Booting FreeBSD under UEFI x86-64 hardware

[JCA]

I have just started looking into what is involved in booting FreeBSD
on UEFI-based x86-64 hardware. I was wondering if anybody in this
group could provide some pointers where to start. I am interested in
the FreeBSD boot code under UEFI in general, with a particular
emphasis on how the FreeBSD loader exploits the secure boot
capabilities supported by recent UEFI versions. I'd be most grateful
if anybody can point me in the right direction on this.