Matthew(黑夜編碼人) <[email protected]>
前言
在前面我們已經講過如何制作軟盤上運行的FreeBSD和OpenBSD系統，現在我們來看看如何制作一個運行在軟盤上的NetBSD系統。同軟盤中的OpenBSD系統一樣，我們還是將系統中的所有配制文件及程序全部存放到NetBSD的內核中，這樣整個系統看起來就是一個文件。下面讓我們具體來看看如何完成這樣一個微系統的制作。
0、NetBSD的啟動過程
當硬盤MBR中的引導程序接過啟動之後，MBR中的程序將讀入硬盤NetBSD分區中的引導程序，引導程序默認情況下會加載/boot，然後由boot載入內核/netbsd，此時內核開始檢測一些硬件和做一些初始化。初始化完成後kernel將mount root device，然後啟動系統初始化進程/sbin/init，init將根據/etc/rc中的設置來進行初始化等。
1、定制RAMDISK內核
要使用RAMDISK in KERNEL就必須在內核配制文件中加入以下選項：
options MEMORY_DISK_HOOKS options MEMORY_DISK_IS_ROOT # force root on memory disk options MEMORY_DISK_SERVER=0 options MEMORY_DISK_ROOT_SIZE=10000 # size of memory disk, in blocks options MEMORY_RBFLAGS=0x00 # boot in to multi-user mode pseudo-device md 1 # memory disk device (ramdisk)
以上的內核參數意義如下：
MEMORY_DISK_ROOT_SIZE : 內存磁盤大小，以塊為單位 MEMORY_RBFLAGS=0x00 : 啟動到多用戶模式
以下是在我機器上使用的一個內核配制文件
include "arch/i386/conf/std.i386"#options INCLUDE_CONFIG_FILE # embed config file in kernel binary
makeoptions COPTS="-Os" # Optimise for space. Implies -O2
# Enable the hooks used for initializing the root memory-disk. options MEMORY_DISK_HOOKS options MEMORY_DISK_IS_ROOT # force root on memory disk options MEMORY_DISK_SERVER=1 # 0 readonly 1 writable options MEMORY_DISK_ROOT_SIZE=10000 # size of memory disk, in blocks options MEMORY_RBFLAGS=0x00 # boot in to multi-user mode
maxusers 48 # estimated number of users
# CPU support. At least one is REQUIRED. options I386_CPU options I686_CPU
# CPU-related options. options MATH_EMULATE # floating point emulation
# This option allows you to force a serial console at the specified # I/O address. #options CONSDEVNAME="\"com\"",CONADDR=0x3f8,CONSPEED=9600
# Avoid irq 5 and 7, the most likely cause of problems on modern laptops. options PCIC_ISA_INTR_ALLOC_MASK=0xff5f
# Standard system options
options INSECURE # disable kernel security levels
options RTC_OFFSET=0 # hardware clock is this many mins. west of GMT #options NTP # NTP phase/frequency locked loop
options USERCONF # userconf(4) support options PIPE_SOCKETPAIR # smaller, but slower pipe(2) options MALLOC_NOINLINE # Not inlining MALLOC saves memory
# File systems file-system FFS # UFS file-system MFS # memory file system file-system MSDOSFS # MS-DOS file system file-system KERNFS # /kern
options VNODE_OP_NOINLINE # Not inlining vnode op calls saves mem
# Networking options options GATEWAY # packet forwarding options INET # IP + ICMP + TCP + UDP #options PFIL_HOOKS # pfil(9) packet filter hooks
# builtin terminal emulations options WSEMUL_VT100 # VT100 / VT220 emulation # different kernel output - see dev/wscons/wsdisplayvar.h options WS_KERNEL_FG=WSCOL_BLACK options WS_KERNEL_BG=WSCOL_WHITE # compatibility to other console drivers #options WSDISPLAY_COMPAT_PCVT # emulate some ioctls #options WSDISPLAY_COMPAT_SYSCONS # emulate some ioctls #options WSDISPLAY_COMPAT_USL # VT handling #options WSDISPLAY_COMPAT_RAWKBD # can get raw scancodes # see dev/pckbc/wskbdmap_mfii.c for implemented layouts #options PCKBD_LAYOUT="(KB_DE | KB_NODEAD)" # allocate a number of virtual screens at autoconfiguration time #options WSDISPLAY_DEFAULTSCREENS=4 # use a large software cursor that doesn't blink options PCDISPLAY_SOFTCURSOR # modify the screen type of the console; defaults to "80x25" #options VGA_CONSOLE_SCREENTYPE="\"80x24\""
# Kernel root file system and dump configuration. config netbsd root on ？ type ？ #config netbsd root on sd0a type ffs #config netbsd root on ？ type nfs
# # Device configuration #
mainbus0 at root
cpu* at mainbus？
apm0 at mainbus0 # Advanced power management
# Basic Bus Support
# PCI bus support pci* at mainbus？ bus ？ pci* at pchb？ bus ？ pci* at ppb？ bus ？
# PCI bridges pchb* at pci？ dev ？ function ？ # PCI-Host bridges pceb* at pci？ dev ？ function ？ # PCI-EISA bridges pcib* at pci？ dev ？ function ？ # PCI-ISA bridges ppb* at pci？ dev ？ function ？ # PCI-PCI bridges # XXX 'puc's aren't really bridges, but there's no better place for them here puc* at pci？ dev ？ function ？ # PCI "universal" comm. cards
# ISA bus support isa0 at mainbus？ isa0 at pceb？ isa0 at pcib？
# ISA Plug-and-Play bus support isapnp0 at isa？
# Coprocessor Support
# Math Coprocessor support npx0 at isa？ port 0xf0 irq 13 # x86 math coprocessor
# Console Devices
# ISA console #pc0 at isa？ port 0x60 irq 1 # pccons generic PC console driver
# wscons pckbc0 at isa？ # pc keyboard controller pckbd* at pckbc？ # PC keyboard #pms* at pckbc？ # PS/2 mouse for wsmouse vga0 at isa？ vga* at pci？ dev ？ function ？ pcdisplay0 at isa？ # CGA, MDA, EGA, HGA wsdisplay* at vga？ console ？ wsdisplay* at pcdisplay？ console ？ wskbd* at pckbd？ console ？ #wsmouse* at pms？ mux 0
pcppi0 at isa？ sysbeep0 at pcppi？
# Serial Devices
# PCI serial interfaces com* at puc？ port ？ # 16x50s on "universal" comm boards #cy* at pci？ dev ？ function ？ # Cyclades Cyclom-Y serial boards
# ISA Plug-and-Play serial interfaces com* at isapnp？ # Modems and serial boards
# ISA serial interfaces #options COM_HAYESP # adds Hayes ESP serial board support com0 at isa？ port 0x3f8 irq 4 # Standard PC serial ports com1 at isa？ port 0x2f8 irq 3 com2 at isa？ port 0x3e8 irq 5 #com3 at isa？ port 0x2e8 irq 9 #ast0 at isa？ port 0x1a0 irq 5 # AST 4-port serial cards #com* at ast？ slave ？ #boca0 at isa？ port 0x100 irq 5 # BOCA 8-port serial cards #com* at boca？ slave ？ #tcom0 at isa？ port 0x100 irq 7 # TC-800 8-port serial cards #com* at tcom？ slave ？ #rtfps0 at isa？ port 0x1230 irq 10 # RT 4-port serial cards #com* at rtfps？ slave ？ #cy0 at isa？ iomem 0xd4000 irq 12 # Cyclades serial cards
# Miscellaneous mass storage devices
# Network Interfaces
# PCI network interfaces fxp* at pci？ dev ？ function ？ # Intel EtherExpress PRO 10+/100B le* at pci？ dev ？ function ？ # PCnet-PCI Ethernet pcn* at pci？ dev ？ function ？ # AMD PCnet-PCI Ethernet rtk* at pci？ dev ？ function ？ # Realtek 8129/8139
amhphy* at mii？ phy ？ # AMD 79c901 Ethernet PHYs urlphy* at mii？ phy ？ # Realtek RTL8150L internal PHYs ukphy* at mii？ phy ？ # generic unknown PHYs
# Pseudo-Devices
# disk/mass storage pseudo-devices pseudo-device md 1 # memory disk device (ramdisk) #pseudo-device vnd 4 # disk-like interface to files
# network pseudo-devices pseudo-device bpfilter 8 # Berkeley packet filter pseudo-device ipfilter # IP filter (firewall) and NAT pseudo-device loop # network loopback pseudo-device ppp 2 # Point-to-Point Protocol pseudo-device pppoe 3
# miscellaneous pseudo-devices pseudo-device pty 2 # pseudo-terminals (Sysinst needs two) # wscons pseudo-devices pseudo-device wsmux # mouse & keyboard multiplexor #pseudo-device wsfont
2、制作ramdisk鏡像
# dd if=/dev/zero of=/ramdisk bs=512 count=9000
# vnconfig -c /dev/vnd0d /ramdisk
# disklabel -r -w /dev/vnd0d rdroot
# newfs -m 0 -S 512 -i 4096 /dev/vnd0a
# mount /dev/vnd0a /mnt
# mkdir /mnt/{dev,bin,sbin,etc}
# cp /dev/MAKEDEV /mnt/dev
# cp /bin/{sh,ls} /mnt/bin
# cp /sbin/init /mnt/sbin
# cd /mnt/dev/ && ./MAKEDEV ramdisk
# echo 'echo "This is my minibsd all in kernel" && /bin/sh' > /mnt/etc/rc
# sync && umount /mnt
# sync && vnconfig -u vnd0d && sync
3、將ramdisk寫入kernel
# mdsetroot /minibsd ramdisk
4、壓縮kernel大小
# gzip -9 -c /minibsd > /minibsd.gz
5、制作目標軟盤
因為系統需要使用/boot（/usr/mdec/boot）來加載kernel，所以我們需要在軟盤上放置boot文件。
# disklabel -B -w -r /dev/fd0a fd1440 # newfs -m 0 -S 512 /dev/fd0a # mount /dev/fd0a /mnt # cp /usr/mdec/boot /mnt # cp /minibsd.gz /mnt/netbsd
現在你的ramdisk in kernel的mininetbsd系統就已經做好了。
