KPTI is the approach adopted by every major operating system,
but not everyone implemented it at the same time.
Linux, being included in the embargo, had a mitigation since at least December
The 4th and 5th of January, DragonflyBSD added a KTPI-like,
The 7th of January 2018, NetBSD did the
and the so did FreeBSD on the 19th
In February 2018, Philip Guenther and Mike
Larkin implemented an equivalent of KTPI in
OpenBSD for AMD64.
Although, to be fair, support for
was added the 10th of January.