geom<->ata forever cycle

5.1-current of 2003-11-20 hangs during kernel initialization with forever
cycle around geom partitioning detection and ATA read failure.
Message rate is too fast to record, no stopping is available, no serial
console.

Previous 5-current on this machine was of 2003-05-23.
How to diagnose?
dmesg of May's current says:

start_init: trying /sbin/init
ad0: UDMA ICRC error cmd=read fsbn 4397730 of 4397730-4397857 retrying
ad0: UDMA ICRC error cmd=read fsbn 4398442 of 4398442-4398569 retrying
ad0: UDMA ICRC error cmd=read fsbn 4398442 of 4398442-4398569 retrying
ad0: UDMA ICRC error cmd=read fsbn 4398442 of 4398442-4398569 retrying
ad0: UDMA ICRC error cmd=read fsbn 4398442 of 4398442-4398569ad0: success settin
g PIO4 on Intel ICH2 chip
 falling back to PIO mode

Main FreeBSD here is 4.9-release which doesn't complaint to crc errors.

Kernel config wasn't changed:

machine		i386
cpu		I486_CPU
cpu		I586_CPU
cpu		I686_CPU
ident		nn15
maxusers	0

#To statically compile in device wiring instead of /boot/device.hints
hints		"GENERIC.hints"		#Default places to look for devices.

makeoptions	DEBUG=-g		#Build kernel with gdb(1) debug symbols

options		SCHED_4BSD
options 	INET			#InterNETworking
options 	INET6			#IPv6 communications protocols
options 	FFS			#Berkeley Fast Filesystem
options 	SOFTUPDATES		#Enable FFS soft updates support
#options 	UFS_ACL			#Support for access control lists
options 	UFS_DIRHASH		#Improve performance on big directories
options 	MSDOSFS			#MSDOS Filesystem
options 	CD9660			#ISO 9660 Filesystem
options 	PROCFS			#Process filesystem (requires PSEUDOFS)
options 	PSEUDOFS		#Pseudo-filesystem framework
options 	COMPAT_43		#Compatible with BSD 4.3 [KEEP THIS!]
options 	COMPAT_FREEBSD4		#Compatible with FreeBSD4
options 	KTRACE			#ktrace(1) support
options 	SYSVSHM			#SYSV-style shared memory
options 	SYSVMSG			#SYSV-style message queues
options 	SYSVSEM			#SYSV-style semaphores
options 	_KPOSIX_PRIORITY_SCHEDULING #Posix P1003_1B real-time extensions
options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev

# Debugging for use in -current
options 	DDB			#Enable the kernel debugger
options 	INVARIANTS		#Enable calls of extra sanity checking
options 	INVARIANT_SUPPORT	#Extra sanity checks of internal structures, required by INVARIANTS
options 	WITNESS			#Enable checks to detect deadlocks and cycles
options 	WITNESS_SKIPSPIN	#Don't run witness on spinlocks for speed

device		isa
device		pci

# ATA and ATAPI devices
device		ata
device		atadisk			# ATA disk drives
device		atapicd			# ATAPI CDROM drives
options 	ATA_STATIC_ID		#Static device numbering

# atkbdc0 controls both the keyboard and the PS/2 mouse
device		atkbdc		# AT keyboard controller
device		atkbd		# AT keyboard
device		psm		# PS/2 mouse

device		vga		# VGA video card driver

device		splash		# Splash screen and screen saver support

# syscons is the default console driver, resembling an SCO console
device		sc

device		agp		# support several AGP chipsets

# Floating point support - do not disable.
device		npx

# Add suspend/resume support for the i8254.
device		pmtimer

# Serial (COM) ports
device		sio		# 8250, 16[45]50 based serial ports

# Pseudo devices - the number indicates how many units to allocate.
device		random		# Entropy device
device		ether
device		loop		# Network loopback
device		ppp		# Kernel PPP
device		tun		# Packet tunnel.
device		pty		# Pseudo-ttys (telnet etc)
device		md		# Memory "disks"

# The `bpf' device enables the Berkeley Packet Filter.
# Be aware of the administrative consequences of enabling this!
device		bpf		# Berkeley packet filter

device		speaker		#Play IBM BASIC-style noises out your speaker

# To include support for VGA VESA video modes
options 	VESA

# Turn on extra debugging checks and output for VESA support.
options 	VESA_DEBUG

# Enable i386 a.out binary support
options 	COMPAT_AOUT

# Enable the linux-like proc filesystem support (requires COMPAT_LINUX
# and PSEUDOFS)
options		COMPAT_LINUX
options 	LINPROCFS

options		MSGBUF_SIZE=131072
#options 	GEOM_BSD
#options 	GEOM_MBR
options 	DDB_TRACE
# KTRACE_REQUEST_POOL option specifies the initial size of this store.
# The size of the pool can be adjusted both at boottime and runtime via
# the kern.ktrace_request_pool tunable and sysctl.
#
options 	KTRACE			#kernel tracing
options 	KTRACE_REQUEST_POOL=101
options 	IPFIREWALL		#firewall
options 	IPFIREWALL_VERBOSE	#enable logging to syslogd(8)
options 	IPFIREWALL_DEFAULT_TO_ACCEPT	#allow everything by default
options 	RANDOM_IP_ID
options 	TCP_DROP_SYNFIN		#drop TCP packets with SYN+FIN
# The rest are optional:
options 	MSDOSFS			#MS DOS File System (FAT, FAT32)
options 	LIBICONV
options 	SC_HISTORY_SIZE=1500	# number of history buffer lines
options 	SC_MOUSE_CHAR=0x3	# char code for text mode mouse cursor
options 	SC_KERNEL_CONS_ATTR=(FG_GREEN|BG_BLACK)
options 	SC_KERNEL_CONS_REV_ATTR=(FG_BLACK|BG_GREEN)
device		pcm
device		smbus		# Bus support, required for smb below.
device		intpm
device		ichsmb
device		smb
device		iicbus		# Bus support, required for ic/iic/iicsmb below.
device		iicbb
device		ic
device		iic
device		iicsmb		# smb over i2c bridge

No loader variables for ATA is set.


-netch-