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diff --git a/book/initrd.html b/book/initrd.html new file mode 100644 index 0000000..d92a5ed --- /dev/null +++ b/book/initrd.html @@ -0,0 +1,102 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><title>4.1. Building the initramfs image</title><link rel="stylesheet" href="stylesheets/lfs.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><link rel="stylesheet" href="stylesheets/lfs-print.css" type="text/css" media="print" /></head><body class="lfs" id="lfs-0.3"><div class="navheader"><h4>LFS live howto - Version 0.3</h4><h3>Chapter 4. initrd</h3><ul><li class="prev"><a accesskey="p" href="ch04.html" title="initrd">Prev</a><p>initrd</p></li><li class="next"><a accesskey="n" href="ch05.html" title="Preparing install">Next</a><p>Preparing install</p></li><li class="up"><a accesskey="u" href="ch04.html" title="Chapter 4. initrd">Up</a></li><li class="home"><a accesskey="h" href="index.html" title="LFS live howto - Version 0.3">Home</a></li></ul></div><div class="sect1" lang="en" xml:lang="en"><h1 class="sect1"><a id="initrd" name="initrd"></a>4.1. Building the initramfs image</h1><div class="admon note"><img alt="[Note]" src="images/note.png" /><h3>Note</h3><p>This chapter is mandatory for both the livecd and the livekey.</p></div><p>To boot our live system, we will need an initramfs image, which will contain a couple of utilities and kernel modules, necessary to find our rootfs and mount it. + </p><p>Create a directory structure:</p><pre class="userinput"><kbd class="command">mkdir -p initramfs/{bin,sbin,dev/{pts,shm},etc,proc,sys,rtmnt,lib}</kbd></pre><p>Copy busybox which we created in the chapter <a class="xref" href="busybox.html" title="2.4. busybox 1.19.2">busybox 1.19.2</a> to the bin directory</p><pre class="userinput"><kbd class="command">cp <path-to-busybox-builddir>/busybox initramfs/bin </kbd></pre><p>Busybox can install symlinks for the desired utilities itself, however this can be done until the init script is running. So for some utilities that we need before this stage, we need to create the symlinks our selfs.</p><pre class="userinput"><kbd class="command">ln -s /bin/busybox initramfs/bin/ash +ln -s /bin/busybox initramfs/bin/mount </kbd></pre><p>We need access to some devicenodes before udev starts:</p><pre class="userinput"><kbd class="command">mknod initramfs/dev/null c 1 3 +mknod initramfs/dev/tty c 5 0 +mknod initramfs/dev/console c 5 1 </kbd></pre><p>Add the necessary kernel modules:</p><pre class="userinput"><kbd class="command">for filename in sd_mod usbcore ehci-hcd usb-storage usb-libusual uhci-hcd ext3 mbcache jbd +do + find /lib/modules/`uname -r` -name "$filename"* -exec cp -r --parents {} initramfs \; +done</kbd></pre><p>This will search for the given modules, and copy them to the initramfs</p><p>Now we need to create the initscript:</p><pre class="userinput"><kbd class="command">cat > initramfs/init << "EOF" +#!/bin/ash + +PATH=/bin:/sbin + +# Mount proc and sysfs + +mount -t proc none /proc +mount -t sysfs none /sys +mount -t devtmpfs none /dev + +# Unpack the busybox + +/bin/busybox --install -s + +# Add modules + +if [ -z $(ls /lib/modules/) ]; then + + depmod -a + + modprobe sd_mod + modprobe usbcore + modprobe ehci-hcd + modprobe usb-storage + modprobe ext3 + +fi + +# Check the command line + +initfile="/sbin/init" +root="" + +# Check the parameterlist for rootdelay + +for arg in $(cat /proc/cmdline); do + case $arg in + + rootdelay=*) + dt=$(echo $arg | cut -d= -f2) + sleep $dt + ;; + esac +done + +# Check the parameterlist for UUID= and LABEL= + +for arg in $(cat /proc/cmdline); do + case $arg in + + root=*) + option=$(echo $arg | cut -d= -f2) + + if [ $option == "LABEL" ] ; then + root=$(findfs LABEL=$(echo $arg | cut -d= -f3)) + fi + + if [ $option == "UUID" ] ; then + root=$(findfs UUID=$(echo $arg | cut -d= -f3)) + fi + + ;; + + init=*) + initfile=$(echo "$@" | cut -d "=" -f 2 ) + + ;; + + esac +done + +if [ $root != "" ] ; then + + mount "${root}" /rtmnt + + if [[ -x "/rtmnt/${initfile}" ]] ; then + + umount /dev + umount /sys + umount /proc + + exec switch_root /rtmnt "${initfile}" + fi +fi + +# We shouldn't come here + +exec ash +EOF +chmod 0755 initramfs/init</kbd></pre><p>Pack our stuff:</p><pre class="userinput"><kbd class="command">cd initramfs +find ./ | cpio -H newc -o > ../initrd +cd .. +gzip initrd</kbd></pre><p>Keep our created initrd.gz for later use.</p></div><div class="navfooter"><ul><li class="prev"><a accesskey="p" href="ch04.html" title="initrd">Prev</a><p>initrd</p></li><li class="next"><a accesskey="n" href="ch05.html" title="Preparing install">Next</a><p>Preparing install</p></li><li class="up"><a accesskey="u" href="ch04.html" title="Chapter 4. initrd">Up</a></li><li class="home"><a accesskey="h" href="index.html" title="LFS live howto - Version 0.3">Home</a></li></ul></div></body></html> |