重新编译安装内核需要安装所有的源码，如果还没有安装源码：
方法一：
可以用sysinstall命令，来安装所有源码。
方法二：
参考 Freebsd6.2 使用cvsup升级ports和src，来升级src（推荐）
安装完源码后，开始配置内核：
1.进入内核配置文件目录
# cd /usr/src/sys/i386/conf
# mkdir /root/kernels
# cp GENERIC /root/kernels/MYKERNEL
# ln -s /root/kernels/MYKERNEL
MYKERNEL为你新内核配置文件的名字
2.编译内核
# cd /usr/src
# make buildkernel KERNCONF=MYKERNEL
3.安装内核
# make installkernel KERNCONF=MYKERNEL
编译内核之前可以配置自己的内核文件 MYKERNEL，使她符合自己的要求。
具体的内核说明可以参考：
http://docs.freebsd.org/doc/6.2-RELEASE/usr/share/doc/zh_CN.GB2312/books/handbook/kernelconfig-config.html
附上我的内核配置文件（在VMware6.0上测试）：
#
# GENERIC -- Generic kernel configuration file for FreeBSD/i386
#
# For more information on this file, please read the handbook section on
# Kernel Configuration Files:
#
# http://www.FreeBSD.org/doc/en_US.ISO8859-1/books/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 ../../conf/NOTES and NOTES files.
# 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 1.429.2.13 2006/10/09 18:41:36 simon Exp $
machine i386
#cpu I486_CPU
#cpu I586_CPU
cpu I686_CPU
ident ANGEL
# 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 # 4BSD scheduler
options PREEMPTION # Enable kernel thread preemption
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 MD_ROOT # MD is a potential root device
#options NFSCLIENT # Network Filesystem Client
#options NFSSERVER # Network Filesystem Server
#options NFS_ROOT # NFS usable as /, requires NFSCLIENT
#options MSDOSFS # MSDOS Filesystem
options CD9660 # ISO 9660 Filesystem
#options PROCFS # Process filesystem (requires PSEUDOFS)
#options PSEUDOFS # Pseudo-filesystem framework
#options GEOM_GPT # GUID Partition Tables.
options COMPAT_43 # Compatible with BSD 4.3 [KEEP THIS!]
options COMPAT_FREEBSD4 # Compatible with FreeBSD4
options COMPAT_FREEBSD5 # Compatible with FreeBSD5
#options SCSI_DELAY=5000 # Delay (in ms) before probing SCSI
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
options ADAPTIVE_GIANT # Giant mutex is adaptive.
# im.rd.bj lighttpd
options ACCEPT_FILTER_HTTP
options MAXFILES=65535
options SYSVMSG
options MSGMNB=8192
options MSGMNI=40
options MSGSEG=512
options MSGSSZ=64
options MSGTQL=2048
options SYSVSHM
options SHMSEG=16
options SHMMNI=32
options SHMMAX=2097152
options SHMALL=4096
device apic # I/O APIC
# Bus support.
device eisa
device pci
# Floppy drives
#device fdc
# ATA and ATAPI devices
device ata
device atadisk # ATA disk drives
#device ataraid # ATA RAID drives
device atapicd # ATAPI CDROM drives
#device atapifd # ATAPI floppy drives
#device atapist # ATAPI tape drives
options ATA_STATIC_ID # Static device numbering
# SCSI Controllers
#device ahb # EISA AHA1742 family
#device ahc # AHA2940 and onboard AIC7xxx devices
#options AHC_REG_PRETTY_PRINT # Print register bitfields in debug
# output. Adds ~128k to driver.
#device ahd # AHA39320/29320 and onboard AIC79xx devices
#options AHD_REG_PRETTY_PRINT # Print register bitfields in debug
# output. Adds ~215k to driver.
#device amd # AMD 53C974 (Tekram DC-390(T))
#device isp # Qlogic family
#device ispfw # Firmware for QLogic HBAs- normally a module
#device mpt # LSI-Logic MPT-Fusion
#device ncr # NCR/Symbios Logic
#device sym # NCR/Symbios Logic (newer chipsets + those of `ncr')
#device trm # Tekram DC395U/UW/F DC315U adapters
#device adv # Advansys SCSI adapters
#device adw # Advansys wide SCSI adapters
#device aha # Adaptec 154x SCSI adapters
#device aic # Adaptec 15[012]x SCSI adapters, AIC-6[23]60.
#device bt # Buslogic/Mylex MultiMaster SCSI adapters
#device ncv # NCR 53C500
#device nsp # Workbit Ninja SCSI-3
#device stg # TMC 18C30/18C50
# SCSI peripherals
#device scbus # SCSI bus (required for SCSI)
#device ch # SCSI media changers
#device da # Direct Access (disks)
#device sa # Sequential Access (tape etc)
#device cd # CD
#device pass # Passthrough device (direct SCSI access)
#device ses # SCSI Environmental Services (and SAF-TE)
# RAID controllers interfaced to the SCSI subsystem
#device amr # AMI MegaRAID
#device arcmsr # Areca SATA II RAID
#device asr # DPT SmartRAID V, VI and Adaptec SCSI RAID
#device ciss # Compaq Smart RAID 5*
#device dpt # DPT Smartcache III, IV - See NOTES for options
#device hptmv # Highpoint RocketRAID 182x
#device rr232x # Highpoint RocketRAID 232x
#device iir # Intel Integrated RAID
#device ips # IBM (Adaptec) ServeRAID
#device mly # Mylex AcceleRAID/eXtremeRAID
#device twa # 3ware 9000 series PATA/SATA RAID
# RAID controllers
#device aac # Adaptec FSA RAID
#device aacp # SCSI passthrough for aac (requires CAM)
#device ida # Compaq Smart RAID
#device mfi # LSI MegaRAID SAS
#device mlx # Mylex DAC960 family
#device pst # Promise Supertrak SX6000
#device twe # 3ware ATA RAID
# 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 kbdmux # keyboard multiplexer
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
# 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
#device agp # support several AGP chipsets
# Power management support (see NOTES for more options)
#device apm
# Add suspend/resume support for the i8254.
device pmtimer
# PCCARD (PCMCIA) support
# PCMCIA and cardbus bridge support
#device cbb # cardbus (yenta) bridge
#device pccard # PC Card (16-bit) bus
#device cardbus # CardBus (32-bit) bus
# Serial (COM) ports
device sio # 8250, 16[45]50 based serial ports
# 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
# If you've got a "dumb" serial or parallel PCI card that is
# supported by the puc(4) glue driver, uncomment the following
# line to enable it (connects to the sio and/or ppc drivers):
#device puc
# PCI Ethernet NICs.
device de # DEC/Intel DC21x4x (``Tulip'')
device em # Intel PRO/1000 adapter Gigabit Ethernet Card
#device ixgb # Intel PRO/10GbE Ethernet Card
#device txp # 3Com 3cR990 (``Typhoon'')
#device vx # 3Com 3c590, 3c595 (``Vortex'')
# PCI Ethernet NICs that use the common MII bus controller code.
# NOTE: Be sure to keep the 'device miibus' line in order to use these NICs!
device miibus # MII bus support
device bce # Broadcom BCM5706/BCM5708 Gigabit Ethernet
device bfe # Broadcom BCM440x 10/100 Ethernet
device bge # Broadcom BCM570xx Gigabit Ethernet
device dc # DEC/Intel 21143 and various workalikes
device fxp # Intel EtherExpress PRO/100B (82557, 82558)
device lge # Level 1 LXT1001 gigabit Ethernet
device nge # NatSemi DP83820 gigabit Ethernet
device nve # nVidia nForce MCP on-board Ethernet Networking
device pcn # AMD Am79C97x PCI 10/100(precedence over 'lnc')
device re # RealTek 8139C+/8169/8169S/8110S
device rl # RealTek 8129/8139
device sf # Adaptec AIC-6915 (``Starfire'')
device sis # Silicon Integrated Systems SiS 900/SiS 7016
device sk # SysKonnect SK-984x & SK-982x gigabit Ethernet
device ste # Sundance ST201 (D-Link DFE-550TX)
device stge # Sundance/Tamarack TC9021 gigabit Ethernet
device ti # Alteon Networks Tigon I/II gigabit Ethernet
device tl # Texas Instruments ThunderLAN
device tx # SMC EtherPower II (83c170 ``EPIC'')
device vge # VIA VT612x gigabit Ethernet
device vr # VIA Rhine, Rhine II
device wb # Winbond W89C840F
device xl # 3Com 3c90x (``Boomerang'', ``Cyclone'')
# ISA Ethernet NICs. pccard NICs included.
device cs # Crystal Semiconductor CS89x0 NIC
# 'device ed' requires 'device miibus'
device ed # NE[12]000, SMC Ultra, 3c503, DS8390 cards
device ex # Intel EtherExpress Pro/10 and Pro/10+
device ep # Etherlink III based cards
device fe # Fujitsu MB8696x based cards
device ie # EtherExpress 8/16, 3C507, StarLAN 10 etc.
device lnc # NE2100, NE32-VL Lance Ethernet cards
device sn # SMC's 9000 series of Ethernet chips
device xe # Xircom pccard Ethernet
# Wireless NIC cards
#device wlan # 802.11 support
#device wlan_wep # 802.11 WEP support
#device wlan_ccmp # 802.11 CCMP support
#device wlan_tkip # 802.11 TKIP support
#device an # Aironet 4500/4800 802.11 wireless NICs.
#device ath # Atheros pci/cardbus NIC's
#device ath_hal # Atheros HAL (Hardware Access Layer)
#device ath_rate_sample # SampleRate tx rate control for ath
#device awi # BayStack 660 and others
#device ral # Ralink Technology RT2500 wireless NICs.
#device wi # WaveLAN/Intersil/Symbol 802.11 wireless NICs.
#device wl # Older non 802.11 Wavelan wireless NIC.
# Pseudo devices.
device loop # Network loopback
device random # Entropy device
device ether # Ethernet support
#device sl # Kernel SLIP
device ppp # Kernel PPP
device tun # Packet tunnel.
device pty # Pseudo-ttys (telnet etc)
device md # Memory "disks"
device gif # IPv6 and IPv4 tunneling
device faith # IPv6-to-IPv4 relaying (translation)
# The `bpf' device enables the Berkeley Packet Filter.
# Be aware of the administrative consequences of enabling this!
# Note that 'bpf' is required for DHCP.
device bpf # Berkeley packet filter
# USB support
device uhci # UHCI PCI->USB interface
device ohci # OHCI PCI->USB interface
device ehci # EHCI PCI->USB interface (USB 2.0)
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 ural # Ralink Technology RT2500USB wireless NICs
#device urio # Diamond Rio 500 MP3 player
#device uscanner # Scanners
# USB Ethernet, requires miibus
#device aue # ADMtek USB Ethernet
#device axe # ASIX Electronics USB Ethernet
#device cdce # Generic USB over Ethernet
#device cue # CATC USB Ethernet
#device kue # Kawasaki LSI USB Ethernet
#device rue # RealTek RTL8150 USB Ethernet
# FireWire support
device firewire # FireWire bus code
#device sbp # SCSI over FireWire (Requires scbus and da)
device fwe # Ethernet over FireWire (non-standard!)
