製作RAMDISK in KERNEL的NetBSD微系統(轉)[@more@]

　　Matthew(黑夜編碼人)

　　前言

　　在前面我們已經講過如何製作軟盤上執行的FreeBSD和OpenBSD系統，現在我們來看看如何製作一個執行在軟盤上的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製檔案及程式全部存放到NetBSD的核心中，這樣整個系統看起來就是一個檔案。下面讓我們具體來看看如何完成這樣一個微系統的製作。

　　0、NetBSD的啟動過程

　　當硬碟MBR中的載入程式接過啟動之後，MBR中的程式將讀入硬碟NetBSD分割槽中的載入程式，載入程式預設情況下會載入/boot，然後由boot載入核心/netbsd，此時核心開始檢測一些硬體和做一些初始化。初始化完成後kernel將mount root device，然後啟動系統初始化程式/sbin/init，init將根據/etc/rc中的設定來進行初始化等。

　　1、定製RAMDISK核心

　　要使用RAMDISK in KERNEL就必須在核心配製檔案中加入以下選項：

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)

　　以上的核心引數意義如下：

　　MEMORY_DISK_ROOT_SIZE : 記憶體磁碟大小，以塊為單位

MEMORY_RBFLAGS=0x00 : 啟動到多使用者模式

　　以下是在我機器上使用的一個核心配製檔案

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 blocksoptions MEMORY_RBFLAGS=0x00 # boot in to multi-user mode
　　maxusers 48 # estimated number of users
　　# CPU support. At least one is REQUIRED.
options I386_CPUoptions 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 systemfile-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 herepuc* 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 Ethernetrtk* at pci? dev ? function ? # Realtek 8129/8139
　　amhphy* at mii? phy ? # AMD 79c901 Ethernet PHYs
urlphy* at mii? phy ? # Realtek RTL8150L internal PHYsukphy* 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 Protocolpseudo-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、製作ramdisk映象

# 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、製作目標軟盤

　　因為系統需要使用/boot（/usr/mdec/boot）來載入kernel，所以我們需要在軟盤上放置boot檔案。

製作RAMDISK in KERNEL的NetBSD微系統(轉)

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