[kees99]

> Intel Atom (...) NetBSD (and a number of other OSes) would (...) refuse to boot

Was it one of those cheap tablets/netbooks that shipped with fully-64-bit-capable CPU (Atom Z3735F) but with dreaded 32-bit-only UEFI firmware?

GRUB can boot NetBSD there, although it's a bit of a hassle to set up.

[wannacboatmovie]

Negative, it was an embedded board. GRUB was not the issue; rather the kernel would hang after partially booting. Affected Illumos as well so it's likely a firmware bug.