Bug 21278

Under the conditions described below, the ahc driver and/or
the 2940UW wedge within a couple of tens of minutes.  The box
is otherwise (usually) still alive. DDB/ps shows nfsd's (which
will be most of the traffic on that disk) waiting on getblk or
biowr.

Fix: 

No idea. I'm at the disposal of anyone who has a clue.

-------------------------------------------

[This config is generated by a script from GENERIC, be sure to
look at the end of it.]

#
#
# For more information on this file, please read the handbook section on
# Kernel Configuration Files:
#
#    http://www.FreeBSD.org/handbook/kernelconfig-config.html
#
# The handbook is also available locally in /usr/share/doc/handbook
# if you've installed the doc distribution, otherwise always see the
# FreeBSD World Wide Web server (http://www.FreeBSD.org/) for the
# latest information.
#
# An exhaustive list of options and more detailed explanations of the
# device lines is also present in the NOTES configuration file. If you are
# in doubt as to the purpose or necessity of a line, check first in NOTES.
#
# $FreeBSD: src/sys/i386/conf/GENERIC,v 1.273 2000/09/01 07:51:23 msmith Exp $

machine		i386
options DDB
cpu		I486_CPU
cpu		I586_CPU
cpu		I686_CPU
ident BLUDNOK_MP
maxusers	32

#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 	MATH_EMULATE		#Support for x87 emulation
options 	INET			#InterNETworking
options 	INET6			#IPv6 communications protocols
options 	FFS			#Berkeley Fast Filesystem
options 	FFS_ROOT		#FFS usable as root device [keep this!]
options 	SOFTUPDATES		#Enable FFS soft updates support
options 	MFS			#Memory Filesystem
#options 	DEVFS			#Device Filesystem
options 	MD_ROOT			#MD is a potential root device
options 	NFS			#Network Filesystem
options 	NFS_ROOT		#NFS usable as root device, NFS required
options 	MSDOSFS			#MSDOS Filesystem
options 	CD9660			#ISO 9660 Filesystem
options 	CD9660_ROOT		#CD-ROM usable as root, CD9660 required
options 	PROCFS			#Process filesystem
options 	COMPAT_43		#Compatible with BSD 4.3 [KEEP THIS!]
options 	SCSI_DELAY=15000	#Delay (in ms) before probing SCSI
options 	UCONSOLE		#Allow users to grab the console
options 	USERCONFIG		#boot -c editor
options 	VISUAL_USERCONFIG	#visual boot -c editor
options 	KTRACE			#ktrace(1) support
options 	SYSVSHM			#SYSV-style shared memory
options 	SYSVMSG			#SYSV-style message queues
options 	SYSVSEM			#SYSV-style semaphores
options 	P1003_1B		#Posix P1003_1B real-time extensions
options 	_KPOSIX_PRIORITY_SCHEDULING
options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
options 	RANDOMDEV		#entropy device

# To make an SMP kernel, the next two are needed
#options 	SMP			# Symmetric MultiProcessor Kernel
#options 	APIC_IO			# Symmetric (APIC) I/O
# Optionally these may need tweaked, (defaults shown):
#options 	NCPU=2			# number of CPUs
#options 	NBUS=8			# number of busses
#options 	NAPIC=1			# number of IO APICs
#options 	NINTR=24		# number of INTs

device		isa
device		eisa
device		pci
options 	COMPAT_OLDISA		# compatability shims for lnc, fe, le
options 	COMPAT_OLDPCI		# compatability shims for lnc, vx

# Floppy drives
device		fdc

# ATA and ATAPI devices
device		ata
device		atadisk			# ATA disk drives
device		atapicd			# ATAPI CDROM drives
device		atapifd			# ATAPI floppy drives
device		atapist			# ATAPI tape drives
options 	ATA_STATIC_ID		#Static device numbering
#options 	ATA_ENABLE_ATAPI_DMA	#Enable DMA on ATAPI devices

# SCSI Controllers
device		ahb		# EISA AHA1742 family
device		ahc		# AHA2940 and onboard AIC7xxx devices
device		amd		# AMD 53C974 (Teckram DC-390(T))
device		isp		# Qlogic family
#device		ncr		# NCR/Symbios Logic
device		sym		# NCR/Symbios Logic (newer chipsets + those of `ncr')

device		adv
device		adw
device		bt
device		aha	1
device		aic

# RAID controllers interfaced to the SCSI subsystem
device		asr		# DPT SmartRAID V, VI and Adaptec SCSI RAID
device		dpt		# DPT Smartcache III, IV - See NOTES for options!
device		mly		# Mylex AcceleRAID/eXtremeRAID

# SCSI peripherals
device		scbus		# SCSI bus (required)
device		da		# Direct Access (disks)
device		sa		# Sequential Access (tape etc)
device		cd		# CD
device		pass		# Passthrough device (direct SCSI access)

# RAID controllers
device		ida		# Compaq Smart RAID
device		amr		# AMI MegaRAID
device		mlx		# Mylex DAC960 family

# atkbdc0 controls both the keyboard and the PS/2 mouse
device		atkbdc	1
device		atkbd
device		psm

device		vga

# splash screen/screen saver
device		splash

# syscons is the default console driver, resembling an SCO console
device		sc	1

# Enable this for the pcvt (VT220 compatible) console driver
#device		vt
#options 	XSERVER			# support for X server on a vt console
#options 	FAT_CURSOR		# start with block cursor
# If you have a ThinkPAD, uncomment this along with the rest of the PCVT lines
#options 	PCVT_SCANSET=2		# IBM keyboards are non-std

# Floating point support - do not disable.
device		npx

# Power management support (see NOTES for more options)
device		apm

# PCCARD (PCMCIA) support
device		card
device		pcic

# Serial (COM) ports
device		sio

# Parallel port
device		ppc
device		ppbus		# Parallel port bus (required)
device		lpt		# Printer
device		plip		# TCP/IP over parallel
device		ppi		# Parallel port interface device
#device		vpo		# Requires scbus and da


# PCI Ethernet NICs.
device		de		# DEC/Intel DC21x4x (``Tulip'')
device		fxp		# Intel EtherExpress PRO/100B (82557, 82558)
device		tx		# SMC 9432TX (83c170 ``EPIC'')
device		vx		# 3Com 3c590, 3c595 (``Vortex'')
device		wx		# Intel Gigabit Ethernet Card (``Wiseman'')

# PCI Ethernet NICs that use the common MII bus controller code.
device		miibus		# MII bus support
device		dc		# DEC/Intel 21143 and various workalikes
device		rl		# RealTek 8129/8139
device		sf		# Adaptec AIC-6915 (``Starfire'')
device		sis		# Silicon Integrated Systems SiS 900/SiS 7016
device		ste		# Sundance ST201 (D-Link DFE-550TX)
device		tl		# Texas Instruments ThunderLAN
device		vr		# VIA Rhine, Rhine II
device		wb		# Winbond W89C840F
device		xl		# 3Com 3c90x (``Boomerang'', ``Cyclone'')

# ISA Ethernet NICs.
device		ed
#device		ex
device		ep
device		cs
device		sn
# WaveLAN/IEEE 802.11 wireless NICs. Note: the WaveLAN/IEEE really
# exists only as a PCMCIA device, so there is no ISA attatement needed
# and resources will always be dynamically assigned by the pccard code.
device		wi
# Aironet 4500/4800 802.11 wireless NICs. Note: the declaration below will
# work for PCMCIA and PCI cards, as well as ISA cards set to ISA PnP
# mode (the factory default). If you set the switches on your ISA
# card for a manually chosen I/O address and IRQ, you must specify
# those paremeters here.
device		an
# BayStack 660 and others
device		awi
# Xircom pccard ethernet
device		xe
# The probe order of these is presently determined by i386/isa/isa_compat.c.
device		ie
device		fe
#device		le
#device		lnc

# Pseudo devices - the number indicates how many units to allocated.
device		loop		# Network loopback
device		ether		# Ethernet support
device		sl		# Kernel SLIP
device		ppp	1	# Kernel PPP
device		tun		# Packet tunnel.
device		pty		# Pseudo-ttys (telnet etc)
device		md		# Memory "disks"
device		gif	4	# IPv6 and IPv4 tunneling
device		faith	1	# IPv6-to-IPv4 relaying (translation)

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

# USB support
device		uhci		# UHCI PCI->USB interface
device		ohci		# OHCI PCI->USB interface
device		usb		# USB Bus (required)
#device		udbp		# USB Double Bulk Pipe devices
device		ugen		# Generic
device		uhid		# "Human Interface Devices"
device		ukbd		# Keyboard
device		ulpt		# Printer
device		umass		# Disks/Mass storage - Requires scbus and da
device		ums		# Mouse
device		urio		# Diamond Rio 500 MP3 player
# USB Ethernet, requires mii
device		aue		# ADMtek USB ethernet
device		cue		# CATC USB ethernet
device		kue		# Kawasaki LSI USB ethernet
options SOFTUPDATES
device vn
options SMP
options APIC_IO
options WITNESS
options SMP_DEBUG
options KTR
options KTR_EXTEND
options KTR_COMPILE=0xffffffff
options KTR_MASK=0x00200200
options KTR_ENTRIES=16384
options DIAGNOSTIC
options INVARIANTS
options INVARIANT_SUPPORT

Copyright (c) 1992-2000 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
	The Regents of the University of California. All rights reserved.
FreeBSD 5.0-CURRENT #4: Thu Sep 14 17:54:31 BST 2000
    rb@bludnok:/source/cleansrc/sys/compile/BLUDNOK_MP
Timecounter "i8254"  frequency 1193182 Hz
CPU: Pentium II/Pentium II Xeon/Celeron (349.07-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0x651  Stepping = 1
  Features=0x183fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR>
real memory  = 134152192 (131008K bytes)
avail memory = 123875328 (120972K bytes)
Programming 24 pins in IOAPIC #0
IOAPIC #0 intpin 2 -> irq 0
FreeBSD/SMP: Multiprocessor motherboard
 cpu0 (BSP): apic id:  0, version: 0x00040011, at 0xfee00000
 cpu1 (AP):  apic id:  1, version: 0x00040011, at 0xfee00000
 io0 (APIC): apic id:  2, version: 0x00170011, at 0xfec00000
Preloaded elf kernel "kernel.ko" at 0xc0680000.
Pentium Pro MTRR support enabled
md0: Malloc disk
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Intel 82443BX (440 BX) host to PCI bridge> on motherboard
pci0: <PCI bus> on pcib0
pcib1: <Intel 82443BX (440 BX) PCI-PCI (AGP) bridge> at device 1.0 on pci0
pci1: <PCI bus> on pcib1
isab0: <Intel 82371AB PCI to ISA bridge> at device 7.0 on pci0
isa0: <ISA bus> on isab0
atapci0: <Intel PIIX4 ATA33 controller> port 0xf000-0xf00f at device 7.1 on pci0
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
uhci0: <Intel 82371AB/EB (PIIX4) USB controller> port 0xe000-0xe01f irq 11 at device 7.2 on pci0
usb0: <Intel 82371AB/EB (PIIX4) USB controller> on uhci0
usb0: USB revision 1.0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
Timecounter "PIIX"  frequency 3579545 Hz
pci0: <Intel 82371AB Power management controller> at 7.3
ahc0: <Adaptec 2940 Ultra SCSI adapter> port 0xe400-0xe4ff mem 0xea000000-0xea000fff irq 16 at device 8.0 on pci0
ahc0: aic7880 Wide Channel A, SCSI Id=7, 16/255 SCBs
pci0: <S3 ViRGE DX/GX graphics accelerator> at 11.0 irq 19
atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
kbd0 at atkbd0
ed0 at port 0x300-0x31f iomem 0xd8000 irq 10 on isa0
ed0: address 00:20:18:72:97:67, type NE2000 (16 bit)
fdc0: <NEC 72065B or clone> at port 0x3f0-0x3f5,0x3f7 irq 6 drq 2 on isa0
fdc0: FIFO enabled, 8 bytes threshold
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
ppc0: <Parallel port> at port 0x378-0x37f irq 7 on isa0
ppc0: Generic chipset (NIBBLE-only) in COMPATIBLE mode
plip0: <PLIP network interface> on ppbus0
lpt0: <Printer> on ppbus0
lpt0: Interrupt-driven port
ppi0: <Parallel I/O> on ppbus0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 16550A
sio1 at port 0x2f8-0x2ff irq 3 on isa0
sio1: type 16550A
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
unknown: <PNP0303> can't assign resources
unknown: <PNP0501> can't assign resources
unknown: <PNP0700> can't assign resources
unknown: <PNP0400> can't assign resources
unknown: <PNP0501> can't assign resources
APIC_IO: Testing 8254 interrupt delivery
APIC_IO: routing 8254 via IOAPIC #0 intpin 2
ad0: 1222MB <QUANTUM FIREBALL_TM1280A> [2484/16/63] at ata0-master using WDMA2
Waiting 15 seconds for SCSI devices to settle
Mounting root from ufs:/dev/ad0s2a
cd0 at ahc0 bus 0 target 6 lun 0
cd0: <PIONEER DVD-ROM DVD-303 1.09> Removable CD-ROM SCSI-2 device
cd0: 10.000MB/s transfers (10.000MHz, offset 8)
cd0: Attempt to query device size failed: NOT READY, Medium not present
da1 at ahc0 bus 0 target 5 lun 0
da1: <IOMEGA ZIP 100 E.08> Removable Direct Access SCSI-2 device
da1: 3.300MB/s transfers
da1: Attempt to query device size failed: NOT READY, Medium not present
da0 at ahc0 bus 0 target 0 lun 0
da0: <IBM DNES-309170W SA30> Fixed Direct Access SCSI-3 device
da0: 40.000MB/s transfers (20.000MHz, offset 8, 16bit)
da0: 8748MB (17916240 512 byte sectors: 255H 63S/T 1115C)
SMP: AP CPU #1 Launched!
How-To-Repeat: 
Set up an SMP box and another -current system and
cross-NFS-mount their /usr/obj.  Buildworld on both
simultaneously, (Both here are getting their sources by NFS
from a third box but I doubt that's relevant.)