Difference between revisions of "Configuring LILO"

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{{todo|(12.16.13-02:25->MD+);(12.16.13-15:15->MD+);(12.17.13-11:45->MW+);(12.17.13-15:25->KY+)|Mike Dean|project=oe 4,oe 5,md,mw,complete}}
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{{todo|Complete(12.16.13-02:25->MD+);(12.16.13-15:15->MD+);(12.17.13-11:45->MW+);(12.17.13-15:25->KY+)|Mike Dean|project=oe 4,oe 5,md,complete,mw}}
  
 
==Configuring LILO==
 
==Configuring LILO==
  
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LILO is easily configurable by editing the lilo.conf file then [[Installing_LILO | running LILO ]] to use the new configuration options. The configuration for LILO created by EMAC and shipped with a system will usually suffice, although customization may be required. The information provided here provides a description for the important lilo configuration options.
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As with any software of moderate or better complexity, configuration is required for LILO to function as desired. The configuration created by EMAC and shipped with a system will usually suffice.  However, sometimes enough customization is required that the bootloader itself will need to be reconfigured.  Even if custom configuration isn't required, some of this information is important for protecting against accidentally overwriting the bootloader on a developer's desktop with a bootloader that was intended for an embedded machine.
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===Typical lilo.conf===
 
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<pre>
 
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boot=/dev/sda
 
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map=/boot/map
 
  
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lba32
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This page describes the parts of the LILO bootloader configuration file, and provides guidance on how to work with it.  The other LILO pages describe how to install and use the bootloader after it has been configured.
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#linear
 
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disk=/dev/sda
 
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bios=0x80
 
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read-only
 
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prompt
 
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timeout=5
 
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vga=normal
 
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install=text
 
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compact
 
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#This is for bootloader input from the serial console (ttyS0,9600,8,n,1):
 
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#serial=0,9600n8
 
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image=/boot/bzImage
 
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        root=/dev/sda1
 
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        label=emac-oe
 
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        #This is for boot messages redirected to the serial console (ttyS0):
 
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        append="console=ttyS0,115200"
 
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</pre>
 
  
 
===Sections of the LILO Configuration File===
 
===Sections of the LILO Configuration File===
  
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The LILO configuration file is split into two sections: global and per-image.  The global section specifies options that pertain to LILO itself and to all images specified in the file.  The per-image section specifies options that apply to a specific image, some of which may override the global options.
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The LILO configuration file is split into two sections: global and per-image.  The global section, as the name implies, specifies options that pertain to LILO itself and to all images specified in the file.  The per-image section specifies options that apply to a specific image, some of which may override the global options.
  
 
====Global Options====
 
====Global Options====
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The LILO configuration file needs the following options, at a minimum, configured for the global settings:
 
The LILO configuration file needs the following options, at a minimum, configured for the global settings:
  
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* <code>disk</code> This option specifies the disk to which the LILO bootloader needs to be written.  This should always point to the device node currently associated with the disk.  For example, when mounted on a desktop, this may be <code>/dev/sdc</code>, which is (usually) the third "SCSI" device connected to the system.  If it were mounted through the IDE subsystem instead, its device node would appear like <code>/dev/hdc</code> instead.
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* <code>disk</code> This option specifies the disk to which the LILO bootloader needs to be written.  This should always point to the device node currently associated with the disk.  For example, when mounted on a desktop, this may be <code>/dev/sdc</code>, which is (usually) the third "SCSI" device connected to the system.  The first would be <code>/dev/sda</code>, the second <code>/dev/sdb</code>, etc.  Even though the device may not be a SCSI device, it may be mounted via a generic SCSI driver, which is why it can appear as a SCSI device.  If it were mounted through the IDE subsystem instead, its device node would appear like <code>/dev/hdc</code> instead.
 
* <code>map</code> This option specifies the location of the map file to use.  Usually, this will be <code>/boot/map</code>.
 
* <code>map</code> This option specifies the location of the map file to use.  Usually, this will be <code>/boot/map</code>.
 
* <code>lba32</code> This option tells LILO to use 32-bit Logical Block Addresses instead of cylinder/head/sector addresses.  This is needed for any disk with more than 1024 cylinders.  Since the vast majority of modern drives have more than 1024 cylinders, this option should always be specified.
 
* <code>lba32</code> This option tells LILO to use 32-bit Logical Block Addresses instead of cylinder/head/sector addresses.  This is needed for any disk with more than 1024 cylinders.  Since the vast majority of modern drives have more than 1024 cylinders, this option should always be specified.
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'''Additional useful options:'''
 
'''Additional useful options:'''
  
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* <code>vga</code> For systems which have video, this option specifies the video mode the device should use while booting.
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* <code>vga</code> For systems which have video, this option specifies the video mode the device should use.  The parameter to pass comes from the BSP (Board Support Profile) layer for the board.  If unsure what to set here, EMAC can provide assistance with this.
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* <code>serial</code> This option allows the bootloader to accept input from a serial line and specifies a serial device and configuration to which a console should be attached. For example, to use the <code>/dev/ttyS0</code> serial device (the default console port on many boards) as a serial console which communicates as 115,200 baud, 8 bits, with no stop bits: <code>serial=0,115200n8</code>
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* <code>serial</code> This useful option specifies a serial device to which a console should be attached, as well as the configuration settings for the console. For example, to use the <code>/dev/ttyS0</code> serial device (the default console port on many boards) as a serial console which communicates as 115,200 baud, 8 bits, with no stop bits: <code>serial=0,115200n8</code>
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* <code>timeout</code> This specifies the amount of time to wait before timing out and continuing on with the boot process using the configured defaults. This allows some time for the user to hit ''TAB'' to specify additional options to the kernel. This value is specified in deciseconds and must be greater than 0.  For example, to set this value to 4.3 seconds: <code>timeout=43</code>
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* <code>timeout</code> This specifies the amount of time to wait before timing out and continuing on with the boot process using the configured defaults. This value is specified in deciseconds.  For example, to set this value to 4.3 seconds: <code>timeout=43</code>
 
* <code>read-only</code> This option tells LILO to mount the root filesystem as read-only.  This is usually desired, since the Linux kernel will remount the device as writeable (if it needs to) once the boot process has been handed over to it.
 
* <code>read-only</code> This option tells LILO to mount the root filesystem as read-only.  This is usually desired, since the Linux kernel will remount the device as writeable (if it needs to) once the boot process has been handed over to it.
 
* <code>install</code> This option specifies the type of screen which will be seen when the bootloader starts.  Normally, this will be set to <code>text</code>, which presents the simple interface shown in the examples on this page.  The <code>menu</code> option provides a nicer way to select an image to boot, but is usually not desirable to have on an embedded machine.  The <code>bitmap</code> option provides a graphical boot screen which looks very nice on a desktop installation, but is usually only used on an embedded machine when the product calls for showing graphics as early in the boot process as possible; a logo is typically placed here in such a case.
 
* <code>install</code> This option specifies the type of screen which will be seen when the bootloader starts.  Normally, this will be set to <code>text</code>, which presents the simple interface shown in the examples on this page.  The <code>menu</code> option provides a nicer way to select an image to boot, but is usually not desirable to have on an embedded machine.  The <code>bitmap</code> option provides a graphical boot screen which looks very nice on a desktop installation, but is usually only used on an embedded machine when the product calls for showing graphics as early in the boot process as possible; a logo is typically placed here in such a case.
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* <code>compact</code>  Speeds up booting by merging read requests.
 
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* <code>append</code> Various append options can be added that will be passed to the kernel during the boot process. In the example, the boot messages will be output to the serial console.
 
  
 
====Per-Image Options====
 
====Per-Image Options====
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The following options are needed to configure images to be available to boot with LILO:
 
The following options are needed to configure images to be available to boot with LILO:
  
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* <code>image</code> This option specifies the location of the kernel to boot.  Commonly, this will be <code>/boot/bzImage</code> or <code>/boot/bzImage-custom-3.10.2</code>. bzImage is commonly a symbolic link to the actual kernel filename. This is done so that lilo.conf does not have to be changed when a new kernel is installed.
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* <code>image</code> This option specifies the location of the kernel to boot.  Commonly, this will be <code>/boot/bzImage</code> or <code>/boot/bzImage-custom-3.10.2</code>
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* <code>root</code> This option specifies the root partition of the device to mount for the image. This is typically <code>/dev/hda1</code> or <code>/dev/sda1</code>
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* <code>root</code> This option specifies the root partition to mount for the image. This is typically <code>/dev/hda1</code> or <code>/dev/sda1</code>
 
* <code>label</code> This option tells LILO by what name to call the image.  For instance, this is usually <code>label=emac-oe</code> for a standard EMAC image, but for a custom product under development, it might be <code>label=custom-image-test-v3</code>
 
* <code>label</code> This option tells LILO by what name to call the image.  For instance, this is usually <code>label=emac-oe</code> for a standard EMAC image, but for a custom product under development, it might be <code>label=custom-image-test-v3</code>
  
 
====Working with LILO Configurations====
 
====Working with LILO Configurations====
  
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The above information describes the common options and how to set them.  Additional information can be found by reading through the manual page for <code>lilo.conf</code>.  This manpage is available on many sites online and on the [http://lilo.alioth.debian.org/olddoc/html/user_21-5.html LILO user's guide.]
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The above information talks about the common options and how to set them.  Additional information can be found by reading through the manual page for <code>lilo.conf</code>.  This manpage is available on many sites online.
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Using these options to create a configuration file is done most easily by copying the EMAC provided LILO configuration file, then modifying the copy.  It is a good practice to make sure a bootable flash card is set aside in case of difficulties with getting the modified flash card back into a bootable state. Also, keep a separate copy of lilo.conf e.g. lilo.conf.boot to use when installing LILO from a Linux PC so that the <code>boot</code> and <code>disk</code> options can be set for installing LILO either on the target device or from the compact flash.
 
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==Next Step==
 
  
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[[Installing LILO]]
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Actually using these options to create a configuration file is done most easily by copying the EMAC provided LILO configuration file, then modifying the copy.  It is a good practice to make sure a bootable flash card is set aside in case of difficulties with getting the modified flash card back into a bootable state.

Revision as of 13:23, 3 January 2014

TODO: {{#todo:Complete(12.16.13-02:25->MD+);(12.16.13-15:15->MD+);(12.17.13-11:45->MW+);(12.17.13-15:25->KY+)|Mike Dean|oe 4,oe 5,md,complete,mw}}

Configuring LILO

As with any software of moderate or better complexity, configuration is required for LILO to function as desired. The configuration created by EMAC and shipped with a system will usually suffice. However, sometimes enough customization is required that the bootloader itself will need to be reconfigured. Even if custom configuration isn't required, some of this information is important for protecting against accidentally overwriting the bootloader on a developer's desktop with a bootloader that was intended for an embedded machine.

This page describes the parts of the LILO bootloader configuration file, and provides guidance on how to work with it. The other LILO pages describe how to install and use the bootloader after it has been configured.

Sections of the LILO Configuration File

The LILO configuration file is split into two sections: global and per-image. The global section, as the name implies, specifies options that pertain to LILO itself and to all images specified in the file. The per-image section specifies options that apply to a specific image, some of which may override the global options.

Global Options

The LILO configuration file needs the following options, at a minimum, configured for the global settings:

  • disk This option specifies the disk to which the LILO bootloader needs to be written. This should always point to the device node currently associated with the disk. For example, when mounted on a desktop, this may be /dev/sdc, which is (usually) the third "SCSI" device connected to the system. The first would be /dev/sda, the second /dev/sdb, etc. Even though the device may not be a SCSI device, it may be mounted via a generic SCSI driver, which is why it can appear as a SCSI device. If it were mounted through the IDE subsystem instead, its device node would appear like /dev/hdc instead.
  • map This option specifies the location of the map file to use. Usually, this will be /boot/map.
  • lba32 This option tells LILO to use 32-bit Logical Block Addresses instead of cylinder/head/sector addresses. This is needed for any disk with more than 1024 cylinders. Since the vast majority of modern drives have more than 1024 cylinders, this option should always be specified.
  • boot This option specifies the device which contains the boot sector. As with the disk option, this should always be the device node associated with the disk on the current system. For example, boot=/dev/sdc

Additional useful options:

  • vga For systems which have video, this option specifies the video mode the device should use. The parameter to pass comes from the BSP (Board Support Profile) layer for the board. If unsure what to set here, EMAC can provide assistance with this.
  • serial This useful option specifies a serial device to which a console should be attached, as well as the configuration settings for the console. For example, to use the /dev/ttyS0 serial device (the default console port on many boards) as a serial console which communicates as 115,200 baud, 8 bits, with no stop bits: serial=0,115200n8
  • timeout This specifies the amount of time to wait before timing out and continuing on with the boot process using the configured defaults. This value is specified in deciseconds. For example, to set this value to 4.3 seconds: timeout=43
  • read-only This option tells LILO to mount the root filesystem as read-only. This is usually desired, since the Linux kernel will remount the device as writeable (if it needs to) once the boot process has been handed over to it.
  • install This option specifies the type of screen which will be seen when the bootloader starts. Normally, this will be set to text, which presents the simple interface shown in the examples on this page. The menu option provides a nicer way to select an image to boot, but is usually not desirable to have on an embedded machine. The bitmap option provides a graphical boot screen which looks very nice on a desktop installation, but is usually only used on an embedded machine when the product calls for showing graphics as early in the boot process as possible; a logo is typically placed here in such a case.

Per-Image Options

The following options are needed to configure images to be available to boot with LILO:

  • image This option specifies the location of the kernel to boot. Commonly, this will be /boot/bzImage or /boot/bzImage-custom-3.10.2
  • root This option specifies the root partition to mount for the image. This is typically /dev/hda1 or /dev/sda1
  • label This option tells LILO by what name to call the image. For instance, this is usually label=emac-oe for a standard EMAC image, but for a custom product under development, it might be label=custom-image-test-v3

Working with LILO Configurations

The above information talks about the common options and how to set them. Additional information can be found by reading through the manual page for lilo.conf. This manpage is available on many sites online.

Actually using these options to create a configuration file is done most easily by copying the EMAC provided LILO configuration file, then modifying the copy. It is a good practice to make sure a bootable flash card is set aside in case of difficulties with getting the modified flash card back into a bootable state.

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