[Help] Linux low level data structures < - > FreeBSD low level data structures

Hello

Is there anyone on either of these lists that have experience with both
linux low level data structures and their equivalents on FreeBSD?

For instance the linux header file:
<linux/agp_backend.h>

which includes the header file:
<linux/list.h>

Then looking at that file:
<linux/types.h>
<linux/stddef.h>
<linux/poison.h>
<linux/const.h>
<linux/kernel.h>

I'll be doing a lot of work trying to find these FreeBSD equivalent of
these types of files to port some code.

Does anyone here have experience with something like this? Is there any
other projects that maps these low level data structures from
Linux <-> FreeBSD, etc?

Best,
Owen