forked from mirrors/nixpkgs
65 lines
1.5 KiB
XML
65 lines
1.5 KiB
XML
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<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink">
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<title>Troubleshooting</title>
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<section>
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<title>Debugging the boot process</title>
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<para>To get a Stage 1 shell (i.e., a shell in the initial ramdisk),
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add <literal>debug1</literal> to the kernel command line. The shell
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gets started before anything useful has been done. That is, no
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modules have been loaded and no file systems have been mounted, except
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for <filename>/proc</filename> and <filename>/sys</filename>.</para>
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<para>To get a Stage 2 shell (i.e., a shell in the actual root file
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system), add <literal>debug2</literal> to the kernel command
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line. This shell is started right after stage 1 calls the stage 2
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<literal>init</literal> script, so the root file system is there but
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no services have been started.</para>
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</section>
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<section>
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<title>Safe mode</title>
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<para>If the hardware autodetection (in
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<filename>upstart-jobs/hardware-scan</filename>) causes problems, add
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<literal>safemode</literal> to the kernel command line. This will
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disable auto-loading of modules for your PCI devices. However, you
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will probably need to explicitly add modules to
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<option>boot.extraKernelModules</option> to get network support
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etc.</para>
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</section>
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<section>
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<title>Maintenance mode</title>
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<para>You can go to maintenance mode by doing
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<screen>
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$ shutdown now</screen>
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This will eventually give you a single-user root shell.
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To get out of maintenance mode, do
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<screen>
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$ initctl emit startup</screen>
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</para>
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</section>
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</chapter>
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