MFC efivar(8) (by imp):

List of revisions merged:
r307070
r307071
r307072
r307074
r307189
r307224
r307339
r307390
r307391
r309776
r314231
r314232
r314615
r314616
r314617
r314618
r314619
r314620
r314621
r314623
r314890
r314925
r314926
r314927
r314928
r315770
r315771

Discussed with: gjb (re), imp
Sponsored by: The FreeBSD Foundation

MFC r306091:
Add a way for the architecture to specify the calling ABI for methods
in the EFI Runtime Services Table. On amd64, the calling conventions
are MS.