>> kld (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
kld
- dynamic kernel linker facility
DESCRIPTION
The LKM (Loadable Kernel Modules) facility has been deprecated in
Fx 3.0
and above in favor of the
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
Fx system makes extensive use of loadable kernel modules, and provides loadable
versions of most file systems, the
NFS
client and server, all the screen-savers, and the
iBCS2
and
Linux
emulators.
modules are placed by default in the
/boot/kernel
directory along with their matching kernel.
The
kldload(8)
program can load either
a.out5
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.
Kernel modules may only be loaded or unloaded if the system security level
kern.securelevel
is less than one.
MODULE TYPES
Device Driver modules
New block and character device
drivers may be loaded into the system with
.
Device nodes for the loaded drivers are automatically created when a
module is loaded and destroyed when it is unloaded by
devfs(5).
You can specify userland programs that will run when new devices
become available as a result of loading modules, or existing devices
go away when modules are unloaded, by configuring
devd(8).
FILES
/boot/kernel
directory containing module binaries built for the kernel also
residing in the directory.
/usr/include/sys/module.h
file containing definitions required to compile a
module
/usr/share/examples/kld
example source code implementing a sample kld module
The
facility appeared in
Fx 3.0
and was designed as a replacement for the
lkm
facility, which was similar in functionality to the loadable kernel modules
facility provided by
SunOS
4.1.3.
AUTHORS
The
facility was originally implemented by
An Doug Rabson Aq 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
`ENOEXEC (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.
