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@@ -10820,6 +10820,47 @@
10820 </para> 10820 </para>
10821 10821
10822 <para> 10822 <para>
10823 By default, the Yocto Project uses SysVinit as the initialization
10824 manager.
10825 However, support also exists for systemd,
10826 which is a full replacement for init with
10827 parallel starting of services, reduced shell overhead and other
10828 features that are used by many distributions.
10829 </para>
10830
10831 <para>
10832 Within the system, SysVinit treats system components as services.
10833 These services are maintained as shell scripts stored in the
10834 <filename>/etc/init.d/</filename> directory.
10835 Services organize into different run levels.
10836 This organization is maintained by putting links to the services
10837 in the <filename>/etc/rcN.d/</filename> directories, where
10838 <replaceable>N/</replaceable> is one of the following options:
10839 "S", "0", "1", "2", "3", "4", "5", or "6".
10840 <note>
10841 Each runlevel has a dependency on the previous runlevel.
10842 This dependency allows the services to work properly.
10843 </note>
10844 </para>
10845
10846 <para>
10847 In comparison, systemd treats components as units.
10848 Using units is a broader concept as compared to using a service.
10849 A unit includes several different types of entities.
10850 Service is one of the types of entities.
10851 The runlevel concept in SysVinit corresponds to the concept of a
10852 target in systemd, where target is also a type of supported unit.
10853 </para>
10854
10855 <para>
10856 In a SysVinit-based system, services load sequentially (i.e. one
10857 by one) during and parallelization is not supported.
10858 With systemd, services start in parallel.
10859 Needless to say, the method can have an impact on system startup
10860 performance.
10861 </para>
10862
10863 <para>
10823 If you want to use SysVinit, you do 10864 If you want to use SysVinit, you do
10824 not have to do anything. 10865 not have to do anything.
10825 But, if you want to use systemd, you must 10866 But, if you want to use systemd, you must