Macbook6,1 - flashed MPB5,5 EFI, unable to revert

Hello everyone,

I have an old MB6,1 (white unibody 2009 core 2 duo model), Apple has not released an EFI update for it, so a lot of users have been flashing the latest EFI for the MBP5,5 which has identical hardware.

I would like to revert to the original EFI MB61.00C8.B00. I've found the EFI dump in the repository here, and my question is, what options do I have for flashing it except OS X?

Right now my Macbook works 100% in Windows (non EFI install), however with OS X the usb ports, trackpad and keyboard are not working. So I'm unable to bless the EFI file and copy it to the firmware folder in the efi partition for flashing.

WHat are my options?

Thanks in advance!

I guess you could try and flash the SPI ROM using a Raspberry Pi and clip?

Well after a lot of NVRAM and SMC resets and attempts, I managed to install Snow Leopard (10.6. and it seems to work okay.

Question is, the bin file from the repository, can it be flashed as a .scap file through the EFI firmware updater?

silencer51 wrote: Question is, the bin file from the repository, can it be flashed as a .scap file through the EFI firmware updater?

No you can't.

apple firmware updates and our SPI ROM dumps are apples and oranges

how did you make your original update?

Yup, been reading up on how Apple distributes its EFI updates.

I originally flashed the MBP5,5 1.7 EFI update essentially by exracting the .scap file from the updater pkg file, then using the -firmware flag with the bless command to copy it to the EFI 'firmware' folder and set the computer in 'EFI update mode' on the next boot (long beep, black screen, progress bar).

Since the computer works fine (no locks whatsoever), is there a way to flash the entire EFI image (from the clean dump found here in the repository) from within an EFI shell - OS X - linux etc? Or is a SIP absolutely necessary even with access to the OS?

Short answer: no

Long answer: maybe

Apples .scap firmware updates contain instructions and formatting for the MacBook to install the payload.

Our EFI dumps are raw hex read from the chip.

It's conceivable that you could reverse engineer the .scap, find the EFI payload section, and insert (probably with some sort of unknown conversion) the raw dump instead. I'm not sure apples update is a complete bios, or simply updates applied to certain offsets

I would wager it would take you far longer to learn all these things and execute the .scap modification than it would to order a raspberry pi, chip adapter, and flash it manually.