1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ |
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4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
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5 | %general-entities; |
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6 | ]> |
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7 | |
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8 | <sect1 id="ch-chroot-kernfs"> |
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9 | <?dbhtml filename="kernfs.html"?> |
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10 | |
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11 | <title>Mounting Virtual Kernel File Systems</title> |
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12 | |
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13 | <note os="a"> |
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14 | <para>The commands in the remainder of the book should be run as |
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15 | the <systemitem class="username">root</systemitem> user. Check |
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16 | that ${CLFS} is set in the |
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17 | <systemitem class="username">root</systemitem> user’s environment |
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18 | before proceeding.</para> |
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19 | </note> |
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20 | |
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21 | <para>Various file systems exported by the kernel are used to communicate |
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22 | to and from the kernel itself. These file systems are virtual in that no |
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23 | disk space is used for them. The content of the file systems resides in |
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24 | memory.</para> |
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25 | |
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26 | <para>Begin by creating directories onto which the file systems will |
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27 | be mounted:</para> |
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28 | |
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29 | <screen><userinput>mkdir -pv ${CLFS}/{dev,proc,run,sys}</userinput></screen> |
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30 | |
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31 | <para>Two device nodes, <filename class="devicefile">/dev/console</filename> |
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32 | and <filename class="devicefile">/dev/null</filename>, are required to be |
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33 | present on the file system. These are needed by the kernel even before |
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34 | starting Udev early in the boot process, so we create them here:</para> |
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35 | |
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36 | <screen><userinput>mknod -m 600 ${CLFS}/dev/console c 5 1 |
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37 | mknod -m 666 ${CLFS}/dev/null c 1 3</userinput></screen> |
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38 | |
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39 | <para>Once the system is complete and booting, the rest of our device |
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40 | nodes will be created by the kernel's |
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41 | <systemitem class="filesystem">devtmpfs</systemitem> file system. For now |
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42 | though, we will just use the <quote>bind</quote> option in the mount command |
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43 | to make our host system's <filename class="directory">/dev</filename> structure appear in the new CLFS file system:</para> |
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44 | |
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45 | <screen><userinput>mount -v -o bind /dev ${CLFS}/dev</userinput></screen> |
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46 | |
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47 | <para>Now mount the remaining file systems:</para> |
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48 | |
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49 | <screen><userinput>mount -vt devpts -o gid=&gid-tty;,mode=620 devpts ${CLFS}/dev/pts |
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50 | mount -vt proc proc ${CLFS}/proc |
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51 | mount -vt tmpfs tmpfs ${CLFS}/run |
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52 | mount -vt sysfs sysfs ${CLFS}/sys</userinput></screen> |
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53 | |
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54 | <para>On some host systems, <filename class="directory">/dev/shm</filename> |
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55 | is a symbolic link to <filename class="directory">/run/shm</filename>. |
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56 | If it is, create a directory in <filename class="directory">/run</filename>:</para> |
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57 | |
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58 | <screen><userinput>[ -h ${CLFS}/dev/shm ] && mkdir -pv ${CLFS}/$(readlink ${CLFS}/dev/shm)</userinput></screen> |
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59 | |
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60 | <para>Remember that if for any reason you stop working on the CLFS system |
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61 | and start again later, it is important to check that these file systems |
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62 | are mounted again before entering the chroot environment.</para> |
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63 | |
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64 | </sect1> |
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