minix/man/man8/monitor.8

.TH MONITOR 8
.SH NAME
monitor, edparams \- load and start Minix, modify boot parameters
.SH SYNOPSIS
.B /boot
.br
.B edparams
.I device
.RI [ command " ...]"
.br
.B boot.com
.I virdisk
.RI [ command " ...]"
.SH DESCRIPTION
.de SP
.if t .sp 0.4
.if n .sp
..
This text describes the Boot Monitor, a boot time interactive program designed
not only to load and start Minix, its most important task, but to also
provide an interface to configure Minix and to boot other operating systems.
.PP
The monitor is controlled with an environment that is modeled after the
Bourne shell.  This environment is filled at startup with default values
that depend on the machine the monitor is running on and the environment
settings saved into the boot parameters sector (the second sector on a
device).  When the environment is loaded, the monitor executes the function
named
.BR main ,
which by default starts a simple menu.
.PP
The environment can be manipulated at boot time from the monitor prompt,
but may also be edited using
.B edparams
on a given device.
.B Edparams
simulates the monitor as much as it can, echoing commands it can't execute
between brackets.  It can also be used in Makefiles and scripts by giving
it commands as arguments.
.PP
The DOS version of the monitor, usually named
.B boot.com
under DOS, boots Minix from a "DOS virtual disk".
.B Boot.com
is a simple COM program that interprets a DOS
file as a disk, loads a Minix kernel from the active partition in the same
way as the BIOS based monitor, and executes it to start Minix.  All the
monitor commands function in the same way, except for the
.B boot
command, it can only load Minix.  The monitor grabs as much free memory as
it can for Minix to work in, as the
.B memory
variable shows.  Further details on how to run Minix under DOS, Windows 95,
or even Windows NT are written down in
.BR dosminix (8).
.SH COMMANDS
The monitor is best described by the commands you can type to the '>'
prompt.  This is known as the "monitor mode".  You can enter this mode by
hitting the Escape key.  These are the monitor commands:
.PP
\fIname\fP = [\fBdevice\fP] \fIvalue\fP
.SP
.RS
Set environment variable.
.br
Changes the value of
.I name
to
.IR value .
The optional word
.B device
marks
.I name
as being subject to device translation.  (See the section on devices.)  These
(name, value) pairs are passed to the kernel who uses them to configure
itself.  These variables are passed by default:
.SP
.B rootdev
.RS
This is the device used as your root device.  It is by default set to
.BR ram,
which means that the device specified by
.B ramimagedev
will be loaded into the RAM disk and used as root.  If you change this
variable then a physical device will be used as root, and the RAM disk will
be uninitialized and have the size specified by
.BR ramsize .
.RE
.SP
.B ramimagedev
.RS
Describes the device to use to initialize the RAM disk if
.B rootdev
is set to
.BR ram .
It's by default set to
.BR bootdev ,
a special name for the device the monitor booted from.
.RE
.SP
.B ramsize
.RS
The size of the RAM disk.  If the RAM disk is used for the root file system
then the root file system is stretched out to
.B ramsize
if possible.
.RE
.SP
.B processor
.RS
Set by default to
.BR 86 ,
.BR 186 ,
.BR 286 ,
.BR 386 ,
.BR 486 ", ..."
depending on the hardware you have.  You can set it to a smaller value to
test your kernel in a more limited environment.
.RE
.SP
.B bus
.RS
The type of system bus, either
.BR xt ,
.BR at
or
.BR mca .
This answers basic questions like: "How many interrupt controllers and how
to initialize?"  Or: "Does the keyboard have LEDs?"
.RE
.SP
.B memory
.RS
List of memory free for use by Minix.  It is a comma separated list of
.IR base:size
pairs denoting the byte offsets and sizes of free memory in hexadecimal.
.B "800:925E0,100000:F00000"
is a typical example of about 585K starting at 2K, and 15M starting at 1M.
(The first 2K are BIOS parameters and the 53K under the 640K boundary is
the monitor itself.)  The very last number you can play with if you know
what you are doing.  Either increase it if the monitor has it wrong, or
decrease it to test if Minix still runs with less memory then normal.
.RE
.SP
.B video
.RS
Describes capabilities of the VDU:
.BR mda ,
.BR cga ,
.B ega
or
.BR vga .
.RE
.SP
.B chrome
.RS
Either
.B color
or
.BR mono .
.RE
.SP
.B c0
.RS
By default
.B at
(AT compatibles),
.B bios
(XT or PS/2), or
.B dosfile
(running under DOS).
The
.B c0
variable binds a driver to the first controller, i.e. the
.B /dev/c0*
devices.  The monitor sets
.B c0
to a suitable default, so that most machines can find their disk.
.RE
.SP
.B console
.RS
If set to a hexadecimal value it makes the monitor set the BIOS video mode to
this value when Minix is started.
This allows the use of video modes with more rows or colums than the
standard 80x25 mode.  You can use any text mode in the 00-FF range, and VESA
extended modes in the 100-FFF range.  Most text modes use a 9x16 font with
400 scanlines on screen, so you see 400/16 = 25 lines.  The text mode can be
modified by adding special flags to the console setting.  Add
2000 to switch to 480 scan lines, adding 20% more lines to the screen.  Add
4000 to select a 9x14 font, so 28 or 34 lines are shown.  Add 8000 instead
to select an 8x8 font showing 50 or 60 lines.  Each setting has drawbacks.
Using 480 scanlines implies a 60 Hz refresh, so the screen may flicker.  The
8x8 font looks squashed.  More letters on screen require more memory, so there
is less for virtual consoles.  Interesting modes to try are 4003 (80x28),
2003 (80x30), 6003 (80x34), 8003 (80x50), A003 (80x60), 109 (132x25),
10A (132x43), 10B (132x50), 10C (132x60).  The 109 VESA mode is often
available, and can be modified like mode 3.  Use mode 7 instead of 3 for
monochrome.  Which modes and flags work can only be found out by experiment.
More parameters may follow the mode number that are of interest
to the console driver, see
.BR boot (8).
.RE
.SP
.B dosfile-d0
.RS
Set by the DOS version of the monitor to the name of the virtual disk, i.e.
the
.I virdisk
argument as shown above.  The "dosfile" driver
will use this as the name of the file to use as a disk.
.RE
.SP
Two variables are only used by the monitor, even though they are passed to the
kernel too:
.SP
.B image
.RS
The name of the file containing the kernel image, by default
.BR minix .
If it refers to a directory however then the newest file inside the
directory is chosen to be the kernel image.  The names inside
.B /minix/
are best set to the Minix version you are using, which looks good when the
monitor prints its name.  Rules for pretty printing image names:
.RS
.SP
A '/' or '_' is changed to a space.
.SP
The first letter is changed from lowercase to uppercase.
.SP
An 'r' if followed by a digit changes to " revision ".
.RE
.RE
.SP
.B label
.RS
If set then only processes marked with this label or without a label are
loaded from the image.
.RE
.SP
.B Installboot \-boot
will create functions to select images and labels.  These functions will set
.B label
and
.B image
and echo what you selected.  The two numbers separated by a colon used as an
image name tell the starting sector and sector count of the image on disk.
.RE
.SP
\fIname\fP() \fIcommand\fP
.RS
Define function.
.br
Functions may be used to bundle a set of commands, so that you can easily
boot Minix with a different set of parameters then normal.  E.g.
.SP
.RS
ram() { rootdev=ram; boot }
.RE
.SP
will allow you to run Minix with the root device on RAM for a change, if you
normally use a real device as root.  There are three predefined functions,
.BR leader ,
with default value an
.B echo
command that shows the monitor's startup banner,
.BR main ,
with default value
.BR menu ,
and
.BR trailer ,
with default value a command that clears the screen.
The monitor executes
.B leader;main
at startup to show the banner message and a menu.  The
.B trailer
function is executed just before Minix is started.  These three functions can
be redefined as you please.
.RE
.SP
\fIname\fP(\fIkey\fP) \fIcommand\fP
.RS
Define kernel selecting function.
.br
The menu command uses functions like these to add menu entries to select
a different kernel from a boot disk.
.B Installboot \-boot
produces these functions when the images are labeled.  The label
.B AT
would give:
.SP
.RS
AT(a) {label=AT;image=42:626;echo AT kernel selected;menu}
.RE
.SP
With the menu option:
.SP
.RS
a	Select AT kernel
.RE
.SP
Typing
.B a
will then execute the
.B AT
function above.
.RE
.SP
\fIname\fP(\fIkey\fP,\fItext\fP) \fIcommand\fP
.RS
User defined menu option.
.br
This variant may be used to make any menu entry you like:
.SP
.RS
dos(d,Boot MS-DOS) boot d0p0
.RE
.SP
.I Text
may be anything, even parentheses if they match.
.RE
.SP
.I name
.RS
Call function.
.br
If
.I name
is a user defined function then its value is expanded and executed in place of
.IR name .
Try a recursive one like 'rec() {rec;xx}' one day.  You can see the monitor
run out of space with nice messages about using
.BR chmem (1)
to increase it's heap.
.RE
.SP
\fBboot\fP [\fB\-\fP\fIopts\fP]
.br
\fBboot\fP \fIdevice\fP
.RS
Boot Minix or another O.S.
.br
Without an argument,
.B boot
will load and execute the Minix image named by the
.B image
variable.  With options the variable
.B bootopts
is first set to
.BI \- opts
before Minix is started, and unset when Minix returns.  With a
.I device
argument,
.B boot
loads the boot sector of
.I device
into memory and jumps to it, starting another operating system.  You would
normally use partitions on the first hard disk for this command (d0p[0\-3]),
using d0 will also work (choosing the active partition).  One can also boot
devices on the second hard disk (d1, d1p[0\-3]) if the bootstrap writer did
not hardwire the disk number to disk 0.
.br
Some Operating Systems can only be booted from the active partition, if
you use a '*', e.g.
.BR "boot *d0p2" ,
then partition 2 is first made active.  You'll then need to use
.SP
.RS
.BI "installboot \-m /dev/c0d0 /usr/mdec/jumpboot" " keys"
.RE
.SP
with
.I keys
chosen so that Minix is booted at startup.  (See
.BR installboot (8).)
.RE
.SP
\fBctty\fP \fIn\fP
.RS
Copies output to and takes input from serial line
.I n
(0-3) at 9600 baud, 8 bits, no parity.
This allows you to control a Minix system remotely through an RS-232
connection.
.RE
.SP
\fBdelay\fP [\fImsec\fP]
.RS
Delay (500 msec default).
.br
Fast booting speed was one of the objectives when this program was created,
so a hard disk boot usually takes only a fraction of a second.  If you need
some time (to hit Escape, or stare at the numbers) you can use
.B delay
to make the monitor pause for a specified number of milliseconds.
.RE
.SP
\fBecho\fP \fIword\fP ...
.RS
Print these words.
.br
Used to display messages, like the startup banner.  Echo normally prints
the words with spaces in between and a newline at the end.  Echo understands
special '\e' escape sequences as follows:
.RS
.SP
\e	(At the end) Don't print a newline.
.br
\en	Print a newline.
.br
\ev	Print the monitor's version numbers.
.br
\ec	Clear the screen.
.br
\ew	Wait until a RETURN is typed
.br
\e\e	Print a backslash.
.RE
.RE
.SP
\fBls\fP [\fIdirectory\fP]
.RS
List contents of a directory.
.br
Useful when looking for kernel images.
.RE
.SP
.B menu
.RS
Menu driven startup.
.br
This command allows you to execute functions defined with a
.IR key .
If no menu functions have been defined then
.B menu
will use this one hidden built-in function:
.SP
.RS
*(=,Start Minix) boot
.SP
.RE
Kernel selecting functions only add new options to this set, but if you
define a two argument function yourself then the above one is no longer
shown, allowing you to customize the menu completely.  Your first
function definition should therefore be one that starts Minix.
.SP
Menu entries are shown in the same order as
.B set
shows them.  If you don't like the order then you have to unset the
functions and retype them in the proper order.
.SP
If you type a key then a scheduled trap is killed and the appropriate menu
function is executed.  If you need more time to choose then hit the
spacebar.  A key not on the menu also kills a trap, but does nothing more.
.RE
.SP
.B save
.RS
Save environment.
.br
This will save all the environment variables and functions with nondefault
values to the parameter sector (the second sector on the boot device), so
they are automatically set the next time you boot the monitor.
.RE
.SP
.B set
.RS
Show environment.
.br
Show the current values of the environment variables and functions.  Default
values are shown between parentheses to distinguish them from values that
were explicitly set.
.RE
.SP
\fBtrap\fP \fImsec\fP \fIfunction\fP
.RS
Schedule function.
.br
Schedules a function to be executed after
.I msec
milliseconds.  Only the monitor mode cannot be interrupted, a scheduled trap
is killed when the prompt is printed.  Example:
.SP
.RS
main() {trap 10000 boot; menu}
.RE
.SP
This gives you 10 seconds to choose a menu option before Minix is booted.
.RE
.SP
\fBunset\fP \fIname\fP ...
.RS
Unset environment variables.
.br
Removes the named variables and functions from the environment, and sets
special variables back to their default values.  This is also the only way
to remove the "device name translation" property from a variable.
.RE
.SP
\fBexit\fP
.RS
Exit the monitor.
.br
Reboot the machine, exit to Minix or exit to DOS as appropriate.
.RE
.SP
\fBoff\fP
.RS
Turn the PC off.
.br
If the PC supports power management then turn it off, otherwise
print some error messages and do nothing.
.RE
.SP
\fB{\fP \fIcommand\fP; ... \fB}\fP
.RS
Bundle commands.
.br
Treat a number of commands as a single command.  Used for function
definitions when a function body must contain more than one command.
.RE
.SH DEVICES
The Minix kernel can't do anything with device names, so they have to be
translated to device numbers before they are passed to the kernel.  This
number is found under the st_rdev field (see
.BR stat (2))
of the file on the boot file system.  The monitor will look for the device
file with the working directory set to '/dev'.  If it can't find the device
name then it will translate names like 'ram', 'fd1', 'c0d1p0', 'c1d0p2s0',
and even the obsolete 'hd2a' to what it itself thinks the numbers should be.
.PP
The special name
.B bootdev
is translated to the name of the device booted from, like 'fd0',
or 'c0d0p1s0', and then searched for in /dev.
.B Bootdev
can only be translated to a device for the first controller, and only if
the disks on that controller are numbered without "gaps".  (The master
device on the second IDE channel is always d2 on Minix.  The BIOS will
call it disk 0, 1, or 2 depending on the number of disks on the first
IDE channel.)
.SP
Controller numbers are meaningless to the BIOS, so everything is assumed to
be attached to controller 0.  You can omit
.B c0
for device names, and it is best to always omit
.B c0
for the
.B boot
command, and to always use the full name for variables passed to Minix.
.SH EXTENSIONS
A few extensions have been made to this program for kernel hackers.  They
may be triggered by setting bits in the flags word in the kernel startup
code (the mpx file.)  The flag bits are:
.TP 10
0x0001
Call kernel in 386 mode.
.TP
0x0002
Do not make space for the bss areas of processes other than the kernel.
.TP
0x0004
Use the stack size set by
.BR chmem (1).
.TP
0x0008
Load MM, FS, etc. into extended memory.
.TP
0x0010
No need to patch process sizes into the kernel.
.TP
0x0020
The kernel can return to the monitor on halt or reboot.
.TP
0x0040
Offer generic BIOS support instead of just INT 13 (disk I/O).
.TP
0x0080
Pass memory lists for free and used memory (processes).
.TP
0x0100
Kernel returns monitor code on shutdown in boot parameters array.
.SH "SEE ALSO"
.BR controller (4),
.BR installboot (8),
.BR usage (8),
.BR boot (8),
.BR dosminix (8).
.SH BUGS
The
.B delay
command will hang forever on the original IBM PC (not the XT!).  Not that it
matters, as everything takes forever on that box.
.PP
By redefining
.B leader
one can easily hide the identity of this program.
.SH ACKNOWLEDGMENTS
Earl Chew, for the inspiration his ShoeLace package provided, unless he wants
to file a "look and feel" suit against me, then I will say I modeled it after
the Sun ROM boot monitor, which is also true.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
.\"
.\" $PchId: monitor.8,v 1.11 2002/02/27 19:36:34 philip Exp $