Does SmartOS actually support Linux containers (aside from the obvious approach of running containers in a Linux VM)? Last I checked, SmartOS just used the word "container" to refer to Solaris Zones.

SmartOS has code specifically in place for using 'lx' branded zones as wrappers for docker containers (which is distinct from its support of kvm)

https://github.com/joyent/smartos-live/blob/master/src/docke...

https://www.cruwe.de/2016/01/27/using-docker-on-smartos-hype...

It's been a while since I've looked in to it, but if memory serves they are using docker filesystem snapshots without modification and running them on a thin translation layer of Linux system calls to Solaris system calls. Hard to find anything backing this up, so I could be way off the mark as to how it's implemented.

EDIT: forgot that's what 'lx' zones are: zones which allow the execution of Linux binaries

you checked a long time ago :)