illumos gate

When save/restore of kernel device state was added to bhyve in #14261, the ability to restore (read: import) state into devices was guarded with a default-off variable switch vmm_allow_state_writes. This was done with the assumption that there would be lingering bugs in and exposed by the ability to import device state. Keeping it as opt-in via mdb -kw meant that we could move forward with integration, and then remove that guard once confidence had been built around that state importation and the emulation logic impacted by it. A few bugs have been found so far (#15118 , #15312, #15251). Once all of those are addressed, it is worth considering the removal of the vmm_allow_state_writes guard, or at least changing it to default-allow.