| 1 | <sect1 id="ch-system-proc">
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| 2 | <title>Mounting the proc and devpts file systems</title>
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| 3 | <?dbhtml filename="proc.html" dir="chapter06"?>
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| 4 |
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| 5 | <para>In order for certain programs to function properly, the
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| 6 | <emphasis>proc</emphasis> and <emphasis>devpts</emphasis> file systems must be
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| 7 | available within the chroot environment. The proc file system is the process
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| 8 | information pseudo file system through which the kernel provides information
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| 9 | about the status of the system. And the devpts file system is nowadays the most
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| 10 | common way pseudo terminals (PTYs) are implemented. Since kernel version 2.4, a
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| 11 | file system can be mounted as many times and in as many places as you like,
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| 12 | thus it's not a problem that these file systems are already mounted on your
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| 13 | host system, especially so because they are virtual file systems.</para>
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| 14 |
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| 15 | <para>First become <emphasis>root</emphasis>, as only <emphasis>root</emphasis>
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| 16 | can mount file systems in unusual places. Then check again that the LFS
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| 17 | environment variable is set correctly by running <userinput>echo
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| 18 | $LFS</userinput> and making sure it shows the path to your LFS partition's
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| 19 | mount point, which is <filename class="directory">/mnt/lfs</filename> if you
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| 20 | followed our example.</para>
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| 21 |
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| 22 | <para>Now make the mount points for these filesystems:</para>
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| 23 |
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| 24 | <screen><userinput>mkdir -p $LFS/{proc,dev/pts}</userinput></screen>
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| 25 |
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| 26 | <para>Mount the <emphasis>proc</emphasis> file system with:</para>
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| 27 |
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| 28 | <screen><userinput>mount proc $LFS/proc -t proc</userinput></screen>
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| 29 |
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| 30 | <para>And mount the <emphasis>devpts</emphasis> file system with:</para>
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| 31 |
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| 32 | <screen><userinput>mount devpts $LFS/dev/pts -t devpts</userinput></screen>
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| 33 |
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| 34 | <para>This last command might fail with an error like:</para>
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| 35 |
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| 36 | <blockquote><screen>filesystem devpts not supported by kernel</screen></blockquote>
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| 37 |
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| 38 | <para>The most likely cause for this is that your host system's kernel was
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| 39 | compiled without support for the devpts file system. You can check which file
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| 40 | systems your kernel supports by peeking into its internals with
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| 41 | <command>cat /proc/filesystems</command>. If a file system type named
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| 42 | <emphasis>devfs</emphasis> is listed there, then we'll be able to work around
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| 43 | the problem by mounting the host's devfs file system on top of the new
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| 44 | <filename>/dev</filename> structure which we'll create later on in the section
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| 45 | on <xref linkend="ch-system-MAKEDEV"/>. If devfs was not listed, do not worry
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| 46 | because there is yet a third way to get PTYs working inside the chroot
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| 47 | environment. We'll cover this shortly in the aforementioned
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| 48 | <xref linkend="ch-system-MAKEDEV"/> section.</para>
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| 49 |
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| 50 | <para>Remember that if for any reason you stop working on your LFS, and start
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| 51 | again later, it's important to check that these file systems are mounted again
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| 52 | before entering the chroot environment, otherwise problems could occur.</para>
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| 53 |
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| 54 | </sect1>
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| 55 |
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