devlinks(1M) manual page
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devlinks - adds /dev entries for miscellaneous devices and pseudo-devices
/usr/sbin/devlinks [ -d ] [ -r rootdir ] [ -t table-file ]
SUNWcsu
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(1M)
is run, since drvconfig(1M)
builds the kernel data structures and the
/devices tree.
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.
- -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.
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.
Example /etc/devlink.tab
fields are:
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.
- /dev
- entries for the
miscellaneous devices for general use
- /devices
- device nodes
- /etc/devlink.tab
- the default rule-file
ddi_create_minor_node(9F)
, disks(1M)
, drvconfig(1M)
,
ports(1M)
, tapes(1M)
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.
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