depmod (8)


       depmod - handle dependency descriptions for loadable kernel modules


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


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

       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 module
       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 run-
       ning  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  guaran-
       teed  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.


       -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

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

       -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

       -u, --unresolved-error
              depmod  2.4  does not set a return code when there are any unre-
              solved 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.  dep-
              mod  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
              different 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/mod-
              ules  in the final distribution, all references will be correct.

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

       -F kernelsyms,--filesyms kernelsyms
              When  building  dependency files for a different kernel than the
              currently running kernel, it is important that depmod  uses  the
              correct  set  of kernel symbols to resolve the kernel references
              in each module.  These symbols can either  be  a  copy  of  Sys-
      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 con-
              tains the symbol versions of the kernel  symbols.   However  you
              can use a even with versioned symbols.


       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.


       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/mod-

       This  is  the  default  strategy,  which can be overridden in /etc/mod-


       /etc/modules.conf (alternatively but deprecated /etc/conf.modules)


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


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


       Jacques Gelinas (
       Bjorn Ekwall (

Linux                          January 26, 2002                      depmod(8)