OpenBSD guests always enable "special mask mode" during boot. As a result of
r275952 this is flagged as an error and the guest cannot boot.
Fix this by implementing the 8259 "special mask mode".
Boot the OpenBSD/amd64 5.6 installer.
, when a mask bit is set in OCW1 it
no bearing on the levels
Minor: should this just be 'atpic->smm = 1' to fit in with the bool-style usage of the variable ?
Address Peter's comments.
Addressed all issues raised in Peter's comments in the new diff.