Bootloaders. They're quite the touchy subject for many of us geekier android lovers. Naturally they've been a hot topic in the news lately, with HTC deciding to lock down phones only to reverse the decision. This is hardly an issue reserved for HTC though. For those who aren't as privy to the underlying workings of computers, what a bootloader is, and what it means for one to be unlocked can be unclear. We're gonna break down for you what a bootloader does (at a non-technical level), what the difference between locked/encrypted/unlocked/signed/etc, which manufacturers are doing what, and why the debate is so hot, and why you should care.
What is a Bootloader and What Does it Do?:
When any computer turns on (including your Android phone) it has to run a small dedicated program that loads the operating system. This program is what we call the bootloader. Because the bootloader is in charge of loading your OS, it rules quite a bit of your ability to load a custom ROM. It is not impossible to customize your phone with a locked bootloader. For instance the Motorola Atrix has several "pseudo ROMs" which consist of mostly cosmetic changes. To load a truly custom ROM though, one with lower level changes, like those that allow you to overclock your phone, the bootloader must be unlocked.
So Why Can't We Just Unlock it?:
This is the tricky part. A lot of terms have been thrown around, misused and confused in regards to bootloaders. So first a few terms:
Locked: Nearly ALL phones sold commercially have a "locked" bootloader. This is not any sort of indicator as to whether or not you will be able to customize you're phone. What matters is how easily it can be unlocked.
Unlocked: Once a phone is unlocked you can basically any software on it from a custom version of Android (aka a custom ROM) or custom recovery, like ClockworkMod Recovery.
Signed/Encrypted: To put this plainly, a signed bootloader requires an obscenely large code to unlock. The security can be more complex, and "key" sizes vary, but this is what has many Android lovers up in arms.
Locked down: This generally means that a bootloader cannot be unlocked, at least not without the "keys" that were used to sign or encrypt the bootloader by the manufacturer. Usually signed or encrypted bootloaders are considered locked down
Even phones like the Nexus line have locked bootloaders, but unlocking them is very simple if you so desire. On most phones this will void the warranty however, but more on that later. Not all phones' bootloaders are as easy to unlock though. Some have been unlocked by exploiting weaknesses in code, while some require the help of the manufacturer, as is the case with Sony Ericsson's newest Xperia phones. It's when we get a "signed" bootloader that trouble starts.
The first phone to really bring the bootloader issue to light was the Motorola Milestone, which was the international version of the original Droid here in the U.S. The bootloader was indeed signed, and to this day has not been truly cracked. For this reason international owners of the Milestone did not have anywhere near the freedom as Droid owners had. Since the Milestone we've seen several different approaches to bootloader policy from different manufacturers, but until recently things had not been going too well.
So Where are We Now?:
We are finally starting to see some progress in the way of bootloaders. Although HTC, who used to be recognized as one of if not THE most hacker friendly manufacturer, did give a scare recently, locking down the Sensation in a complete 180 after giving us some of the most customizable Android phones ever. As mentioned Sony Ericsson is starting to let developers unlock their SE phones by following a process and instructions from SE. Samsung and LG have yet to implement anything to completely lock down the bootloader. Finally there is Motorola. They started the locked bootloader fiasco for Android, and many of their devices remain completely locked down. We are all still waiting for their promised "fix," which will allow users to unlock the bootloader on "certain devices," but with no details other than it will come in late 2011.
So Why Does Any of this Matter?:
Flashing custom ROMs is not for everyone, and neither is rooting. That's a major reason why manufacturer's don't listen more ernestly to those of us who want full control over our phones, we're simply not that big a percentage of the market. Furthermore manufacturers have other reasons motivating them to lock bootloaders, like the possibility of people bricking their phones, then trying to return them. Solutions have been suggested, but an in-depth analysis of the arguments if for another time. For now I will wrap up by saying that Android is meant to be free. It's open source. Manufacturer's don't have to pay to use it, or even any of its logos. Many people love Android over iOS, overlooking that it's not as polished in some areas for the freedom it brings them. When you buy a phone it's yours, you aren't leasing it from the carrier, no where in your contract does it say Motorola can come to your house and take back your phone if they don't like how you use it.
If you have any questions feel free to hit up this thread! I'll be watching it and answering questions anyone asks there as best I can. Also feel free to leave your opinion on the bootloader issue either in the thread or the comments.