Installing LILO

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TODO: {{#todo:Review(12.16.13-03:15->MD+)|Mike Dean|oe 4,oe 5,md,Review,mw}}

Installing LILO

LILO can be installed onto a disk for use by the local machine, or it can be installed onto a removable storage device for use in booting on a different machine. Both installation methods are discussed here. Usually, the former method will be used to update the existing bootloader for new kernels, new kernel configurations, or new boot time options. The latter method is generally used to initially set up a bootable storage device which is intended to be inserted into an embedded system for which it is being created.

Installing Onto the Local Machine

Before LILO can be used to boot a system, it must be installed onto the boot device. It must also be reinstalled any time the configuration is changed, or the new configuration will not take effect. Fortunately, installing LILO is easy.

The easiest way to install LILO onto the local system's Master Boot Record, using the default configuration file (/etc/lilo.conf), is to type: 

root@oe:/# lilo

Unfortunately, it is often not feasible to install LILO this way. This method works well for systems where only a small change is required to the default configuration, but is not often what is desired on an embedded system. Many times, an alternate file will be used to store the new configuration so that a breaking change to a known-good configuration file will not leave the system without a usable configuration file. If a configuration file in an alternate location needs to be used, it will have to be specified like this: 

root@oe:/# lilo -C /etc/alternate_lilo_configuration_file.conf

The -C (capital C) switch tells lilo to use the configuration file specified after the switch when installing itself.

Installing LILO Onto a Removable Drive

Unfortunately, the last method shown above is still not what you need to do when your embedded machine's root drive is not in the running embedded system. If you have a Compact Flash disk, for instance, containing your Linux filesystem, and it is mounted on your desktop Linux development machine, you will need to jump through a few hoops to install the bootloader onto the Compact Flash card. This method is usually necessary when you don't yet have a bootable disk for your embedded machine.

Two sets of directions for doing this are given here. The first set of directions is generic, and will work for desktop Linux distributions which do not include an automounter or have an automounter which doesn't interfere with the process. The second set details a known workaround. The following steps will need to be performed to install LILO onto a removable drive:

Installing from a System with No Automounter or a Non-Interfering Automounter

For simpler systems without an automounter, or with an automounter that doesn't try to protect the user from possibly malicious code, follow these directions.

  1. Mount the drive.

    1. Insert the flash card into the development system's card reader.

    2. Find out where the device node for the card was created (assuming the development machine uses udev) by using dmesg.
      user@ldc:~/# dmesg | tail -n 15
...
[126468.154762] sd 6:0:0:0: [sdb] 7831152 512-byte logical blocks: (4.00 GB/3.73 GiB)
[126468.182196]  sdb: sdb1
[126468.688061] kjournald starting.  Commit interval 5 seconds
[126468.691223] EXT3-fs (sdb1): using internal journal
[126468.691225] EXT3-fs (sdb1): recovery complete
[126468.694526] EXT3-fs (sdb1): mounted filesystem with ordered data mode
[173828.541718] sdb: detected capacity change from 4009549824 to 0
[179577.977554] sd 6:0:0:0: [sdb] 7831152 512-byte logical blocks: (4.00 GB/3.73 GiB)
[179577.994839]  sdb: sdb1
[179578.376157] kjournald starting.  Commit interval 5 seconds
[179578.381428] EXT3-fs (sdb1): using internal journal
[179578.381433] EXT3-fs (sdb1): recovery complete
[179578.384661] EXT3-fs (sdb1): mounted filesystem with ordered data mode

    3. Since the device node sdb1 was created for the flash card (in this example), that device needs to be mounted somewhere accessible. In this example, the /mnt/cfcard directory is used:
      user@ldc:~/# sudo su
[sudo] password for user:
root@ldc:~/# mkdir -p /mnt/cfcard
root@ldc:~/# mount /dev/sdb1 /mnt/cfcard
root@ldc:~/#

  2. Bind mount the device nodes into the filesystem so that LILO will be able to communicate with the flash card: 

    root@ldc:~/# cd /mnt/cfcard
root@ldc:/mnt/cfcard# mount --bind /dev dev/
root@ldc:/mnt/cfcard#

  3. chroot into the filesystem: 

    root@ldc:/mnt/cfcard# chroot .
root@ldc:/#

  4. Run lilo with the appropriate LILO configuration file. Be sure to double check to ensure that the configuration file is correct, because a mistake here could render the desktop system unbootable. 

    root@ldc:/# lilo -C /etc/lilo.conf.boot
Warning: '/proc/partitions' does not exist, disk scan bypassed
Added emac-oe *
One warning was issued.
root@ldc:/#

    Note that the warning here is normal, because LILO is being installed inside a chroot which doesn't have a mounted /proc virtual filesystem.

  5. Exit the chroot and unmount the device: 

    root@ldc:/# exit
root@ldc:/mnt/cfcard# cd ..
root@ldc:/mnt# umount cfcard

  6. It is now safe to remove the flash card and put it into the embedded machine.

Workaround for the Ubuntu Automounter (and Possibly Others)

On many Linux desktops, a memory card will be automounted when it is inserted. While this is a nice convenience feature for most users, it comes at the expense of developers. This automount feature can be a source of frustration for those who haven't already found a way around the issues it causes.

Fortunately, we at EMAC have already found a method which works reliably on our recommended Linux distribution, Ubuntu 12.04 LTS, and have documented it here. On other systems, such as Debian, a workaround may not be needed. If your system automounts, see below.

  1. Insert the flash card into your card reader and wait for the file browser window to appear. If a messagebox appears asking you to choose what to do, tell it to open a file browser for browsing the files on the card.

  2. Keep the file browser window open, and stash it away for later use.

  3. Open a terminal and create a /mnt/cfcard directory, if it does not exist: 

    user@ubuntu:/# mkdir /mnt/cfcard

  4. Find out the device name of the card by looking for the location where the card was mounted. The file browser window will list the name of the card under Devices in the left pane. Often times, the name will be EMAC_OE. Look for this name in the output of the df command: 

    user@ubuntu:/# df -hT | grep EMAC
/dev/sdb1                       ext3      3.7G  223M  3.3G   7% /media/EMAC_OE

  5. From the output of this command, we can see that the /media/EMAC_OE mountpoint was mounted onto the /dev/sdb1 device. Therefore, this is the device in which we're interested.

  6. Mount the device on the directory from step 3, without unmounting it first: 

    user@ubuntu:/# mount /dev/sdb1 /mnt/cfcard
user@ubuntu:/#

  7. Now, switch to the root user account (if you aren't already root) and bind mount the host system's /dev directory to the cfcard's /dev directory. This will provide the device node file that will be needed for LILO to be able to talk to the flash card. NOTE: If you use the method shown here to switch to the root user, use your user's password at the password prompt. 

    user@ubuntu:/# sudo su
[sudo] password for user: 
root@ubuntu:/# cd /mnt/cfcard
root@ubuntu:/mnt/cfcard#
root@ubuntu:/mnt/cfcard# mount --bind /dev dev/
root@ubuntu:/mnt/cfcard#

  8. Now, use the chroot command to make the directory where you mounted the card the effective root directory for your terminal session: 

    root@ubuntu:/mnt/cfcard# chroot .
root@ubuntu:/#

  9. Now that you're effectively running inside the filesystem on the flash card, you are able to run LILO to install the bootloader. First, be sure to double check to ensure that the configuration file you're using points to the correct device node (in this example, /dev/sdb1) so that you don't overwrite the bootloader on your desktop (see Configuring LILO for more information). If you overwrite the bootloader on your desktop, it will render your desktop system unbootable! So make sure to double check this if you value the ability to boot your desktop.

  10. When you are sure you're using the right device node, run LILO to install the bootloader: 

    root@ubuntu:/# lilo -C /etc/lilo.conf.boot
Warning: '/proc/partitions' does not exist, disk scan bypassed
Added emac-oe *
One warning was issued.
root@ubuntu:/#

    The warning, in this case, is normal. It appears because you're in a fake "running system," which means the virtual files in the /proc/ filesystem aren't mounted and able to provide information; hence, the non-existence of the /proc/partitions file.

  11. Now, you need to umount the device: 

    root@ubuntu:/# exit
root@ubuntu:/mnt/cfcard# cd ..
root@ubuntu:/mnt# umount cfcard/dev
root@ubuntu:/mnt# umount cfcard
root@ubuntu:/mnt# exit
user@ubuntu:/#

  12. Retrieve the file browser you stashed away earlier, and unmount the automounted directory for the card by clicking on the eject symbol next to the name of the device in the left pane.

  13. It is now safe to eject the card and put it into your embedded machine.

Next Steps

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