kmod/man/modprobe.d.5.scd
Emil Velikov 11d09ac414 man: modprobe.d: document the config file order handling
The modprobe.d configuration order/handling aligns with existing tools
such as sysctl.d, even though there is no mention in the manual.

Reorder the list in SYNOPSIS and add a bit of verbiage describing things.

Section is inspired by sysctl.d(5) and sysctl(8).

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
2024-07-09 00:18:21 -05:00

180 lines
7.6 KiB
Markdown

MODPROBE.D(5) "kmod" "modprobe.d"
# NAME
modprobe.d - Configuration directory for modprobe
# SYNOPSIS
@SYSCONFDIR@/modprobe.d/\*.conf
/run/modprobe.d/\*.conf
/usr/local/lib/modprobe.d/\*.conf
@DISTCONFDIR@/modprobe.d/\*.conf
/lib/modprobe.d/\*.conf
# DESCRIPTION
Because the *modprobe* command can add or remove more than one module, due to
modules having dependencies, we need a method of specifying what options are to
be used with those modules. One can also use them to create convenient aliases:
alternate names for a module, or they can override the normal *modprobe*
behavior altogether for those with special requirements (such as inserting more
than one module).
Note that module and alias names (like other module names) can have - or \_ in
them: both are interchangeable throughout all the module commands as underscore
conversion happens automatically.
The format of files under modprobe.d is simple: one command per line, with blank
lines and lines starting with '#' ignored (useful for adding comments). A '\\'
at the end of a line causes it to continue on the next line, which makes the
file a bit neater.
# CONFIGURATION DIRECTORIES AND PRECEDENCE
Configuration files are read from directories in listed in SYNOPSYS in that
order of precedence. Once a file of a given filename is loaded, any file of the
same name in subsequent directories is ignored.
All configuration files are sorted in lexicographic order, regardless of the
directory they reside in. Configuration files can either be completely replaced
(by having a new configuration file with the same name in a directory of higher
priority) or partially replaced (by having a configuration file that is ordered
later).
# COMMANDS
alias _wildcard_ _modulename_
This allows you to give alternate names for a module. For example:
"alias my-mod really_long_modulename" means you can use "modprobe
my-mod" instead of "modprobe really_long_modulename". You can also use
shell-style wildcards, so "alias my-mod\* really_long_modulename" means
that "modprobe my-mod-something" has the same effect. You can't have
aliases to other aliases (that way lies madness), but aliases can have
options, which will be added to any other options.
Note that modules can also contain their own aliases, which you can see
using *modinfo*. These aliases are used as a last resort (ie. if there
is no real module, *install*, *remove*, or *alias* command in the
configuration).
blacklist _modulename_
Modules can contain their own aliases: usually these are aliases
describing the devices they support, such as "pci:123...". These
"internal" aliases can be overridden by normal "alias" keywords, but
there are cases where two or more modules both support the same devices,
or a module invalidly claims to support a device that it does not: the
*blacklist* keyword indicates that all of that particular module's
internal aliases are to be ignored.
install _modulename_ _command..._
This command instructs *modprobe* to run your command instead of
inserting the module in the kernel as normal. The command can be any
shell command: this allows you to do any kind of complex processing you
might wish. For example, if the module "fred" works better with the
module "barney" already installed (but it doesn't depend on it, so
*modprobe* won't automatically load it), you could say "install fred
/sbin/modprobe barney; /sbin/modprobe --ignore-install fred", which
would do what you wanted. Note the *--ignore-install*, which stops the
second *modprobe* from running the same *install* command again. See
also *remove* below.
The long term future of this command as a solution to the problem of
providing additional module dependencies is not assured and it is
intended to replace this command with a warning about its eventual
removal or deprecation at some point in a future release. Its use
complicates the automated determination of module dependencies by
distribution utilities, such as mkinitrd (because these now need to
somehow interpret what the *install* commands might be doing. In a
perfect world, modules would provide all dependency information without
the use of this command and work is underway to implement soft
dependency support within the Linux kernel.
If you use the string "$CMDLINE_OPTS" in the command, it will be
replaced by any options specified on the modprobe command line. This can
be useful because users expect "modprobe fred opt=1" to pass the "opt=1"
arg to the module, even if there's an install command in the
configuration file. So our above example becomes "install fred
/sbin/modprobe barney; /sbin/modprobe --ignore-install fred
$CMDLINE_OPTS"
options _modulename_ _option..._
This command allows you to add options to the module _modulename_ (which
might be an alias) every time it is inserted into the kernel: whether
directly (using *modprobe* _modulename_) or because the module being
inserted depends on this module.
All options are added together: they can come from an *option* for the
module itself, for an alias, and on the command line.
remove _modulename_ _command..._
This is similar to the *install* command above, except it is invoked
when "modprobe -r" is run.
softdep _modulename_ pre: _modules..._ post: _modules..._
The *softdep* command allows you to specify soft, or optional, module
dependencies. _modulename_ can be used without these optional modules
installed, but usually with some features missing. For example, a driver
for a storage HBA might require another module be loaded in order to use
management features.
pre-deps and post-deps modules are lists of names and/or aliases of
other modules that modprobe will attempt to install (or remove) in order
before and after the main module given in the _modulename_ argument.
Example: Assume "softdep c pre: a b post: d e" is provided in the
configuration. Running "modprobe c" is now equivalent to "modprobe a b c
d e" without the softdep. Flags such as --use-blacklist are applied to
all the specified modules, while module parameters only apply to module
c.
Note: if there are *install* or *remove* commands with the same
_modulename_ argument, *softdep* takes precedence.
weakdep _modulename_ _modules..._
The *weakdep* command allows you to specify weak module dependencies.
Those are similar to pre softdep, with the difference that userspace
doesn't attempt to load that dependency before the specified module.
Instead the kernel may request one or multiple of them during module
probe, depending on the hardware it's binding to. The purpose of weak
module is to allow a driver to specify that a certain dependency may be
needed, so it should be present in the filesystem (e.g. in initramfs)
when that module is probed.
Example: Assume "weakdep c a b". A program creating an initramfs knows
it should add a, b, and c to the filesystem since a and b may be
required/desired at runtime. When c is loaded and is being probed, it
may issue calls to request_module() causing a or b to also be loaded.
# COMPATIBILITY
A future version of kmod will come with a strong warning to avoid use of the
*install* as explained above. This will happen once support for soft
dependencies in the kernel is complete. That support will complement the
existing softdep support within this utility by providing such dependencies
directly within the modules.
# COPYRIGHT
This manual page originally Copyright 2004, Rusty Russell, IBM Corporation.
Maintained by Jon Masters and others.
# SEE ALSO
*modprobe*(8), *modules.dep*(5)
# AUTHORS
*Jon Masters* <jcm@jonmasters.org>
Developer
*Robby Workman* <rworkman@slackware.com>
Developer
*Lucas De Marchi* <lucas.de.marchi@gmail.com>
Developer