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Why should we flash the boot file when flashing a custom rom?

OP ravi_buz

11th June 2014, 08:37 AM   |  #1  
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I have been using Samsung for a long time and so this process seems weird. All we use to do there was just put the custom ROM and GAAPS and flash it via recovery and wipe phone. But when i was going through a lot of forums here..i see that the OP has asked people to flash the boot file using command prompt and then flash the ROM. Is this process really required even if we have the dual recovery installed?
11th June 2014, 08:42 AM   |  #2  
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If the updater script in the .zip does not have the correct commands to install the boot.img itself it has to be manually flashed.
Untill recently this was always the case, it was not possible to flash a kernel using recovery, it had to be done via fastboot.

I think this is probably a hangover from then, but now it can be done in recovery.

Also, if you have just unlocked, but do not have recovery installed the quickest way to get recovery is to flash the boot.img using fastboot, then flash the update.zip.
If you already have recovery, just flash the update.zip and the boot.img will be flashed.

This is only for roms int he original development section, as they require a custom kernel, roms in the development section will work on the stock kernel, so there is no need to flash a boot.img at all
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11th June 2014, 09:47 AM   |  #3  
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Actually you need to flash different kernels for different roms... Like Stock-based(Sony) Roms can be either run on Stock Kernel(Sony) or Stock-Based Custom Kernel(like DooMKerneL). while AOSP Roms(like CM11) should be run on AOSP-based Custom Kernels(like Pimped Kernel).

You can flash custom Kernels only if you have unlocked your bootloader. if you have recovery on locked bootloader, then you can flash only Stock-based roms because they dont need a different kernel becoz they run on Sony Kernel itself. If you have a unlocked bootloader you can flash custom kernel, Then you can use both Stock-based Roms or AOSP-based Roms by flashing respective kernels.

If you already have Custom rom installed and changing to another Custom rom, Then if you are changing from (Stock-Based Rom to another Stock-Based Rom) or (AOSP-based Rom to another AOSP-based Rom) then you need not flash the kernel again, you can just wipe all partitions and install the new Custom rom over it. But if you are Cross flashing from (Stock-Based Rom to AOSP-Based Rom) or (AOSP-based Rom to Stock-based Rom), Then you should flash respective kernel, wipe partitions and install the rom over it.

if you dont know, whether the rom is Stock-based or AOSP-based, it will be mentioned in the OP of each Thread.Usually Roms that are available for a wide range of devices across OEMs are AOSP. Roms like CM, AOKP, PAC, Carbon, etc. are all AOSP roms.

Hope it helped.
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