For those who are interested (e.g. @ Smithx10), the kebe.com/~danmcd/webrevs/mlxcx directory has a newly-built-today PI that includes not only the now-upstreamed illumos#16023 ( jinni ), but also two under-review commits from Alex Wilson, PLUS a WIP for ethernet Media support. (The extended CX-6 and beyond makes media support... challenging.)

So if you're sporting a CX-6 and are using cables beyond SFP28+, you probably wanna give this a spin.

ALex's two under-review commits are illumos#14433 and illumos#14677 ( jinni )