[migueldeicaza]

It has been a while since I rebuilt the XNU kernel, a few years perhaps, but it is possible, and it works.

These instructions are a lot better than the ones that I had to follow a few years back - I might try it, just need to find a guinea pig :-)

[Wowfunhappy]

XNU itself is one of the ones that can definitely be built outside of Apple! Lots of people have made custom kernels over the years.