Android General Question - ROM, CWM, TWRP, Boot Loader and more ?????

Hello Guys

I am new to android rooting and custom rom, i have many question, hope you guys will be able to help me here.

1) What is BootLoader ?

2) Does all phone have bootloader ?

3) What is CWM and TWRP are they both same ?

4) what is the use ?

5) Can we install it permanently on phone ?

6) when a phone is root and after that if we do a factory reset, will the root status remain or will it go back to unroot ?

7) can we again unroot a phone and claim warranty ?

8) How can i backup my rom ?

9) What is recovery ?

10) does all phone have different recovery ?

11) where to find recory of a phone ?

12) can we backup rom without rooting phone ?

13) when a rom backup is done, does it backup factory image or all installed app from google play ?

Please help, i need to know all this before i do anything with any android phone.

thanks in advance

XDA-Developers

i hope somebody answer at least in yes or no

- - - Updated - - -

lenovo has provided open source code for its phone online, is it useful

*support.lenovo.com/hr/hr/products/phones/a-series/a6000/downloads/DS104622

Better read that wiki.

1) What is BootLoader ? - Bootloader - XDA-Developers

2) Does all phone have bootloader ? - Yes

3) What is CWM and TWRP are they both same ? - What is CWM Recovery | ClockworkMod | In Detail | Root My AndroidRoot My Android TWRP is similar to CWM - What Is TWRP Recovery & How To Install & Use It On Android [Guide]

4) what is the use ? - Explained in that article

5) Can we install it permanently on phone ? - Yes

6) when a phone is root and after that if we do a factory reset, will the root status remain or will it go back to unroot ? - It may remain rooted. It's not recommended to factory reset a root phone, instead flash a rom.

7) can we again unroot a phone and claim warranty ? - Some devices come with a root tripper, if it's tripped you will lose warranty. Some devices do not come with root tripper. Check in XDA. But safe to say if you root a phone the warranty gets void, that risk is always there.

8) How can i backup my rom ? - Use a recovery tool like CWM.

9) What is recovery ? - Check answer to Q3.

10) does all phone have different recovery ? - Different phones come with different recovery, you can't use it yourself, that's why you need CWM or TWRP, those are different for different phones. Check answer to Q11.

11) where to find recory of a phone ? - ClockworkMod Recovery - XDA-Developers

12) can we backup rom without rooting phone ? - No

13) when a rom backup is done, does it backup factory image or all installed app from google play ? - Everything, you need to take Nandroid backup: How to Create Nandroid Backup & Restore it to your Android Device

Tl;dr answers:

Skyh3ck said:
Hello Guys

I am new to android rooting and custom rom, i have many question, hope you guys will be able to help me here.

1) What is BootLoader ? It is a piece of code that runs before a OS boots. Basically it allows you to choose what OS to boot into. In case of phones, a bootloader allows you to choose between booting the OS and Recovery mode (such as CWM or TWRP).

2) Does all phone have bootloader ? Besically, yes. At least all smartphones. I don't think Java or custom firmware phones have those.

3) What is CWM and TWRP are they both same ? CWM is ClockWorkMod, a recovery (as mentioned above) developed by Koushik Dutta. TWRP is Team Win Recovery Project, it is developed by a group called Team Win.

4) what is the use ? It is a platform outside your phone's main OS that allows you to flash ROMs or updates to your phone. It would not be possible to do so from within your OS when your phone is running it.

5) Can we install it permanently on phone ? Yes.

6) when a phone is root and after that if we do a factory reset, will the root status remain or will it go back to unroot ? Depends. The factory reset image usually resides in the system partition. If you flash a ROM is pre-rooted, it might replace the system image, in which case, you might maintain your rooted status.

7) can we again unroot a phone and claim warranty ? Depends on phone. Check XDA for steps. But its possible for many phones. Some however could be irreversible.

8) How can i backup my rom ? Use the above mentioned recoveries. Boot into one and select the option to backup your ROM. It will create a zip file containing a dump of your phone's current OS on your phone's SDcard (real or emulated). In case something goes wrong, just boot recovery and restore it from this file.

9) What is recovery ? As mentioned above, its an environment outside of your OS.

10) does all phone have different recovery ? Depends on phones. Cyanogenmod phones have their own recovery by default, others may or may not have it depending on the manufacturer's policies. That does not mean that you cannot install or replace one.

11) where to find recory of a phone ? Generally there is a key combination that you have to press to access the recovery (ex. vol down + power on for OnePlus One) when starting the phone. Check the combination for your phone online.

12) can we backup rom without rooting phone ? Depends. Backing up a ROM requires access to system internals, which might not be accessible without root. Definitely not backup from a recovery.

13) when a rom backup is done, does it backup factory image or all installed app from google play ? It will backup the current OS in its current state. That is when you recover using it, you will get back all your apps, contacts, messages, etc. at the time when you took that backup. That is why it is a good idea to take backups frequently so that you can get back to a state as fresh as possible when you recover.

Please help, i need to know all this before i do anything with any android phone.

thanks in advance

You're welcome.

But read the links in tkin's post to get a more detailed explanation.

Thanks read the links its informative, however i still have few questions

can we install multiple recovery like CWM and TWRP same time on phone, is it possible ?

Can we flash a rom with TWRP, which is taken by CWM or vice versa, or it has to be flashed with same recovery ?

I did a back up of my stock rom, with TWRP, it created a Folder in sd card TWRP> Backup etc, however its not a zip file, its actually a folder, however i have seen that it has to be a zip file, do i have to zip it manually or what ?

where can i request recovery image for my phone ?

Answers below:

Skyh3ck said:
can we install multiple recovery like CWM and TWRP same time on phone, is it possible ? No. You will have to choose one and stick with it. You can change your recovery if you want though.

Can we flash a rom with TWRP, which is taken by CWM or vice versa, or it has to be flashed with same recovery ? ROMs are standard zip files containing apks and system binaries. There is nothing about them that makes them unique to a particular recovery. Therefore, yes, you can flash a ROM with any recovery.

I did a back up of my stock rom, with TWRP, it created a Folder in sd card TWRP> Backup etc, however its not a zip file, its actually a folder, however i have seen that it has to be a zip file, do i have to zip it manually or what ? That's probably TWRP's way of backing up the ROM. Should not matter IMHO since it can function the same way.

where can i request recovery image for my phone ? Look on XDA forums

I think analogy would help you better.

Windows PC => Android Phone
OS installation media => Rom zip files
Backup or System Restore Image => Backup done by TWRP/CWM/any other method

You shouldn't restore somebody else's backup. But the ROM zip files made for a particular phone model can be flashed by any phones of the same model.

ROM zip files =/= ROM backups.

I backe up my rom with TWRP, and it made a folder, do i have to create a zip or just leave it like that, can i rename it ? i will keep it saved in my external drive for future use ?

so it means, i can flash any rom made for the same phone, no matter how it was backed up, and i can use any method (CWM or TWRP), got it. (correct me if i am wrong)

what is source code use for ? can one design a new rom with that ?

ROM's aren't made from backups.

Take regular backups if you want and keep deleting old ones which you don't need.

Leave the folder as it is. Don't fiddle with it unless you know how TWRP/CWM actually works.

OEMs release sources of the phones and then devs make rom using those sources on Android SDK (most probably). I believe ROM development is completely beyond the scope of this discussion so I'll refrain from further comment.

is it very complex, to develop a ROM ?

I mean, i dont know anything about programming, except writing a basic macro for excel, if someone with good knowledge of programming get those source code and develop a ROM ?

Skyh3ck said:
is it very complex, to develop a ROM ?

I mean, i dont know anything about programming, except writing a basic macro for excel, if someone with good knowledge of programming get those source code and develop a ROM ?

[HOW TO] Beginners Guide to Android ROM Development - XDA Forums
[GUIDE] [how to] CREATE OWN ROM [FOR ANY ANDâ€¦ | Android Development and Hacking | XDA Forums
[Guide]Complete Android ROM development and â€¦ | Android Development and Hacking | XDA Forums

TL;DR, ROM development is a PITA and that's why you don't see custom roms for every other phone out there.

Even then bugs will be there. You won't want to brick your phone by flashing a new rom which you made.

K

Do boosters such has nitro booster and l speed work? Or are they just placebo effect?

kalam_gohab said:
Do boosters such has nitro booster and l speed work? Or are they just placebo effect?

If it uses shiny graphics, then its probably placebo effect.

I use Advanced Task Killer. It kills running processes and frees RAM.

Skyh3ck said:
is it very complex, to develop a ROM ?

I mean, i dont know anything about programming, except writing a basic macro for excel, if someone with good knowledge of programming get those source code and develop a ROM ?

Rather than building rom learn java and build apps, better prospect and satisfaction overall.

tkin said:
Rather than building rom learn java and build apps, better prospect and satisfaction overall.

Plus, to build a ROM, you also need to know C since ROMs are built using the Android NDK (Native Development Kit).

Is learning java is easy

Skyh3ck said:
Is learning java is easy

If you know basic of programming language then it won't be that difficult, took me around 1-2 months to get working knowledge. If not then start by learning C.

I learned c , c++, vb long back. But never touch it after that. Now thinking to start it as a hobby

Skyh3ck said:
Is learning java is easy

If you know C++ then Java won't be hard. Otherwise you will have to clear your concept of OOP first and then start learning Java because everything in Java is OOP.

will have to start reading now, thanks anyway, back to android,

who are clockwork and twrp people, are they officially supported by google,

how they pull recovery image ?

Skyh3ck said:
will have to start reading now, thanks anyway, back to android,

who are clockwork and twrp people, are they officially supported by google,

how they pull recovery image ?

No. They are not.

does all company provide source code ? is it a big thing to do ?

if source code is provided, can a programmer enable OTG and other function with it ?

while flashing a rom, if the phone gets bricked (no hardware damage of any kind) can it be made in working condition again, if rom is available ?

Skyh3ck said:
does all company provide source code ? is it a big thing to do ?

if source code is provided, can a programmer enable OTG and other function with it ?

while flashing a rom, if the phone gets bricked (no hardware damage of any kind) can it be made in working condition again, if rom is available ?

1. No
2. Probably No
3. Depends on the device. Mostly not possible.
4. Yes, phone can be unbricked by flashing stock rom on fastboot.

thanks,

i have heard a lot about Cynogen Mod, who are those guys, is it something great to have on phone.

can we request rom for any phone like mine Lenovo A6000 Plus, do they provide update

Skyh3ck said:
thanks,

i have heard a lot about Cynogen Mod, who are those guys, is it something great to have on phone.

can we request rom for any phone like mine Lenovo A6000 Plus, do they provide update

Cyanogenmod used to be an alternative Android build made by hobbyists that you could get and flash to your phone. However, now they are now known as Cyanogen OS and are a legitimate company who provides OEM copies of android to device manufacturers.

DeSmOnD dAvId said:
Plus, to build a ROM, you also need to know C since ROMs are built using the Android NDK (Native Development Kit).

For ROM development u require Java
For kernel development you need C though

ZTR said:
For ROM development u require Java
For kernel development you need C though

No. Java is needed for apps that run on the DVM (ART now).

But the DVM itself runs on linux, whose binaries are built in C.