Index: sys/arm64/conf/GENERIC
===================================================================
--- sys/arm64/conf/GENERIC
+++ sys/arm64/conf/GENERIC
@@ -184,9 +184,10 @@
 device		e6000sw		# Marvell mv88e6085 based switches
 
 # Block devices
-device		ahci
-device		scbus
-device		da
+device		ahci		# AHCI-compatible SATA controllers
+device		scbus		# SCSI bus (required for ATA/SCSI)
+device		ch		# SCSI media changers
+device		da		# Direct Access (disks)
 
 # ATA/SCSI peripherals
 device		cd		# CD