Bug #298 ยป boot-chapter.diff
| chapter.sgml 24 Aug 2006 20:08:42 -0000 | ||
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<para>The options you can give to the components in the &os;
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bootstrap to control the boot process.</para>
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</listitem>
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<listitem>
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<para>The basics of &man.device.hints.5;.</para>
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</listitem>
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</itemizedlist>
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<note>
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case the boot manager usually has more code in the first
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<emphasis>track</emphasis> of the disk or within some OS's file system.
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(A boot manager is sometimes also called a <emphasis>boot
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loader</emphasis>, but FreeBSD uses that term for a later stage of
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loader</emphasis>, but &os; uses that term for a later stage of
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booting.) Popular boot managers include <application>boot0</application>
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(a.k.a. <application>Boot Easy</application>, the standard &os; boot
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manager), <application>Grub</application>,
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<application>boot0</application> and <application>LILO</application>.</para>
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<formalpara><title>The <application>boot0</application> Boot Manager:</title>
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<para>The MBR installed by FreeBSD's installer or &man.boot0cfg.8;, by
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<para>The MBR installed by &os;'s installer or &man.boot0cfg.8;, by
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default, is based on <filename>/boot/boot0</filename>.
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(The <application>boot0</application> program is very simple, since the
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program in the <abbrev>MBR</abbrev> can only be 446 bytes long because of the slice
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<example id="boot-boot0-example">
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<title><filename>boot0</filename> Screenshot</title>
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<!-- todo: reed: what should be here? -->
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<screen>F1 DOS
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F2 FreeBSD
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F2 DF/FBSD
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F3 Linux
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F4 ??
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F5 Drive 1
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<indexterm><primary>loader</primary></indexterm>
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<indexterm><primary>loader configuration</primary></indexterm>
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<!-- XXX talk about the boot menu -->
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<para>The loader will then read
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<filename>/boot/loader.rc</filename>, which by default reads
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in <filename>/boot/defaults/loader.conf</filename> which
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on these variables, loading whichever modules and kernel are
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selected.</para>
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<para>Finally, by default, the loader issues a 10 second wait
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for key presses, and boots the kernel if it is not interrupted.
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If interrupted, the user is presented with a prompt which
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understands the easy-to-use command set, where the user may
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adjust variables, unload all modules, load modules, and then
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finally boot or reboot.</para>
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<para>Finally, by default, the loader will show you the booting
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menu where you can select different options. This menu issues
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a 10 second wait for key presses, and boots the kernel if it
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is not interrupted. If the user selects
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<option>"Escape to loader prompt"</option>, the user is presented
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with a prompt which understands the easy-to-use command set,
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where the user may adjust variables, unload all modules,
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load modules, and then finally boot or reboot.</para>
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</sect3>
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<indexterm><primary>single-user mode</primary></indexterm>
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<listitem>
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<para>To simply boot your usual kernel, but in single-user
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mode:</para>
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<screen><userinput>boot -s</userinput></screen>
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mode you can select the <option>"Boot DragonFly in single user mode"</option>.</para>
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</listitem>
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<listitem>
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<screen><userinput>unload</userinput>
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<userinput>load <replaceable>kernel.old</replaceable></userinput></screen>
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<para>You can use <filename>kernel.GENERIC</filename> to
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refer to the generic kernel that comes on the install
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disk, or <filename>kernel.old</filename> to refer to
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<para>You can use <filename>kernel.old</filename> to refer to
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your previously installed kernel (when you have upgraded
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or configured your own kernel, for example).</para>
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<para>This mode can be reached through the <link
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linkend="boot-autoreboot">automatic reboot
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sequence</link>, or by the user booting with the
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<option>-s</option> option or setting the
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<envar>boot_single</envar> variable in
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<command>loader</command>.</para>
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sequence</link>, with the
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<option>"Boot DragonFly in single user mode"</option>
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menu option, by the user booting with the
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<option>-s</option> option from the loader prompt or setting the
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<envar>boot_single</envar> variable in
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<command>loader</command>.</para>
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<para>It can also be reached by calling
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&man.shutdown.8; without the reboot
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