2Apr il 2003, 17:00:47 The Complete FreeBSD (starting.mm), page 523 29 Star ting and stopping the system In this chapter: • Star ting the system • Things you can do before booting • What are you going to boot? • Running the ker nel • Single-user mode • Shutting down and rebooting the system • FreeBSD without disks • Networ k booting • Disk substitutes In this chapter: • Star ting the system • Things you can do before booting • What are you going to boot? • Running the ker nel • Single-user mode • Shutting down and rebooting the system • FreeBSD without disks • Networ k booting • Disk substitutes Before you can run FreeBSD, you need to start it up. That’snormally pretty straightforward: you turn the machine on, a lot of things scroll offthe screen, and about a minute later you have a login: prompt or an X login windowonthe screen. Sometimes, though, the process is of more interest. Youhav e anumber of options when booting, and it’salso a source of a number of problems, so it pays to understand it. In this chapter we’ll look at the following topics: • In the next section, we’ll look at the startup process in more detail. • On page 525 we’ll look at howtocontrol the boot process. • If something goes wrong, and the system doesn’tcome up, those messages that scrolled offthe screen are very important. We’lllook at what theymean on page 525. • It’snot so obvious that you need to adhere to a procedure when shutting down the system. We’ll look at the hows and whys on page 537. • There are a number of ways of starting the system for particular applications. On page 538 we’ll look at howtorun FreeBSD without a disk. starting.mm,v v4.19 (2003/04/02 04:32:28) 523 The Complete FreeBSD 524 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 524 Star ting the system When you power up the system, or when you reboot, a number of actions occur before the system is up and running. Starting the system is usually called ‘‘bootstrapping,’’ after the story of Baron von Munchhausen pulling himself up by his own bootstraps. The following sequence describes the sequence on the PC architecture, but there are only relatively minor differences on other platforms. • First, the BIOS 1 performs tests that check that the machine is working correctly and determines the hardware configuration. This Power On Self Test or POST has nothing to do with FreeBSD. • Next, the BIOS bootstrap loads the Master Boot Record from the first sector of the first disk on the system (C: in BIOS parlance) into memory and executes it. This step is the same for all operating systems on PCs. • It’suptothis bootstrap to decide which operating system to boot. The bootstrap in the MBR may or may not be part of the FreeBSD system. FreeBSD can install two different MBRs, as we sawonpage 66. The standard MBR works without intervention, while the boot manager givesyou the choice of booting from any partition on the disk. • The FreeBSD bootstrap first loads the second-levelbootstrap, BTX,from the next 15 sectors on disk and executes it. • The second-levelboot locates the third-levelbootstrap, called loader,and loads it into memory. loader is an intelligent bootstrap component that allows preloading of multiple kernel components. See the man page loader(8) for more information. By default, loader locates the kernel, the file /boot/kernel/kernel on the root file system, and loads it into memory.You can interrupt the loader at this point, for example to load different or additional files. • The kernel performs its own tests to look for hardware it knows about. It’squite verbose about this, and prints messages about both the hardware it finds and the hardware it doesn’tfind. This operation is called probing.Most kernels are built to recognize a large selection of hardware, so it’snormal to have more ‘‘not found’’ messages than ‘‘found’’messages. • After the probe, the kernel starts twoprocesses. The first, process 0, is the swapper and is responsible for emergencyclearing of memory when the standard virtual memory algorithms aren’tfast enough. • Process 1 is called init.Asthe name suggests, it is responsible for starting up the system and daemons. When coming up in the default multi-user mode, it spawns a shell to execute the shell script /etc/rc. 1. More accurately,the system firmware. The firmware is called BIOS (Basic Input/Output System)onthe i386 architecture, SRM on the Alpha architecture, and Open Firmware on a number of other architectures. starting.mm,v v4.19 (2003/04/02 04:32:28) 525 Chapter 29: Starting and stopping the system 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 525 • /etc/rc first reads in the description files /etc/defaults/rc.conf,which contains defaults for a number of configuration variables, and /etc/rc.conf,which contains your modifications to the defaults. It then proceeds to perform the steps necessary to bring up the system, first starting virtual disk drivers, mounting swap space and checking the file system integrity if necessary. • When /etc/rc exits, init reads the file /etc/ttys and starts processes as determined there. It spends the rest of its life looking after these processes. Things you can do before booting Youcan do a number of things before you boot the system: • The most obvious thing to do is to decide what you’re going to boot. The boot loader givesyou the chance to load different operating systems or different FreeBSD kernels and modules. We’lllook at that below. • In addition, you can set a number of options for the kernel loader,including specification of hardware and software characteristics. We’lllook at that on page 527. What are you going to boot? If you have multiple operating systems on your system, you can use the boot manager described on page 64, to choose which one to boot. Forexample, if you have two disks, the first of which contains four partitions, the first stage of the boot looks something like this: F1: FreeBSD F2: Windows F3: Linux F4: FreeBSD F5: Drive 1 Default: F1 After 10 seconds, the boot manager attempts to load the bootstrap from the default partition; you can choose anyofthe selections by pressing the corresponding function key. Ifyou press F5,you get a menu showing the partitions on the second disk, with F5 to return to the first disk. If you choose to boot FreeBSD, the bootstrap loaders load, and you see something like: / this is a ‘‘twirling baton’’ BTX loader 1.00 BTX version is 1.01 BIOS drive A: is disk0 BIOS drive C: is disk1 BIOS drive D: is disk1 starting.mm,v v4.19 (2003/04/02 04:32:28) What are you going to boot? 526 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 526 BIOS 639kB/130048kB available memory These messages are printed by BTX.Ifyou’re loading from disk, the / character at the end of the previous line keeps changing through -, \,and | before going back to / again, giving the impression that the character is rotating. This display,called a twirling baton, is your indication that the system hasn’tcrashed and burned. It’snormal for it to takea fewseconds before the baton starts to twirl. Next, loader prints its prompt: FreeBSD/i386 bootstrap loader, Revision 0.8 (grog@freebie.example.com, Thu Jun 13 13:06:03 CST 2002) Loading /boot/defaults/loader.conf Hit [Enter] to boot immediately, or any other key for command prompt. Booting [kernel] in 6 seconds . this counts down from 10 seconds At this point, you would normally continue with the boot, either by pressing the Enter keyorjust waiting the 10 seconds. We’llsee what happens then on page 529. Sometimes you may want to change software or hardware characteristics. In this case, you press the ‘‘anyother key’’ (by tradition the space bar) and enter commands to the loader. Loader commands There are twoways to communicate with the loader: • Anumber of files in the directory /boot on the root file system tell the loader what to do. Most are not intended to be changed, but you can create a file called /boot/loader.conf,into which you can enter commands to override the commands in /boot/defaults/loader.conf.We’ll look at this below. • In addition, the file /boot/device.hints takes the place of manyconfiguration file entries and allows you to set hardware characteristics such as information about IRQ, DMA, I/O address and other settings for the hardware. You can change these values during booting. The CD-ROM installation installs /boot/device.hints,but a kernel install does not. You’ll find it in the conf directory for your architecture. Forexample, /usr/src/sys/i386/conf includes the configuration file GENERIC and the correspond- ing hints file GENERIC.hints.Install it likethis: # cp /usr/src/sys/i386/conf/GENERIC.hints /boot/device.hints The hints file contains entries of the following nature: hint.sio.0.at="isa" hint.sio.0.port="0x3F8" hint.sio.0.flags="0x10" hint.sio.0.irq="4" hint.sio.1.at="isa" hint.sio.1.port="0x2F8" starting.mm,v v4.19 (2003/04/02 04:32:28) 527 Chapter 29: Starting and stopping the system 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 527 hint.sio.1.irq="3" hint.sio.2.at="isa" hint.sio.2.disabled="1" hint.sio.2.port="0x3E8" hint.sio.2.irq="5" hint.sio.3.at="isa" hint.sio.3.disabled="1" hint.sio.3.port="0x2E8" hint.sio.3.irq="9" These entries describe the serial port configuration. Theyreplace the older method of hard coding the information in the kernel. For example, the hints above contain the configuration information contained in these lines of the Release 4 configuration file: device sio0 at isa? port IO_COM1 flags 0x10 irq 4 device sio1 at isa? port IO_COM2 irq 3 device sio2 at isa? disable port IO_COM3 irq 5 device sio3 at isa? disable port IO_COM4 irq 9 The corresponding line in the Release 5 configuration file is: device sio #8250, 16[45]50 based serial ports More importantly,though, this means that you don’tneed to recompile the kernel if you change the hardware addresses. • Youcan enter commands directly to the command prompt. When you hit the space bar,you get the following prompt: Type ’?’ for a list of commands, ’help’ for more detailed help. ok ? Available commands: reboot reboot the system heap show heap usage bcachestat get disk block cache stats boot boot afile or loaded kernel autoboot boot automatically after a delay help detailed help ?list commands show show variable(s) set set avariable unset unset avariable more show contents of a file lsdev list all devices include read commands from a file ls list files load load akernel or module unload unload all modules lsmod list loaded modules pnpscan scan for PnP devices The most important of these commands are set, show, load, unload and boot.We’ll see some examples of their use in the following sections. Note, however, that if you have accidentally hit the ‘‘any’’key during boot and just want to continue with the boot, you just have toenter boot. starting.mm,v v4.19 (2003/04/02 04:32:28) What are you going to boot? 528 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 528 loader.conf Much of the behaviour of the loader is controlled by entries in /boot/defaults/loader.conf. Youshouldn’tchange this file, though: put changes in a file /boot/loader.conf,which may not exist. There are a large number of possible entries; in /boot/defaults/loader.conf you’ll see the default values, frequently commented out because the loader already knows the defaults. Here are some of the more interesting ones: kernel="kernel" verbose_loading="NO" # Set to YES for verbose loader output #autoboot_delay="10" # Delay in seconds before autobooting #console="vidconsole" # Set the current console #currdev="disk1s1a" # Set the current device module_path="/boot/kernel;/boot/modules;/modules" # Set the module search path #prompt="\${interpret}" # Set the command prompt #root_disk_unit="0" # Force the root disk unit number #rootdev="disk1s1a" # Set the root filesystem • The kernel entry givesthe name of the kernel, relative tothe kernel directory /boot/kernel.Sometimes it might be of interest to change this value, for example when testing. • console=vidconsole tells the loader where to output its messages. vidconsole is short for video console;you can also select comconsole if you have a serial terminal connected to a specified serial port. • currdev specifies where to look for the root file system. If you have multiple BIOS partitions on a disk, you can select the correct one with this value. There are manymore options to the loader; read the man page for more details. Loading other modules at boot time By default, loader loads only the kernel. That may not be what you want. You might want to load a different kernel, or you may want to load a kld as well. There are twoways to do this. If you only want to do this once, you can interrupt the boot sequence by pressing the space bar,and tell loader what to do: Booting [kernel] in 6 seconds . this counts down from 10 seconds (space bar hit) Type ’?’ for a list of commands, ’help’ for more detailed help. ok unload not the kernel we wanted OK load /boot/kernel.old/kernel load the old kernel /boot/kernel.old/kernel text=0x3e474c data=0x52f00+0x81904 syms=[0x4+0x4cab0+0x4+0x5 b458] OK load /boot/kernel.old/vinum.ko and the old vinum module /boot/kernel.old/vinum.ko text=0x149a4 data=0xaf75c+0x164 syms=[0x4+0x11e0+0x4+0xcac] ok boot then start the kernel Copyright (c) 1992-2002 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-RELEASE #0: Sat 15 Feb 16:30:26 CST 2003 grog@monorchid.example.org:/usr/src/sys/i386/compile/BUMBLE Preloaded elf kernel "/boot/kernel.old/kernel" at 0xc072a000. starting.mm,v v4.19 (2003/04/02 04:32:28) 529 Chapter 29: Starting and stopping the system 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 529 Preloaded elf module "/boot/kernel.old/vinum.ko" at 0xc072a0bc. Timecounter "i8254" frequency 1193182 Hz (etc) This example shows twoseparate activities: one is changing the kernel from /boot/ker- nel/kernel to /boot/kernel.old/kernel,and the other is loading the vinum kld. You don’t need to reload the kernel to load the vinum module. Automatic kld load The method described above iscumbersome if you want to load the kld every time you boot. In this case, it’seasier to add the following line to /boot/loader.conf : vinum_load="YES" To see what commands you can use, look in /boot/defaults/loader.conf,where you would find all normal configuration entries commented out. . ccd_load="NO" # Concatenated disk driver vinum_load="NO" # Concatenated/mirror/raid driver md_load="NO" # Memory disk driver (vnode/swap/malloc) . Don’tchange this file; it’sdesigned to be replaced on upgrade, and anychanges would get lost when you upgrade. Running the kernel The next step in the boot process is to run the kernel. This is what happens by default if you do nothing at the Booting [kernel] prompt, or if you press Enter.Ifyou have interrupted the boot process, you continue with the command: ok boot The following example shows the output of booting an Abit BP6 dual processor motherboard. This board also has four IDE controllers on board, and the system had two SCSI host adapters connected to it. The loader transfers control to the kernel it has preloaded. Messages from the kernel are in high-intensity text (brighter than normal). This is the most common time to see them, though theysometimes appear during normal machine operation. These messages also get copied to the kernel message buffer,and you can retrieve the most recent messages with the dmesg program. In the course of time, other messages may fill the buffer,and you will no longer be able to find the boot messages with dmesg,soone of the final steps in the startup savesthe content of the boot messages in the file /var/run/dmesg.boot, which should always contain the complete startup messages. In the case of laptops, the message buffer normally does not get cleared on shutdown, not evenifthe power goes down, so you may find logs for multiple boots. starting.mm,v v4.19 (2003/04/02 04:32:28) Running the ker nel 530 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 530 Once it has finished loading, the kernel prints some summary information and then calls all configured drivers to examine the hardware configuration of the machine on which it is running. This is called probing for the devices. If you have time to followit, it’sa good idea to confirm that it’scorrect. Much of it appears so quickly that you can’tfollow it, but that’snot a problem. Once the boot is complete, you can examine it with the dmesg command. If something goes wrong, it won’t scroll offthe screen. The place where it stops is then of interest. Under normal circumstances, we see something like: Copyright (c) 1992-2002 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-RELEASE #0: Sat 15 Feb 16:30:26 CST 2003 grog@monorchid.example.org:/usr/src/sys/i386/compile/BUMBLE Preloaded elf kernel "/boot/kernel/kernel" at 0xc0663000. Here the kernel identifies itself with information about the release number,when and where it was built, and where it was loaded from. Timecounter "i8254" frequency 1193182 Hz CPU: Pentium II/Pentium II Xeon/Celeron (467.73-MHz 686-class CPU) Origin = "GenuineIntel" Id = 0x665 Stepping = 5 Features=0x183fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,P AT,PSE36,MMX,FXSR> real memory =134217728 (128 MB) avail memory = 123465728 (117 MB) The lines above identify the basic hardware. There is one time counter (some motherboards have two), the CPU is a Celeron, Pentium II or Xeon, and it runs at 466 MHz. This information is relatively reliable. The real memory value is the size of RAM. Some older systems reserve1kBofRAM in real mode, but this should not have any effect on the value of real memory.Available memory is the memory available to users after the kernel has been loaded and initialized. On some older machines, the kernel reports only 16 MB although the system has more memory.This is due to BIOS incompatibilities, and occurs surprisingly often on big- name machines. To fixit, build a custom kernel that specifies the memory size explicitly—see the description of the MAXMEM parameter,which is described in the verbose configuration file /usr/src/sys/i386/conf/NOTES. This machine is in fact a multiprocessor with twoCPUs, so we see: Programming 24 pins in IOAPIC #0 IOAPIC #0 intpin 2 -> irq 0 IOAPIC #0 intpin 16 -> irq 10 IOAPIC #0 intpin 17 -> irq 9 IOAPIC #0 intpin 18 -> irq 11 FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs 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 The IOAPIC is the I/O Advanced Programmable Interrupt Controller used by SMP machines only.Itreassigns some interrupt requests. This information is provided in case starting.mm,v v4.19 (2003/04/02 04:32:28) 531 Chapter 29: Starting and stopping the system 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 531 you need to debug the kernel. None of this appears for a normal machine. Initializing GEOMetry subsystem Pentium Pro MTRR support enabled npx0: <math processor> on motherboard numeric coprocessor,onchip npx0: INT 16 interface Using $PIR table, 7 entries at 0xc00fdda0 The GEOMetry subsystem is a disk I/O system that was introduced in FreeBSD Release 5. This processor is a P6 class processor,soithas Memory Type RangeRegisters or MTRRs, which are used to optimize memory usage. Next we look at the other chips on the motherboard, starting with the so-called ‘‘chipset,’’ the processor support chips. pcib0: <Intel 82443BX (440 BX) host to PCI bridge> at pcibus 0 on motherboard pci0: <PCI bus> on pcib0 agp0: <Intel 82443BX (440 BX) host to PCI bridge> mem 0xe0000000-0xe3ffffff at devic e0.0 on pci0 pcib1: <PCIBIOS PCI-PCI bridge> at device 1.0 on pci0 pci1: <PCI bus> on pcib1 This motherboard has an Intel 82443 BX chipset with twoPCI buses. Next we see some of the devices on the motherboard: pci1: <Matrox MGA G200 AGP graphics accelerator> at 0.0 isab0: <Intel 82371AB PCI to ISA bridge> at device 7.0 on pci0 isa0: <ISA bus> on isab0 ISA bus atapci0: <Intel PIIX4 ATA33 controller> port 0xf000-0xf00f at device 7.1 on pci0 ata0: at 0x1f0 irq 14 on atapci0 primary IDE controller ata1: at 0x170 irq 15 on atapci0 secondary IDE controller uhci0: <Intel 82371AB/EB (PIIX4) USB controller> port 0xc000-0xc01f irq 10 at device 7.2 on pci0 USB controller usb0: <Intel 82371AB/EB (PIIX4) USB controller> on uhci0 USB bus 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: <bridge, PCI-unknown> at device 7.3 (no driver attached) The system doesn’tknowwhich devices are implemented internally in the chipset, which are separate chips on the mother board, and which are on plug-in boards. So far it has found the IDE controllers, but not the disks; it’ll look for them later. Next we find twoSymbios SCSI host adapters: sym0: <875> port 0xc400-0xc4ff mem 0xec002000-0xec002fff,0xec003000-0xec0030ff irq 1 0atdevice 9.0 on pci0 sym0: Symbios NVRAM, ID 7, Fast-20, SE, NO parity sym0: open drain IRQ line driver, using on-chip SRAM sym0: using LOAD/STORE-based firmware. sym0: SCAN FOR LUNS disabled for targets 0. sym1: <875> port 0xc800-0xc8ff mem 0xec001000-0xec001fff,0xec000000-0xec0000ff irq 9 at device 13.0 on pci0 sym1: No NVRAM, ID 7, Fast-20, SE, parity checking The first Symbios adapter is on IRQ 10. It is on ID 7, likemost SCSI host adapters, and it doesn’tsupport parity.The second board is on IRQ 9 and does support parity,but it starting.mm,v v4.19 (2003/04/02 04:32:28) Running the ker nel 532 2April 2003, 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 532 doesn’thav e aBIOS. This is not a problem for FreeBSD, which doesn’tuse the BIOS, butifitwere in the system by itself, the POST would not find it. In this particular case, the BIOS on the other Symbios board does in fact find the second host adapter. dc0: <Macronix 98715AEC-C 10/100BaseTX> port 0xe000-0xe0ff mem 0xe7800000-0xe78000ff irq 11 at device 11.0 on pci0 dc0: Ethernet address: 00:80:c6:f9:a6:c8 miibus0: <MII bus> on dc0 dcphy0: <Intel 21143 NWAY media interface> on miibus0 dcphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto This is a Macronix Ethernet card with associated PHY interface at IRQ 11. After that, we return to on-board peripherals, in this case twoadditional IDE controllers and legacy ISA peripherals: atapci1: <HighPoint HPT366 ATA66 controller> port 0xd800-0xd8ff,0xd400-0xd403,0xd000 -0xd007 irq 11 at device 19.0 on pci0 ata2: at 0xd000 on atapci1 ThirdIDE controller atapci2: <HighPoint HPT366 ATA66 controller> port 0xe400-0xe4ff,0xe000-0xe003,0xdc00 -0xdc07 irq 11 at device 19.1 on pci0 Fourth IDE controller ata3: at 0xdc00 on atapci2 orm0: <Option ROMs> at iomem 0xc0000-0xc7fff,0xc8000-0xc87ff on isa0 fdc0: ready for input in output Floppy controller fdc0: cmd 3 failed at out byte 1 of 3 The floppydrivercommand failure here is caused by the lack of anyfloppydrive onthis machine. atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0 atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0 keyboard kbd0 at atkbd0 vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0 sc0: <System console> at flags 0x100 on isa0 system console sc0: VGA <16 virtual consoles, flags=0x300> sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0 first serial port sio0: type 16550A it’sabuffered UART sio1 at port 0x2f8-0x2ff irq 3 on isa0 second serial port sio1: type 16550A sio2 not found at 0x3e8 no moreserial I/O ports sio3 not found at 0x2e8 UNIX starts counting device numbers from 0, whereas Microsoft starts counting from 1. Devices /dev/sio0 through /dev/sio3 are known as COM1: through COM4: in the Microsoft world. ppc0: <Parallel port> at port 0x378-0x37f irq 7 on isa0 parallel port controller ppc0: Generic chipset (NIBBLE-only) in COMPATIBLE mode plip0: <PLIP network interface> on ppbus0 lpt0: <Printer> on ppbus0 line printer on parallel port lpt0: Interrupt-driven port ppi0: <Parallel I/O> on ppbus0 alternate I/O on the same port Next, on this multiprocessor board, we get some SMP-specific messages. The system tests the IO-APIC, which can sometimes cause problems, and then starts the second processor: starting.mm,v v4.19 (2003/04/02 04:32:28) [...]... to specify the root path as an IP address, because no name services are available when the root file system is mounted Other Ethernet bootstraps If your Ethernet card doesn’t have a boot ROM, you can make one with the net/etherboot port, or you can copy the necessary information to a floppy disk or CD-R and use that to start the bootstrap In either case, you first build the port and then copy the data to... firewall rules block TFTP In the following sections we’ll look at the example of setting up bumble.example.org as a diskless machine Setting up the file systems There are a number of ways to put the files on the NFS server: • You might copy the files in the root and /usr file systems of the server machine • You could install FreeBSD on a separate disk and NFS mount it where the remote system can access it By... Clearly, the first thing you need to do is to create this file system Next, you need to find a way to boot the system There are a few possibilities here: • You can boot a minimal system from floppy disk or CD-ROM and use this to mount the file systems remotely This is different from running the system from floppy or CD-ROM: in this case, the disk device serves effectively as a bootstrap, and the operating system. .. machine by just turning off the power The results could be devastating The correct way to shut a system down is with the shutdown command To quote the man page shutdown(8): Shutdown provides an automated shutdown procedure for super-users to nicely notify users when the system is shutting down, saving them from system administrators, hackers, and gurus, who would otherwise not bother with such niceties... root file system is accessible, and it is mounted read-only The reason for this is that the file system may be damaged and require repair before you can write to it If you do need to write to the root file system, you should first check the consistency of the file system with fsck, after which you can mount it with the -u (update) option For example, npx0 on motherboard npx0: INT 16 interface end of the probes... all systems • When building system software, you can use the same /usr/src and /usr/obj directories as long as all systems maintain the same release of FreeBSD You can even have different kernels: each kernel build directory carries the name of the of the configuration file, which by convention matches the name of the system The big problem is /etc In particular, /etc/rc.conf contains information like the. .. on the system, daemons may be doing things in the background To avoid this problem, you can stop the boot process before most of the daemons have been started and enter single-user mode To do this, set the boot_single variable, or specify the -s flag at boot time: ok boot -s As soon as the device probes have been completed, the system startup is interrupted, and you are prompted for a shell Only the. .. 255H 63S/T 522C) device Queueing Enabled device Queueing Enabled Here, we have four disks, one each on the first and third IDE controllers, both as master, and two on the second SCSI host adapter There is nothing on the first host adapter Finally, the system starts Vinum and mounts the root file system and the swap partition: Mounting root from ufs:/dev/ad0s1a vinum: loaded vinum: reading configuration from... 17:00:47 The Complete FreeBSD ( /tools/tmac.Mn), page 537 537 Chapter 29: Starting and stopping the system Table 29-1: init levels Level 0 1 6 c q Signal SIGUSR2 SIGTERM SIGINT SIGTSTP SIGHUP Action Halt and turn the power off Go to single-user mode Reboot the machine Block further logins Rescan the ttys(5) file You can also enter single-user mode from a running FreeBSD system with the shutdown command,... [0.0.0.0].1063 Ready to answer queries With the exception of the first line, all the messages come from named They may come in the middle of the first line, rather than waiting for the end of the line Next, /etc/rc enables quotas if asked, and then runs the third network pass, which starts our choice of mountd, nfsd, rpc.lockd, rpc.statd, nfsiod, amd, rwhod and kerberos: Starting final network daemons: . Setting up the file systems There are a number of ways to put the files on the NFS server: • Youmight copythe files in the root and /usr file systems of the server. With the exception of the first line, all the messages come from named.Theymay come in the middle of the first line, rather than waiting for the end of the