The calculations outlined at https://github.com/osresearch/heads/pull/1282#discussion_r1072473677
Sums to having 'ifdtool -f layout.txt ifd_shrinked.bin && cat layout.txt'
The example for T440p:
00000000:00000fff fd
00021000:00bfffff bios
00003000:00020fff me
00001000:00002fff gbe
Here: 00bfffff-00021000=BDEFFF
Which is exact result of @rbeslow's calculations.
There is an issue on haswell, maybe because of car, maybe because of non native memory init blob.
But this is not the case for xx20/xx30 boards.
e7f1e3e7a7