snapshot of april 12th wont boot at all

I have (possibly) similar problem, running kernel from March 29 as
fall-back (older kernel, latest world).

* OS: HardenedBSD-12 on amd64 Athlon II X3 460
* Kernels built yesterday: MYKERN & HARDENEDBSD (GENERIC with Debug).
  Both kernels fail. No errors encountered during buildworld/kernel.
  World installs normally.
* Boot process: Grub -> /boot/loader -> Kernel Selection. No EFI (MBR).
  Grub has own partition (ext2fs), /boot/loader on ZFS.
* zpool: Striped on 2 HDD's, scrub returns clean pool.

FAILURE POINT: System freeze, completely unresponsive, requires hard
reset.
* Initially seems like failure is at "Mount Root from zpool/ROOT/bsd".
  Further inspection of dmesg shows garbled text at services stage
  (start reading /etc/rc.conf)
* /etc/rc.conf: Everything disabled for bug hunting. Cause does not
  seem related to linux / radeonkms either.
* Selecting "Safe Mode" (kern.smp.disabled ?) gets me to single-user
  mode, and later multi-user but system freezes as soon as I login.
  Not 100% sure about this behaviour though, as I have been at it since
  early morning yesterday.
* Have not tried with ACPI disabled. Dmesg: Firmware Warning (ACPI):
  32/64X length mismatch in FADT/Gpe0Block: 64/32 (20180313/tbfadt-748)

There was a recent bug involving databases failing to start due to
"limits: NO: No such file or directory". I have Mariadb-Server-100
installed with the new patch for this bug. I wonder whether these two
could be related?

Would prefer not posting my verbose boot log dmesg file here, can email
it (or download link) to developers (at FreeBSD.org) if needed though.

Regards.

-- 
HardenedBSD_amd64_12-Current_RadeonKMS
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