DragonFly On-Line Manual Pages

KLD(4)                DragonFly Kernel Interfaces Manual                KLD(4)

NAME
     kld -- dynamic kernel linker facility

DESCRIPTION
     The LKM (Loadable Kernel Modules) facility has been deprecated in
     FreeBSD 3.0 and above in favor of the kld interface.  This interface,
     like its predecessor, allows the system administrator to dynamically add
     and remove functionality from a running system.  This ability also helps
     software developers to develop new parts of the kernel without constantly
     rebooting to test their changes.

     Various types of modules can be loaded into the system.  There are
     several defined module types, listed below, which can be added to the
     system in a predefined way.  In addition, there is a generic type, for
     which the module itself handles loading and unloading.

     The DragonFly system makes extensive use of loadable kernel modules, and
     provides loadable versions of most filesystems, the NFS client and
     server, and all the screen-savers.  kld modules are placed by default in
     the /boot/kernel directory.

     The kld interface is used through the kldload(8), kldunload(8) and
     kldstat(8) programs.

     The kldload(8) program can load either a.out(5) or ELF formatted loadable
     modules.  The kldunload(8) program unloads any given loaded module, if no
     other module is dependent upon the given module.  The kldstat(8) program
     is used to check the status of the modules currently loaded into the
     system.

FILES
     /boot/kernel    directory containing module binaries shipped with the
                     system
     <sys/module.h>  file containing definitions required to compile a kld
                     module
     /usr/share/examples/kld
                     example source code implementing a sample kld module

SEE ALSO
     kldfind(2), kldfirstmod(2), kldload(2), kldnext(2), kldstat(2),
     kldunload(2), kldload(8), kldstat(8), kldunload(8)

HISTORY
     The kld facility appeared in FreeBSD 3.0 and was designed as a
     replacement for the lkm(4) facility, which was similar in functionality
     to the loadable kernel modules facility provided by SunOS 4.1.3.

AUTHORS
     The kld facility was originally implemented by Doug Rabson
     <dfr@FreeBSD.org>.

BUGS
     If a module B, is dependent on another module A, but is not compiled with
     module A as a dependency, then kldload(8) fails to load module B, even if
     module A is already present in the system.

     If multiple modules are dependent on module A, and are compiled with
     module A as a dependency, then kldload(8) loads an instance of module A
     when any of the modules are loaded.

     If a custom entry point is used for a module, and the module is compiled
     as an `ELF' binary, then kldload(8) fails to execute the entry point.

     kldload(8) returns the cryptic message `Exec format error' for any error
     encountered while loading a module.

     When system internal interfaces change, old modules often cannot detect
     this, and such modules when loaded will often cause crashes or mysterious
     failures.

DragonFly 4.7                  December 12, 2014                 DragonFly 4.7