164 lines
5.0 KiB
Groff
164 lines
5.0 KiB
Groff
.\" Copyright (c) 2003 Hiten M. Pandya
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 1, 2010
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.Dt SYSINIT 9
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.Os
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.Sh NAME
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.Nm SYSINIT ,
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.Nm SYSUNINIT
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.Nd a framework for dynamic kernel initialization
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/kernel.h
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.Fn SYSINIT "uniquifier" "enum sysinit_sub_id subsystem" "enum sysinit_elem_order order" "sysinit_cfunc_t func" "const void *ident"
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.Fn SYSUNINIT "uniquifier" "enum sysinit_sub_id subsystem" "enum sysinit_elem_order order" "sysinit_cfunc_t func" "const void *ident"
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.Sh DESCRIPTION
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.Nm
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is a mechanism for scheduling the execution of initialization and teardown
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routines.
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This is similar to init and fini routines with the addition of explicit
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ordering metadata.
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It allows runtime ordering of subsystem initialization in the kernel as well
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as kernel modules (KLDs).
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.Pp
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The
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.Fn SYSINIT
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macro creates a
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.Vt struct sysinit
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and stores it in a startup linker set.
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The
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.Vt struct sysinit
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type as well as the subsystem identifier constants
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.Pq Dv SI_SUB_*
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and initialization ordering constants
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.Pq Dv SI_ORDER_*
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are defined in
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.In sys/kernel.h :
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.Bd -literal
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struct sysinit {
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enum sysinit_sub_id subsystem; /* subsystem identifier*/
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enum sysinit_elem_order order; /* init order within subsystem*/
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sysinit_cfunc_t func; /* function */
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const void *udata; /* multiplexer/argument */
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};
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.Ed
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.Pp
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The
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.Fn SYSINIT
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macro takes a
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.Fa uniquifier
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argument to identify the particular function dispatch data,
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the
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.Fa subsystem
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type of startup interface, the subsystem element
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.Fa order
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of initialization within the subsystem, the
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.Fa func
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function to call,
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and the data specified in
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.Fa ident
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argument to pass the function.
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.Pp
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The
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.Fn SYSUNINIT
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macro behaves similarly to the
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.Fn SYSINIT
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macro except that it adds the data to a shutdown linker set.
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.Pp
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The startup linker set for the kernel is scanned during boot to build a
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sorted list of initialization routines.
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The initialization routines are then executed in the sorted order.
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The
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.Fa subsystem
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is used as the primary key and is sorted in ascending order.
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The
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.Fa order
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is used as the secondary key and is sorted in ascending order.
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The relative order of two routines that have the same
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.Fa subsystem
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and
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.Fa order
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is undefined.
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.Pp
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The startup linker sets for modules that are loaded together with the kernel
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by the boot loader are scanned during the
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.Dv SI_SUB_KLD
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subsystem initialization.
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These modules' initialization routines are sorted and merged into the kernel's
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list of startup routines and are executed during boot along with the kernel's
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initialization routines.
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Note that this has the effect that any initialization routines in a kernel
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module that are scheduled earlier than
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.Dv SI_SUB_KLD
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are not executed until after
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.Dv SI_SUB_KLD
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during boot.
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.Pp
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The startup linker set for a kernel module loaded at runtime via
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.Xr kldload 2
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is scanned, sorted, and executed when the module is loaded.
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.Pp
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The shutdown linker set for a kernel module is scanned, sorted, and executed
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when a kernel module is unloaded.
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The teardown routines are sorted in the reverse order of the initialization
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routines.
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The teardown routines of the kernel and any loaded modules are
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.Sy not
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executed during shutdown.
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.Sh EXAMPLES
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This example shows the SYSINIT which displays the copyright notice during boot:
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.Bd -literal -offset indent
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static void
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print_caddr_t(void *data)
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{
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printf("%s", (char *)data);
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}
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SYSINIT(announce, SI_SUB_COPYRIGHT, SI_ORDER_FIRST, print_caddr_t,
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copyright);
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.Ed
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.Sh SEE ALSO
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.Xr kld 4 ,
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.Xr DECLARE_MODULE 9 ,
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.Xr DEV_MODULE 9 ,
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.Xr DRIVER_MODULE 9 ,
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.Xr MTX_SYSINIT 9 ,
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.Xr SYSCALL_MODULE 9
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.Sh HISTORY
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The
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.Nm
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framework first appeared in
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.Fx 2.2 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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framework was written by
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.An Terrence Lambert Aq terry@FreeBSD.org .
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.Pp
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This manual page was written by
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.An Hiten Pandya Aq hmp@FreeBSD.org .
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