the only method to have complete custom ROM working, is to flash ROM in recovery and then reboot the device, enter fastboot mode and flash boot.img using fastboot flash boot boot.img command.
The second problem of unlocked bootlader is even more serious, but so far it affects only 2 devices: One X+ and One. Those who used htev.com before probably noticed, that bootloader wipes user data, including content of virtual SD card (because virtual SD card = /data/media).
This is no surprise, because every user is warned about it and have a chance to step back. As long as all appliions coming with stock ROM are stored on /system partition, there are no side effects. But for some very strange rson in One X+ and One, some of the stock appliions like Flashlight, Calculator, Ringtone-trimmer, PDF Viewer, Teeter, Sound Recorder and more, are stored on /data partition instd. Result? After bootloader with official tool you end up without having some of the basic appliions like Calculator or Flashlight, because /data partition (as mentioned above) has been wiped. System partition on One is almost 2 GB big. Not enough to include few more .apk files?
What is more, missing stock appliions on /data partition makes your device not capable to receive any OTA updates from . Why? Because every OTA update checks MD5 checksum of every file that originally came with your device. So even if you didn't flash any custom ROM and your /system partition is unmodified, you won't be able to install OTA update.


This is an example of updater-script part from OTA:
assert(apply__check("/data/preload/Calculator.apk","85aa7b00ec97ffe7179739c8815bf102c4f8666e","7055f0376e6b56be6414fdf8495b82db7fd38564")||apply__check("/data/preload/Calculator.apk.uninstall","85aa7b00ec97ffe7179739c8815bf102c4f8666e","7055f0376e6b56be6414fdf8495b82db7fd38564"));
Once assert will fail, OTA update will cancel the installation process. I think every user should be warned, that bootloader results in no longer OTA updates support.
To summarize:Unlocked devices via htev.com can't have boot.img flashed via custom recovery.Unlocked One X+ and Onevia htev.com will loose some basic appliions like Flashlight or Calculator.Unlocked One X+ and Onevia htev.com will loose possibility to receive OTA updates unless user will flash original RUU.exe, which are not officially available for customers.Conclusion: Is it worth to buy One? Yes! It is currently the best device on the market. If you are not planning to flash any custom ROM - don't unlock your bootloader. And if you want to flash custom ROM, it will probably contain missing appliions anyway. This is far too grt device and I believe HTev tm will sort out above issues soon!
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