85b23d1138
of the __pcb_spare longs. Except that fields were changed and one of the spare values was used and the __pcb_spare field was reduced from two to one long. Now VM86 bios calls can trash the first 4 bytes of the next page following the kernel stack/pcb. This Is Bad(TM). This bug has been present in 5.2-release and onwards, and is still in RELENG_5. Instead of tempting fate and trying to use "spare" fields, explicitly reserve them.