.\" -*- nroff -*-
.TH DEVINFO 5 "January 1995" "Version 1.4"
.SH NAME
DEVINFO \- device entry database
.SH DESCRIPTION
.B DEVINFO 
is a text file that describes all the possible devices for a system.
It is used by
.BR MAKEDEV (8)
to create special file entries in 
.BR /dev .
It may be named either
.BR /dev/DEVINFO " or " /etc/devinfo .
Information about custom local devices, if any, should be placed in
.BR DEVINFO.local " or " /etc/devinfo.local ,
which has the same syntax.
.LP
The file format is free-form. Both C, C++, and shell comments are
understood. There are basically four statements:
.TP
.RI "ignore { " proc-device... " }"
This causes the specified names to be ignored if found in
.BR /proc/devices .
.TP
.RI "batch { " device... " }"
This creates a "batch" \- a collection of devices which will all be
created when the batch is invoked. For example, in the standard 
.BR DEVINFO ,
"generic" is a batch.
.TP
.RI "block " device-spec
This defines one or more block devices.
.TP
.RI "char " device-spec
This defines one or more character devices.
.LP
Here is a sample
.IR device-spec :
.RS
.nf
(std, 1) {
    mem (kmem) : 1
    null (public) : 3
    core -> "/proc/kcore"
}
.fi
.RE
.LP
This example defines a group of devices called "std", with major
number 1. Running
.B "\"MAKEDEV std\""
will create all the devices in the group; running, for example,
.B "\"MAKEDEV null\""
would make just the one device "null".
.LP
It is possible to specify, instead of just "std", something like
"std=foo". In this case, the stuff on the right-hand side of the
equals sign specifies a name from 
.BR /proc/devices ,
and the major number will be retrieved from there if present. If an
entry from 
.BR /proc/devices
is specified, the explicit major number may be omitted. In this case,
if the number is not found in /proc/devices, attempts to create the
device will be rejected.
.LP
Inside the braces is a list of specific devices. The name in
parenthesis is the "class" - this is something specified in 
.B MAKEDEV.cfg
(q.v.) that determines the ownership and permissions of the special
file created. In the above example, the device "mem" was set to have
the class "kmem", but "null" was set to be "public". Ordinarily you'd
define "public" to be mode 666, but "kmem" to be mode 660 and owned by
group kmem. The number after the colon is the minor number for this
particular device \- for instance, 3 for "null".
.LP
You may also specify a symbolic link with "->". For instance, above,
"core" was made a link to 
.BR /proc/kcore .
Note that names may contain any characters, but names that contain
things other than alphanumerics, dash, and underscore should be put in
double quotes.
.LP
An entire range of devices can be created: you may specify a range of
numbers in brackets, like this:
.RS
.nf

tty[1-8] (tty) : 1

.fi
.RE
This creates tty1\-tty8 with minor device numbers starting with 1.
If you specify the range in hex (prefixed by 0x) the device names will
be created numbered in hex, as is normal for ptys. The range may
appear inside the name string, but there may only be one range.
.LP
There is a special syntax for creating the entire banks of devices for
a hard drive:
.RS
.nf

    hd[a-d] 8/64

.fi
.RE
What this means is as follows: create hda, and 8 partitions on hda
(hda1 through hda8), starting with minor number 0. Then create hdb,
and 8 partitions, starting with minor number 64. Then hdc, etc., with
minor number 64*2 = 128. And so forth. These are automatically placed
in the class "disk". The necessary groups and batches are created so
you can ask 
.B MAKEDEV
to create "hd" or "hda" or "hda1" and expect it to do the correct
thing. 
.LP
Note that simple arithmetic is permitted for specifying the minor
device number, as this often makes things much clearer and less likely
to be accidentally broken.
.SH "SEE ALSO"
.BR MAKEDEV (8),
.BR MAKEDEV.cfg (5)