depmod
DEPMOD(8) Linux Module Support DEPMOD(8)NAME
depmod - handle dependency descriptions for loadable ker nel modulesSYNOPSIS
depmod -[aA] [-enqsvVru] [-C configfile] [-F kernelsyms] [-b basedirectory] [forced_version] depmod [-enqsvru] [-F kernelsyms] module1.o module2.o ...OPTIONS
-a Search for modules in all directories specified in the (optional) configuration file /etc/mod ules.conf. -A Compare file timestamps and, if necessary, act like depmod -a. This option only updates the dependency file if anything has changed. -e Show all the unresolved symbol for each module. -i Ignore symbol versions when building dependency list. This is useful especially if you use a ver sioned kernel and want to build dependencies against a System.map file (see the -F option). Use this with care, because if the symbol versions don't match, modprobe or insmod won't be able to load the modules eventhough depmod succeeds. -n Write the dependency file on stdout instead of in the /lib/modules tree. -s Write all error messages via the syslog daemon instead of stderr. -v Show the name of each module as it is being pro cessed. -q Tell depmod to keep quiet and not to complain about missing symbols. -V Show the release version name of depmod -r 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 mod ules that are not owned by root. Use of -r is a major security exposure and is not recommended. -u 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. The following options are useful for people managing dis tributions; -b 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 environ ment, the basedirectory 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 basedi rectory path. This means that when the file tree is moved back from basedirectory/lib/modules into /lib/modules in the final distribution, all refer ences will be correct. -C configfile Use the file configfile instead of /etc/mod ules.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)). -F kernelsyms When building dependency files for a different ker nel than the currently running kernel, it is impor tant 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 tem.map from the other kernel, or a copy of the output from /proc/ksyms. If your kernel uses ver sioned symbols, you must use a copy of the /proc/ksyms output, since that file contains the symbol versions of the kernel symbols, unless you use the -i option. For compatibility, -m kernel syms is identical to -F kernelsymsDESCRIPTION
The depmod and modprobe utilities are intended to make a Linux modular kernel manageable for all users, administra tors 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 module or stack of modules. The normal use of depmod is to include the line /sbin/dep mod -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 now is optional. For boot-up pur poses, the option -q might be more appropriate since that make depmod silent about unresolved symbols. It is also possible to create the dependency file immedi ately after compiling a new kernel. If you do "depmod -a 2.2.99" when you have compiled kernel 2.2.99 and its mod ules 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. 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 mod ules_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)AUTHOR
Jacques Gelinas (jack@solucorp.qc.ca) Bjorn Ekwall (bj0rn@blox.se) Linux August 15, 2001 DEPMOD(8)