Kernel Source - Noob question

[Mihai Vintila]

Hi,
I want to compile only mlx drivers since they don't seem available by 
default. But i'm having a hard time finding the source for FreeBSD 10.1 
p10.
Can you guys indicate what is the best way to do it without recompiling 
full kernel.
Right now i've taken the src.tgz from 
ftp://ftp.freebsd.org/pub/FreeBSD/snapshots/amd64/10.1-STABLE/
Compiled the modules but when i try to load them i end up with:

KLD mlx4.ko: depends on kernel - not available or version mismatch
linker_load_file: Unsupported file type

Kernel i'm using is FreeBSD nvme 10.1-RELEASE-p10 FreeBSD 
10.1-RELEASE-p10 #0: Wed May 13 06:54:13 UTC 2015 
root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64


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Best regards,
Vintila Mihai Alexandru