[Q] rooting/bootloader - Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A

Hi I would like to ask whether rooting the phone is the same as unlocking bootloader. Thanks!

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No, it's not.
Rooting allows you to view and edit system files.
Unlocking the bootloader allows you to install custom (non-official) kernels.

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So rooting my phone and unlocking the bootloader is 2 different issue?
Or does rooting my phone actually unlocks my bootloader as well?

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Rooting does not unlock bootloader.
Unlocking bootloader can help root your phone (installing a pre-rooted kernel, for example).

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Is it then possible to install a custom firmware without unlocking the bootloader or will there be problems if I install a custom firmware without unlocking the bootloader.

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These two custom ROMs are the only ones that can be installed without unlocking the bootloader.
http://forum.xda-developers.com/showthread.php?t=1705255
http://forum.xda-developers.com/showthread.php?t=1578109

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OK THANKS! SHALL GO CHECK IT OUT And can I ask, does the phone by itself already have a kernel? If it has, what is the use of installing another one?

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Stock ROMs have their stock kernels.
Custom kernels can add some features, such as (for example) the chance to overclock the CPU. Almost every custom ROM needs a custom kernel to work properly.

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Feanor88 said:
Stock ROMs have their stock kernels.
Custom kernels can add some features, such as (for example) the chance to overclock the CPU. Almost every custom ROM needs a custom kernel to work properly.
Click to expand...
Click to collapse
Wrong. Custom ROMs do not need custom kernel to *function or work properly*.
The custom ROMs are installed at the Read Only Memory of your phone.
For that, you need to use an installer which has to be somewhere outside the Read Only Memory. Only such location on your phone is the kernel. So a custom kernel does nothing but adds an installer outside the Read Only Memory (that is the CWM Recovery).
Now to intall a kernel, you need an installer outside of your Read Only Memory as well as the kernel. That's the PC, and the installer is Flashtool. So, flashtool is used to install custom kernels on your phone.
Note: The two ROMs which can be installed on locked bootloaders are exceptions to this rule.
Thanks,
Rick
Sent from my SK17i using XDA

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If it were like you said, any custom kernel could work with any custom ROM, as long as it has a Recovery to flash the ROM. There are different custom kernels because there are different ROMs, and each custom ROM works only with one or more custom kernels, but not with everyone. If you were right, one single kernel with recovery would be usable for every custom ROM.

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Feanor88 said:
If it were like you said, any custom kernel could work with any custom ROM, as long as it has a Recovery to flash the ROM. There are different custom kernels because there are different ROMs, and each custom ROM works only with one or more custom kernels, but not with everyone. If you were right, one single kernel with recovery would be usable for every custom ROM.
Click to expand...
Click to collapse
Yea. It would be. Infact it is.
However, ROMs like CM9, which are NOT based on the stock ROM will not be able to work on the stock kernel. It will require a kernel which has been designed specifically for CM9. On the other hand, we had seen MiniCMSandwich, which looks like CM, but is based on stock ROM. This will work on any kernel that has a custom recovery. MESA, Rage, X, Stock Exteneded and so on...
So, to put it in other words, suppose you plan to flash an HTC Phone ROM as it came in the HTC device on your Xperia Device. You plan to just change the drivers. You will need a kernel which is designed for the HTC ROM.
But, if you, on the other hand, start with the Xperia ROM and change the aspects of this ROM into the HTC ROM's, you can make the ROM work on any of MESA, X, Rage or extended.
Thanks,
Rick
Sent from my SK17i using XDA

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DragonClawsAreSharp said:
Yea. It would be. Infact it is.
However, ROMs like CM9, which are NOT based on the stock ROM will not be able to work on the stock kernel. It will require a kernel which has been designed specifically for CM9. On the other hand, we had seen MiniCMSandwich, which looks like CM, but is based on stock ROM. This will work on any kernel that has a custom recovery. MESA, Rage, X, Stock Exteneded and so on...
Click to expand...
Click to collapse
Stock extended, yeah. Try to run MiniCMSandwich on Gingerbread stock extended kernel. Will it work? Of course not. All the kernels you named are based on stock ICS kernel, so it's simple to run ICS based ROMs on them. This doesn't mean that every kernel with recovery can make them work

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Feanor88 said:
Stock extended, yeah. Try to run MiniCMSandwich on Gingerbread stock extended kernel. Will it work? Of course not. All the kernels you named are based on stock ICS kernel, so it's simple to run ICS based ROMs on them. This doesn't mean that every kernel with recovery can make them work
Click to expand...
Click to collapse
Stock GB is to Stock ICS is same as Stock Xperia ICS is to Stock HTC ICS. They are different ROMs. Completely.
The ROMs have instructions according to which it behaves with the kernel. These instructions are all same for kernels that are based on stock ICS. So if you want to try any ROM that is based on stock ICS and such kernel will do.
But CM, GB, HTC ROMs and so on, are completely different.
Say you want to port an HTC ROM to Xperia ICS. You can do the following (I am taking example of the bootanimation file)
1. Simply change the bootanimation.zip file at /system/media of the stock ICS ROM.
So your ROM is based on the stock ROM itself. You just change the files, not the way the files are accessed. You do not even change the way the kernel is accessed. So any kernel based on stock ICS *with recovery* will do.
2. Change the whole Read Only Memory Partition.
This makes all the files replaced, the way HTC has made the ROM. This time you will need a kernel *again with recovery*, built to be accessed by the very specific ROM.
Thanks,
Rick
Sent from my SK17i using XDA