DEVLINKS(8) Maintenance Commands and Procedures DEVLINKS(8)

NAME

devlinks - adds /dev entries for miscellaneous devices and pseudo-
devices

SYNOPSIS

/usr/sbin/devlinks [-d] [-r rootdir] [-t table-file]

DESCRIPTION

devfsadm(8) is now the preferred command for /dev and /devices and
should be used instead of devlinks.


devlinks creates symbolic links from the /dev directory tree to the
actual block- and character-special device nodes under the /devices
directory tree. The links are created according to specifications
found in the table-file (by default /etc/devlink.tab).


devlinks is called each time the system is reconfiguration-booted,
and can only be run after drvconfig(8) is run.


The table-file (normally /etc/devlink.tab) is an ASCII file, with one
line per record. Comment lines, which must contain a hash character
(`#') as their first character, are allowed. Each entry must contain
at least two fields, but may contain three fields. Fields are
separated by single TAB characters.


The fields are:

devfs-spec
Specification of devinfo nodes that will have links
created for them. This specification consists of
one or more keyword-value pairs, where the keyword
is separated from the value by an equal-sign (`='),
and keyword-value pairs are separated from one
another by semicolons.

The possible keywords are:

type
The devinfo device type. Possible
values are specified in
ddi_create_minor_node(9F)


name
The name of the node. This is the
portion of the /devices tree entry name
that occurs before the first `@' or `:'
character.


addr[n]
The address portion of a node name.
This is the portion of a node name that
occurs between the `@' and the `:'
characters. It is possible that a node
may have a name without an address
part, which is the case for many of the
pseudo-device nodes. If a number is
given after the addr it specifies a
match of a particular comma-separated
subfield of the address field: addr1
matches the first subfield, addr2
matches the second, and so on. addr0 is
the same as addr and matches the whole
field.


minor[n]
The minor portion of a node name - the
portion of the name after the `:'. As
with addr above, a number after the
minor keyword specifies a subfield to
match.

Of these four specifications, only the type
specification must always be present.


name
Specification of the /dev links that correspond to
the devinfo nodes. This field allows devlinks to
determine matching /dev names for the /devices
nodes it has found. The specification of this field
uses escape-sequences to allow portions of the
/devices name to be included in the /dev name, or
to allow a counter to be used in creating node
names. If a counter is used to create a name, the
portion of the name before the counter must be
specified absolutely, and all names in the
/dev/-subdirectory that match (up to and including
the counter) are considered to be subdevices of the
same device. This means that they should all point
to the same directory, name and address under the
/devices/-tree

The possible escape-sequences are:

\D
Substitute the device-name (name) portion
of the corresponding devinfo node-name.


\An
Substitute the nth component of the address
component of the corresponding devinfo node
name. Sub-components are separated by
commas, and sub-component 0 is the whole
address component.


\Mn
Substitute the nth sub-component of the
minor component of the corresponding
devinfo node name. Sub-components are
separated by commas, and sub-component 0 is
the whole minor component.


\Nn
Substitute the value of a 'counter'
starting at n. There can be only one
counter for each dev-spec, and counter-
values will be selected so they are as low
as possible while not colliding with
already-existing link names.

In a dev-spec the counter sequence should
not be followed by a digit, either
explicitly or as a result of another
escape-sequence expansion. If this occurs,
it would not be possible to correctly match
already-existing links to their counter
entries, since it would not be possible to
unambiguously parse the already-existing
/dev-name.


extra-dev-link
Optional specification of an extra /dev link that
points to the initial /dev link (specified in field
2). This field may contain a counter escape-
sequence (as described for the dev-spec field) but
may not contain any of the other escape-sequences.
It provides a way to specify an alias of a
particular /dev name.

OPTIONS

The following options are supported:

-d
Debugging mode - print out all devinfo nodes found,
and indicate what links would be created, but do not
do anything.


-r rootdir
Use rootdir as the root of the /dev and /devices
directories under which the device nodes and links
are created. Changing the root directory does not
change the location of the /etc/devlink.tab default
table, nor is the root directory applied to the
filename supplied to the -t option.


-t table-file
Set the table file used by devlinks to specify the
links that must be created. If this option is not
given, /etc/devlink.tab is used. This option gives a
way to instruct devlinks just to perform a
particular piece of work, since just the links-types
that devlinks is supposed to create can be specified
in a command-file and fed to devlinks.

ERRORS

If devlinks finds an error in a line of the table-file it prints a
warning message on its standard output and goes on to the next line
in the table-file without performing any of the actions specified by
the erroneous rule.


If it cannot create a link for some filesystem-related reason it
prints an error-message and continues with the current rule.


If it cannot read necessary data it prints an error message and
continues with the next table-file line.

EXAMPLES

Example 1: Using the /etc/devlink.tab Fields

The following are examples of the /etc/devlink.tab fields:


type=pseudo;name=win win\M0
type=ddi_display framebuffer/\M0 fb\N0


The first example states that all devices of type pseudo with a name
component of win will be linked to /dev/winx, where x is the minor-
component of the devinfo-name (this is always a single-digit number
for the win driver).


The second example states that all devinfo nodes of type ddi_display
will be linked to entries under the /dev/framebuffer directory, with
names identical to the entire minor component of the /devices name.
In addition an extra link will be created pointing from /dev/fbn to
the entry under /dev/framebuffer. This entry will use a counter to
end the name.

FILES

/dev
entries for the miscellaneous devices for general
use


/devices
device nodes


/etc/devlink.tab
the default rule-file

SEE ALSO

devfs(4FS), attributes(7), devfsadm(8), ddi_create_minor_node(9F)

BUGS

It is very easy to construct mutually-contradictory link
specifications, or specifications that can never be matched. The
program does not check for these conditions.

July 15, 2002 DEVLINKS(8)