Build 100 of OpenSolaris introduced fast reboot, quite a nifty feature. However, in certain fault scenarios, having fast reboot on by default is not desired. Fast reboot bypasses BIOS involvement in the boot process. But after certain classes of failure, BIOS engagement is desired. Examples include BIOS deconfiguring faulty components or BIOS collecting error information that may be lost or discarded after OS reboot.
Earlier this week 6880616 putback interfaces that allow Solaris FMA to disable fast reboot on terminal errors. The FMA changes to take advantage of these interfaces is close behind, planned to make build 125 (6883623.