It was possible cause of kernel panic. Pointed Out by: phk@FreeBSD.ORG
(a NetBSD port for NEC PC-98x1 machines). They are ncv for NCR 53C500, nsp for Workbit Ninja SCSI-3, and stg for TMC 18C30 and 18C50. I thank NetBSD/pc98 and bsd-nomads people. Obtained from: NetBSD/pc98