F5/LineRate did it but it got NACKed in a fairly underhanded and unfortunate way on the mailing lists :/ https://github.com/Seb-LineRate/freebsd/commits/seb/stable-1...
That patch set does not implement transparent creation of 1GB mappings. It also contains dubious things like this, which make me think the branch was a WIP: https://github.com/Seb-LineRate/freebsd/commit/66a8d3474d410...
The only mailing list thread I see regarding this is here, and it doesn't seem particularly underhanded to me: https://lists.freebsd.org/pipermail/freebsd-hackers/2014-Nov...
All the technical critique seems fair but it seemed like they (both as an individual and as a company) were a first time contributor and no outreach was really done to pull them in further. I guess LineRate imploded within F5 so there could have been structural problems inside there prevented them from doing a fully baked contribution anyway.
Can you clarify what you mean by "underhanded and unfortunate way?" The thread I can see on freebsd-hackers@ had a little feedback, including some very valid critiques (the code was developed against 9.x, then ported to 10.x without testing, at a time when 11 was CURRENT) and the original author just didn't follow up at all:
https://lists.freebsd.org/pipermail/freebsd-hackers/2014-Nov...
But maybe I'm missing something?
See also: https://lists.freebsd.org/pipermail/freebsd-hackers/2013-Sep...
Given alc@ was an author on the paper (and the paper's FreeBSD 4.x implementation supported multiple superpage sizes), I'm not really sure why FreeBSD's pmap doesn't have support for 1GB page promotions.