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Firmware Downgrade Lockout?

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RMSfan
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Default Firmware Downgrade Lockout?

Hey guys, I am curious about the Droid 2 and how it prevents firmware downgrading. Specifically, why it can't be downgraded from the current Gingerbread version (system version .629) to one of the prior versions (.608, .621, etc.). If custom firmwares (i.e. CyanogenMod) can be installed, why can't older stock firmwares? How is the phone "aware" when you install an older firmware, even though the memory has been wiped? Does the bootloader have a protected area of memory reserved for keeping track of what the latest firmware installation is?

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sd_shadow
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Because of the locked bootloader, custom roms only change part of the system.

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RMSfan
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Quote:
Originally Posted by sd_shadow View Post
Because of the locked bootloader, custom roms only change part of the system.
Why isn't it possible that the area of memory where the bootloader stores it's memory (i.e. the latest known firmware to it) can be erased?

(I'm thinking in PC Terms here. The BIOS/UEFI stores memory in a CMOS, the CMOS can cleared which causes the BIOS to go back to default settings.).
 
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google encrypted bootloader
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