HelenOS sources

ZONE_RESERVED     114 kernel/arch/amd64/src/mm/frame.c 			    ZONE_RESERVED);
ZONE_RESERVED     114 kernel/arch/ia32/src/mm/frame.c 			    ZONE_RESERVED);
ZONE_RESERVED     200 kernel/generic/src/ddi/ddi.c 	if (zones.info[znum].flags & (ZONE_FIRMWARE | ZONE_RESERVED)) {
ZONE_RESERVED    1312 kernel/generic/src/mm/frame.c 		    (flags & ZONE_RESERVED) ? 'R' : '-',
ZONE_RESERVED    1423 kernel/generic/src/mm/frame.c 	    (flags & ZONE_RESERVED) ? 'R' : '-',
HelenOS homepage, sources at GitHub