DEPMOD(8)						       Linux Module Support							 DEPMOD(8)

NAME

       depmod - handle dependency descriptions for loadable kernel modules

SYNOPSIS

       depmod [-aA] [-ehnqrsuvV] [-C configfile] [-F kernelsyms] [-b basedirectory] [forced_version]
       depmod [-enqrsuv] [-F kernelsyms] module1.o module2.o ...

DESCRIPTION

       The  depmod  and  modprobe  utilities are intended to make a Linux modular kernel manageable for all users, administrators and distribution
       maintainers.

       Depmod creates a "Makefile"-like dependency file, based on the symbols it finds in the set of modules mentioned on the command line or from
       the directories specified in the configuration file.  This dependency file is later used by modprobe to automatically load the correct mod-
       ule or stack of modules.

       The normal use of depmod is to include the line

       /sbin/depmod -a

       somewhere in the rc-files in /etc/rc.d, so that the correct module dependencies will be available immediately  after  booting  the  system.
       Note  that  the	option	-a  is now optional.  For boot-up purposes, the option -q might be more appropriate since that makes depmod silent
       about unresolved symbols.

       It is also possible to create the dependency file immediately after compiling a new kernel.  If you do  "depmod -a 2.2.99"  when  you  have
       compiled  kernel 2.2.99 and its modules the first time, while still running e.g. 2.2.98, the file will be created in the correct place.	In
       this case however, the dependencies on the kernel will not be guaranteed to be correct.	See  the  options  -F, -C and -b  above  for  more
       information on handling this.

       While  building	the relationship between modules and the symbols exported by other modules, depmod does not consider the GPL status of the
       modules nor of the exported symbols.  That is, depmod will not flag an error if a module without a GPL compatible license refers to  a  GPL
       only  symbol  (EXPORT_SYMBOL_GPL  in the kernel).  However insmod will refuse to resolve GPL only symbols for non-GPL modules so the actual
       load will fail.

OPTIONS

       -a, --all
	      Search for modules in all directories specified in the (optional) configuration file /etc/modules.conf.

       -A, --quick
	      Compare file timestamps and, if necessary, act like depmod -a.  This option  only  updates  the  dependency  file  if  anything  has
	      changed.

       -e, --errsyms
	      Show all the unresolved symbols for each module.

       -h, --help
	      Display a summary of options and immediately exit.

       -n, --show
	      Write the dependency file on stdout instead of in the /lib/modules tree.

       -q, --quiet
	      Tell depmod to keep quiet and not to complain about missing symbols.

       -r, --root
	      Some  users  compile  modules under a non-root userid then install the modules as root.  This process can leave the modules owned by
	      the non-root userid, even though the modules directory is owned by root.	If the non-root userid is  compromised,  an  intruder  can
	      overwrite existing modules owned by that userid and use this exposure to bootstrap up to root access.

	      By  default,  modutils  will  reject  attempts to use a module that is not owned by root.  Specifying -r will suppress the error and
	      allow root to load modules that are not owned by root.

	      Use of -r is a major security exposure and is not recommended.

       -s, --syslog
	      Write all error messages via the syslog daemon instead of stderr.

       -u, --unresolved-error
	      depmod 2.4 does not set a return code when there are any unresolved symbols.  The next major release of modutils (2.5)  will  set  a
	      return  code  for  unresolved  symbols.	Some distributions want a non-zero return code in modutils 2.4 but that change might cause
	      problems for users who expect the old behaviour.	If you want a non-zero return code in depmod 2.4, specify  -u.	 depmod  2.5  will
	      silently ignore the -u flag and will always give a non-zero return code for unresolved symbols.

       -v, --verbose
	      Show the name of each module as it is being processed.

       -V, --version
	      Display the version of depmod.

       The following options are useful for people managing distributions:

       -b basedirectory, --basedir basedirectory
	      If the directory tree /lib/modules containing the sub-trees of modules is moved somewhere else in order to handle modules for a dif-
	      ferent environment, the -b option tells depmod where to find the moved image of the /lib/modules tree.  The file references  in  the
	      depmod output file that is built, modules.dep, will not contain the basedirectory path.  This means that when the file tree is moved
	      back from basedirectory/lib/modules into /lib/modules in the final distribution, all references will be correct.

       -C configfile, --config configfile
	      Use the file configfile instead of /etc/modules.conf.  The environment variable MODULECONF can also be used to  select  a  different
	      configuration file from the default /etc/modules.conf (or /etc/conf.modules (deprecated)).

       When environment variable
	      UNAME_MACHINE is set, modutils will use its value instead of the machine field from the uname() syscall.	This is mainly of use when
	      you are compiling 64 bit modules in 32 bit user space or vice versa, set UNAME_MACHINE to the type of the modules being built.  Cur-
	      rent  modutils  does  not support full cross build mode for modules, it is limited to choosing between 32 and 64 bit versions of the
	      host architecture.

       -F kernelsyms,--filesyms kernelsyms
	      When building dependency files for a different kernel than the currently running kernel, it is important that depmod uses  the  cor-
	      rect  set  of kernel symbols to resolve the kernel references in each module.  These symbols can either be a copy of System.map from
	      the other kernel, or a copy of the output from /proc/ksyms.  If your kernel uses versioned symbols, it is best to use a copy of  the
	      /proc/ksyms  output, since that file contains the symbol versions of the kernel symbols.	However you can use a System.map even with
	      versioned symbols.

CONFIGURATION

       The behavior of depmod and modprobe can be adjusted by the (optional) configuration file /etc/modules.conf.
       See modprobe(8) and modules.conf(5) for a complete description.

STRATEGY

       Each time you compile a new kernel, the command "make modules_install" will create a new directory, but won't change the default.

       When you get a module unrelated to the kernel distribution you should  place  it  in  one  of  the  version-independent	directories  under
       /lib/modules.

       This is the default strategy, which can be overridden in /etc/modules.conf.

FILES

       /etc/modules.conf (alternatively but deprecated /etc/conf.modules)
       /lib/modules/*/modules.dep,
       /lib/modules/*

SEE ALSO

       modules.conf(5), modprobe(8), modinfo(8), lsmod(8), ksyms(8)

BUGS

       depmod [ -V | --version ] should exit immediately.  Instead, it prints the version information and behaves as if no options were given.

AUTHORS

       Jacques Gelinas (jack@solucorp.qc.ca)
       Bjorn Ekwall (bj0rn@blox.se)

Linux								 January 26, 2002							 DEPMOD(8)