I take a slightly different approach for my implementation that allows me to use the standard go toolchain. I use nasm for the early ASM code and patch the go build tool's output (see: https://github.com/achilleasa/gopher-os/blob/master/Makefile...) to bypass the link step and replace it with a manual call to ld that links the go object files with the output from nasm.

I will be talking about this approach in more detail in GolangUK '17.