[Q] Everyone keeps talking about bootloader downgrade

Zalmoxis12 said:

But what is it exactly? What does it mean?

I mean I already did Autorec and all I know is that it downgraded the bootloader. No idea what that actually means, so I can understand what happened and more importantly how can I restore it (i.e upgrade it back) and what are the consequences of these actions.

Any developer around that can actually explain?

Click to expand...

Click to collapse

Jellybean (12B) was the last bootloader to be able to be used with loki (the exploit to be able to flash custom recoveries/ROMs/kernels). Google patched the bootloader in the KitKat update (24A) so loki was useless. You could root, but couldn't flash the previously mentioned items. Being able to downgrade the bootloader allowed this. So even tho you'd be running KK, you're using a JB bootloader.

Zalmoxis12 said:

I know this. I was asking what the bootloader actually is and how does it relate and connect with the other partitions.

Is it like some sort of MBR?

Click to expand...

Click to collapse

http://searchenterpriselinux.techtarget.com/definition/boot-loader

Zalmoxis12 said:

I know this. I was asking what the bootloader actually is and how does it relate and connect with the other partitions.

Is it like some sort of MBR?

Click to expand...

Click to collapse

bootloader loads all the partitions and makes sure they work together, two examples of the stuff bootloader handles:
-bootloader boots
-bootloader then loads kernel making sure nothing wrong and if there is then you get no boot and instead you are thrown to fastboot to fix the problem
-after kernel loads bootloader loads system if corrupted/missing you get stuck in a bootloop unless you have custom recovery then you get stuck in recovery
-bootloader loads rest of partitions while the system/kernel begin to boot rom

when doing ota:
-phone reboots and loads bootloader
-bootloader loads ota into a partition on phone designed to decompile and apply ota into system/kernel partitions
-bootloader makes sure that system/ota are correct and compatible to apply update
-bootloader does root check process in the rtf partition and if rooted bootloader cancels ota process

so in short bootloader is most important asset, it is what decides the kernel to boot(you can mod a bootloader so that you can have too kernels and this is also how you create multi boot for boot more than one rom), it boots the rom, and it handles all other partitions in more than one way