What are all the IMAGES in a ROM ?! - Basics Tutorial

itxtutor

Editor in Chief
Staff member
May 15, 2015
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#1
Hey guys, i think i should write a short explanation of all the images which are in a rom which is meant to be flash with SP-FLash tools.


Android is splitted in 6 main partitions. You have theses partitions:

  • boot It contains the Linux kernel. The device will not boot without this partition. Wiping this partition from recovery should only be done if absolutely required and once done, the device must NOT be rebooted before installing a new one, which can be done by installing a ROM that includes a /boot partition.



  •  System - As the name suggests, this partition contains the entire Android OS. This includes the Android GUI and all the system applications that come pre-installed on the device. Wiping this partition will remove Android from the device without rendering it unbootable, and you will still be able to put the phone into recovery or bootloader mode to install a new ROM.



  • Recovery - It contains the recovery system (android e3 recovery or CWM if you installed it, or some china shit
    ) The recovery partition can be considered as an alternative boot partition, that lets the device boot into a recovery console for performing advanced recovery and maintenance operations on it.



  • DATA - Contains your personal data (do not share it with a backup) So this partition contains the user’s data like your contacts, sms, settings and all android applications that you have installed. While you are doing factory reset on your device, this partition will wipe out, Then your device will be in the state, when you use for he first time, or the way it was after the last official or custom ROM installation.



  • Cache is the partition where Android stores frequently accessed data and app components. Wiping the cache doesn’t effect your personal data but simply gets rid of the existing data there, which gets automatically rebuilt as you continue using the device.



  • Misc  This partition contains miscellaneous system settings in form of on/off switches. These settings may include CID (Carrier or Region ID), USB configuration and certain hardware settings etc. This is an important partition and if it is corrupt or missing, several of the device’s features will will not function normally.


But Android is one thing, your phone also have a lot of bios, firmwares, and bootloaders. Theses are not saved by traditional backup utilities such as CWM.


Theses partitions includes:


* UBoot - Very important, this thing is the low level bootloader. It starts Linux !


* Modem Firmware - used to dial with your GSM provider


* DSP Firmware - Make video playback smoother using DSP resources.


* NV - It's some kind of encryption key with some low levels parameters. Very important !


* Lots of misc stuffs - Like the boot logo, the kernel panics logs (record the boot-up errors to help the debugging process), etc ...


* Lots of important misc stuffs


Now how does a flashable image look like ? Lets take a look at this NEO M1 ROM :





And what does each image do ?

  • Boot.img : boot.img contains the kernel and ramdisk, critical files necessary to load the device before the filesystem can be mounted. Having a wrong Boot.img on your phone can refuse it to boot !



  • cache.img Contains the cache data where Android stores frequently accessed data and app components. not really needed and should be unticked when trying to flash a device.



  • Checksum.ini verifies md5 checksum , if you get a checksum error before flashing, just delete it




  • EBR1, EBR2 Are your partitions. 1+2 Means 2 Partitions. You can also edit the size of them , Check out this thread : http://www.chinaphonearena.com/forum/Thread-Tutorial-How-to-modify-your-EBR-and-change-your-partitions-for-MTK6589T-MTK6582



  • UBOOT (LK.BIN)  U-Boot is an universal boot loader for embedded systems, targeting different platforms including ARM. Uboot and BootIMG are important files on your phone. If your device is not booting or your display is not working ( black or stripes ) , you should reflash and check those files.



  • Logo.bin As the name suggests, this is your bootlogo
    It can be changed using this tutorial :  http://www.chinaphonearena.com/forum/Thread-Tool-MTK-boot-logo-logo-bin-Editor



  • MBR  Stands for Master-Boot-Record. MBR is generally referred to as first sector (size : 512 bytes) of any partitioned drive whereas volume or partition boot record holds code to initiate booting and is invoked by MBR.  So in short words, it defines your partitions.



  • Scatter File : Scatter is a file which is used to describe the loads of regions in a specific android device running MediaTeks ARM architecture. Bascially it tells the flash tool  where to flash each image.



  • Preloader : this is really important. The preloader communicates with your PC. It´s needed when you want to flash your device. Due to the preloader your phone should be detected as a port on your pc and should be flashable. Downloading a wrong pre-loader can brick your phone , so be careful ! Never flash the preloader if not needed. There are different states of the pre-loader (like META Mode). Even when you think your phone is bricked, mostly you can revive it.



  • Recovery.img Thats you recovery. It must be "tailored" to each device. You cant flash a recovery image from a different device, but you can create your own CWM recovery using MTK droid tools.



  • Secro.img Is an important file for the baseband and the IMEI. You need to reflash it to rebuild the structure. But anyway you have to restore your IMEI too.



  • System.img  As the name suggests, this partition contains the entire Android OS. You can try different system.img from other phones without a problem. just be sure to have a backup when you try them




  • User Data : Contains your personal data (do not share it with a backup) So this partition contains the user’s data like your contacts, sms, settings and all android applications that you have installed. While you are doing factory reset on your device, this partition will wipe out, Then your device will be in the state, when you use for he first time, or the way it was after the last official or custom ROM installation.

I hope this helps you to understand the rom structure



Best,


steven
 
Last edited by a moderator:

mrsim

KingOfNoobs
Staff member
Mar 1, 2014
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#2
FUCKING FANTASTIC..a noob's guide....this should be a video on your YouTube channel.... :blum2:
 
Last edited by a moderator:

Tomzzy

New Member
Jul 4, 2014
16
0
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#3
Awwwesome....now I have some good knowledge on the img files..i m luvin it 



"Life's most persistent and urgent question is, 'What are you doing for others?'" -Martin Luther King, Jr
 

itxtutor

Editor in Chief
Staff member
May 15, 2015
60,104
471
113
#7
wouldnt recommend flashing system.img´s from different phones, even when they have the same SoC... but yes its possible.
 
Dec 11, 2014
59
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#10
Thanks for this great info , I would like to ask about this (actually i'm asking a lot of questions these days), when i great backup of my rom  i see files with tar extension like system.ext4.tar , what's the different between those and the ones with .img extension? are these files have the same content but different types ? and if i want to share the rom do i need to share those too?
 
Dec 16, 2014
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#12
Uno e un'immagine e altro E con zip. CONDIVIDERE l'immagine dovrebbe Essere lo Stesso in ENTRAMBI.
Ciao ottima Esempi ... !!! io ho flashato Una rom presa da needrom per alpi stelle sm MTK 6582 n9002 doppio formato sim formato con metodo + scaricare ora al riavvio non ricarica la batteria Anche se dice di ricarica puro da spento si scarica e diventa di fuoco Dietro la Fotocamera posteriore e in Più non funziona Il Tocco da cosa Dipende QUESTI Errori Quale di lima della rom E sbagliato? e di piu aiutarmi per favore?
 
Dec 16, 2014
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#15
scusate il mio amico ... english solo per favore ... non possiamo capire quello che stai dicendo ... mi dispiace
Hello good explanation ... !!! I flashed a ROM socket for needrom star n9002 alps sm MTK 6582 Dual SIM format with format method + downlod now restart does not charge the battery even though it says in charging even when turned off you download and become fire behind the camera and in the rear more does not work the Touch It depends on what THESE Mistakes Which file rom And wrong? poteti help me please? thanks so much
 

mrsim

KingOfNoobs
Staff member
Mar 1, 2014
16,207
2,366
113
47
London UK
#16
ok maybe it is just your english is not so good...but what is a rom socket...???


do you mean a rom...without the socket...lol


please start a new thread in hardware and software support...thank you


 


http://www.china-devices.com/Forum-Hardware-Software-Support


 


try and give as much information as possible,your device,a link to the rom you tried to flash,which version of sp flash tools you used...if you are rooted or not...everything you can think of


do you have a backup...everything
 
Dec 16, 2014
30
0
6
#17
ok forse è solo il vostro inglese non è così buono ... ma cos'è una presa rom ... ???


vuoi dire un rom ... senza la presa ... lol


lanciate un nuovo thread in hardware e supporto software ... grazie http://www.china-devices.com/Forum-Hardware-Software-Support cercare di dare quante più informazioni possibili, il dispositivo, un collegamento al rom si è tentato di lampeggiare, quale versione di strumenti in flash sp hai usato ... se sono radicate o no ... tutto ciò che si può pensare di fare di avere un backup ... tutto