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Root vs. Unlocked bootloader

13th May 2011, 03:36 AM   |  #1  
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In this thread I intend to give some basic insight about these two concepts, which are closely entwined with our phone's experience. I'm not a tech guy, but I think this little summary might clear some doubts for people who are new to this kind of issues (people who come from other non-Android phones especially). All feedback is welcome, in particular the one of people who can expand the topic with their knowledge.

"Root" is the common way to refer to the fact to the user account which has superuser rights on the device. Superuser rights imply full control over your phone's capacities, which are determined by the software and the hardware of the device. Non-superuser accounts have limitations, usually established for the sake of software security (for example, not allowing a user to disable critical functions such as phone or GPS), hardware safety (not allowing to change the processor's frequency speed, aka overclocking the CPU) or, in some cases, for someone's profit (disabling wi-fi tethering is a typical one as users are forced to buy data plans in order to use their devices to tether). In Android's case, Superuser is composed of an app* and a set of instructions to give this app root rights.

The bootloader is a program which accesses the internal storage and, basically, controls the loading of the programs and data necessary to initiate the sequence of launching the OS (aka booting, thus the name bootloader). We say that a bootloader is locked when it is programmed in such a way that it won't allow to load the device if it detects data from third-party sources. Unlocked bootloaders do allow these data and will load what these data contain, which will be usually a modified version of the phone's firmware, known as "Custom ROM".

As we can see, there was the fear that one would need to have unlocked bootloaders (i.e the ability to load third-party data in the booting sequence) in order to gain root rights. This would have been terribly inconvenient because only a minority of users will have unlocked bootloaders, since the phones with unlocked bootloaders by default are the ones sold carrier-unlocked. Said carrier-free phones will be a minority as the phone is pretty expensive: most Xperia Plays will be sold using carrier subsidies.

However, our fellow member Chainfire found an exploit (a programming loophole) in Gingerbread which allows said app and instructions to be loaded without the need of touching the bootloaders. Basically, his Gingerbreak program allows the user to have root rights without loading any bootloader-sensitive data. This widens the possibilities for the majority of users who will buy this phone with a subsidy.

*edit 3* Later on, it has become possible to unlock the bootloader even for SIM-locked devices, thanks to different unlockers like Alejandrissimo and Jinx13. This means that, provided that you pay what they charge, you can have your device set up without the bothers of having to buy a SIM-free phone. What's better: their method of unlocking the bootloader SIM-unlocks the phone as well.

I think this is more or less a succint framework of ideas which allows us to define "root" and "unlocked bootloaders" properly. As they say, knowing is half the battle, so I hope this nugget of information allows users to deal with their phones with more confidence.

*edit* as of version 2.3.3, this information has changed. Gingerbreak doesn't work with 2.3.3 anymore, and it seems now that the only way to root with locked bootloaders is to flash a 2.3.2 rom with FlashTool and update through OTA.

*edit2* note that this explanations pertains mostly to the Xperia Play. Other devices are NAND-locked, which means for us that they need unlocked bootloaders to even get root access.

*Note that Android is built in such a way that every app is a user account with limited rights (the ones specified before you download it). Thus, Superuser is a user account as any other app and the set of instructions is meant to give this user account root rights.
Last edited by Logseman; 18th October 2011 at 12:50 PM.
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13th May 2011, 04:32 AM   |  #2  
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Thank you! This was very helpful in clarifying some things.
9th June 2011, 07:24 PM   |  #3  
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"As we can see, there was the fear that one would need to have unlocked bootloaders (i.e the ability to load third-party data in the booting sequence) in order to gain root rights. This would have been terribly inconvenient because only a minority of users will have unlocked bootloaders, since the phones with unlocked bootloaders by default are the ones sold carrier-unlocked. Said carrier-free phones will be a minority as the phone is pretty expensive: most Xperia Plays will be sold using carrier subsidies"

by carrier unlocked do you mean sim unlocked? sorry 4 noob question
15th June 2011, 01:53 PM   |  #4  
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Indeed, that is what I mean.
15th June 2011, 08:24 PM   |  #5  
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Quote:
Originally Posted by Logseman

Indeed, that is what I mean.

Alright, I asked this question and it was answered, but I want to make sure before I try anything.

I just found out from SE that my phone is the Rogers version. It's obviously been unlocked because I'm using it on AT&T.

What I don't know, though, is whether the bootloader is unlocked. Another member recommended that I check TrackID to see if it worked because it depends on the manufacturer DRM's that are wiped in unlocking the bootloader. It did work, so I assume it's still locked, but I wanted to confirm because of being carrier unlocked.

Sent from my R800a using XDA App
15th June 2011, 09:59 PM   |  #6  
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If TrackID works, your bootloader is locked, regardless of simlock.
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16th June 2011, 03:34 AM   |  #7  
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I have a Sim-Unlocked Xperia Play from Rogers that I am using on ATT's network. My phone is boot-locked. When powered off, if I hold the search key while plugging in the USB cable, I do not get a blue light.

I was able to flash the firmware by holding the back key while plugging in the usb cable (with the phone off). I get a green light when I do this. Using flashtool, I was able get 2.3.3 rooted by loading the 2.3.2 firmware, rooting, and then updating OTA.

I bricked my phone several times while loading the firmware and each time I was able to fix it with flashtool or Sony Ericsson's Upgrade Utility. I found that you need a good USB cable, and even then it failed sometimes. I just kept trying and eventually it worked.
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23rd July 2011, 05:09 AM   |  #8  
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We wanted to provide an update on HTC’s progress with bringing bootloader unlocking to our newest phones. We know how excited some of you are for this capability, and we’ve put significant resources behind making this change as soon as possible. While we wish we could flip a simple switch and unlock all bootloaders across our device portfolio, this is actually a complex challenge that requires a new software build and extensive testing to deliver the best possible customer experience.

We’re thrilled to announce today that software updates to support bootloader unlocking will begin rolling out in August for the global HTC Sensation, followed by the HTC Sensation 4G on T-Mobile USA and the HTC EVO 3D on Sprint. We’re in the testing phase for the unlocking capability now, and we expect it to be fully operational by early September for devices that have received the software updates. We'll continue rolling out the unlocking capability over time to other devices as part of maintenance releases and new shipments.

HTC continues its commitment to unlocking bootloaders and supporting the developer community. Because of the importance of this community to us, please expect an update on this about every few weeks as we make progress toward launch. Thank you for your patience and continued support!

(they claim it will come to only two devices for starters the EVO 3D and the Sensation 4G and then it will slowly rollout to other devices that already have 2.3 or enough internal memory on them, this will all start in last August an early September for the first two droids listed... and others will soon follow suit, the only question is do you want you bootloader to come unlocked stock? Or will you buy it locked and be able to sit around and wait for your device to get an update to do so?? LOL
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23rd July 2011, 07:22 AM   |  #9  
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thats why my phone couldnt flash back to 2.3.2..(?)

I live in singapore.. phones are not carrier specific.. so does that mean my BL was unlocked even before I used gingerbreak?
Last edited by LemonPlusTea; 23rd July 2011 at 07:31 AM.
23rd July 2011, 12:27 PM   |  #10  
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I know this doesnt pertain to the play per se, but maybe you should add that, with nand locked devices, an unlocked bootloader is required to acheive full root, just incase someone with another device googles this question and ends up here

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