Originally Posted by rescbr
I'm not so sure about cab method not affecting BL. Many files inside of this cab seems to have to do with the CE Bootloader (ULDR), which seems to be related to modes such as Factory Test, etc.
Zune can flash bootloaders (Nokia.First.dll is flashed by Zune). Even if Zune couldn't flash bootloaders, it is possible that some software/driver inside one of those .cabs does the flashing step.
OEM_7x30_MODEM.cab.pkg is very interesting, unfortunately encrypted. Why is there a MODEM file? Is it the firmware for the ARM9 "hypervisor" (REX/AMSS) core (MODEM filename suggests this)?
Another question that just popped on my head: Qualcomm/Nokia OSBL runs in the ARM9 core or in ARM11 core? This page suggests that OSBL runs on ARM9. Is this valid to Nokia too? ULDR seems to be equivalent to hboot.
Does other .cab updates contains such files (MODEM, ULDR, etc)?
Windows Phone has access to the AMSS, ADSP & EMMCBOOT.MBN. In fact, it has access to the 3rd partition of the phone where that is stored, so it probably can also modify the contents on the rest of partitions, including the bootloader. The problem is if you need the unlocked bootloader to unlock windows, and you need to unlock windows to unlock the bootloader... infinite loop
That is unless someone finds a hole in some Nokia firmware..