[coreboot] GM45 ich9deblob and intel ME question

Arthur Heymans arthur at aheymans.xyz
Sun Jun 4 12:58:59 CEST 2017


Michal Widlok <michalwd1979 at gmail.com> writes:

> Hello,
> I know that libreboot completely remove intel ME from old boards based
> on GM45 chipset (like lenovo T400), and recently I found that it is
> possible to neutralize it on newer chipsets also:
> https://github.com/corna/me_cleaner
> Since some of my T400 laptops still running on original BIOS (mostly
> because of external video card and battery management with tp_smapi),
> I was thinking if it is possible to use ich9deblob to remove intel ME
> from original bios image. I have a special connector added to the
> laptops so reading/writing flash images is quick and easy now.

I think having a different descriptor with no ME region works to some
extend with vendor, YMMV.
> The question is: Can I generate new descriptors with ich9deblob from
> factory.rom (original bios image) and then add the descriptors with
> "dd" to it just like to the libreboot image? Like:
> flashrom -r factory.rom
> ich9deblob

There are some flaws in ich9deblob so I'd recommend taking a look at
blobltool in util/blobtool.

With blobtool you can generate a descriptor:
blobltool ifd-x200.spec ifd-x200.set x200-descriptor

Due to a current limitation of flashrom (patches are pending) you need a
file of same size as your flash. so you need to pad x200-descriptor
dd if=/dev/zero bs=1 count=8188k >> x200-descriptor

(8188k is 8m - 4K, adapt accordingly to your flashsize)

> dd if=deblobbed_descriptor.bin of=factory.rom bs=1 count=12k conv=notrunc
> flashrom -w factory.rom

If you want to update only one region of flash (in this case descriptor)
I highly recommend using flashrom layouts to do just that.

Create a layout using ifdtool:
     ifdtool vendor_bios.rom -f vendor_layout
Then only flash the descriptor region:
     flashrom -w x200-descriptor --layout vendor_layout --image fd

> Thanks in advance,
> Michael Widlok

Arthur Heymans

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