Porting feature to ancient U-boot V.S porting ancient hardware code patches to new U-boot

[Mr Academia Euforia]

Hi there,

I'm working on certain feature to be added to ONIE that is running on
Broadcom's Helix4 -based network switch. Part of the task is to add FIT
signature signing to U-boot versions supported by ONIE. ONIE as part of the
build process uses uboot snapshots, and applies platform patches on top of
it.

The list of U-boot snapshots to pick from is as follows:
2012.10, 2013.01.01, 2015.10, 2018.03

My platform by default, uses the oldest, 2012.10 and this version does not
support FIT signatures.

I was thinking how to address that, and came up with two solutions, neither
being better (in my mind):

1) Create patch set based on the difference between more recent U-boot
versions and 2012 that would be focused around fit image signatures,

2) Pick 2018.03 as code base.

Problems I see:

Ad 1) I can't find any repository that would contain commits from that far
away history-wise. Did U-boot project even use any public repository in
2012 ? General problem here is how to prepare patchset,

Ad 2) The problem is that platform code patches don't apply on more recent
U-boot versions. Some of the files no longer exist, some code has been
refactored, etc.

Could you guys offer me any sort of advise on how to approach this ?

Best regards