> Martin Polden

Trimming the OpenBSD kernel

I've been building a few OpenBSD custom kernels lately and I've noticed that you can really strip it down a bit.

Ok, here's size of the GENERIC kernel that is installed by default:

[root@fw:/]$ du -sh bsd.GENERIC
5.1M bsd.GENERIC

The GENERIC kernel comes loaded with a lot of stuff, including PCMCIA/USB/SCSI/Audio/Radio etc. In the first kernel I compiled I didn't remove much, mainly SCSI and audio support. This was the result:

[root@fw:/]$ du -sh bsd.old
4.3M bsd.old

I wanted to remove even more drivers from it so I stripped it down ever further. This was the result of the second kernel:

[root@fw:/FW]$ du -sh /bsd
2.9M /bsd

As you can see, I managed to remove 2.2M from the GENERIC kernel.

Final config

Here is my final config file:

#       $OpenBSD: GENERIC,v 1.431 2005/08/16 16:40:48 deraadt Exp $
#
# For further information on compiling OpenBSD kernels, see the config(8)
# man page.
#
# For further information on hardware support for this architecture, see
# the intro(4) man page.  For further information about kernel options
# for this architecture, see the options(4) man page.  For an explanation
# of each device driver in this file see the section 4 man page for the
# device.

machine         i386
include         "../../../conf/GENERIC"
maxusers        32                      # estimated number of users

#option         I386_CPU        # CPU classes; at least one is REQUIRED
#option         I486_CPU
#option         I586_CPU
option          I686_CPU
#option         GPL_MATH_EMULATE        # floating point emulation.

option          USER_PCICONF    # user-space PCI configuration

#option         VM86            # Virtual 8086 emulation
option          USER_LDT        # user-settable LDT; see i386_set_ldt(2)
option          APERTURE        # in-kernel aperture driver for XFree86

#option         KGDB            # Remote debugger support; exclusive of DDB
#option         "KGDB_DEVNAME=\"pccom\"",KGDBADDR=0x2f8,KGDBRATE=9600

#option         DUMMY_NOPS      # speed hack; recommended

option          COMPAT_SVR4     # binary compatibility with SVR4
option          COMPAT_IBCS2    # binary compatibility with SCO and ISC
option          COMPAT_LINUX    # binary compatibility with Linux
option          COMPAT_FREEBSD  # binary compatibility with FreeBSD
option          COMPAT_BSDOS    # binary compatibility with BSD/OS
option          COMPAT_AOUT     # a.out binaries are emulated

#option         NTFS            # Experimental NTFS support

# or use                root on nfs swap on nfs
config          bsd     swap generic

mainbus0 at root

cpu0    at mainbus?
bios0   at mainbus0
apm0    at bios0 flags 0x0000   # flags 0x0101 to force protocol version 1.1
pcibios0 at bios0 flags 0x0000  # use 0x30 for a total verbose

isa0    at mainbus0
isa0    at pcib?
isa0    at ichpcib?
isa0    at gscpcib?
eisa0   at mainbus0
pci*    at mainbus0

#acpi0  at mainbus?
#acpitimer* at acpi?
#hpet*  at acpi?

option          ACPIVERBOSE
#option         ACPI_ENABLE

option          PCIVERBOSE
option          EISAVERBOSE
#option         USBVERBOSE

pchb*   at pci?                 # PCI-Host bridges
ppb*    at pci?                 # PCI-PCI bridges
pci*    at ppb?
pci*    at pchb?
pcib*   at pci?                 # PCI-ISA bridge
ichpcib* at pci?                # Intel ICHx/ICHx-M LPC bridges
gscpcib* at pci?                # NS Geode SC1100 PCI-ISA bridge
gpio*   at gscpcib?

# power management and other environmental stuff
#amdpm* at pci?                 # AMD768MPX
elansc* at pci?                 # AMD Elan SC520 System Controller
gpio*   at elansc?
geodesc* at pci?                # Geode SC1100/SCx200 IAOC
#piixpm* at pci?                # Intel PIIX PM
#gscpm* at pci?                 # NS Geode SC1100 SMI/ACPI module
#ichwdt* at pci?                # Intel 6300ESB ICH watchdog timer

# National Semiconductor LM7[89] and compatible hardware monitors
lm0     at isa? port 0x290
#lm1    at isa? port 0x280
#lm2    at isa? port 0x310
nsclpcsio* at isa? port 0x2e            # NS PC87366 LPC Super I/O
nsclpcsio* at isa? port 0x4e
gpio*   at nsclpcsio?
gscsio* at isa? port 0x2e               # NS Geode SC1100 Super I/O
gscsio* at isa? port 0x15c
iic0    at gscsio?                      # ACCESS.bus 1
iic1    at gscsio?                      # ACCESS.bus 2
lmtemp0 at iic1 addr 0x48               # NS LM75/LM77 temperature sensor

it0     at isa? port 0x290              # IT8705F, IT8712F and SiS970 hardware
                                        # monitors
viaenv* at pci?                         # VIA VT82C686A hardware monitor
viasio* at isa? port 0x2e flags 0x0000  # VIA VT1211 LPC Super I/O
viasio* at isa? port 0x4e flags 0x0000
aps0    at isa? port 0x1600             # ThinkPad Active Protection System

# ISA PCMCIA controllers
#option PCMCIAVERBOSE
#pcic0  at isa? port 0x3e0 iomem 0xd0000 iosiz 0x10000
#pcic1  at isa? port 0x3e2 iomem 0xe0000 iosiz 0x4000
#pcic2  at isa? port 0x3e4 iomem 0xe0000 iosiz 0x4000
#tcic0  at isa? disable port 0x240 iomem 0xd0000 iosiz 0x10000

# ISA Plug-and-Play PCMCIA controllers
#option DEBUG_ISAPNP
#pcic*  at isapnp?

# PCI PCMCIA controllers
pcic*  at pci?

# PCMCIA bus support
pcmcia*       at pcic?
#pcmcia* at tcic?

# CardBus bus support
cardbus*        at cardslot?
#pcmcia*                at cardslot?
cbb*            at pci?
cardslot*       at cbb?

# USB Controllers
#ehci*  at pci?                         # Enhanced Host Controller
#ehci*  at cardbus?                     # Enhanced Host Controller
#uhci*  at pci?                         # Universal Host Controller (Intel)
#ohci*  at pci?                         # Open Host Controller
#ohci*  at cardbus?                     # Open Host Controller

# USB bus support
#usb*   at ehci?
#usb*   at uhci?
#usb*   at ohci?

# USB devices
#uhub*  at usb?                 # USB Hubs
#uhub*  at uhub?                # USB Hubs
#umodem*        at uhub?                # USB Modems/Serial
#ucom*  at umodem?
#uvisor*        at uhub?                # Handspring Visor
#ucom*  at uvisor?
#uvscom*        at uhub?                # SUNTAC Slipper U VS-10U serial
#ucom*  at uvscom?
#ubsa*  at uhub?                # Belkin serial adapter
#ucom*  at ubsa?
#uftdi* at uhub?                # FTDI FT8U100AX serial adapter
#ucom*  at uftdi?
#uplcom* at uhub?               # I/O DATA USB-RSAQ2 serial adapter
#ucom*  at uplcom?
#umct*  at uhub?                # MCT USB-RS232 serial adapter
#ucom*  at umct?
#uipaq* at uhub?                # iPAQ serial adapter
#ucom*  at uipaq?
#uaudio* at uhub?               # USB Audio
#audio* at uaudio?
#umidi* at uhub?                # USB MIDI
#midi*  at umidi?
#ulpt*  at uhub?                # USB Printers
#umass* at uhub?                # USB Mass Storage devices
#scsibus* at umass?
#atapiscsi* at umass?
#uhidev*        at uhub?                # Human Interface Devices
#ums*   at uhidev?              # USB mouse
#wsmouse* at ums? mux 0
#ukbd*  at uhidev?              # USB keyboard
#wskbd* at ukbd? mux 1
#uhid*  at uhidev?              # USB generic HID support
#aue*   at uhub?                # ADMtek AN986 Pegasus Ethernet
#atu*   at uhub?                # Atmel AT76c50x based 802.11b
#axe*   at uhub?                # ASIX Electronics AX88172 USB Ethernet
#cue*   at uhub?                # CATC USB-EL1201A based Ethernet
#kue*   at uhub?                # Kawasaki KL5KUSB101B based Ethernet
#cdce*  at uhub?                # CDC Ethernet
#upl*   at uhub?                # Prolific PL2301/PL2302 host-to-host `network'
#udav*  at uhub?                # Davicom DM9601 based Ethernet
#url*   at uhub?                # Realtek RTL8150L based adapters
#wi*    at uhub?                # WaveLAN IEEE 802.11DS
#urio*  at uhub?                # Diamond Multimedia Rio 500
#uscanner* at uhub?             # USB Scanners
#usscanner* at uhub?            # USB SCSI scanners, e.g., HP5300
#scsibus* at usscanner?
#uyap*  at uhub?                # Y@P firmware loader
#udsbr* at uhub?                # D-Link DSB-R100 radio
#radio* at udsbr?               # USB radio
#ubt*   at uhub?                # USB Bluetooth
#ugen*  at uhub?                # USB Generic driver
#ural*  at uhub?                # Ralink RT2500
#option NATM
#ueagle* at uhub?               # Analog Devices Eagle ADSL
puc*    at pci?                 # PCI "universal" communication device

npx0    at isa? port 0xf0 irq 13        # math coprocessor
isadma0 at isa?
isapnp0 at isa?

option  WSDISPLAY_COMPAT_USL            # VT handling
option  WSDISPLAY_COMPAT_RAWKBD         # can get raw scancodes
option  WSDISPLAY_DEFAULTSCREENS=6
option  WSDISPLAY_COMPAT_PCVT           # emulate some ioctls

pckbc0          at isa?         # PC keyboard controller
pckbd*          at pckbc?       # PC keyboard
pms*            at pckbc?       # PS/2 mouse for wsmouse
pmsi*           at pckbc?       # PS/2 "Intelli"mouse for wsmouse
vga0            at isa?
option          PCIAGP
vga*            at pci?
pcdisplay0      at isa?         # CGA, MDA, EGA, HGA
wsdisplay*      at vga?
wsdisplay*      at pcdisplay?
wskbd*          at pckbd? mux 1
wsmouse*        at pms? mux 0
wsmouse*        at pmsi? mux 0

pcppi0          at isa?
sysbeep0        at pcppi?

pccom0  at isa? port 0x3f8 irq 4        # standard PC serial ports
pccom1  at isa? port 0x2f8 irq 3
pccom2  at isa? port 0x3e8 irq 5
#pccom3 at isa? port 0x2e8 irq 9        # (conflicts with some video cards)
ast0    at isa? port 0x1a0 irq 5        # AST 4-port serial card
#ast1   at isa? port 0x2a0 irq 6        # 2nd AST 4-port serial card
pccom*  at ast?
#boca0  at isa? port 0x100 irq 5        # BOCA 8-port serial cards
#pccom* at boca?
#addcom0        at isa? port 0x108 irq 5        # Addonics FlexPort
#pccom* at addcom?
#rtfps0 at isa? port 0x1230 irq 10      # RT 4-port serial cards
#pccom* at rtfps?
#hsq0   at isa? port 0x140 irq 10       # Hostess 4-port serial card
#pccom* at hsq?
#pccom*  at pcmcia?                      # PCMCIA modems/serial ports
#pccom*  at isapnp?
#pccom*  at puc?
#pccom*  at cardbus?

# option for using CD1400 handshaking for incoming data
# requires a special cable that exchanges the RTS and DTR lines
# options CY_HW_RTS
cy0     at isa? iomem 0xd4000 irq 12    # ISA cyclom serial card
cy*     at pci?                         # PCI cyclom serial card
#cz*    at pci?                         # Cyclades-Z multi-port serial boards

lpt0    at isa? port 0x378 irq 7        # standard PC parallel ports
lpt1    at isa? port 0x278
lpt2    at isa? port 0x3bc
lpt*    at puc?

lms0    at isa? port 0x23c irq 5        # Logitech bus mouse
lms1    at isa? port 0x238 irq 5
mms0    at isa? port 0x23c irq 5        # Microsoft InPort mouse
mms1    at isa? port 0x238 irq 5

wsmouse*        at lms? mux 0
wsmouse*        at mms? mux 0

#bha0   at isa? port 0x330              # BusLogic [57]4X SCSI controllers
#bha1   at isa? disable port 0x334      # BusLogic [57]4X SCSI controllers
#bha2   at isa? disable
#bha*   at pci?
#bha*   at eisa?                # XXX eisa still runs in isa-compat
#scsibus* at bha?
#aha0   at isa? port 0x330      # Adaptec 154[02] SCSI controllers
#aha1   at isa? port 0x334      # Adaptec 154[02] SCSI controllers
#aha*   at isapnp?
#scsibus* at aha?
#ahb*   at eisa?                # Adaptec 174[024] SCSI controllers
#scsibus* at ahb?
#ahc0   at isa?                 # Adaptec 284x SCSI controllers
#ahc*   at eisa?                # Adaptec 274x, aic7770 SCSI controllers
#ahc*   at pci?                 # Adaptec 2940/3940/78?? SCSI controllers
#scsibus* at ahc?
#ahd*   at pci?                 # Adaptec 79?? SCSI controllers
#scsibus* at ahd?
#mpt*   at pci?                 # LSI Fusion-MPT SCSI/Fibre
#scsibus* at mpt?
#dpt*   at pci?                 # DPT SmartCache/SmartRAID PCI
#dpt*   at eisa?                # DPT SmartCache/SmartRAID EISA
#scsibus* at dpt?
#gdt*   at pci?                 # ICP Vortex GDT RAID controllers
#scsibus* at gdt?
#twe*   at pci?                 # 3ware Escalade RAID controllers
#scsibus* at twe?
#aac*   at pci?                 # Adaptec FSA RAID controllers
#scsibus* at aac?
#ami*   at pci?                 # AMI MegaRAID controllers
#scsibus* at ami?
#cac*   at pci?                 # Compaq Smart ARRAY [234]* RAID controllers
#cac*   at eisa?
#scsibus* at cac?
#ciss*  at pci?                 # Compaq Smart ARRAY [56]* RAID controllers
#scsibus* at ciss?
#iha*   at pci?                 # Initio Ultra/UltraWide SCSI controllers
#scsibus* at iha?
#isp*   at pci?                 # Qlogic ISP [12]0x0 SCSI/FibreChannel
#scsibus* at isp?
#aic0   at isa? port 0x340 irq 11 # Adaptec 152[02] SCSI controllers
#aic*   at pcmcia?              # PCMCIA based aic SCSI controllers
#aic*   at isapnp?              # isapnp configured aic SCSI controllers
#scsibus* at aic?
#esp*   at pcmcia?              # PCMCIA based NCR 53C9X SCSI
#scsibus* at esp?
#siop*  at pci?                 # NCR 538XX SCSI controllers(new)
#scsibus* at siop?
#adv*   at pci?                 # AdvanSys 1200A/B and ULTRA SCSI
#scsibus* at adv?
#adw*   at pci?                 # AdvanSys ULTRA WIDE SCSI
#scsibus* at adw?
#pcscp* at pci?                 # AMD 53c974 PCscsi-PCI SCSI
#scsibus* at pcscp?
#sea0   at isa? disable iomem 0xc8000 irq 5 # Seagate ST0[12] SCSI controllers
#scsibus* at sea?
#trm*   at pci?                 # Tekram DC-3x5U SCSI Controllers
#scsibus* at trm?
#uha0   at isa? port 0x330      # UltraStor [13]4f SCSI controllers
#uha1   at isa? disable port 0x334 # UltraStor [13]4f SCSI controllers
#uha*   at eisa?                # UltraStor 24f SCSI controllers
#scsibus* at uha?
#wds0   at isa? disable port 0x350 irq 15 drq 6 # WD7000 and TMC-7000 controllers
#wds1   at isa? port 0x358 irq 11 drq 5
#scsibus* at wds?

#sd*    at scsibus?             # SCSI disk drives
#st*    at scsibus?             # SCSI tape drives
#cd*    at scsibus?             # SCSI CD-ROM drives
#ch*    at scsibus?             # SCSI autochangers
#ss*    at scsibus?             # SCSI scanners
#safte* at scsibus?             # SCSI accessed fault-tolerant enclosures
#ses*   at scsibus?             # SCSI enclosure services
#uk*    at scsibus?             # unknown SCSI

fdc0    at isa? port 0x3f0 irq 6 drq 2  # standard PC floppy controllers
#fdc1   at isa? port 0x370
fd*     at fdc? flags 0x00

#mcd0   at isa? port 0x300 irq 10       # Mitsumi CD-ROM drives

# IDE controllers
pciide* at pci? flags 0x0000

wdc0    at isa? port 0x1f0 irq 14 flags 0x00
wdc1    at isa? port 0x170 irq 15 flags 0x00
#wdc*    at pcmcia?
wdc*    at isapnp?

# IDE hard drives
wd*     at wdc? flags 0x0000
wd*     at pciide? flags 0x0000

# ATAPI<->SCSI
#atapiscsi* at wdc?
#atapiscsi* at pciide?
#scsibus* at atapiscsi?

#wt0    at isa? port 0x308 irq 5 drq 1  # Archive and Wangtek QIC tape drives

# Networking devices
#we0    at isa? port 0x280 iomem 0xd0000 irq 9  # WD/SMC 80x3 ethernet
#we1    at isa? port 0x300 iomem 0xcc000 irq 10 #
#we2    at isa? port 0x280 iomem 0xd0000 irq 3  # WD/SMC 80x3 ethernet
#we*    at isapnp?
#ec0    at isa? port 0x250 iomem 0xd8000 irq 9  # 3C503 ethernet
#ne0    at isa? port 0x240 irq 9                # NE[12]000 ethernet
#ne1    at isa? port 0x300 irq 10               # NE[12]000 ethernet
#ne2    at isa? port 0x280 irq 9                # NE[12]000 ethernet
#ne*    at isapnp?                              # NE[12]000 PnP ethernet
#eg0    at isa? disable port 0x310 irq 5        # 3C505/Etherlink+ ethernet
#el0    at isa? disable port 0x300 irq 9        # 3C501 ethernet
#ep0    at isa?                                 # 3C509 ethernet
#ep*    at isapnp?                              # 3C509 PnP ethernet
#ep*    at isa?                                 # 3C509 ethernet
#ef*    at isapnp?                              # 3C515 PnP ethernet
#ie0    at isa? port 0x360 iomem 0xd0000 irq 7  # StarLAN and 3C507
#ie1    at isa? port 0x300 irq 10               # EtherExpress
#lc0    at isa? port 0x200                      # DEC EtherWorks
#lc1    at isa? port 0x280                      # DEC EtherWorks
#le0    at isa? port 0x360 irq 15 drq 6         # IsoLan, NE2100, and DEPCA
#ex0    at isa? port 0x320 irq 5                # Intel EtherExpress PRO/10
#tr0    at isa? port 0xa20 iomem 0xd8000        # IBM TROPIC based Token-Ring
#tr1    at isa? port 0xa24 iomem 0xd0000        # IBM TROPIC based Token-Ring
#tr*    at isa?                         # 3COM TROPIC based Token-Ring
#ep0    at eisa?
#ep*    at eisa?                        # 3C579 ethernet
#fea*   at eisa?                        # DEC DEFEA FDDI
#lmc*   at pci?                         # Lan Media Corp SSI/T3/HSSI
#san*   at pci?                         # Sangoma PCI AFT card
#le*    at pci?                         # PCnet-PCI based ethernet
#le*    at isapnp?
#pcn*   at pci?                         # AMD PCnet-PCI Ethernet
#de*    at pci?                         # DC21X4X-based ethernet
fxp*    at pci?                         # EtherExpress 10/100B ethernet
fxp*    at cardbus?                     # Intel PRO/100 ethernet
#ne*    at pci?                         # NE2000-compat ethernet
#ep0    at pci?                         # 3C59x ethernet
#ep*    at pci?                         # 3C59x ethernet
#ne*    at pcmcia?                      # PCMCIA based NE2000 ethernet
#ep*    at pcmcia?                      # PCMCIA based 3C5xx ethernet
#sm*    at pcmcia?                      # PCMCIA based sm ethernet
#xe*    at pcmcia?                      # Xircom ethernet
#fpa*   at pci?                         # DEC DEFPA FDDI
xl*     at pci?                         # 3C9xx ethernet
xl*     at cardbus?                     # 3C575/3C656 ethernet
rl*     at pci?                         # RealTek 81[23]9 ethernet
rl*     at cardbus?                     # RealTek 81[23]9 ethernet
#mtd*   at pci?                         # Myson MTD800/803/891
#epic*  at pci?                         # SMC EPIC/100 ethernet
#tl*    at pci?                         # Compaq Thunderlan ethernet
#vr*    at pci?                         # VIA Rhine ethernet
#wb*    at pci?                         # Winbond W89C840F ethernet
#sf*    at pci?                         # Adaptec AIC-6915 ethernet
#sis*   at pci?                         # SiS 900/7016 ethernet
#ste*   at pci?                         # Sundance ST201 ethernet
dc*     at pci?                         # 21143, "tulip" clone ethernet
dc*     at cardbus?                     # 21143, "tulip" clone ethernet
#ti*    at pci?                         # Alteon Tigon 1Gb ethernet
#skc*   at pci?                         # SysKonnect GEnesis 984x
#sk*    at skc?                         #  each port of above
#em*    at pci?                         # Intel Pro/1000 ethernet
#txp*   at pci?                         # 3com 3CR990
#nge*   at pci?                         # NS DP83820/DP83821 GigE
#bge*   at pci?                         # Broadcom BCM570x (aka Tigon3)
#re*    at pci?                         # Realtek 8169/8169S/8110S
#re*    at cardbus?                     # Realtek 8169/8169S/8110S
#stge*  at pci?                         # Sundance TC9021 GigE
#lge*   at pci?                         # Level1 LXT1001 GigE
#hme*   at pci?                         # Sun Happy Meal
#bce*   at pci?                         # Broadcom BCM4401
#vge*   at pci?                         # VIA VT612x
#musycc*        at pci?                         # Conexant HDLC controller
#art*   at musycc?                      # Accoom Artery E1/T1 cards

# Wireless network cards
#ath*   at pci?                         # Atheros AR5k (802.11a/b/g)
#ath*   at cardbus?                     # Atheros AR5k (802.11a/b/g)
#atw*   at pci?                         # ADMtek ADM8211 (802.11)
#atw*   at cardbus?                     # ADMtek ADM8211 (802.11)
#wi*    at pci?                         # WaveLAN IEEE 802.11DS
#wi*    at pcmcia?                      # WaveLAN IEEE 802.11DS
#awi*   at pcmcia?                      # Bay Networks IEEE 802.11FH
#an*    at pci?                         # Aironet IEEE 802.11DS
#an*    at isapnp?                      # Aironet IEEE 802.11DS
#an*    at pcmcia?                      # Aironet IEEE 802.11DS
#cnw*   at pcmcia?                      # Xircom Netwave
#ray*   at pcmcia?                      # Raylink Aviator2.4/Pro 802.11FH
#ipw*   at pci?                         # Intel PRO/Wireless 2100
#iwi*   at pci?                         # Intel PRO/Wireless 2200BG/2915ABG
#ral*   at pci?                         # Ralink RT2500
#ral*   at cardbus?                     # Ralink RT2500
#rtw*   at pci?                         # Realtek 8180
#rtw*   at cardbus?                     # Realtek 8180

# Media Independent Interface (mii) drivers
exphy*  at mii?                         # 3Com internal PHYs
inphy*  at mii?                         # Intel 82555 PHYs
iophy*  at mii?                         # Intel 82553 PHYs
icsphy* at mii?                         # ICS 1890 PHYs
lxtphy* at mii?                         # Level1 LXT970 PHYs
nsphy*  at mii?                         # NS and compatible PHYs
nsphyter*       at mii?                 # NS and compatible PHYs
qsphy*  at mii?                         # Quality Semi QS6612 PHYs
luphy*  at mii?                         # Lucent LU6612 PHY
sqphy*  at mii?                         # Seeq 8x220 PHYs
rlphy* at mii?                          # RealTek 8139 internal PHYs
mtdphy* at mii?                         # Myson MTD972 PHYs
dcphy*  at mii?                         # Digital Clone PHYs
acphy*  at mii?                         # Altima AC101 PHYs
amphy*  at mii?                         # AMD 79C873 PHYs
tqphy*  at mii?                         # TDK 78Q212x PHYs
bmtphy* at mii?                         # Broadcom 10/100 PHYs
brgphy* at mii?                         # Broadcom Gigabit PHYs
eephy* at mii?                          # Marvell 88E1000 series PHY
xmphy*  at mii?                         # XaQti XMAC-II PHYs
nsgphy* at mii?                         # NS gigabit PHYs
urlphy* at mii?                         # Realtek RTL8150L internal PHY
rgephy* at mii?                         # Realtek 8169S/8110S PHY
ciphy*  at mii?                         # Cicada CS8201 10/100/1000 copper PHY
ukphy*  at mii?                         # "unknown" PHYs

#pss0    at isa? port 0x220 irq 7 drq 6  # Personal Sound System
#sp0     at pss0 port 0x530 irq 10 drq 0 # sound port driver

#eap*    at pci?                         # Ensoniq AudioPCI S5016
#eso*    at pci?                         # ESS Solo-1 PCI AudioDrive
#sv*     at pci?                         # S3 SonicVibes (S3 617)
#neo*    at pci?                         # NeoMagic 256AV/ZX
#cmpci*  at pci?                         # C-Media CMI8338/8738
#auich*  at pci? flags 0x0000            # i82801 ICH AC'97 audio
#auixp*  at pci?                         # ATI IXP AC'97 Audio
#autri*  at pci? flags 0x0000            # Trident 4D WAVE
#auvia*  at pci?                         # VIA VT82C686A
#clcs*   at pci?                         # CS4280 CrystalClear audio
#clct*   at pci?                         # CS4281 CrystalClear audio
#fms*    at pci?                         # Forte Media FM801
#maestro* at pci?                        # ESS Maestro PCI
#esa*    at pci?                         # ESS Maestro3 PCI
#yds*    at pci? flags 0x0000            # Yamaha YMF Audio
#emu*    at pci?                         # SB Live!
#sb0     at isa? port 0x220 irq 5 drq 1  # SoundBlaster
#sb*     at isapnp?
#ess*    at isapnp?                      # ESS Tech ES188[78], ES888
#wss0    at isa? port 0x530 irq 10 drq 0 # Windows Sound System
#wss*    at isapnp?
#pas0    at isa? port 0x220 irq 7 drq 1  # ProAudio Spectrum
#gus0    at isa? port 0x220 irq 7 drq 1 drq2 6   # Gravis (drq2 is record drq)
#ym*     at isapnp?
#mpu*    at isapnp?
#mpu*    at isa? port 0x300              # generic MPU, Yamaha SW60XG
#aria0  at isa? port 0x280 irq 10 drq 0 flags 0x1 # Prometheus Aria 16

# OPL[23] FM synthesizers
#opl0   at isa? port 0x388      # use only if not attached to sound card
#opl*   at eso?
#opl*   at sb?
#opl*   at ess?
#opl*   at yds?

# MIDI support
#midi*  at pcppi?               # MIDI interface to the PC speaker
#midi*  at sb?                  # SB MPU401 port
#midi*  at opl?                 # OPL FM synth
#midi*  at ym?
#midi*  at mpu?
#midi*  at autri?
#midi*  at eap?

spkr0   at pcppi?               # PC speaker

# Audio Support
#audio* at sb?
#audio* at gus?
#audio* at pas?
#audio* at sp?
#audio* at ess?
#audio* at wss?
#audio* at ym?
#audio* at eap?
#audio* at eso?
#audio* at sv?
#audio* at neo?
#audio* at cmpci?
#audio* at clcs?
#audio* at clct?
#audio* at auich?
#audio* at auixp?
#audio* at autri?
#audio* at auvia?
#audio* at fms?
#audio* at maestro?
#audio* at esa?
#audio* at yds?
#audio* at emu?

#bktr0  at pci?

# FM-Radio devices
#gtp*   at pci?                 # Gemtek/Guillemot Radio PCI Radio Card
#sfr0   at isa? port 0x384      # SoundForte RadioLink SF16-FMR FM Radio Card
#sf2r0  at isa? port 0x384      # SoundForte RadioLink SF16-FMR2 FM Radio Card
#az0    at isa? port 0x350      # Aztech/PackardBell FM Radio Card
#rt0    at isa? port 0x30c      # AIMS Lab Radiotrack FM Radio Card
#rt*    at isapnp?
#rtii0  at isa? port 0x30c      # AIMS Lab Radiotrack II FM Radio Card

# FM-Radio support
#radio* at bktr?
#radio* at fms?
#radio* at gtp?
#radio* at sfr?
#radio* at sf2r?
#radio* at az?
#radio* at rt?
#radio* at rtii?

# Joystick driver. Probe is a little strange; add only if you have one.
#joy0   at isa? port 0x201
#joy*   at isapnp?

#wdt0   at pci?                 # Ind Computer Source PCI-WDT50x driver

# crypto support
#hifn*  at pci?                 # Hi/fn 7751 crypto card
#lofn*  at pci?                 # Hi/fn 6500 crypto card
#nofn*  at pci?                 # Hi/fn 7814/7851/7854 crypto card
#ubsec* at pci?                 # Bluesteel Networks 5xxx crypto card
#safe*  at pci?                 # SafeNet SafeXcel 1141/1741
#ises*  at pci?                 # Pijnenburg PCC-ISES

# I2O
iop*    at pci?                 # I2O
ioprbs* at iop?                 # Random block storage
scsibus* at ioprbs?

pseudo-device   pctr            1
pseudo-device   mtrr            1       # Memory range attributes control
pseudo-device   nvram           1
pseudo-device   sequencer       1
#pseudo-device  raid            4       # RAIDframe disk driver
pseudo-device   bio             1       # ioctl multiplexing device
pseudo-device   hotplug         1       # devices hot plugging

# mouse & keyboard multiplexor pseudo-devices
pseudo-device   wsmux           2
pseudo-device   crypto          1

Helper script

Here is a simple bash script to make the compiling easier:

#!/usr/local/bin/bash

# just a simple bash script for building a kernel on OpenBSD
# by martin.polden at c2i.net
#
# place your kernel config in /usr/src/sys/arch/${ARCH}/conf/
# run this script with the name of your config as the first argument

CONFIG="${1}";
ARCH=`uname -m`;
SYS=`uname -s`;

if [ $# = 0 ];
then
  echo "usage: buildkernel config-file";
  exit 3
elif [ $SYS != "OpenBSD" ];
then
  echo "You're not running OpenBSD. Shame on you!";
  exit 4
elif [ ! -e "/usr/src/sys/arch/${ARCH}/conf/${CONFIG}" ];
then
  echo "Kernel config (${CONFIG}) does not exist in /usr/src/sys/arch/${ARCH}/conf/";
  exit 5
else
  mkdir /${CONFIG} && cd /${CONFIG};
  cp /usr/src/sys/arch/${ARCH}/conf/${CONFIG} .;
  config -s /usr/src/sys -b . ${CONFIG};
  make clean && make depend && make;
  cp /bsd /bsd.backup;
fi

echo "Your kernel (${CONFIG}) has been compiled in /${CONFIG}";
echo "Type 'cd /${CONFIG} && make install' to install your kernel";
echo "A backup of your old kernel has been created in /bsd.backup";

exit 0