NAME¶
SYSINIT
,
SYSUNINIT
—
a framework for dynamic kernel initialization
SYNOPSIS¶
#include
<sys/param.h>
#include
<sys/kernel.h>
SYSINIT
(
uniquifier,
enum sysinit_sub_id
subsystem,
enum
sysinit_elem_order order,
sysinit_cfunc_t
func,
const void
*ident);
SYSUNINIT
(
uniquifier,
enum sysinit_sub_id
subsystem,
enum
sysinit_elem_order order,
sysinit_cfunc_t
func,
const void
*ident);
DESCRIPTION¶
SYSINIT
is a mechanism for scheduling the
execution of initialization and teardown routines. This is similar to init and
fini routines with the addition of explicit ordering metadata. It allows
runtime ordering of subsystem initialization in the kernel as well as kernel
modules (KLDs).
The
SYSINIT
() macro creates a
struct sysinit and stores it in a startup
linker set. The
struct sysinit type as well
as the subsystem identifier constants
(
SI_SUB_*
) and initialization ordering
constants (
SI_ORDER_*
) are defined in
<sys/kernel.h>
:
struct sysinit {
enum sysinit_sub_id subsystem; /* subsystem identifier*/
enum sysinit_elem_order order; /* init order within subsystem*/
sysinit_cfunc_t func; /* function */
const void *udata; /* multiplexer/argument */
};
The
SYSINIT
() macro takes a
uniquifier argument to identify the
particular function dispatch data, the
subsystem type of startup interface, the
subsystem element
order of initialization
within the subsystem, the
func function to
call, and the data specified in
ident
argument to pass the function.
The
SYSUNINIT
() macro behaves similarly to
the
SYSINIT
() macro except that it adds the
data to a shutdown linker set.
The startup linker set for the kernel is scanned during boot to build a sorted
list of initialization routines. The initialization routines are then executed
in the sorted order. The
subsystem is used as
the primary key and is sorted in ascending order. The
order is used as the secondary key and is
sorted in ascending order. The relative order of two routines that have the
same
subsystem and
order is undefined.
The startup linker sets for modules that are loaded together with the kernel by
the boot loader are scanned during the
SI_SUB_KLD
subsystem initialization. These
modules' initialization routines are sorted and merged into the kernel's list
of startup routines and are executed during boot along with the kernel's
initialization routines. Note that this has the effect that any initialization
routines in a kernel module that are scheduled earlier than
SI_SUB_KLD
are not executed until after
SI_SUB_KLD
during boot.
The startup linker set for a kernel module loaded at runtime via
kldload(2) is scanned, sorted, and executed when
the module is loaded.
The shutdown linker set for a kernel module is scanned, sorted, and executed
when a kernel module is unloaded. The teardown routines are sorted in the
reverse order of the initialization routines. The teardown routines of the
kernel and any loaded modules are
not executed
during shutdown.
EXAMPLES¶
This example shows the SYSINIT which displays the copyright notice during boot:
static void
print_caddr_t(void *data)
{
printf("%s", (char *)data);
}
SYSINIT(announce, SI_SUB_COPYRIGHT, SI_ORDER_FIRST, print_caddr_t,
copyright);
SEE ALSO¶
kld(4),
DECLARE_MODULE(9),
DEV_MODULE(9),
DRIVER_MODULE(9),
MTX_SYSINIT(9),
SYSCALL_MODULE(9)
HISTORY¶
The
SYSINIT
framework first appeared in
FreeBSD 2.2.
AUTHORS¶
The
SYSINIT
framework was written by
Terrence Lambert
⟨terry@FreeBSD.org⟩.
This manual page was written by
Hiten Pandya
⟨hmp@FreeBSD.org⟩.