<refnamediv>
<refname>bootup</refname>
- <refpurpose>The System Bootup Process</refpurpose>
+ <refpurpose>System bootup process</refpurpose>
</refnamediv>
<refsect1>
<para>A number of different components are involved in the
system boot. Immediately after power-up, the system
BIOS will do minimal hardware initialization, and hand
- control over to a boot loader stored on a persistant
+ control over to a boot loader stored on a persistent
storage device. This boot loader will then invoke an
OS kernel from disk (or the network). In the Linux
case this kernel now (optionally) extracts and
storage technologies backing them), and then
(optionally) jumps back into the initrd code which
unmounts/detaches the root file system and the storage
- it resides on. As last step the system powered down.</para>
+ it resides on. As last step the system is powered down.</para>
<para>Additional information about the system boot
process may be found in
target units are available, as listed on
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
- <para>The follow chart is a structural overview of
+ <para>The following chart is a structural overview of
these well-known units and their position in the
boot-up logic. The arrows describe which units are
pulled in and ordered before which other units. Units
v
basic.target
|
- _________________/| emergency.service
- / | |
- | | v
- v v <emphasis>emergency.target</emphasis>
- (various system (various system
- services services)
- required for |
- graphical UIs) v
- | <emphasis>multi-user.target</emphasis>
- | |
- | _________________/
- |/
+ __________________________________/| emergency.service
+ / | | |
+ | | | v
+ v v v <emphasis>emergency.target</emphasis>
+ display- (various system (various system
+ manager.service services services)
+ | required for |
+ | graphical UIs) v
+ | | <emphasis>multi-user.target</emphasis>
+ | | |
+ \_______________ | _________________/
+ \|/
v
<emphasis>graphical.target</emphasis></programlisting>
-<programlisting> (conflicts with (conflicts with
- all system all file system
- services) mounts, swaps,
- | cryptsetup
- | devices, ...)
- | |
- v v
- shutdown.target umount.target
- | |
- \_______ ______/
- \ /
- v
- (various low-level
- services)
- |
- v
- final.target
- |
- __________________________/ \_____________________
- / | | \
- | | | |
- v v v v
-reboot.service poweroff.service halt.service kexec.service
- | | | |
- v v v v
-<emphasis>reboot.target</emphasis> <emphasis>poweroff.target</emphasis> <emphasis>halt.target</emphasis> <emphasis>kexec.target</emphasis></programlisting>
+<programlisting> (conflicts with (conflicts with
+ all system all file system
+ services) mounts, swaps,
+ | cryptsetup
+ | devices, ...)
+ | |
+ v v
+ shutdown.target umount.target
+ | |
+ \_______ ______/
+ \ /
+ v
+ (various low-level
+ services)
+ |
+ v
+ final.target
+ |
+ _____________________________________/ \_________________________________
+ / | | \
+ | | | |
+ v v v v
+systemd-reboot.service systemd-poweroff.service systemd-halt.service systemd-kexec.service
+ | | | |
+ v v v v
+ <emphasis>reboot.target</emphasis> <emphasis>poweroff.target</emphasis> <emphasis>halt.target</emphasis> <emphasis>kexec.target</emphasis></programlisting>
<para>Commonly used system shutdown targets are <emphasis>emphasized</emphasis>.</para>
</refsect1>