Last time we discussed about What is Difference Between Recovery Mode and DFU Mode. Here is the second part of our jargon buster highlights the difference between Baseband and Bootloader. When Apple releases new firmware they usually updates the baseband revision of phone while bootloader remains same. Apple can’t update your bootloader while upgrading your iPhone firmware as this is normally un-erasable. Bootloader can be installed once and non volatile in nature. The Baseband is the processor that manages all of the activities of the antenna from wifi to bluetooth and of course the cellular signal. It is updatable and has been with iPhone updates through iTunes.

Baseband Bootloader

The baseband bootloader is the code which runs before the baseband FW, it is responsible for signature checking and updating the baseband. There are lots of confusions between Baseband and Bootloader. iPhone 2G has two Bootloaders 3.9 and 4.6 both are vulnerable and the best thing is Apple stops playing with iPhone 2G baseband from the last year. iPhone 3G initially comes with bootloader 5.8 followed by 5.9, 6.2 and the latest is 6.4

Baseband

The baseband in the iPhone manages all functions which require an antenna. It is separate
from the OS and is it’s own processor, with it’s own firmware. It’s firmware is called the baseband firmware. The baseband processor has its own RAM and firmware in NOR flash, separate from the ARM core resources. The baseband is a resource to the OS. The Wi-Fi and bluetooth are managed by the main CPU, although the baseband stores their MAC addresses in it’s NVRAM.

Bootloader

A bootloader is some code that is executed when the device is powered on. Two bootloaders
you may have heard of are the baseband bootloader and iBoot. Bootloaders perform integrity checks on data and prevent unsigned, non-apple code from being loaded. They essentially police the iPhone OS, making sure everything is the way Apple want it to be. PwnageTool,WinPwn and QuickPwn patch out integrity checks from the bootloaders (LLB, iBoot) and the kernel, allowing unsigned code to be executed.

In general, this is the code which is run prior to the main firmware and is responsible for loading the main FW and in some cases performs signature checking. Both the baseband and the main iPhone OS have bootloaders, and these are entirely different. PwnageTool and WinPwn allow control over the main OS bootloader, while BootNeuter allows control over the Baseband Bootloader.

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