BOOT(8) System Manager's Manual BOOT(8)
boot - from power on to the login prompt
At power on the machine reads the first sector of the boot device into memory and executes it. This bootstrap code loads /boot, the Minix
Boot Monitor. The monitor loads the kernel binaries from /minix, or the newest file in /minix if it is a directory.
The Minix system is now running, the different tasks initialize themselves and control is transferred to the last one, init.
Init is the grandparent of all Minix processes, it is responsible for starting login processes on each terminal, but first it runs /etc/rc.
/etc/rc checks the state of the system and starts daemons. First it sets the keyboard translation to the mapping in /etc/keymap if
present, then it reads the time zone from /etc/timeinfo followed by a call to readclock(8) to set Minix time from the hardware clock. Next
the file systems are checked if necessary and the /usr file system is mounted.
The system is now ready for multiuser startup, /etc/rc starts the update(8) and cron(8) daemons, and initializes the network services.
/etc/rc finally recovers crashed editor buffers and cleans out the tmp directories.
Init reads /etc/ttytab and starts a getty(8) for each enabled terminal line to allow a user to log in.
Many features of the drivers inside the kernel are controlled by settings in the boot environment. The values of these variables are usu-
ally colon or comma separated numbers configuring the driver. DPETH0 = 300:10 tells the ethernet driver to use I/O address 0x300, inter-
rupt request 10, and the default memory address (0xD0000, values may be omitted) for the first ethernet board. (Note that IRQ 2 is redi-
rected to IRQ 9 on AT's and PS/2's, so use 9 if a device is jumpered for 2.)
Variables that are special to both the monitor and the kernel are described in monitor(8). This section lists extra variables or variable
hd = at | bios | esdi | xt
Choose the driver that is to be used for the hard disk, in order: IBM/AT (classic AT or newer IDE), BIOS (generic driver), ESDI
(some PS/2's), or IBM/XT. By default the first of these drivers that is enabled is used. Most drivers are present in the kernel as
distributed, but may be taken out by modifying /usr/include/minix/config.h. (An XT should always use the BIOS driver, not the XT
driver, because BIOS calls are cheap on an XT. The XT driver can be used on AT machines with an old XT controller.)
DPETHn = on | off
Turn an ethernet board on or off. The driver is by default in "sink" mode for all boards. The sink mode allows one to use the
driver without an ethernet board installed. The driver will play /dev/null for that device, i.e. nothing comes in, and anything
send out is dropped on the floor. If the board is turned on then the driver will use it to send out packets, if it is turned off
then the driver will fail for that board.
DPETHn = I/O-addr:irq:mem_addr
Set the I/O address (hex), IRQ (decimal) and memory address (hex) of the n-th ethernet board and turn it on. By default they are
configured as 280:3:D0000 and 300:5:CC000. The memory address is ignored for the Novell ethernet boards, but may be explicitly set
to zero to indicate that the board is a Novell ethernet board. You do not need to specify the IRQ with modern Western Digital 8013
compatible ethernet cards, the driver asks the board what its IRQ is. (Note that the default IRQ conflicts with the second serial
line, so the serial line is turned off if the ethernet board is configured for IRQ 3.)
DPETHn_EA = e0:e1:e2:e3:e4:e5
Set the ethernet address of the n-th ethernet board. The address is normally obtained from the ethernet board, so only in excep-
tional circumstances is this setting ever needed. (Use the address of the main server if you want a career change.)
AHA0 = I/O-addr:bus-on:bus-off:tr-speed
Configure the Adaptec 154xA SCSI host adapter to use the given I/O address (hex), Bus-on time (decimal), Bus-off time (decimal) and
transfer speed (hex). The default is 330:15:1:00. The default transfer speed is always 5.0 Mb/s (code 00) ignoring the jumper set-
sdn = target,lun
Program SCSI disk sdn to have the given target and logical unit number. The target and lun of a tape or other SCSI device may be
changed by setting the sdn variable that would be used had it been a disk. So tape device st7 can be set to target 4, lun 1 with
MCD = I/O-addr:irq
I/O address (hex) and IRQ (decimal) of the Mitsumi CD-ROM driver, by default 300:10.
To use TCP/IP you have to compile a kernel with networking enabled, and unless you are running standalone you have to enable the ethernet
driver. See the DPETHn boot variable above. The driver supports these ethernet cards: Western Digital 8003, Western Digital 8013, SMC
Elite Ultra 16, Novell NE1000, Novell NE2000. Many newer variants of the WD8013, now under the SMC brand, are also supported.
You are likely to use TCP/IP in one of three situations:
Standalone with no connection to a network.
In a small network with no support from a "big" host.
Connected to a large network with address and name servers.
In each situation you need a different set of configuration files.
The machine is configured with a fixed IP address: 22.214.171.124. This is one of the addresses Sun used to give to machines without a regis-
tered network address. This address is normally blocked at gateways, so it can do no damage if used in a real net by accident. You need
one file, /etc/hosts, that should look like this (using the name "darask" as an example):
In a network where the Minix machine can't obtain its IP address and name from a different host you need specify the ethernet address to
host name translation in the /etc/ethers file for use by the RARP daemon. Suppose you have two machines in your network then /etc/ethers
could look like this:
Use hostaddr -e to find out what the six octet ethernet address of a host is. Use the address as printed: lowercase hex digits, no leading
zeros. The /etc/hosts file shows their IP addresses:
Warning! Do not add ethernet addresses of diskless workstations to your ethers file. A Sun for instance has the stupid habit of booting
from the first RARP server that answers, probably your Minix machine...
In a network with a central network administration your machine's IP address and name are given by the RARP and name services of the spe-
cial servers on the network. For a new machine you need to apply for an IP address and host name with your network administrator supplying
the ethernet address of your machine. You don't need any configuration files now, the irdpd and nonamed daemons automatically find a
router and a name server.
Note that no knowledge of the IP address or hostname of the Minix machine itself is necessary, it all comes from the RARP and name servers.
A series of Minix machines can therefore set up identically. Even if you have no RARP or name servers you can still set them up identi-
cally if you list all the Minix hosts in the hosts and ethers files.
Simpler configuration tools
The rarpd, irdpd and nonamed daemons are complex little programs that try to obtain information about their surroundings automatically to
tell the machine what its place in the network is. It should come as no surprise that there are simpler utilities to configure a machine.
On a memory starved machine it may even be wise to configure a machine statically to get rid of the daemons. The first daemon, rarpd, can
be replaced by:
ifconfig -h host-IP-address
to set the IP address of the machine. Note that this is only necessary if there is no external RARP service. The second daemon irdpd can
be replaced by setting a static route:
add_route -g router-IP-address
(if there is a router.) The last daemon, nonamed, can be replaced by an entry in /etc/resolv.conf that specifies an external name daemon:
The ifconfig and add_route calls can be placed in the file /etc/rc.net. The calls to the daemons will have to be edited out of /etc/rc.
Note that these changes undo all the efforts to make Minix TCP/IP autoconfigurable. Make very sure that all the IP addresses are correct,
and that the IP address of your machine is unique. (Mistakenly using the address of a main server will make all other machines look at
your machine, and will make all the users of all other machines look at you.)
/boot Minix Boot Monitor.
/minix Kernel image, or directory containing them.
/etc/rc First of the system initialization files.
/etc/hosts Name to IP address mapping.
/etc/ethers Name to ethernet address mapping.
monitor(8), init(8), inet(8), loadkeys(8), readclock(8), fsck(1), update(8), cron(8), ttytab(5), getty(8), hostaddr(1), ifconfig(8),
irdpd(8), nonamed(8), rarpd(8), hosts(5), ethers(5), set_net_default(8).
Checking File Systems.
If the system has crashed then fsck is called for the root and /usr file systems. It is wise to reboot if the root file system must
Finish the name of device to mount as /usr: /dev/
If the name of the /usr file system has not been set in /etc/fstab. You can type a device name, say fd0.
hostaddr: unable to fetch IP address
TCP/IP misconfiguration. The RARP may have failed because the ethernet address of the machine is not entered in either the remote or
the local ethers file. Either talk to your Network Administrator, or make an ethers and a hosts file.
If you see an IP address instead of a host name then the system failed to translate the IP address. Either talk to your Network
Administrator to have the reverse address translation tables fixed, or make a hosts file.
The names "darask" and "burask" are names of cities from the Dutch translation of the novel "The Many-Colored Land" by Julian May. The
author of this text likes names of hosts to be things that contain people, like cities and ships.
Indefinite hangs are possible if I/O addresses or IRQ's are wrong. A driver may babble about addresses and IRQ's, but that does not mean
that what it says is true, it may just be configured that way. It is very difficult to find peripherals on a PC automatically, and Minix
doesn't even try.
Kees J. Bot (email@example.com)