You need to use initramfs with your kernel, so that kernel you boot from external drive is not alone but has some tools. Then you need to tell to your initramfs scripts to take care of encryption of your data and _swap_ partitions. Both dracut (redhat initramfs tool) and genkernel (gentoo initramfs tool) handle that.
With genkernel, this is what I currently have in /etc/default/grub. That's all I need, really.
GRUB_CMDLINE_LINUX="crypt_root=UUID=7e2c0396-7cc2-4468-9431-c85f81a4c9b2 root=UUID=d098a3ad-ff13-4a44-b4e6-d9e83cddd7ad crypt_swap=UUID=976f44a3-25c2-4869-b3b5-61808f3bc20d swap=UUID=5adcdf03-abaf-4cd3-8902-45228be2abe5 root_key=key swap_key=key root_keydev=UUID=d5878b0f-1997-467a-8f3b-65e78b16fb67 swap_keydev=UUID=d5878b0f-1997-467a-8f3b-65e78b16fb67 rootfstype=ext4 rootflags=rw,relatime,data=ordered resume=UUID=5adcdf03-abaf-4cd3-8902-45228be2abe5 "
With dracut, you want to look at options having "luks" in their names.
But running the /boot on external USB seems to cause more issues than when I merely have /boot partition and a partition with LVM inside LUKS volume on the same physical disk.
I want to know if FreeBSD works that way, as I hear some FreeBSD on FreeBSDTalk and other podcasts say they have made big strides on laptop support (jokes abound with resume/sleep issues) on different laptops, but I am curious how far these improvements go.
I believe Linux or BSD can do whatever you want, just be careful with what you want.
Linux has spoied me so bad I never noticed the former, and I am shocked by the latter.
Nice to get a response from a completely ignorant BSD and security notice, by the way. :-) I guess I could ego trip and say "how can I trust this user" but I suspect others will chuckle like me.
No idea about Intel Rapid Start. I don't really deal with that side of the system.
Important question, that makes me suffer in other *nix platforms: does anyone run a rig like this AND it work properly with sleep/hibernation and resume?