Fix errors reported by textproc/igor:
- wrap long line - use two spaces at sentence start - use tabs instead of spaces - space after content - straggling <tag> Event: vBSDcon FreeBSD Hackathon
This commit is contained in:
Benedict Reuschling
parent
de67b5b784
commit
24285bff3c
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=53372
1 changed files with 62 additions and 52 deletions
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@ -4,26 +4,38 @@
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$FreeBSD$
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-->
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<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="sysinit">
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<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
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xml:id="sysinit">
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<title>The SYSINIT Framework</title>
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<indexterm><primary>SYSINIT</primary></indexterm>
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<indexterm><primary>dynamic initialization</primary></indexterm>
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<indexterm><primary>kernel initialization</primary>
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<secondary>dynamic</secondary></indexterm>
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<indexterm><primary>kernel modules</primary></indexterm>
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<indexterm><primary>kernel linker</primary></indexterm>
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<indexterm>
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<primary>SYSINIT</primary>
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</indexterm>
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<indexterm>
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<primary>dynamic initialization</primary>
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</indexterm>
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<indexterm>
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<primary>kernel initialization</primary>
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<secondary>dynamic</secondary>
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</indexterm>
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<indexterm>
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<primary>kernel modules</primary>
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</indexterm>
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<indexterm>
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<primary>kernel linker</primary>
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</indexterm>
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<para>SYSINIT is the framework for a generic call sort and dispatch
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mechanism. FreeBSD currently uses it for the dynamic
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initialization of the kernel. SYSINIT allows FreeBSD's kernel
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mechanism. FreeBSD currently uses it for the dynamic
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initialization of the kernel. SYSINIT allows FreeBSD's kernel
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subsystems to be reordered, and added, removed, and replaced at
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kernel link time when the kernel or one of its modules is loaded
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without having to edit a statically ordered initialization routing
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and recompile the kernel. This system also allows kernel modules,
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and recompile the kernel. This system also allows kernel modules,
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currently called <firstterm>KLD's</firstterm>, to be separately
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compiled, linked, and initialized at boot time and loaded even
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later while the system is already running. This is accomplished
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later while the system is already running. This is accomplished
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using the <quote>kernel linker</quote> and <quote>linker
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sets</quote>.</para>
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@ -32,13 +44,13 @@
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<variablelist>
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<varlistentry>
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<term>Linker Set</term>
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<listitem>
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<para>A linker technique in which the linker gathers
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statically declared data throughout a program's source files
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into a single contiguously addressable unit of
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data.</para>
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</listitem>
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<term>Linker Set</term>
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<listitem>
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<para>A linker technique in which the linker gathers
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statically declared data throughout a program's source
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files into a single contiguously addressable unit of
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data.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect1>
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@ -51,24 +63,25 @@
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<para>SYSINIT relies on the ability of the linker to take static
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data declared at multiple locations throughout a program's
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source and group it together as a single contiguous chunk of
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data. This linker technique is called a <quote>linker
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set</quote>. SYSINIT uses two linker sets to maintain two data
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data. This linker technique is called a <quote>linker
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set</quote>. SYSINIT uses two linker sets to maintain two data
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sets containing each consumer's call order, function, and a
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pointer to the data to pass to that function.</para>
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<para>SYSINIT uses two priorities when ordering the functions for
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execution. The first priority is a subsystem ID giving an
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overall order for SYSINIT's dispatch of functions. Current predeclared
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ID's are in <filename><sys/kernel.h></filename> in the enum
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list <literal>sysinit_sub_id</literal>. The second priority used
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is an element order within the subsystem. Current predeclared
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subsystem element orders are in
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overall order for SYSINIT's dispatch of functions. Current
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predeclared ID's are in
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<filename><sys/kernel.h></filename> in the enum
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list <literal>sysinit_sub_id</literal>. The second priority
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used is an element order within the subsystem. Current
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predeclared subsystem element orders are in
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<filename><sys/kernel.h></filename> in the enum list
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<literal>sysinit_elem_order</literal>.</para>
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<indexterm><primary>pseudo-devices</primary></indexterm>
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<indexterm><primary>pseudo-devices</primary></indexterm>
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<para>There are currently two uses for SYSINIT. Function dispatch
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<para>There are currently two uses for SYSINIT. Function dispatch
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at system startup and kernel module loads, and function dispatch
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at system shutdown and kernel module unload. Kernel subsystems
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often use system startup SYSINIT's to initialize data
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@ -77,11 +90,11 @@
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Device drivers should avoid using <literal>SYSINIT()</literal>
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directly. Instead drivers for real devices that are part of a
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bus structure should use <literal>DRIVER_MODULE()</literal> to
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provide a function that detects the device and, if it is present,
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initializes the device. It will do a few things specific to
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devices and then call <literal>SYSINIT()</literal> itself.
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For pseudo-devices, which are not part of a bus structure,
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use <literal>DEV_MODULE()</literal>.</para>
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provide a function that detects the device and, if it is
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present, initializes the device. It will do a few things
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specific to devices and then call <literal>SYSINIT()</literal>
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itself. For pseudo-devices, which are not part of a bus
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structure, use <literal>DEV_MODULE()</literal>.</para>
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</sect1>
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@ -92,15 +105,15 @@
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<title>Interface</title>
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<sect3>
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<title>Headers</title>
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<title>Headers</title>
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<programlisting><sys/kernel.h></programlisting>
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<programlisting><sys/kernel.h></programlisting>
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</sect3>
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<sect3>
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<title>Macros</title>
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<title>Macros</title>
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<programlisting>SYSINIT(uniquifier, subsystem, order, func, ident)
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<programlisting>SYSINIT(uniquifier, subsystem, order, func, ident)
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SYSUNINIT(uniquifier, subsystem, order, func, ident)</programlisting>
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</sect3>
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</sect2>
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@ -109,14 +122,13 @@ SYSUNINIT(uniquifier, subsystem, order, func, ident)</programlisting>
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<title>Startup</title>
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<para>The <literal>SYSINIT()</literal> macro creates the
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necessary SYSINIT data in SYSINIT's startup data set for
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SYSINIT to sort and dispatch a function at system startup and
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module load. <literal>SYSINIT()</literal> takes a uniquifier
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that SYSINIT uses to identify the particular function dispatch
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data, the subsystem order, the subsystem element order, the
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function to call, and the data to pass the function. All
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functions must take a constant pointer argument.
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</para>
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necessary SYSINIT data in SYSINIT's startup data set for
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SYSINIT to sort and dispatch a function at system startup and
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module load. <literal>SYSINIT()</literal> takes a uniquifier
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that SYSINIT uses to identify the particular function dispatch
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data, the subsystem order, the subsystem element order, the
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function to call, and the data to pass the function. All
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functions must take a constant pointer argument.</para>
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<example>
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<title>Example of a <literal>SYSINIT()</literal></title>
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@ -138,9 +150,7 @@ void foo_arg(void *vdata)
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struct foo *foo = (struct foo *)vdata;
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foo_data(foo);
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}
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SYSINIT(bar, SI_SUB_FOO, SI_ORDER_FOO, foo_arg, &foo_voodoo);
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</programlisting>
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</example>
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SYSINIT(bar, SI_SUB_FOO, SI_ORDER_FOO, foo_arg, &foo_voodoo);</programlisting></example>
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<para>Note that <literal>SI_SUB_FOO</literal> and
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<literal>SI_ORDER_FOO</literal> need to be in the
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@ -153,7 +163,8 @@ SYSINIT(bar, SI_SUB_FOO, SI_ORDER_FOO, foo_arg, &foo_voodoo);
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handle tuning kernel parameters.</para>
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<example>
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<title>Example of Adjusting <literal>SYSINIT()</literal> Order</title>
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<title>Example of Adjusting <literal>SYSINIT()</literal>
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Order</title>
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<programlisting>static void
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mptable_register(void *dummy __unused)
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@ -171,8 +182,8 @@ SYSINIT(mptable_register, SI_SUB_TUNABLES - 1, SI_ORDER_FIRST,
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<title>Shutdown</title>
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<para>The <literal>SYSUNINIT()</literal> macro behaves similarly
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to the <literal>SYSINIT()</literal> macro except that it adds
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the SYSINIT data to SYSINIT's shutdown data set.</para>
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to the <literal>SYSINIT()</literal> macro except that it adds
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the SYSINIT data to SYSINIT's shutdown data set.</para>
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<example>
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<title>Example of a <literal>SYSUNINIT()</literal></title>
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@ -192,8 +203,7 @@ struct foo_stack foo_stack = {
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void foo_flush(void *vdata)
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{
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}
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SYSUNINIT(barfoo, SI_SUB_FOO, SI_ORDER_FOO, foo_flush, &foo_stack);
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</programlisting>
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SYSUNINIT(barfoo, SI_SUB_FOO, SI_ORDER_FOO, foo_flush, &foo_stack);</programlisting>
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</example>
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</sect2>
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</sect1>
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