updated

LDP/howto/linuxdoc/LILO.sgml

@@ -10,7 +10,7 @@
 
 <title>Lilo mini-Howto
 <author>Miroslav Skoric (<tt/m.skoric@eunet.yu/)
-<date>v3.00, 24 July 2000
+<date>v3.1, 28 October 2000
 <abstract>
 LILO is the most used <bf/Li/nux <bf/Lo/ader for the x86 flavour of
 Linux; I'll call it Lilo rather than LILO here because I don't
@@ -23,6 +23,7 @@ referred to /usr/doc/lilo*
 <p>
 This version of Lilo mini-HOWTO is based on work of Cameron Spitzer
 (<tt/cls@truffula.sj.ca.us/) and Alessandro Rubini (<tt/rubini@linux.it/).
+There is also a contribution from Tony Harris (<tt/tony@nmr.mgh.harvard.edu/)
 </abstract>
 
 <!-- Table of contents -->
@@ -212,6 +213,109 @@ nothing special needs to be done to uninstall Lilo.  Just run Linux'
 <em>fdisk</em> to remove Linux partitions from the partition
 table. You must also mark the DOS partition as bootable.
 
+<sect1>How to make a ram disk?
+
+by Tony Harris
+16 Oct 2000
+ram disk eenie-weenie HOWTO
+
+<p>
+If your root file system is on a device for which your kernel has no
+compiled-in driver, you will need to use <tt/lilo/ to load that driver
+as a module very early in the boot cycle.
+There are only two easy steps:
+
+<itemize>
+<item>make a ram disk image with <tt/mkinitrd/
+
+<item>modify lilo.conf to point to the image
+
+</itemize>
+
+First, I cd over to <tt//boot/:
+
+System.map                  chain.b                module-info-2.2.16-3ext3
+System.map-2.2.16-3         initrd-2.2.16-3.img    vmlinux-2.2.16-3
+System.map-2.2.16-3ext3     vmlinux-2.2.16-3ext3
+vmlinuz                     kernel.h
+boot.b                      map                    vmlinuz-2.2.16-3
+bz.2.2.15.juke.Image        module-info            vmlinuz-2.2.16-3ext3
+bzImage-2.2.14              module-info-2.2.16-3
+
+
+<p>
+Here you can see that I have a 2.2.16-3 kernel and I have added a 
+second kernel with ext3 support (<tt/vmlinuz-2.2.16-3ext3/). There is
+already a ram disk image for my first kernel (<tt/initrd-2.2.16-3.img/)
+
+To make a new image for the second kernel, I type the following (stuff I
+type is in bold):
+
+<tt//boot#/ mkinitrd initrd-2.2-16-3ext3.img 2.2.16-3ext3
+
+<tt/mkinitrd/ is a shellscript that looks at the modules needed by my 
+kernel, then makes an ext2 filesystem containing them.
+If we look inside the image we see this is the case:
+
+<tt//boot#/ cat initrd-2.2.16-3ext3.img | gunzip > /tmp/myimage
+<tt//boot#/ file /tmp/myimage
+<tt//tmp/myimage: Linux/i386 ext2 filesystem/
+
+<p>
+You do not have to look inside your image. Only making the image and
+modifying lilo.conf are necessary steps. However, discussion of the ramdisk
+image is provided for pedagogic purposes.
+
+In order to look inside, I need to mount the image as though it were
+a filesystem:
+
+<tt//boot#/ mount /tmp/myimage /mnt/tmp -t ext2 -o loop=/dev/loop3
+
+<tt//boot#/ ls /mnt/tmp
+<tt/bin  dev  etc  lib  linuxrc/
+
+<tt//boot#/ find /mnt/tmp
+
+<tt//mnt/tmp/
+<tt//mnt/tmp/lib/
+<tt//mnt/tmp/lib/aic7xxx.o/
+<tt//mnt/tmp/bin/
+<tt//mnt/tmp/bin/sh/
+<tt//mnt/tmp/bin/insmod/
+<tt//mnt/tmp/etc/
+<tt//mnt/tmp/dev/
+<tt//mnt/tmp/dev/console/
+<tt//mnt/tmp/dev/null/
+<tt//mnt/tmp/dev/ram/
+<tt//mnt/tmp/dev/systty/
+<tt//mnt/tmp/dev/tty1/
+<tt//mnt/tmp/dev/tty2/
+<tt//mnt/tmp/dev/tty3/
+<tt//mnt/tmp/dev/tty4/
+<tt//mnt/tmp/linuxrc/
+
+The most important part of this ram disk image is (<tt/aic7xxx.o/, 
+which is my scsi module.
+
+Finally, I move on to the last step, modifying (<tt//etc/lilo.conf/:
+
+Here is my entry in (<tt/lilo.conf/ that corresponds to the kernel and 
+image I just created:
+
+<tt/image=/boot/vmlinuz-2.2.16-3ext3/
+<tt/label=linux.ext3/
+<tt/initrd=/boot/initrd-2.2.16-3ext3.img/
+<tt/read-only/
+<tt/root=/dev/hdb3/
+
+That's it. Run <tt/lilo/ as root and reboot.
+
+<p>
+If you have problems, check out the kernel <tt/HOWTO/. There are a
+couple things you need to have covered: you need your kernel modules
+compiled and living in (<tt//etc/conf.modules/.
+
+
 <sect>The Simple Configuration
 <p>
 Most Lilo installations use a configuration file like the