diff options
Diffstat (limited to 'man/bootup.xml')
| -rw-r--r-- | man/bootup.xml | 143 |
1 files changed, 81 insertions, 62 deletions
diff --git a/man/bootup.xml b/man/bootup.xml index 65923528d4..a596e85b70 100644 --- a/man/bootup.xml +++ b/man/bootup.xml @@ -50,18 +50,20 @@ <refsect1> <title>Description</title> - <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 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 + <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 + persistent storage device. This boot loader will then + invoke an OS kernel from disk (or the network). In the + Linux case this kernel (optionally) extracts and executes an initial RAM disk image (initrd) such as <citerefentry><refentrytitle>dracut</refentrytitle><manvolnum>8</manvolnum></citerefentry> - which looks for the root file system. After the root - file system is found and mounted the initrd hands over - control to the system manager (such as + which looks for the root file system (possibly using + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> + for this). After the root file system is found and + mounted the initrd hands over control to the host's + system manager (such as <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>) stored on the OS image which is then responsible for probing all remaining hardware, mounting all necessary @@ -132,35 +134,35 @@ v sysinit.target | - _________________/|\___________________ - / | \ - | | | - v | v - (various | rescue.service - sockets...) | | - | | v - v | <emphasis>rescue.target</emphasis> - sockets.target | - | | - \_________________ | - \| + ____________________________________/|\________________________________________ + / | | | \ + | | | | | + v v | v v + (various (various | (various rescue.service + timers...) paths...) | sockets...) | + | | | | v + v v | v <emphasis>rescue.target</emphasis> + timers.target paths.target | sockets.target + | | | | + \__________________|_________________ | ___________________/ + \|/ v basic.target | - __________________________________/| 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> - | | | - \_______________ | _________________/ + ____________________________________/| 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> + <emphasis>graphical.target</emphasis></programlisting> <para>Target units that are commonly used as boot targets are <emphasis>emphasized</emphasis>. These @@ -174,23 +176,41 @@ </refsect1> <refsect1> - <title>Initrd System Manager Bootup</title> - <para>The default target in the initrd is the initrd.target. The bootup process is - identical to the System Manager Bootup until it reaches basic.target. From there, - systemd approaches the special initrd.target. If the root device can be mounted at - /sysroot, the sysroot.mount unit becomes active and the initrd-root-fs.target is - reached. - The initrd-parse-etc.service scans /sysroot/etc/fstab for a possible /usr mountpoint - and additional entries marked with the <emphasis>x-initrd.mount</emphasis> option. - All entries found are mounted below /sysroot, and the initrd-fs.target is reached. - The initrd-cleanup.service isolates to the initrd-switch-root.target, where cleanup - services can run. As the very last step, the initrd-switch-root.service is activated, - which will cause the system to switch its root to /sysroot. + <title>Bootup in the Initial RAM Disk (initrd)</title> + <para>The initial RAM disk implementation (initrd) can + be set up using systemd as well. In this case boot up + inside the initrd follows the following + structure.</para> + + <para>The default target in the initrd is + <filename>initrd.target</filename>. The bootup process + begins identical to the system manager bootup (see + above) until it reaches + <filename>basic.target</filename>. From there, systemd + approaches the special target + <filename>initrd.target</filename>. If the root device + can be mounted at <filename>/sysroot</filename>, the + <filename>sysroot.mount</filename> unit becomes active + and <filename>initrd-root-fs.target</filename> is + reached. The service + <filename>initrd-parse-etc.service</filename> scans + <filename>/sysroot/etc/fstab</filename> for a possible + <filename>/usr</filename> mount point and additional + entries marked with the + <emphasis>x-initrd.mount</emphasis> option. All + entries found are mounted below + <filename>/sysroot</filename>, and + <filename>initrd-fs.target</filename> is reached. The + service <filename>initrd-cleanup.service</filename> + isolates to the + <filename>initrd-switch-root.target</filename>, where + cleanup services can run. As the very last step, the + <filename>initrd-switch-root.service</filename> is + activated, which will cause the system to switch its + root to <filename>/sysroot</filename>. </para> -<programlisting> - (identical to System Manager Bootup) - : +<programlisting> : (beginning identical to above) : v basic.target @@ -203,13 +223,13 @@ | initrd-root-fs.target | | | v - | initrd-parse-etc.service - (custom initrd services) | - | v + v initrd-parse-etc.service + (custom initrd | + services...) v | (sysroot-usr.mount and | various mounts marked | with fstab option - | x-initrd.mount) + | x-initrd.mount...) | | | v | initrd-fs.target @@ -225,11 +245,11 @@ | v ______________________/| - / | + / v | initrd-udevadm-cleanup-db.service - | | - (custom initrd services) | - | | + v | + (custom initrd | + services...) | \______________________ | \| v @@ -239,17 +259,16 @@ initrd-switch-root.service | v - switch-root -</programlisting> + Transition to Host OS</programlisting> </refsect1> <refsect1> <title>System Manager Shutdown</title> - <para>System shutdown also consists of various target - units with some minimal ordering structure - applied:</para> + <para>System shutdown with systemd also consists of + various target units with some minimal ordering + structure applied:</para> |