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man/man4/console.4
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.TH CONSOLE 4
.SH NAME
console, keyboard, log \- system console
.SH DESCRIPTION
The TTY device driver manages two devices related to the main user
interface, the system screen and the keyboard. These two together are
named "the Console".
.SS "The Screen"
The screen of a PC can be managed by a Monochrome Display Adapter, a
Hercules card, a Color Graphics Adapter, an Enhanced Graphics Adapter,
or a Video Graphics Array. To the console driver these devices are
seen as a block of video memory into which characters can be written to
be displayed, an I/O register that sets the video memory origin to the
character that is to be displayed on the top-left position of the
screen, and an I/O register that sets the position of the hardware
cursor. Each character within video memory is a two-byte word. The low
byte is the character code, and the high byte is the "attribute byte",
a set of bits that controls the way the character is displayed,
character and background colours for a colour card, or
intensity/underline/reverse video for monochrome.
.PP
These are the characteristics of the adapters in text mode:
.PP
.RS
.nf
.ta +15n +15n
Adapter Usable memory Mono/Colour
.ta +1n +15n +15n
MDA 4K M
Hercules 4K M
CGA 16K C
EGA 32K M or C
VGA 32K M or C
.fi
.RE
.PP
MDA and Hercules are the same to the console driver, because the graphics
mode of the Hercules is of no use to Minix. EGA and VGA are also mostly
seen as the same in text mode. An EGA adapter is either a monochrome or a
colour device depending on the screen attached to it. A VGA adapter can run
in either monochrome or colour (grayscale) mode depending on how the Boot
Monitor has initialized it.
.PP
The driver uses the video origin to avoid copying the screen contents when
scrolling up or down. Instead the origin is simply moved one line. This is
named "hardware scrolling", as opposed to copying memory: "software
scrolling".
.PP
The video origin is also used to implement several virtual consoles inside
the video memory of the adapter. Each virtual console gets a segment of
video memory. The driver chooses which console to display by moving the
video origin. Note that an MDA or Hercules adapter can only support one
console. CGA can support up to four 80x25 consoles, and EGA and VGA can
have eight. It is best to configure one less console to leave some video
memory free so that hardware scrolling has some space to work in.
.PP
Character codes are used as indices into a display font that is stored in the
adapter. The default font is the IBM character set, which is an ASCII
character set in the low 128 codes, and a number of mathematical, greek,
silly graphics, and accented characters in the upper 128 codes. This font
is fixed in the MDA, Hercules and CGA adapters, but can be replaced by a
user selected font for the EGA and VGA adapters.
.PP
A number of control characters and escape sequences are implemented by the
driver. The result is upward compatible with the ANSI standard terminal.
The
.BR termcap (5)
type is
.BR minix .
Normal characters written to the console are displayed at the cursor
position and the cursor is advanced one column to the right. If an entire
line is filled then the cursor wraps to the first column of the next line
when the next character must be displayed. The screen is scrolled up if
needed to start a new line. Some characters have special effects when sent
to the console. Some even have arguments in the form of comma separated
decimal numbers. These numbers default to the lowest possible value when
omitted. The top-left character is at position (1, 1). The following
control characters and escape sequences are implemented by the console:
.PP
.ta +10n +20n
Sequence Name Function
.in +31n
.ti -30n
^@ Null Ignored (padding character)
.ti -30n
^G Bell Produce a short tone from the speaker
.ti -30n
^H Backspace Move the cursor back one column, wrapping from the
left edge up one line to the right edge
.ti -30n
^I Horizontal Tab Move to the next tab stop, with each tab stop at
columns 1, 9, 25, etc. Wrap to the next line if necessary.
.ti -30n
^J Line Feed Move one line down, scrolling the screen up if
necessary
.ti -30n
^K Vertical Tab Same as LF
.ti -30n
^L Form Feed Same as LF
.ti -30n
^M Carriage Return Move to column 1
.ti -30n
^[ Escape Start of an escape sequence
.ti -30n
^[M Reverse Index Move one line up, scrolling the screen down if
necessary
.ti -30n
^[[\fIn\fPA Cursor Up Move the cursor up \fIn\fP lines
.ti -30n
^[[\fIn\fPB Cursor Down Move the cursor down \fIn\fP lines
.ti -30n
^[[\fIn\fPC Cursor Forward Move the cursor right \fIn\fP columns
.ti -30n
^[[\fIn\fPD Cursor Backward Move the cursor left \fIn\fP columns
.ti -30n
^[[\fIm\fP;\fIn\fPH Cursor Position Move the cursor to line \fIm\fP,
column \fIn\fP
.ti -30n
^[[\fIs\fPJ Erase in Display Clear characters as follows:
.br
\fIs\fP = 0: From cursor to end of screen
.br
\fIs\fP = 1: From start of screen to cursor
.br
\fIs\fP = 2: Entire screen
.ti -30n
^[[\fIs\fPK Erase in Line Clear characters as follows:
.br
\fIs\fP = 0: From cursor to end of line
.br
\fIs\fP = 1: From start of line to cursor
.br
\fIs\fP = 2: Entire line
.ti -30n
^[[\fIn\fPL Insert Lines Insert \fIn\fP blank lines
.ti -30n
^[[\fIn\fPM Delete Lines Delete \fIn\fP lines
.ti -30n
^[[\fIn\fP@ Insert Characters Insert \fIn\fP blank characters
.ti -30n
^[[\fIn\fPP Delete Characters Delete \fIn\fP characters
.ti -30n
^[[\fIn\fPm Character Attribute Set character attribute as follows:
.br
\fIn\fP = 0: Normal (default) attribute
.br
\fIn\fP = 1: Bold (high intensity fg colour)
.br
\fIn\fP = 4: Underline (mono) / Cyan (colour)
.br
\fIn\fP = 5: Blinking
.br
\fIn\fP = 7: Reverse Video
.br
\fIn\fP = 30: Black foreground colour
.br
\fIn\fP = 31: Red
.br
\fIn\fP = 32: Green
.br
\fIn\fP = 33: Brown
.br
\fIn\fP = 34: Blue
.br
\fIn\fP = 35: Magenta
.br
\fIn\fP = 36: Cyan
.br
\fIn\fP = 37: Light Gray
.br
\fIn\fP = 39: Default fg colour (lt gray)
.br
\fIn\fP = 40\-47: Same for background colour
.br
\fIn\fP = 49: Default bg colour (black)
.br
Note: The "bold" versions of black, brown and lt gray become dark gray,
yellow and white.
.in -31n
.PP
The console device implements the following ioctl to copy a font into
font memory on EGA and VGA adapters:
.PP
.RS
.BI "ioctl(" fd ", TIOCSFON, u8_t " font "[256][32]);"
.RE
.PP
Font memory consists of 256 character definitions of 32 lines per character
and 8 pixels per line. The first line is the topmost line of the character.
The leftmost pixel is lit if the most significant bit of a line is set, etc.
How many lines are used depends on the current video mode. The 80x25 video
mode used by Minix has an 8x16 character cell, 80x28 has 8x14 characters,
and 132x43 or 132x50 has 8x8 characters. The boot variable
.B console
is used by both the Boot Monitor and the console driver to set the video
mode, software scrolling on/off, and VGA screen blank timeout. See
.BR boot (8).
.SS "The Keyboard"
The keyboard produces key codes for each key that is pressed. These keys
are transformed into character codes or sequences according to the current
keyboard translation table. The format of this table is described in
.BR keymap (5).
The character codes can be read from the console device unless they map to
special hotkeys. The hotkeys are as follows:
.PP
.ta +17n
Name Key Function
.in +18n
.ti -17n
CTRL\-ALT\-DEL Send an abort signal to process 1 (init). Init then
halts the system
.ti -17n
CTRL\-ALT\-KP-. Likewise for keypad period
.ti -17n
F1 Process table dump
.ti -17n
F2 Show memory map
.ti -17n
F3 Toggle software/hardware scrolling
.ti -17n
F5 Show network statistics
.ti -17n
CTRL\-F7 Send a quit signal to all processes connected to the console
.ti -17n
CTRL\-F8 Send an interrupt signal
.ti -17n
CTRL\-F9 Send a kill signal. If CTRL\-F8 or CTRL\-F7 don't get 'em,
then this surely will. These keys are for disaster recovery. You would
normally use DEL and CTRL\-\e to send interrupt and quit signals.
.\" .ig VC
.ti -17n
ALT\-F1 Select virtual console 0 (/dev/console)
.ti -17n
ALT\-F2 Select virtual console 1 (/dev/ttyc1)
.ti -17n
ALT\-F(\fIn\fP+1) Select virtual console \fIn\fP
(/dev/ttyc\fIn\fP)
.ti -17n
ALT\-Left Select previous virtual console
.ti -17n
ALT\-Right Select next virtual console
.\" ..
.in -18n
.PP
.\"XXX
The keyboard map is set with the
.B KIOCSMAP
ioctl whose precise details are currently hidden in the
.B loadkeys
utility.
.SS "Log device"
The
.B log
device can be used by processes to print debug messages onto the console.
The console is a terminal type device, so it is taken from processes when a
session leader exits. This does not happen with the log device.
.SH "SEE ALSO"
.BR tty (4),
.BR loadkeys (1),
.BR keymap (5),
.BR boot (8).
.SH NOTES
Output processing turns Line Feeds into CR LF sequences. Don't let this
surprise you. Either turn off output processing or use one of the synonyms
for LF.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
.\" minor editing of man page by asw 07.08.96
man/man4/controller.4
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.TH CONTROLLER 4
.SH NAME
controller, disk, tape, at, bios, esdi, aha1540, ncr810, dosfile, fatfile \- controllers, disks and tapes
.SH DESCRIPTION
.de SP
.if t .sp 0.4
.if n .sp
..
The
.BI c n *
family of devices refer to drivers that control disks, disk like devices,
and tapes. Minix contains a number of drivers for several different
controllers. These controllers can have disks, cdroms and tapes attached to
them. Boot Monitor variables specify which drivers are activated using
the variables
.BR c0 ,
.BR c1 ,
etc. The names of the devices in
.BR /dev
that correspond with the driver for controller 0 are all named beginning
with
.BR c0 .
.PP
For each controller, the minor device numbers are organized as follows:
.PP
.RS
.nf
.ta +\w'122-127nnmm'u +\w'd0p0s0nnmm'u +\w'disk 0, part 0, subpart 0nnmm'u
.ft B
minor device what? obsolete
.ft P
0 d0 disk 0 hd0
1 d0p0 disk 0, partition 0 hd1
2 d0p1 disk 0, partition 1 hd2
3 d0p2 disk 0, partition 2 hd3
4 d0p3 disk 0, partition 3 hd4
5 d1 disk 1 hd5
6 d1p0 disk 1, partition 0 hd6
7 d1p1 disk 1, partition 1 hd7
8 d1p2 disk 1, partition 2 hd8
9 d1p3 disk 1, partition 3 hd9
\&... ...
39 d7p3 disk 7, partition 3 hd39
.SP
64 t0n tape 0, non-rewinding
65 t0 tape 0, rewind on close
66 t1n tape 1, non-rewinding
67 t1 tape 1, rewind on close
\&... ...
78 t7n tape 7, non-rewinding
79 t7 tape 7, rewind on close
.SP
120 r0 raw access device 0
121 r1 raw access device 1
\&... ...
127 r7 raw access device 7
.SP
128 d0p0s0 disk 0, part 0, subpart 0 hd1a
129 d0p0s1 disk 0, part 0, subpart 1 hd1b
130 d0p0s2 disk 0, part 0, subpart 2 hd1c
131 d0p0s3 disk 0, part 0, subpart 3 hd1d
132 d0p1s0 disk 0, part 1, subpart 0 hd2a
\&... ...
144 d1p0s0 disk 1, part 0, subpart 0 hd6a
\&... ...
255 d7p3s3 disk 7, part 3, subpart 3 hd39d
.fi
.RE
.PP
The device names in
.B /dev
also name the controller, of course, so the usual place for the Minix
root device, the first subpartition of the second partition of disk 0 on
controller 0 is
.BR /dev/c0d0p1s0 .
Note that everything is numbered from 0! The first controller is controller
0, the first disk is disk 0, etc. So the second partition is
.BR p1 .
.PP
The fourth column in the table above shows the disk devices names that were
used by previous versions of Minix for what is now controller 0. These
devices are no longer present in
.BR /dev .
.SS Disks
Most disks are arrays of 512 byte sectors. The disk devices are normally
block devices, which means they are block buffered by the Minix file system
cache using 1024 byte blocks. The FS cache allows I/O at any byte offset,
and takes care of cutting and pasting incomplete blocks together. If one
creates a character device for a disk device, then I/O must be in multiples
of the disk block size.
.PP
For each disk there is a device that covers the entire disk, these are named
.BR c0d0 ,
.BR c0d1 ,
etc, up to
.B c0d7
for controller 0. If a partition table is placed in the first sector of the
disk, then the disk is subdivided into regions named partitions. Up to four
partitions may be defined, named
.BR c0d0p0
to
.BR c0d0p3
for disk 0 on controller 0. To make things interesting you can also place a
partition table in the first sector of a Minix partition, which divides the
partition into up to four subpartitions. Normally Minix is installed into a
single partition, with the root, swap and /usr file systems in subpartitions.
.PP
If a partition is an extended partition then it contains a linked list of
partition tables each of which may specify a logical partition. Up to four
of these logical partitions are presented by the driver as subpartitions of
the extended partition.
.PP
A sector containing a partition table starts with 446 bytes of boot code,
followed by four partition table entries of 16 bytes each, and ends with
the magic number 0xAA55 (little endian, so first 0x55 then 0xAA.) Partition
table information is defined in <ibm/partition.h>:
.PP
.nf
.ta +2n +29n +37n
/* Description of entry in the partition table. */
struct part_entry {
unsigned char bootind; /* boot indicator 0/ACTIVE_FLAG */
unsigned char start_head; /* head value for first sector */
unsigned char start_sec; /* sector value + high 2 cyl bits */
unsigned char start_cyl; /* low 8 cylinder bits */
unsigned char sysind; /* system indicator */
unsigned char last_head; /* h/s/c for the last sector */
unsigned char last_sec;
unsigned char last_cyl;
unsigned long lowsec; /* logical first sector */
unsigned long size; /* size of partition in sectors */
};
.ta +24n +7n +37n
#define ACTIVE_FLAG 0x80 /* value for active in bootind field */
#define NR_PARTITIONS 4 /* number of entries in table */
#define PART_TABLE_OFF 0x1BE /* offset of table in boot sector */
/* Partition types (sysind). */
#define NO_PART 0x00 /* unused entry */
#define MINIX_PART 0x81 /* Minix partition type */
.fi
.PP
The cylinder numbers are encoded in a very strange way, bits 8 and 9 are
in the high two bits of the sector number. The sector numbers count from 1,
not 0! More useful are the lowsec and size fields however, they simply give
the location of the partition as an absolute sector offset and length within
the drive.
.PP
The partition table entry defined above is specific to IBM type disks. The
device drivers use another partition entry structure to pass information on
a partition. This is what <minix/partition.h> looks like:
.sp
.nf
.ta +2n +25n
struct partition {
u64_t base; /* byte offset to the partition start */
u64_t size; /* number of bytes in the partition */
unsigned cylinders; /* disk geometry for partitioning */
unsigned heads;
unsigned sectors;
};
.fi
.PP
The base and size fields are the byte offset and length of a partition.
The geometry of the disk is also given for the benefit of
partition table editors. This information can be obtained from an open disk
device with the call:
.sp
.RS
.ft B
ioctl(\fIfd\fP, DIOCGETP, &\fIentry\fP);
.ft R
.RE
.sp
One can change the placement of the device to the lowsec and size fields of
.I entry
by using the
.B DIOCSETP
call instead. Only the base and size fields are used for
.BR DIOCSETP .
.PP
The partition tables when read from disk by the driver are checked and
truncated to fit within the primary partition or drive. The first sector
is normally left free for the partition table.
.PP
The partition tables are read when the in-use count (opens and mounts)
changes from 0 to 1. So an idle disk is automatically repartitioned on the
next access. This means that DIOCSETP only has effect if the disk is in
use.
.SS "Disk-like devices"
Devices like a CD-ROM are treated as read-only disks, and can be accessed
using disk devices. A CD-ROM usually has a block size of 2048 bytes, but
the driver knows this, and allows one to read at any byte offset by reading
what isn't needed into a scratch buffer.
.SS Tapes
There are two kinds of tape devices: Non-rewinding, and rewind-on-close.
The non-rewinding devices treat the tape as a series of files. The
rewind-on-close devices look at the tape as a single file, and when you close
such a device the tape is told to rewind.
See
.BR mt (1),
and
.BR mtio (4)
for a description of the commands that may be sent to the tape, either from
the command prompt or from a program.
.PP
There are two kinds of tape drives: Fixed and variable block size tape
drives. Examples of the first kind are cartridge
tapes, with a fixed 512 bytes block size. An Exabyte tape drive has a
variable block size, with a minimum of 1 byte and a maximum of 245760 bytes
(see the documentation of such devices.)
The maximum is truncated to 32767 bytes for Minix-86 and 61440 bytes for
Minix-vmd, because the driver can't move more bytes in a single request.
.PP
A read or write to a fixed block size tape must be a precise multiple of the
block size, any other count gives results in an I/O error. A read from a
variable block sized tape must be large enough to accept the block that is
read, otherwise an I/O error will be returned. A write can be any size
above the minimum, creating a block of that size. If the write count is
larger than the maximum block size then more blocks are written until the
count becomes zero. The last block must be larger than the minimum of
course. (This minimum is often as small as 1 byte, as for the Exabyte.)
.PP
The
.B mt blksize
command may be used to select a fixed block size for a variable block sized
tape. This will speed up I/O considerably for small block sizes. (Some
systems can only use fixed mode and will write an Exabyte tape with 1024
byte blocks, which read very slow in variable mode.)
.PP
A tape is a sequence of blocks and filemarks. A tape may be opened and
blocks may be read from it upto a filemark, after that all further reads
return 0. After the tape is closed and reopened one can read the blocks
following the filemark if using a non-rewinding device. This makes the tape
look like a sequence of files.
.PP
If a tape has been written to or opened in write-only mode, then a filemark
is written if the tape is closed or if a space command is issued. No extra
filemark is written if the drive is instructed to write filemarks.
.SS "Raw Access Devices"
Under Minix-vmd one can use the raw access devices to program a SCSI
device entirely from user mode. The disk and tape devices probe for devices
when opened, start disks and load tapes, but the raw access devices do
nothing at all. Given an open file descriptor to any SCSI character device
(not just the raw access devices) one can use the following ioctl:
.PP
.RS
ioctl(fd, SCIOCCMD, &scsicmd)
.RE
.PP
The structure whose address is passed as the third argument is defined
in <sys/scsi.h> as follows:
.PP
.RS
.nf
struct scsicmd {
void *cmd;
size_t cmdlen;
void *buf;
size_t buflen;
void *sense;
size_t senselen;
int dir;
};
.fi
.RE
.PP
.B Cmd
and
.B cmdlen
hold the address and length of an object holding a Group 0 or Group 1
SCSI command. The next two fields describe a buffer of at most 8 kilobytes
used in the data in or out phase.
.B Dir
is 0 if data is to be read from the device, 1 if data is written to the
device. If the ioctl succeeds then 0 is returned, otherwise -1 with
.B errno
set to
.B EIO
and the request sense info returned in the buffer described by the sense and
senselen fields. If the sense key is zero on error then a host adapter
error occurred, this means that the device is most likely turned off or not
present.
.SH DRIVERS
By setting the Boot variables
.BR c0
to
.BR c3
under Minix, or
.BR c0
to
.BR c4
under Minix-vmd one attaches a set of disk and tape devices to a driver.
See
.BR boot (8)
for a list of boot variables that configure each of these drivers.
The following drivers are available:
.SS at
The standard IBM/AT disk driver that also supports IDE disks. This is the
default driver for controller 0 on AT class machines. (Most PCs are in that
class.)
.SS bios
A disk driver that uses BIOS calls to do disk I/O. This is the default
driver on anything but an AT. (Old XTs and PS/2s.) On an XT this is the
best driver you can use, but on any other machine this driver may be
somewhat slow, because the system has to switch out of protected mode to
make a BIOS call. On a fast enough machine with a high enough setting of
DMA_SECTORS (see
.BR config (8))
it works well enough.
.SS esdi
A hard disk driver for use on some PS/2 models.
.SS "xt \fR(Minix only)"
A hard disk driver for IBM/XT type hard disks. Useful for old 286 based
machines that have such a disk. On XTs you are better off with the
.B bios
driver.
.SS aha1540
A SCSI driver for the Adaptec 1540 host adapter family, which includes the
1540, 1540A, 1540B, 1540C, 1540CF, 1640, and 1740. Also supported is the
compatible BusLogic 545.
.SS ncr810
This will eventually become a Symbios 810 SCSI driver. (Formerly owned by
NCR.) KJB has read the docs on this card three times, but has still done
nothing, the lazy bum.
.SS dosfile
The "DOS file as disk" driver that is used when Minix is running
under DOS. It treats a large DOS file as a Minix disk. Only primary
partitions are supported, there are no subpartitions. This is the default
driver when Minix is started under DOS.
.SS fatfile
Uses a large file on a FAT file system as a disk. It needs one of the other
disk drivers to do the actual I/O. This driver only knows how to interpret
a FAT file system to find the file to use. With a fast native disk driver
this driver is much faster than the
.B dosfile
driver.
.SH FILES
.TP 25
/dev/c*d*
Disks devices.
.TP
/dev/c*d*p*
Partitions.
.TP
/dev/c*d*p*s*
Subpartitions.
.TP
/dev/c*t*n, /dev/c*t*
Tapes.
.TP
/dev/c*r*
Raw access devices.
.SH "SEE ALSO"
.BR dd (1),
.BR mt (1),
.BR eject (1),
.BR ioctl (2),
.BR int64 (3),
.BR mtio (4),
.BR boot (8),
.BR config (8),
.BR monitor (8),
.BR part (8),
.BR repartition (8).
.SH BUGS
The subpartitioning is incompatible with the MS-DOS method of extended
partitions. The latter does not map well to the sparse minor device number
space.
.PP
The primary partition table is sorted by lowsec like MS-DOS does, subpartition
tables are not. Just think about what happens when you delete a partition in
the MS-DOS scheme.
.PP
Don't move a partition that is mounted or kept open by some process. The
file system may write cached blocks to the new location.
.PP
The BIOS driver is not slow at all on a buffered disk.
.PP
Some IDE disks send an interrupt when they spin down under hardware power
management. The driver acknowledges the interrupt as it is supposed to do by
reading the status register. The disk then spins up again... You have to
disable the spin down in the computer setup to fix the problem.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
man/man4/dev.4
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.TH DEV 4
.SH NAME
dev \- device files in /dev
.SH DESCRIPTION
Device files are the eyes and ears of the system. Through the device files
one has access to the disks, terminals and other parts of the machine.
Single bytes or disk blocks may be transferred to or from a device with
ordinary
.BR read (2)
or
.BR write (2)
calls, byte positions set with
.BR lseek (2),
or more complicated control functions performed with
.BR ioctl(2).
.PP
Device files as found in
.B /dev
have several attributes that must be considered. Here are two examples as
.B "ls \-l"
shows them:
.PP
.RS
.nf
.if t .ft C
brw-rw-rw- 1 root operator 2, 1 Jun 10 1995 fd1
crw--w---- 1 kjb tty 4, 0 May 11 09:41 console
.if t .ft P
.fi
.RE
.PP
Most attributes are the same as for a regular file and have the same
function. The file type and the major and minor device numbers are special
to devices.
.PP
Character devices are marked with a
.B c
as a file type letter. Any I/O on a character device is sent down to the
device driver without any interpretation. This means that a process doing
the I/O must know the characteristics of the device and deal with them
appropriately.
.PP
Block devices provoke the file system server into buffering the data on
those devices. Data read or written by processes is passed through the file
system block cache. Unaligned bytes read or written are extracted or
reassembled by the file server from or to whole blocks in the cache. The
file server transfers data to or from the device driver as blocks to
positions at block size boundaries. These blocks are Minix blocks of 1024
bytes, disk devices usually have a 512 byte block size. Only block devices
can be mounted as part of the file system tree if they contain a Minix file
system.
.PP
The major device number (2 for
.B fd1
and 4 for
.BR console )
are used by FS to find the device driver that manages a device. The minor
device number (1 for
.B fd1
and 0 for
.BR console )
is passed to the driver to select a device among a number of related devices
that are all managed by that driver. The device drivers are usually kernel
tasks under Minix, small processes that are contained within the address
space of the kernel. The following tasks and associated devices exist:
.SS "Memory (major 1)"
The
.BR ram ,
.BR mem ,
.BR kmem ,
and
.BR null
devices are managed by the memory task.
The
.B ram
device is a block device for a chunk of memory that is the RAM disk. Any
byte read from or written to the
.B ram
device is copied from or to that memory chunk.
The
.B mem
device is a character device for the entire address space of the system, but
.B kmem
only for the kernel data area. These two devices allow programs like
.BR ps (1)
to hunt around the system looking for interesting bits.
The
.B null
device is a data sink. It happily swallows any bytes written to it, and
returns nothing on a read.
.SS "Floppy disk (major 2)"
The
.BR fd0 ,
.BR fd0p0 ,
.BR fd0p1 ,
.BR fd0p2 ,
and
.BR fd0p3
block devices are the first floppy disk and the four partitions that may
exist on a that floppy disk. Likewise are
.BR fd1
and
.BR fd1p[0\-3]
the device and partitions for the second floppy disk. The floppy disk
devices are described in detail in
.BR fd (4).
Partitioning in general is explained in
.BR controller (4).
.SS "Controller 0 (major 3)"
The first hard disk on controller 0 can be accessed by block device
.BR c0d0 .
This device addresses the entire hard disk from the first to the last
sector. A hard disk is normally partitioned in up to four primary
partitions,
.BR c0d0p0 ,
.BR c0d0p1 ,
.BR c0d0p2 ,
and
.BR c0d0p3 .
Each of these devices accesses a range of sectors on the
.B c0d0
device. It is customary to give each operating system on a disk a primary
partition. So the Windows C: "drive" can be on
.BR c0d0p0 ,
and Minix can be on
.BR c0d0p1 .
Minix wants to have several partitions on its own, so
.B c0d0p1
can be further subdivided into the subpartitions
.BR c0d0p1s0 ,
.BR c0d0p1s1 ,
.BR c0d0p1s2 ,
and
.BR c0d0p1s3 .
.B /dev
contains devices for the first and second hard disk
.RB ( c0d0
and
.BR c0d1 ),
their primary partitions
.RB ( c0d[01]p[0\-3] )
and subpartitions thereof
.RB ( c0d[01]p[0\-3]s[0\-3] ).
More detail can be found in
.BR controller (4).
.SS "Terminals (minor 4)"
The TTY driver manages the system console device, aptly named
.BR console ,
the serial lines,
.BR tty00
and
.BR tty01 ,
and the pseudo ttys.
Through the console device one can display characters on a screen attached
to a monochrome, Hercules, color, or VGA adapter. The
.BR ttyc1 ,
.BR ttyc2 ,
etc. devices are the so-called "virtual consoles" that share the one
console display. One can select which virtual console is to be visible on
the screen and take input from the keyboard.
To allow remote login the devices with minor numbers of 128 or higher offer
virtual terminals. These pseudo ttys come in tty, pty pairs that form a
pipe between processes running under the tty, and a controlling process
attached to the pty side.
See also
.BR console (4),
and
.BR tty (4).
.SS "Anonymous TTY (major 5)"
This is just one device named
.BR tty
that is a synonym for the controlling tty of a process. This device is not
managed by any device driver, but is handled by FS itself. A process can
get access to the terminal it is running under by using
.BR /dev/tty .
.SS "Line printer (major 6)"
The
.B lp
device sends any bytes written to it to the printer.
.SS "TCP/IP (major 7)"
The TCP/IP task is not a kernel task, but a server like MM and FS. It sits
between FS and the DP8390 task that manages the ethernet boards. Together
they implement the TCP/IP protocol. See also
.BR ip (4).
.SS "Controller 1 (major 8)"
Like controller 0 (major 3), but managing a second controller with devices
.BR /dev/c1* .
.SS "Controller 2 (major 10)"
Like controller 0.
.SS "Controller 3 (major 12)"
Like controller 0.
.SS "Audio (major 13)"
The
.B audio
device can be used to produce or record air vibrations using a Soundblaster
16 type audio card. See
.BR audio (4).
.SS "Mixer (major 14)"
The
.B mixer
device is used to control the audio driver.
.SH FILES
.TP 10
.B /dev/*
All Minix devices
.SH "SEE ALSO"
.BR read (2),
.BR write (2),
.BR lseek (2),
.BR ioctl (2),
.BR console (4),
.BR fd (4),
.BR controller (4),
.BR ip (4),
.BR tty (4),
.BR MAKEDEV (8).
.SH DIAGNOSTICS
There are five prominent errors that processes accessing device files may
provoke:
.IP "ENODEV \- No such device" 5
There is no driver managing the device class this device belongs to. Either
the driver is configured out, or it is not loaded (inet).
.IP "ENXIO \- No such device or address"
This device is not available. Either the driver does not support it at all,
or the hardware isn't available, i.e. accessing the second disk on a system
with only one disk.
.IP "EACCES \- Permission denied"
This error may cause a lot of head scratching if
.B ls \-l
shows a device file to be writable. The media you are trying to access is
simply physically write protected!
.IP "EINVAL \- Invalid argument"
Devices may not like reads or writes that are not block multiples, or very
big transfers, etc. The device manual page should list the limits.
.IP "EIO \- I/O error"
This may be a real I/O error, i.e. a read or write on the device failing due
to a media error. But it may also be the result of an operation that a
device can't do, or an empty tape drive, etc.
.SH NOTES
Some devices are not present by default. The
.BR MAKEDEV
script knows how to make them.
.SS "MS-DOS/Windows equivalents"
The names of MS-DOS/Windows devices probably map to Minix devices as follows:
.PP
.RS
.nf
.ta +\w'COM1mmm'u +\w'c0d1, c0d2, c0d3mmm'u
A: fd0
B: fd1
C: c0d0p0 (usually the first partition)
D: c0d1p0, c0d2p0 (if it's another disk)
D: c0d0p1s0 (if it's an extended partition)
D: c0d1, c0d2, c0d3 (if it's a CD-ROM)
CON console
COM1 tty00 (UNIX counts from 0)
LPT1 lp
.fi
.RE
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
man/man4/fd.4
+88
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@@ -0,0 +1,88 @@
.TH FD 4
.SH NAME
fd \- floppy disk
.SH DESCRIPTION
The
.B fd*
devices refer to the Floppy disk driver using the NEC PD765 floppy disk
controller. These diskettes are arrays of 512 byte sectors, although Minix
always works with two sectors at a time due to its 1024 byte block size. You
can read or write any number of bytes however, Minix takes care of cutting
and pasting incomplete blocks together.
.PP
The driver is normally configured for two floppy disk devices
.B fd0
and
.BR fd1 .
It can handle two more, but it is unlikely that the average PC can.
.PP
On the first access to an
.B fd
device (by
.BR open (2)
or
.BR mount (2)),
the driver will execute a series of read tests to determine the floppy type.
This works ok for all floppy types except the true 360k type, because it
is indistinguishable from the 720k type. This only means that the size of
the floppy is not estimated right.
.PP
Bits 2\-6 of the minor device number may be set to the floppy disk type
to make it known to the driver what type of diskette it is reading or
writing. The non-auto devices should be used for formatting, or when one wants to
be absolutely sure that the device is accessed right. These devices exist for
drive 0:
.sp
.nf
.ta +4n +7n +9n +8n
type device minor media
.ta +5n +7n +9n +7n
0 fd0 0 autodetect
1 pc0 4 360k, 5.25"
2 at0 8 1.2M, 5.25"
3 qd0 12 360k in a 720k, 5.25" drive
4 ps0 16 720k, 3.5"
5 pat0 20 360k in a 1.2M, 5.25" drive
6 qh0 24 720k in a 1.2M, 5.25" drive
7 PS0 28 1.44M, 3.5"
.fi
.DT
.PP
Type 4 may also be used for the rarely seen 720k, 5.25" floppies (type 2 made
them obsolete fast.) Note that these "types" only describe the floppies from
a software point of view, type 1 and 4 drives use the same parameters.
.PP
If the format bit (bit 7) is set, then the driver interprets write commands
as track formatting requests. This is used by the
.BR format (1)
command.
.PP
If the type bits are set to 28, 29, 30, or 31, then the driver uses a
partition table found in sector 0 to partition the floppy. The partitions
of
.B fd0
may be accessed as
.B fd0p0
through
.BR fd0p3 .
See
.BR controller (4)
for a description of the partition table, and associated ioctl commands.
.SH FILES
/dev/fd[0\-3], /dev/pc[0\-3], /dev/at[0\-3], /dev/qd[0\-3], /dev/ps[0\-3],
/dev/pat[0\-3], /dev/qh[0\-3], /dev/PS[0\-3], /dev/fd[0\-3]p[0\-3]
.SH "SEE ALSO"
.BR format (1),
.BR controller (4),
.BR part (8).
.SH BUGS
The driver does not know the size of a 360k diskette in a 360k 5.25"
drive, because it uses the 720k parameters for it. So it will happily try
to read past the end making all kinds of interesting noises. It's a good
thing these drives are practically obsolete.
.PP
The partition table is only read when the drive motor is off and only for
an auto or partition device. The driver assumes that a floppy in a drive
with a running motor can't have been replaced all of a sudden.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
man/man4/ip.4
+1466
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File diff suppressed because it is too large Load Diff
man/man4/lp.4
+28
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@@ -0,0 +1,28 @@
.TH LP 4
.SH NAME
lp \- line printer
.SH DESCRIPTION
The
.B lp
device refers to the line printer attached to the parallel port. Any byte
written to this device is printed. Only one process may have the device
open.
.PP
The
.B write (2)
call may return with a smaller count then the number of bytes requested to
write. The next write call is then likely to fail with the error code
.B EAGAIN
if the printer is out of paper, or
.B EIO
if the printer is turned off.
.SH FILES
.TP 10
/dev/lp
Parallel port device.
.SH "SEE ALSO"
.BR lp (1).
.SH BUGS
Only one parallel port is supported.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
man/man4/mtio.4
+98
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@@ -0,0 +1,98 @@
.TH MTIO 4
.SH NAME
mtio \- magnetic tape commands
.SH SYNOPSIS
.B "#include <sys/types.h>"
.br
.B "#include <sys/mtio.h>"
.br
.B "#include <sys/ioctl.h>"
.SH DESCRIPTION
.de SP
.if t .sp 0.4
.if n .sp
..
The magnetic tape devices described in
.BR sd (4)
may be sent commands or queried for their status using the following ioctl
calls:
.PP
.RS
.BR ioctl ( \fIfd ,
.BR MTIOCTOP ,
.RB & "struct mtop" )
.br
.BR ioctl ( \fIfd ,
.BR MTIOCGET ,
.RB & "struct mtget" )
.RE
.PP
The struct mtop, struct mtget and associated definitions are defined in
<sys/mtio.h> as follows:
.PP
.nf
/* Tape operations: ioctl(fd, MTIOCTOP, &struct mtop) */
.ta +4n +7n +15n
struct mtop {
short mt_op; /* Operation (MTWEOF, etc.) */
int mt_count; /* Repeat count. */
};
.ta +17n +5n
#define MTWEOF 0 /* Write End-Of-File Marker */
#define MTFSF 1 /* Forward Space File mark */
#define MTBSF 2 /* Backward Space File mark */
#define MTFSR 3 /* Forward Space Record */
#define MTBSR 4 /* Backward Space Record */
#define MTREW 5 /* Rewind tape */
#define MTOFFL 6 /* Rewind and take Offline */
#define MTNOP 7 /* No-Operation, set status only */
#define MTRETEN 8 /* Retension (completely wind and rewind) */
#define MTERASE 9 /* Erase the tape and rewind */
#define MTEOM 10 /* Position at End-Of-Media */
#define MTMODE 11 /* Select tape density */
#define MTBLKZ 12 /* Select tape block size */
/* Tape status: ioctl(fd, MTIOCGET, &struct mtget) */
.ta +4n +7n +15n
struct mtget {
short mt_type; /* Type of tape device. */
/* Device dependent "registers". */
short mt_dsreg; /* Drive status register. */
short mt_erreg; /* Error register. */
/* Misc info. */
off_t mt_resid; /* Residual count. */
off_t mt_fileno; /* Current File Number. */
off_t mt_blkno; /* Current Block Number within file. */
off_t mt_blksize; /* Current block size. */
};
.fi
.PP
See
.BR mt (1)
for a detailed description on what each operation does. The mt_type field
is always zero, there is no use for it yet. Mt_dsreg is 0 (OK), 1 (Error),
or 2 (EOF encountered.) Mt_erreg holds the SCSI sense key of the last
operation. Mt_blksize is the current tape block size in bytes, zero if the
block size is variable.
.PP
Note that one can issue these commands on a file descriptor that is in use
to read or write data, something that
.B mt
can't do. So you can add eof markers in the middle of an output stream,
or get the status of a device before a rewind-on-close tape rewinds.
.PP
The driver will automatically add an end of file marker to a tape that is
written to if you execute a space command. If you write eof markers
yourself then the driver will not add one extra on close.
.SH "SEE ALSO"
.BR mt (1),
.BR sd (4).
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)
man/man4/tty.4
+736
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@@ -0,0 +1,736 @@
.TH TTY 4
.SH NAME
tty, termios \- terminals
.SH DESCRIPTION
The
.B tty
driver family takes care of all user input and output. It governs the
keyboard, the console, the serial lines, and pseudo ttys. Input on any of
these devices undergoes "input processing", and output undergoes "output
processing" according to the standard termios terminal interface.
.SS "Input processing"
Each terminal device has an input queue. This queue is used to store
preprocessed input characters, and to perform the backspacing and erase
functions. Some special characters like a newline make the contents of the
queue available to a process reading from the terminal. Characters up to
and including the newline, or another so-called "line break", may be read by
a process. The process need not read all characters at once. An input line
may be read byte by byte if one wants to. A line break just makes
characters available for reading, thats all.
.PP
When data is made available depends on whether the tty is in canonical mode
or not. In canonical mode the terminal processes input line by line. A
line ends with a newline
.RB ( NL ),
end-of-file
.RB ( EOF ),
or end-of-line
.RB ( EOL ).
Characters that have not been delimited by such a line break may be erased
one by one with the
.B ERASE
character or all at once with the
.B KILL
character. Once a line break is typed the characters become available to a
reading process and can no longer be erased. Once read they are removed
from the input queue. Several lines may be gathered in the input queue if
no reader is present to read them, but a new reader will only receive one
line. Two line breaks are never returned in one read call. The input queue
has a maximum length of
.B MAX_CANON
characters. Any more characters are discarded. One must use
.B ERASE
or
.B KILL
to make the terminal functioning again if the input queue fills up. If
nonblocking I/O is set then \-1 is returned with
.B errno
set to
.B EAGAIN
if the reader would otherwise be blocked.
.PP
In non-canonical mode (raw mode for short) all characters are immediately
available to the reader in principle. One may however tune the terminal to
bursty input with the
.B MIN
and
.B TIME
parameters, see the raw I/O parameters section below. In raw mode no
characters are discarded if the input queue threatens to overflow if the
device supports flow control.
.SS "Output processing"
Characters written to a terminal device may undergo output processing, which
is usually just inserting a carriage returns before newlines. A writer
may return before all characters are output if the characters can be stored
in the output buffers. If not then the writer may be blocked until space is
available. If non-blocking I/O is set then only the count of the number of
bytes that can be processed immediately is returned. If no characters can
be written at all then \-1 is returned with
.B errno
set to
.BR EAGAIN .
.SS "Special characters"
Some characters have special functions in some of the terminal modes. These
characters are as follows, with the Minix defaults shown in parentheses:
.TP 5
.BR INTR " (^?)"
Special input character that is recognized if
.B ISIG
is set. (For
.B ISIG
and other flags see the various modes sections below.) It causes a
.B SIGINT
signal to be sent to all processes in the terminal process group. (See the
section on session leaders below.)
.TP
.BR QUIT " (^\e)"
Special input character if
.B ISIG
is set. Causes a
.B SIGQUIT
signal to be sent to the terminal process group.
.TP
.BR ERASE " (^H)"
Special input character if
.B ICANON
is set. Erases the last character in the current line.
.TP
.BR KILL " (^U)"
Special input character if
.B ICANON
is set. Erases the entire line.
.TP
.BR EOF " (^D)"
Special input character if
.B ICANON
is set. It is a line break character that is not itself returned to a
reader. If EOF is typed with no input present then the read returns zero,
which normally causes the reader to assume that end-of-file is reached.
.TP
.BR CR " (^M)"
Special input character if
.B IGNCR
or
.B ICRNL
is set. It is a carriage return ('\er'). If
.B IGNCR
is set then
.B CR
is discarded. If
.B ICRNL
is set and
.B IGNCR
is not set then
.B CR
is changed into an
.B NL
and has the same function as
.BR NL.
.TP
.BR NL " (^J)"
Special input character if
.B ICANON
is set. It is both a newline ('\en') and a line break.
.br
Special output character if
.B OPOST
and
.B ONLCR
are set. A
.B CR NL
sequence is output instead of just
.BR NL .
(Minix specific, but almost mandatory on any UNIX-like system.)
.TP
.BR TAB " (^I)"
Special character on output if
.B OPOST
and
.B XTABS
are set. It is transformed into the number of spaces necessary to reach a
column position that is a multiple of eight. (Only needed for terminals
without hardware tabs.)
.TP
.BR EOL " (undefined)"
Special input character if
.B ICANON
is set. It is an additional line break.
.TP
.BR SUSP " (^Z)"
Special input character if job control is implemented and
.B ISIG
is set. It causes a
.B SIGTSTP
signal to be send to the terminal process group. (Minix does not have job
control.)
.TP
.BR STOP " (^S)"
Special input character if
.B IXON
is set. It suspends terminal output and is then discarded.
.TP
.BR START " (^Q)"
Special output character if
.B IXON
is set. It starts terminal output if suspended and is then discarded. If
.B IXANY
is also set then any other character also starts terminal output, but they
are not discarded.
.TP
.BR REPRINT " (^R)"
Special input character if
.B IEXTEN
and
.B ECHO
are set. Reprints the input queue from the last line break onwards. A
reprint also happens automatically if the echoed input has been messed up by
other output and
.B ERASE
is typed.
.TP
.BR LNEXT " (^V)"
Special input character if
.B IEXTEN
is set. It is the "literal next" character that causes the next character
to be input without any special processing.
.TP
.BR DISCARD " (^O)"
Special input character if
.B IEXTEN
is set. Causes output to be discarded until it is typed again. (Implemented
only under Minix-vmd.)
.PP
All of these characters except
.BR CR ,
.B NL
and
.B TAB
may be changed or disabled under Minix. (Changes to
.B START
and
.B STOP
may be ignored under other termios implementations.) The
.B REPRINT
and
.B LNEXT
characters are Minix extensions that are commonly present in other
implementations. \s-2POSIX\s+2 is unclear on whether
.BR IEXTEN,
.BR IGNCR
and
.BR ICRNL
should be active in non-canonical mode, but under Minix they are.
.SS "Terminal attributes"
The attributes of a terminal, such as whether the mode should be canonical or
non-canonical, are controlled by routines that use the
.B termios
structure as defined in
.BR <termios.h> :
.PP
.RS
.nf
.ta +4n +10n +15n
struct termios {
tcflag_t c_iflag; /* input modes */
tcflag_t c_oflag; /* output modes */
tcflag_t c_cflag; /* control modes */
tcflag_t c_lflag; /* local modes */
speed_t c_ispeed; /* input speed */
speed_t c_ospeed; /* output speed */
cc_t c_cc[NCCS]; /* control characters */
};
.fi
.RE
.PP
The types
.BR tcflag ,
.B speed_t
and
.B cc_t
are defined in
.B <termios.h>
as unsigned integral types.
.SS "Input Modes"
The
.B c_iflag
field contains the following single bit flags that control input processing:
.TP 5
.B ICRNL
Map
.B CR
to
.B NL
on input.
.TP
.B IGNCR
Ignore
.B CR
on input. This flag overrides
.BR ICRNL .
.TP
.B INLCR
Map
.B NL
to
.B CR
on input. This is done after the
.B IGNCR
check.
.TP
.B IXON
Enable start/stop output control.
.TP
.B IXOFF
Enable start/stop input control. (Not implemented.)
.TP
.B IXANY
Allow any character to restart output. (Minix specific.)
.TP
.B ISTRIP
Strip characters to seven bits.
.TP
.B IGNPAR
Ignore characters with parity errors. (Not implemented.)
.TP
.B INPCK
Enable input parity checking. (Not implemented.)
.TP
.B PARMRK
Mark parity errors by preceding the faulty character with '\e377', '\e0'.
The character '\e377' is preceded by another '\e377' to avoid ambiguity.
(Not implemented.)
.TP
.B BRKINT
Send the signal
.B SIGINT
to the terminal process group when receiving a break condition. (Not
implemented.)
.TP
.B IGNBRK
Ignore break condition. If neither
.B BRKINT
or
.B IGNBRK
is set a break is input as a single '\e0', or if
.B PARMRK
is set as '\e377', '\e0', '\e0'.
(Breaks are always ignored.)
.SS "Output Modes"
The
.B c_oflag
field contains the following single bit flags that control output processing:
.TP
.B OPOST
Perform output processing. This flag is the "main switch" on output
processing. All other flags are Minix specific.
.TP
.B ONLCR
Transform an
.B NL
to a
.B CR NL
sequence on output. Note that a key labeled "RETURN" or "ENTER" usually
sends a
.BR CR .
In line oriented mode this is normally transformed into
.B NL
by
.BR ICRNL .
.B NL
is the normal UNIX line delimiter ('\en'). On output an
.B NL
is transformed into the
.B CR NL
sequence that is necessary to reach the first column of the next line.
(This is a common output processing function for UNIX-like systems, but not
always separately switchable by an
.B ONLCR
flag.)
.TP
.B XTABS
Transform a
.B TAB
into the number of spaces necessary to reach a column position that is a
multiple of eight.
.TP
.B ONOEOT
Discard
.B EOT
(^D) characters. (Minix-vmd only.)
.SS "Control Modes"
The
.B c_cflag
field contains the following single bit flags and bit field for basic
hardware control:
.TP
.B CLOCAL
Ignore modem status lines.
.TP
.B CREAD
Enable receiver. (The receiver is always enabled.)
.TP
.B CSIZE
Number of bits per byte.
.B CSIZE
masks off the values
.BR CS5 ,
.BR CS6 ,
.BR CS7
and
.BR CS8
that indicate that 5, 6, 7 or 8 bits are used.
.TP
.B CSTOPB
Send two stop bits instead of one. Two stop bits are normally used at 110
baud or less.
.TP
.B PARENB
Enable parity generation.
.TP
.B PARODD
Generate odd parity if parity is generated, otherwise even parity.
.TP
.B HUPCL
Drop the modem control lines on the last close of the terminal line. (Not
implemented.)
.SS "Local Modes"
The
.B c_lflag
field contains the following single bit flags that control various functions:
.TP
.B ECHO
Enable echoing of input characters. Most input characters are echoed as
they are. Control characters are echoed as
.BI "^" X
where
.I X
is the letter used to say that the control character is
.BI CTRL\- X\fR.
The
.BR CR ,
.BR NL
and
.BR TAB
characters are echoed with their normal effect unless they are escaped by
.BR LNEXT .
.TP
.B ECHOE
If
.B ICANON
and
.B ECHO
are set then echo
.B ERASE
and
.B KILL
as one or more backspace-space-backspace sequences to wipe out the last
character or the entire line, otherwise they are echoed as they are.
.TP
.B ECHOK
If
.B ICANON
and
.B ECHO
are set and
.B ECHOE
is not set then output an
.B NL
after the
.B KILL
character. (For hardcopy terminals it is best to unset
.B ECHOE
and to set
.BR ECHOK .)
.TP
.B ECHONL
Echo
.B NL
even if
.B ECHO
is not set, but
.B ICANON
is set.
.TP
.B ICANON
Canonical input. This enables line oriented input and erase and kill
processing.
.TP
.B IEXTEN
Enable implementation defined input extensions.
.TP
.B ISIG
Enable the signal characters
.BR INTR ,
.BR QUIT
and
.BR SUSP .
.TP
.B NOFLSH
Disable the flushing of the input and output queues that is normally done if
a signal is sent.
.TP
.B TOSTOP
Send a
.B SIGTTOU
signal if job control is implemented and a background process tries to
write. (Minix has no job control.)
.SS "Input and output speed"
The input and output speed are encoded into the
.B c_ispeed
and
.B c_ospeed
fields.
.B <termios.h>
defines the symbols
.BR B0 ,
.BR B50 ,
.BR B75 ,
.BR B110 ,
.BR B134 ,
.BR B150 ,
.BR B200 ,
.BR B300 ,
.BR B600 ,
.BR B1200 ,
.BR B1800 ,
.BR B2400 ,
.BR B4800 ,
.BR B9600 ,
.BR B19200 ,
.BR B38400 ,
.BR B57600
and
.BR B115200
as values used to indicate the given baud rates. The zero baud rate,
.BR B0 ,
if used for the input speed causes the input speed to be equal to the
output speed. Setting the output speed to zero hangs up the line. One
should use the functions
.BR cfgetispeed() ,
.BR cfgetospeed() ,
.BR cfsetispeed()
and
.BR cfsetospeed()
to get or set a speed, because the
.B c_ispeed
and
.B c_ospeed
fields may not be visible under other implementations. (The
.B c_ispeed
and
.B c_ospeed
fields and the
.B B57600
and
.B B115200
symbols are Minix specific.)
.SS "Special characters"
The
.B c_cc
array contains the special characters that can be modified. The array has
length
.B NCCS
and is subscripted by the symbols
.BR VEOF ,
.BR VEOL ,
.BR VERASE ,
.BR VINTR ,
.BR VKILL ,
.BR VMIN ,
.BR VQUIT ,
.BR VTIME ,
.BR VSUSP ,
.BR VSTART ,
.BR VSTOP ,
.BR VREPRINT ,
.BR VLNEXT
and
.BR VDISCARD .
All these symbols are defined in
.BR <termios.h> .
Some implementations may give the same values to the
.B VMIN
and
.B VTIME
subscripts and the
.B VEOF
and
.B VEOL
subscripts respectively, and may ignore changes to
.B START
and
.BR STOP .
(Under Minix all special characters have their own
.I c_cc
slot and can all be modified.)
.SS "Raw I/O Parameters"
The
.B MIN
and
.B TIME
parameters can be used to adjust a raw connection to bursty input.
.B MIN
represents a minimum number of bytes that must be received before a read
call returns.
.B TIME
is a timer of 0.1 second granularity that can be used to time out a read.
Setting either of these parameters to zero has special meaning, which leads
to the following four possibilities:
.TP 5
.B "MIN > 0, TIME > 0"
.B TIME
is an inter-byte timer that is started (and restarted) when a byte is
received. A read succeeds when either the minimum number of characters
is received or the timer expires. Note that the timer starts
.B after
the first character, so the read returns at least one byte.
.TP
.B "MIN > 0, TIME = 0"
Now the timer is disabled, and a reader blocks indefinitely until at least
.B MIN
characters are received.
.TP
.B "MIN = 0, TIME > 0"
.B TIME
is now a read timer that is started when a read is executed. The read will
return if the read timer expires or if at least one byte is input. (Note
that a value of zero may be returned to the reader.)
.TP
.B "MIN = 0, TIME = 0"
The bytes currently available are returned. Zero is returned if no bytes
are available.
.SS "User Level Functions"
Termios attributes are set or examined, and special functions can be
performed by using the functions described in
.BR termios (3).
.SS "Session Leaders and Process Groups"
With the use of the
.B setsid()
function can a process become a session leader. A session leader forms a
process group with a process group id equal to the process id of the session
leader. If a session leader opens a terminal device file then this terminal
becomes the controlling tty of the session leader. Unless the terminal is
already the controlling tty of another process, or unless the
.B O_NOCTTY
flag is used to prevent the allocation of a controlling tty. The process
group of the session leader is now remembered as the terminal process group
for signals sent by the terminal driver. All the children and grandchildren
of the session leader inherit the controlling terminal and process group
until they themselves use
.BR setsid() .
.PP
The controlling tty becomes inaccessible to the children of the session
leader when the session leader exits, and a hangup signal is sent to all
the members of the process group. The input and output queues are flushed
on the last close of a terminal and all attributes are reset to the default
state.
.PP
A special device
.B /dev/tty
is a synonym for the controlling tty of a process. It allows a process to
reach the terminal even when standard input, output and error are
redirected. Opening this device can also be used as a test to see if a
process has a controlling tty or not.
.PP
For Minix a special write-only device
.B /dev/log
exists for processes that want to write messages to the system console.
Unlike the console this device is still accessible when a session leader
exits.
.PP
Minix-vmd also has a
.B /dev/log
device, but this device is read-write. All messages written to the log
device or to the console when X11 is active can be read from
.BR /dev/log .
The system tries to preserve the log buffer over a reboot so that panic
messages reappear in the log if the system happens to crash.
.SS "Pseudo Terminals"
Pseudo ttys allow a process such as a remote login daemon to set up a
terminal for a remote login session. The login session uses a device like
.B /dev/ttyp0
for input and output, and the remote login daemon uses the device
.B /dev/ptyp0
to supply input to or take output from the login session and transfer this
to or from the originating system. So the character flow may be: Local
user input sent to the remote system is written to
.B /dev/ptyp0
by the remote login daemon, undergoes input processing and appears on
.B /dev/ttyp0
as input to the login session. Output from the login session to
.B /dev/ttyp0
undergoes output processing, is read from
.B /dev/ptyp0
by the remote login daemon and is send over to the local system to be
displayed for the user. (So there are only four data streams to worry about
in a pseudo terminal.)
.PP
A pseudo terminal can be allocated by trying to open all the controlling
devices
.BI /dev/pty nn
one by one until it succeeds. Further opens will fail once a pty is open.
The process should now fork, the child should become session leader, open
the tty side of the pty and start a login session.
.PP
If the tty side is eventually closed down then reads from the pty side will
return zero and writes return \-1 with
.B errno
set to
.BR EIO .
If the pty side is closed first then a
.B SIGHUP
signal is sent to the session leader and further reads from the tty side
return zero and writes return \-1 with
.B errno
set to
.BR EIO .
(Special note: A line erase may cause up to three times the size of the
tty input queue to be sent to the pty reader as backspace overstrikes. Some
of this output may get lost if the pty reader cannot accept it all at once
in a single read call.)
.SS "Backwards compatibility"
The
.BR TIOCGETP ,
.BR TIOCSETP ,
.BR TIOCGETC
and
.BR TIOCSETC
ioctl functions that are used by the old
.B sgtty
terminal interface are still supported by the terminal driver by emulation.
Note that these old functions cannot control all termios attributes, so the
terminal must be in a relatively sane state to avoid problems.
.SH FILES
The list below shows all devices that Minix and Minix-vmd have. Not all of
these devices are configured in by default, as indicated by the numbers
(i/j/k, l/m/n) that tell the minimum, default and maximum possible number of
these devices for Minix (i/j/k) and Minix-vmd (l/m/n).
.TP 20
.B /dev/console
System console.
.TP
.B /dev/ttyc[1-7]
Virtual consoles. (0/1/7, 0/1/7)
.TP
.BR /dev/log
Console log device.
.TP
.B /dev/tty0[0-3]
Serial lines. (0/2/2, 4/4/4)
.TP
.B /dev/tty[p-w][0-f]
Pseudo ttys. (0/0/64, 1/32/128)
.TP
.B /dev/pty[p-w][0-f]
Associated pseudo tty controllers.
.SH "SEE ALSO"
.BR stty (1),
.BR termios (3),
.BR setsid (2),
.BR read (2),
.BR write (2).
.SH BUGS
A fair number of flags are not implemented under Minix (yet). Luckily they
are very limited utility and only apply to RS-232, not to the user interface.
.SH AUTHOR
Kees J. Bot (kjb@cs.vu.nl)