Difference between revisions of "Syslinux"

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[[Category:Boot loaders]]
 
[[Category:Boot loaders]]
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[[es:Syslinux]]
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[[fr:Syslinux]]
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[[it:Syslinux]]
 
[[tr:Syslinux]]
 
[[tr:Syslinux]]
 
[[zh-CN:Syslinux]]
 
[[zh-CN:Syslinux]]
[[it:Syslinux]]
 
 
{{Article summary start}}
 
{{Article summary start}}
 
{{Article summary text|Describes installing and configuring Syslinux, a collection of bootloaders.}}
 
{{Article summary text|Describes installing and configuring Syslinux, a collection of bootloaders.}}
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{{Article summary end}}
 
{{Article summary end}}
  
Syslinux is a collection of boot loaders capable of booting from hard drives, CDs, and over the network via PXE. It supports the fat, ext2, ext3, ext4, and btrfs file systems.
+
{{Merge|Network_Installation_Guide#Pxelinux|No mention of PXE capability in this article}}
  
{{Note|Since Syslinux 4, Extlinux and Syslinux are the same thing.}}
+
[[Wikipedia:SYSLINUX|Syslinux]] is a collection of boot loaders capable of booting from hard drives, CDs, and over the network via PXE. It supports the [[Wikipedia:File Allocation Table|FAT]], [[Wikipedia:ext2|ext2]], [[Ext3|ext3]], [[Ext4|ext4]], and [[Btrfs]] file systems.
  
{{Note|Syslinux does not support [[UEFI]] as of May 2012. According to upstream, UEFI support will be eventually added to Syslinux, but there is no time-frame as to when it will be functional.}}
+
{{Note|Since Syslinux 4, Extlinux and Syslinux are the same thing.}}
 +
{{Note|Syslinux UEFI support is present in version 6.00-preXX and is currently of alpha quality. See [[UEFI_Bootloaders#SYSLINUX]] for more info.}}
  
 
== Syslinux Boot Process ==
 
== Syslinux Boot Process ==
#'''Load MBR'''. At boot, the computer loads the [[MBR]] ({{ic|/usr/lib/syslinux/mbr.bin}}).  
+
# '''Load MBR'''. At boot, the computer loads the [[MBR]] ({{ic|/usr/lib/syslinux/mbr.bin}}).  
#'''Search active partition'''. The MBR looks for the partition that is marked as active (boot flag).  
+
# '''Search active partition'''. The MBR looks for the partition that is marked as active (boot flag).  
#'''Execute volume boot record'''. Once found, the volume boot record (VBR) will be executed. In the case of ext2/3/4 and fat12/16/32, the starting sector of {{ic|ldlinux.sys}} is hard-coded into the VBR.
+
# '''Execute volume boot record'''. Once found, the volume boot record (VBR) will be executed. In the case of ext2/3/4 and FAT12/16/32, the starting sector of {{ic|ldlinux.sys}} is hard-coded into the VBR.
#'''Execute ldlinux.sys'''. The VBR will execute ({{ic|ldlinux.sys}}). Therefore, if the location of {{ic|ldlinux.sys}} changes, syslinux will no longer boot. (In the case of btrfs, the above method will not work since files move around resulting in the sector location of {{ic|ldlinux.sys}} changing. Therefore, the entire Syslinux code needs to be stored outside the filesystem. The code is stored in the sectors following the VBR.)  
+
# '''Execute ldlinux.sys'''. The VBR will execute ({{ic|ldlinux.sys}}). Therefore, if the location of {{ic|ldlinux.sys}} changes, Syslinux will no longer boot. (In the case of Btrfs, the above method will not work since files move around resulting in the sector location of {{ic|ldlinux.sys}} changing. Therefore, the entire Syslinux code needs to be stored outside the filesystem. The code is stored in the sectors following the VBR.)  
#'''Search configuration file'''. Once Syslinux is fully loaded, it looks for a configuration file, either {{ic|extlinux.conf}} or {{ic|syslinux.cfg}}.  
+
# '''Search configuration file'''. Once Syslinux is fully loaded, it looks for a configuration file, either {{ic|extlinux.conf}} or {{ic|syslinux.cfg}}.  
#'''Load configuration'''. If one is found, the configuration file is loaded. If no configuration file is found, you will be given a syslinux prompt.
+
# '''Load configuration'''. If one is found, the configuration file is loaded. If no configuration file is found, you will be given a Syslinux prompt.
  
==Installation==
+
== Installation ==
===Automatic Install ===
+
 
The syslinux-install_update script will install Syslinux, copy COM32 modules to {{ic|/boot/syslinux}}, set the boot flag, and install the MBR. It can handle MBR and GPT disks along with softraid.
+
[[Pacman|Install]] {{Pkg|syslinux}} from the [[official repositories]].
 +
 
 +
=== Automatic Install ===
 +
The {{ic|syslinux-install_update}} script will install Syslinux, copy/symlink {{ic|*.c32}} modules to {{ic|/boot/syslinux}}, set the boot flag and install the boot code in the MBR. It can handle [[Master Boot Record|MBR]] and [[GUID Partition Table|GPT]] disks along with software RAID.
 
   
 
   
1. Install {{Pkg|syslinux}}:
+
:1. If you use a separate boot partition make sure that it is mounted. Check with {{ic|lsblk}}; if you don't see a {{ic|/boot}} mountpoint, mount it before you go any further.
pacman -S syslinux
+
2. Make sure {{ic|/boot}} is mounted<br/>
+
3. Run {{ic|syslinux-install_update script}} {{ic|-i}} (install) {{ic|-a}} (set boot flag) {{ic|-m}} (install mbr)
+
/usr/sbin/syslinux-install_update -iam
+
4. Edit {{ic|/boot/syslinux/syslinux.cfg}}
+
  
===Manual Install ===
+
:2. Run {{ic|syslinux-install_update}} with flags: {{ic|-i}} (install the files), {{ic|-a}} (mark the partition ''active'' with the ''boot'' flag), {{ic|-m}} (install the ''MBR'' boot code):
{{Note| If you are unsure of which partition table you are using (MBR or GPT), you are likely using the MBR partition table.  Most of the time GPT will create a special MBR-style partition (type 0xEE) using the whole disk which will be displayed with the following command:
+
# syslinux-install_update -i -a -m
  fdisk -l /dev/sda
+
 
 +
:3. Edit {{ic|/boot/syslinux/syslinux.cfg}}.
 +
 
 +
{{Note|For this to work with [[GUID Partition Table|GPT]], the {{pkg|gptfdisk}} package is needed as the backend for setting the boot flag.}}
 +
 
 +
=== Manual Install ===
 +
{{Note| If you are unsure of which partition table you are using (MBR or GPT), you are likely using the MBR partition table.  Most of the time GPT will create a special MBR-style partition (type {{ic|0xEE}}) using the whole disk which will be displayed with the following command:
 +
  # fdisk -l /dev/sda
  
 
or alternatively:
 
or alternatively:
  sgdisk -l /dev/sda
+
  # sgdisk -p /dev/sda
  
 
will show "GPT: not present" if it is not a GPT disk.
 
will show "GPT: not present" if it is not a GPT disk.
 
}}
 
}}
  
{{Note| If you are trying to rescue an installed system with a live CD, be sure to [[Change_Root|chroot]] into it before executing these commands. If you do not chroot first, you must prepend all file paths (not {{ic|/dev/}} paths) with the mount point.}}
+
{{Note| If you are trying to rescue an installed system with a live CD, be sure to [[Change_Root|chroot]] into it before executing these commands. If you do not chroot first, you must prepend all file paths (not {{ic|/dev/}} paths) with the mount point.}}
  
Make sure you have the {{Pkg|syslinux}} package installed. Then install Syslinux onto your boot partition, which must contain a fat, ext2, ext3, ext4, or btrfs file system.
+
Your boot partition, on which you plan to install Syslinux, must contain a FAT, ext2, ext3, ext4, or Btrfs file system. You should install it on a mounted directory, not a {{ic|/dev/sdXY}} device. You do not have to install it on the root directory of a file system, e.g., with device {{ic|/dev/sda1}} mounted on {{ic|/boot}} you can install Syslinux in the {{ic|syslinux}} directory:
You should install it on a mounted directory, not a {{ic|/dev/sdXY}} device. You do not have to install it on the root directory of a file system, e.g., with device {{ic|/dev/sda1}} mounted on {{ic|/boot}} you can install syslinux in the syslinux directory:
+
  # mkdir /boot/syslinux
  mkdir /boot/syslinux
+
  # extlinux --install /boot/syslinux  
  extlinux --install /boot/syslinux  
+
  
====MBR Partition Table====
+
==== MBR Partition Table ====
Next you need mark your boot partition active in your partition table. Applications capable of doing this include {{ic|fdisk}}, {{ic|cfdisk}}, {{ic|sfdisk}}, {{ic|(g)parted}}. It should look like this:
+
{{Box||See the main article: [[Master Boot Record]]|#E5E5FF|#FCFCFC}}
fdisk -l /dev/sda
+
[...]
+
  Device Boot      Start        End      Blocks  Id  System
+
/dev/sda1  *        2048      104447      51200  83  Linux
+
/dev/sda2          104448  625142447  312519000  83  Linux
+
  
Install the master boot record:
+
Next you need to mark your boot partition active in your partition table. Applications capable of doing this include {{ic|fdisk}}, {{ic|cfdisk}}, {{ic|sfdisk}}, {{ic|parted/gparted}}. It should look like this:
dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/mbr.bin of=/dev/sda
+
{{hc|# fdisk -l /dev/sda|
<!-- conv=notrunc helps if {{ic|/dev/sda}} is actually a file not a block device -->
+
[...]
 +
  Device Boot      Start        End      Blocks  Id  System
 +
/dev/sda1  *        2048      104447      51200  83  Linux
 +
/dev/sda2          104448  625142447  312519000  83  Linux
 +
}}
  
{{Note|1=An alternate MBR doesn't work properly in '''Syslinux 4.05''' - it always invokes first partition. This bug was fixed in this commit: https://git.kernel.org/?p=boot/syslinux/syslinux.git;a=commit;h=794ff174175734a0974e1846f0db29040b096e45.}}
+
Install the MBR:
 +
# dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/mbr.bin of=/dev/sda
  
An alternate MBR which Syslinux provides is: altmbr.bin. This MBR does ''not'' scan for bootable partitions; instead, the last byte of the MBR is set to a value indicating which partition to boot from. Here is an example of how {{ic|altmbr.bin}} can be copied into position:
+
An alternate MBR which Syslinux provides is: {{ic|altmbr.bin}}. This MBR does ''not'' scan for bootable partitions; instead, the last byte of the MBR is set to a value indicating which partition to boot from. Here is an example of how {{ic|altmbr.bin}} can be copied into position:
 +
# printf '\x5' | cat /usr/lib/syslinux/altmbr.bin - | dd bs=440 count=1 iflag=fullblock conv=notrunc of=/dev/sda
  
printf '\x5' | cat /usr/lib/syslinux/altmbr.bin - | dd bs=440 count=1 iflag=fullblock conv=notrunc of=/dev/sda
+
In this case, a single byte of value 5 is appended to the contents of {{ic|altmbr.bin}} and the resulting 440 bytes are written to the MBR on device {{ic|sda}}. Syslinux was installed on the first logical partition ({{ic|/dev/sda5}}) of the disk.
  
In this case, a single byte of value 5 is appended to the contents of {{ic|altmbr.bin}} and the resulting 440 bytes are written to the MBR on device sda. Syslinux was installed on the first logical partition ({{ic|/dev/sda5}}) of the disk.
+
==== GUID Partition Table aka GPT ====
 +
{{Box||See the main article: [[GUID Partition Table]]|#E5E5FF|#FCFCFC}}
  
====GUID Partition Table aka GPT====
+
Bit 2 of the attributes for the {{ic|/boot}} partition needs to be set.
Main article [[GUID Partition Table]].
+
# sgdisk /dev/sda --attributes=1:set:2
  
Bit 2 of the attributes for the {{ic|/boot}} partition need to be set.
+
This would toggle the attribute ''legacy BIOS bootable'' on partition 1. To check:
 
+
  # sgdisk /dev/sda --attributes=1:show
sgdisk /dev/sda --attributes=1:set:2
+
 
+
This would toggle the attribute legacy BIOS bootable on partition 1.
+
 
+
Verify:
+
  sgdisk /dev/sda --attributes=1:show
+
 
  1:2:1 (legacy BIOS bootable)
 
  1:2:1 (legacy BIOS bootable)
  
Install the master boot record:
+
Install the MBR:
  dd bs=440 conv=notrunc count=1 if=/usr/lib/syslinux/gptmbr.bin of=/dev/sda
+
  # dd bs=440 conv=notrunc count=1 if=/usr/lib/syslinux/gptmbr.bin of=/dev/sda
  
====Rebooting====
+
==== Rebooting ====
When you reboot your system now, you will have a syslinux prompt. To automatically boot your system or get a boot menu, you still need to create a configuration file.
+
When you reboot your system now, you will have a Syslinux prompt. To automatically boot your system or get a boot menu, you still need to create a configuration file.
  
 
== Configuration ==
 
== Configuration ==
The syslinux configuration file, {{ic|syslinux.cfg}}, should be created in the same directory where you installed syslinux. In our case, {{ic|/boot/syslinux/}}.
+
The Syslinux configuration file, {{ic|syslinux.cfg}}, should be created in the same directory where you installed Syslinux. In our case, {{ic|/boot/syslinux/}}.
  
The bootloader will look for either {{ic|syslinux.cfg}} (preferred) or {{ic| extlinux.conf}}
+
The bootloader will look for either {{ic|syslinux.cfg}} (preferred) or {{ic|extlinux.conf}}
  
'''Tips''':
+
{{Tip|
*Instead of {{ic|LINUX}}, the keyword {{ic|KERNEL}} can also be used. {{ic|KERNEL}} tries to detect the type of the file, while {{ic|LINUX}} always expects a Linux kernel.  
+
* Instead of {{ic|LINUX}}, the keyword {{ic|KERNEL}} can also be used. {{ic|KERNEL}} tries to detect the type of the file, while {{ic|LINUX}} always expects a Linux kernel.  
*{{ic|TIMEOUT}} value is in units of 1/10 of a second.
+
* {{ic|TIMEOUT}} value is in units of '''1/10''' of a second.
 +
}}
  
 
=== Examples ===
 
=== Examples ===
 
==== Basic Config ====
 
==== Basic Config ====
This is a simple configuration file that will show a boot: prompt and automatically boot after 5 seconds.
+
This is a simple configuration file that will show a {{ic|boot:}} prompt and automatically boot after 5 seconds.
  
Note: the partition in question needs to be whatever you have as / (root), not /boot.
+
{{Note|The partition in question needs to be whatever you have as {{ic|/}} (root), not {{ic|/boot}}.}}
  
Config:
+
Configuration:
 +
{{hc|/boot/syslinux/syslinux.cfg|<nowiki>
 
  PROMPT 1
 
  PROMPT 1
 
  TIMEOUT 50
 
  TIMEOUT 50
Line 118: Line 123:
 
         LINUX ../vmlinuz-linux
 
         LINUX ../vmlinuz-linux
 
         APPEND root=/dev/sda2 ro
 
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux-fallback.img
+
         INITRD ../initramfs-linux-fallback.img</nowiki>
 +
}}
  
 
If you want to boot directly without seeing a prompt, set {{ic|PROMPT}} to {{ic|0}}.
 
If you want to boot directly without seeing a prompt, set {{ic|PROMPT}} to {{ic|0}}.
  
If you want to use [[UUID]] for persistent device naming instead of device names, change:
+
If you want to use [[UUID]] for persistent device naming instead of device names, change the {{ic|APPEND}} line to your equivalent {{ic|UUID}} of the root partition:
  APPEND root=/dev/sda2 ro
+
APPEND root='''UUID='''978e3e81-8048-4ae1-8a06-aa727458e8ff ro
 +
 
 +
If you use encryption [[LUKS]] change the {{ic|APPEND}} line to use your encrypted volume:
 +
  APPEND root=/dev/mapper/<group>-<name> cryptdevice=/dev/sda2:<name> ro
  
to:
+
If you are using software [[Wikipedia:RAID|RAID]] using [http://neil.brown.name/blog/mdadm mdadm], change the {{ic|APPEND}} line to accommodate your RAID arrays. As an example the following accommodates three RAID 1 array's and sets the appropriate one as root:
  APPEND root=UUID=<uuid here> ro
+
  APPEND root=/dev/md1 ro md=0,/dev/sda2,/dev/sdb2 md=1,/dev/sda3,/dev/sdb3 md=2,/dev/sda4,/dev/sdb4
  
 
==== Text Boot menu ====
 
==== Text Boot menu ====
Syslinux also allows you to use a boot menu. To use it, copy the menu COM32 module to your syslinux directory:
+
Syslinux also allows you to use a boot menu. To use it, copy the {{ic|menu}} COM32 module to your Syslinux directory:
 
  # cp /usr/lib/syslinux/menu.c32 /boot/syslinux/
 
  # cp /usr/lib/syslinux/menu.c32 /boot/syslinux/
  
Line 135: Line 144:
 
  # ln -s /usr/lib/syslinux/menu.c32 /boot/syslinux/
 
  # ln -s /usr/lib/syslinux/menu.c32 /boot/syslinux/
  
Config:
+
Configuration:
 +
{{hc|/boot/syslinux/syslinux.cfg|<nowiki>
 
  UI menu.c32
 
  UI menu.c32
 
  PROMPT 0
 
  PROMPT 0
Line 153: Line 163:
 
         LINUX ../vmlinuz-linux
 
         LINUX ../vmlinuz-linux
 
         APPEND root=/dev/sda2 ro
 
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux-fallback.img
+
         INITRD ../initramfs-linux-fallback.img</nowiki>
 +
}}
  
For more details about the menu system, see http://git.kernel.org/?p=boot/syslinux/syslinux.git;a=blob;f=doc/menu.txt.
+
For more details about the menu system, see [http://git.kernel.org/?p=boot/syslinux/syslinux.git;a=blob;f=doc/menu.txt the Syslinux documentation].
  
 
==== Graphical Boot menu ====
 
==== Graphical Boot menu ====
Syslinux also allows you to use a graphical boot menu. To use it, copy the vesamenu COM32 module to your syslinux folder:
+
Syslinux also allows you to use a graphical boot menu. To use it, copy the {{ic|vesamenu}} COM32 module to your Syslinux folder:
 
  # cp /usr/lib/syslinux/vesamenu.c32 /boot/syslinux/
 
  # cp /usr/lib/syslinux/vesamenu.c32 /boot/syslinux/
  
Line 164: Line 175:
 
  # ln -s /usr/lib/syslinux/vesamenu.c32 /boot/syslinux/
 
  # ln -s /usr/lib/syslinux/vesamenu.c32 /boot/syslinux/
  
[http://projects.archlinux.org/archiso.git/tree/configs/releng/syslinux This config] uses the same menu design as the Arch Install CD. The background file can be found there too.
+
[https://projects.archlinux.org/archiso.git/tree/configs/releng/syslinux This config] uses the same menu design as the Arch Install CD. The background file can be found there too.
  
Config:
+
Configuration:
 +
{{hc|/boot/syslinux/syslinux.cfg|<nowiki>
 
  UI vesamenu.c32
 
  UI vesamenu.c32
 
  DEFAULT arch
 
  DEFAULT arch
Line 208: Line 220:
 
         LINUX ../vmlinuz-linux
 
         LINUX ../vmlinuz-linux
 
         APPEND root=/dev/sda2 ro
 
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux-fallback.img
+
         INITRD ../initramfs-linux-fallback.img</nowiki>
 +
}}
  
 
Since Syslinux 3.84, {{ic|vesamenu.c32}} supports the {{ic|MENU RESOLUTION $WIDTH $HEIGHT}} directive.
 
Since Syslinux 3.84, {{ic|vesamenu.c32}} supports the {{ic|MENU RESOLUTION $WIDTH $HEIGHT}} directive.
 
To use it, insert {{ic|MENU RESOLUTION 1440 900}} into your config for a 1440x900 resolution.
 
To use it, insert {{ic|MENU RESOLUTION 1440 900}} into your config for a 1440x900 resolution.
The background picture has to have exactly the right resolution, however, as syslinux will otherwise refuse to load the menu.
+
The background picture has to have exactly the right resolution, however, as Syslinux will otherwise refuse to load the menu.
  
 
=== Auto Boot ===
 
=== Auto Boot ===
If you don't want to see the syslinux menu at all, comment out all UI commands and make sure there is a DEFAULT set.
+
If you don't want to see the Syslinux menu at all, comment out all {{ic|UI}} commands and make sure there is a {{ic|DEFAULT}} set in your {{ic|syslinux.cfg}}.
  
 
=== Chainloading ===
 
=== Chainloading ===
If you want to chainload other operating systems (such as Windows) or boot loaders, copy (or symlink) the {{ic|chain.c32}} module to the syslinux directory (for details, see the instructions in the previous section). Then create a section in the configuration file:
+
If you want to chainload other operating systems (such as Windows) or boot loaders, copy (or symlink) the {{ic|chain.c32}} module to the Syslinux directory (for details, see the instructions in the previous section). Then create a section in the configuration file:
 
+
{{hc|/boot/syslinux/syslinux.cfg|
 +
...
 
  LABEL windows
 
  LABEL windows
 
         MENU LABEL Windows
 
         MENU LABEL Windows
 
         COM32 chain.c32
 
         COM32 chain.c32
 
         APPEND hd0 3
 
         APPEND hd0 3
 +
...
 +
}}
  
{{ic|hd0 3}} is the third partition on the first BIOS drive - drives are counted from zero, but partitions are counted from one. For more details about chainloading, see [http://syslinux.zytor.com/wiki/index.php/Comboot/chain.c32].
+
{{ic|hd0 3}} is the third partition on the first BIOS drive - drives are counted from zero, but partitions are counted from one.  
  
If you have [[grub2]] installed in your boot partition, you can chainload it by using:  
+
If you are unsure about which drive your BIOS thinks is "first", you can instead use the MBR identifier, or if you are using GPT, the filesystem labels. To use the MBR identifier, run the command
 +
{{hc|# fdisk -l /dev/sdb|<nowiki>
 +
Disk /dev/sdb: 128.0 GB, 128035676160 bytes
 +
255 heads, 63 sectors/track, 15566 cylinders, total 250069680 sectors
 +
Units = sectors of 1 * 512 = 512 bytes
 +
Sector size (logical/physical): 512 bytes / 512 bytes
 +
I/O size (minimum/optimal): 512 bytes / 512 bytes
 +
Disk identifier: 0xf00f1fd3
 +
 
 +
Device Boot      Start        End      Blocks  Id  System
 +
/dev/sdb1            2048    4196351    2097152    7  HPFS/NTFS/exFAT
 +
/dev/sdb2        4196352  250066943  122935296    7  HPFS/NTFS/exFAT</nowiki>
 +
}}
  
 +
replacing {{ic|/dev/sdb}} with the drive you wish to chainload. Using the hexadecimal number under Disk identifier: {{ic|0xf00f1fd3}} in this case, the syntax in {{ic|syslinux.cfg}} is
 +
{{hc|/boot/syslinux/syslinux.cfg|
 +
...
 +
LABEL windows
 +
        MENU LABEL Windows
 +
        COM32 chain.c32
 +
        APPEND mbr:0xf00f1fd3
 +
...
 +
}}
 +
 +
For more details about chainloading, see [http://www.syslinux.org/wiki/index.php/Comboot/chain.c32 the Syslinux wiki].
 +
 +
If you have [[GRUB]] installed on the same partition, you can chainload it by using:
 +
{{hc|/boot/syslinux/syslinux.cfg|<nowiki>
 +
...
 
  LABEL grub2
 
  LABEL grub2
 
         MENU LABEL Grub2
 
         MENU LABEL Grub2
 
         COM32 chain.c32
 
         COM32 chain.c32
 
         append file=../grub/boot.img
 
         append file=../grub/boot.img
 +
...</nowiki>
 +
}}
  
 
This may be required for booting from ISO images.
 
This may be required for booting from ISO images.
 +
 +
=== Chainloading other Linux systems ===
 +
Chainloading another bootloader such as Windows' is pretty obvious, as there is a definite bootloader to chain to.  But with Syslinux, it is only able to load files residing on the same partition as the configuration file.  Thus, if you have another version of Linux on a separate partition, without a shared {{ic|/boot}}, it becomes necessary to employ Extlinux. Essentially, Extlinux can be installed on the partition superblock and be called as a separate bootloader from the MBR installed by Syslinux. Extlinux is part of the Syslinux project and is included with the {{Pkg|syslinux}} package.
 +
 +
The following instructions assume you have Syslinux installed already. These instructions will also assume that the typical Arch Linux configuration path of {{ic|/boot/syslinux}} is being used and the chainloaded {{ic|/}} is on {{ic|/dev/sda3}}. 
 +
 +
From a booted Linux (likely the partition that Syslinux is set up to boot), mount the other root partition to your desired mount point.  In this example this will be {{ic|/mnt}}.  Also, if a separate {{ic|/boot}} partition is used on the second operating system, that will also need to be mounted.  The example assumes this is {{ic|/dev/sda2}}.
 +
# mount /dev/sda3 /mnt
 +
# mount /dev/sda2 /mnt/boot (only necessary for separate /boot)
 +
Install Extlinux and copy necessary {{ic|*.c32}} files
 +
# extlinux -i /mnt/boot/syslinux
 +
# cp /usr/lib/syslinux/{chain,menu}.c32 /mnt/boot/syslinux
 +
 +
Create {{ic|/mnt/boot/syslinux/syslinux.cfg}}.  Below is an example:
 +
{{hc|/boot/syslinux/syslinux.cfg '''on /dev/sda3'''|<nowiki>
 +
timeout 10
 +
 +
ui menu.c32
 +
 +
 +
label Other Linux
 +
    linux /boot/vmlinuz-linux
 +
    initrd /boot/initramfs-linux.img
 +
    append root=/dev/sda3 ro quiet
 +
 +
 +
label MAIN
 +
    com32 chain.c32
 +
    append hd0 0</nowiki>
 +
}}
 +
 +
taken from [[User:Djgera|Djgera's user wiki page]].
  
 
=== Using memtest ===
 
=== Using memtest ===
Use this {{ic|LABEL}} section to launch memtest (install the {{Pkg|memtest86+}} package):
+
Install {{Pkg|memtest86+}} from the [[official repositories]].
  
 +
Use this {{ic|LABEL}} section to launch [[Wikipedia:Memtest86|memtest]]:
 +
{{hc|/boot/syslinux/syslinux.cfg|
 +
...
 
  LABEL memtest
 
  LABEL memtest
 
         MENU LABEL Memtest86+
 
         MENU LABEL Memtest86+
 
         LINUX ../memtest86+/memtest.bin
 
         LINUX ../memtest86+/memtest.bin
 +
...
 +
}}
  
 
=== HDT ===
 
=== HDT ===
HDT (Hardware Detection Tool) displays hardware information. Like before, the {{ic|.c32}} file has to be copied or symlinked from {{ic|/boot/syslinux/}}.
+
[http://hdt-project.org/ HDT (Hardware Detection Tool)] displays hardware information. Like before, the {{ic|.c32}} file has to be copied or symlinked from {{ic|/boot/syslinux/}}.
For PCI info, either copy or symlink {{ic|/usr/share/hwdata/pci.ids}} to {{ic|/boot/syslinux/pci.ids}}
+
For PCI info, either copy or symlink {{ic|/usr/share/hwdata/pci.ids}} to {{ic|/boot/syslinux/pci.ids}} and add the following to your configuration file:
 
+
{{hc|/boot/syslinux/syslinux.cfg|
 
  LABEL hdt
 
  LABEL hdt
 
         MENU LABEL Hardware Info
 
         MENU LABEL Hardware Info
 
         COM32 hdt.c32
 
         COM32 hdt.c32
 +
}}
  
 
=== Reboot and power off ===
 
=== Reboot and power off ===
 
Use the following sections to reboot or power off your machine:
 
Use the following sections to reboot or power off your machine:
 
+
{{hc|/boot/syslinux/syslinux.cfg|
 
  LABEL reboot
 
  LABEL reboot
 
         MENU LABEL Reboot
 
         MENU LABEL Reboot
Line 261: Line 344:
 
         MENU LABEL Power Off
 
         MENU LABEL Power Off
 
         COMBOOT poweroff.com
 
         COMBOOT poweroff.com
 +
}}
  
 
=== Clear Menu ===
 
=== Clear Menu ===
 
To clear the screen when exiting the menu, add the following line:
 
To clear the screen when exiting the menu, add the following line:
 +
{{hc|/boot/syslinux/syslinux.cfg|
 
  MENU CLEAR
 
  MENU CLEAR
 +
}}
  
 
=== Keyboard remapping ===
 
=== Keyboard remapping ===
 
If you often have to edit your boot parameters, you might want to remap your keyboard layout. This allows you to enter "=", "/" and other characters easily on a non-US keyboard.
 
If you often have to edit your boot parameters, you might want to remap your keyboard layout. This allows you to enter "=", "/" and other characters easily on a non-US keyboard.
  
First you have to create a compatible keymap (for example a german one):
+
First you have to create a compatible keymap (for example a German one):
  cp /usr/share/kbd/keymaps/i386/qwerty/us.map.gz ./
+
  # cp /usr/share/kbd/keymaps/i386/qwerty/us.map.gz ./
  cp /usr/share/kbd/keymaps/i386/qwertz/de.map.gz ./
+
  # cp /usr/share/kbd/keymaps/i386/qwertz/de.map.gz ./
  gunzip {de,us}.map.gz
+
  # gunzip {de,us}.map.gz
  mv de.{,k}map
+
  # mv de.{,k}map
  mv us.{,k}map
+
  # mv us.{,k}map
  keytab-lilo de > de.ktl
+
  # keytab-lilo de > de.ktl
  
 
Copy {{ic|de.ktl}} as root to {{ic|/boot/syslinux/}} and set ownership to root:
 
Copy {{ic|de.ktl}} as root to {{ic|/boot/syslinux/}} and set ownership to root:
  chown root:root /boot/syslinux/de.ktl
+
  # chown root:root /boot/syslinux/de.ktl
  
Now edit {{ic|syslinux.conf}} and add
+
Now edit {{ic|syslinux.conf}} and add:
 +
{{hc|/boot/syslinux/syslinux.cfg|
 
  KBDMAP de.ktl
 
  KBDMAP de.ktl
 +
}}
  
==Troubleshooting==
+
=== Hiding the menu ===
===I have a Syslinux Prompt - Yikes!===
+
Use the option:
You can type in the {{ic|LABEL}} name of the entry that you want to boot (as per your {{ic|syslinux.cfg}}). If you used the example configs, just type:
+
{{hc|/boot/syslinux/syslinux.cfg|
 +
MENU HIDDEN
 +
}}
 +
to hide the menu while displaying only the timeout. Press any key to bring up the menu.
 +
 
 +
== Troubleshooting ==
 +
=== Using the Syslinux prompt===
 +
You can type in the {{ic|LABEL}} name of the entry that you want to boot (as per your {{ic|syslinux.cfg}}). If you used the example configurations, just type:
 
  boot: arch
 
  boot: arch
  
If you get an error that the config file could not be loaded, you can pass your needed boot parameters, e.g.:
+
If you get an error that the configuration file could not be loaded, you can pass your needed boot parameters, e.g.:
 
  boot: ../vmlinuz-linux root=/dev/sda2 ro initrd=../initramfs-linux.img
 
  boot: ../vmlinuz-linux root=/dev/sda2 ro initrd=../initramfs-linux.img
  
If you do not have access to {{ic|boot:}} in ramfs, and therefore temporarily unable to boot kernel again,
+
If you do not have access to {{ic|boot:}} in [[Ramdisk|ramfs]], and therefore temporarily unable to boot kernel again,
 
+
:1. Create a temporary directory, in order to mount your root partition (if it does not exist already):
1) Create temp directory, in order to mount your root partition (if it does not exist already):
+
   # mkdir -p /new_root
 
+
:2. Mount {{ic|/}} under {{ic|/new_root}} (in case {{ic|/boot/}} is on the same partition, otherwise you will need to mount them both):
   mkdir -p /new_root
+
 
+
2) Mount {{ic|/}} under {{ic|/new_root}} (in case {{ic|/boot/}} is on the same partition, otherwise you will need to mount them both):
+
 
{{Note|If {{ic|/boot}} is on its own ext2 partition then busybox cannot mount it.}}
 
{{Note|If {{ic|/boot}} is on its own ext2 partition then busybox cannot mount it.}}
+
   # mount /dev/sd[a-z][1-9] /new_root
   mount /dev/sd[a-z][1-9] /new_root
+
  
3) Use {{ic|vim}} and edit {{ic|syslinux.cfg}} again to suit your needs and save file.
+
:3. Use {{ic|vim}} and edit {{ic|syslinux.cfg}} again to suit your needs and save file.
 +
:4. Reboot.
  
4) Reboot.
+
=== No Default or UI found on some computers ===
 +
Certain motherboard manufacturers have less compatibility for booting from USB devices than others. While an ext4 formatted USB drive may boot on a more recent computer, some computers may hang if the boot partition containing the ''kernel'' and ''initrd'' are not on a FAT16 partition. To prevent an older machine from loading {{ic|ldlinux}} and failing to read {{ic|syslinux.cfg}}, use {{ic|cfdisk}} to create a FAT16 partition (<=2GB) and format using {{Pkg|dosfstools}}:
 +
# mkfs.msdos -F 16 /dev/sda1
  
===No Default or UI found on some computers===
+
then install and configure Syslinux.
Certain motherboard manufacturers have less compatibility for booting from USB devices than others.  While an ext4 formatted USB drive may boot on a more recent computer, some computers may hang if the boot partition containing the kernel and initrd are not on a fat16 partition.  To prevent an older machine from loading ldlinux and failing to read {{ic|syslinux.cfg}}, use cfdisk to create a fat16 partition (<=2GB) and format with
+
pacman -S dosfstools
+
mkfs.msdos -F 16 /dev/sda1
+
  
then install and configure syslinux.
+
=== Missing Operating System ===
 
+
If you get this message, check if the partition that contains {{ic|/boot}} has the boot flag enabled. If the flag is enabled, then perhaps this partition starts at sector 1 rather than sector 63 or 2048.  Check this with {{ic|fdisk -l}}.  If it starts at sector 1, you can move the partition(s) with {{ic|gparted}} from a rescue disk. Or, if you have a separate boot partition, you can back up {{ic|/boot}} with  
===MISSING OPERATING SYSTEM===
+
  # cp -a /boot /boot.bak
 
+
and then boot up with the Arch install disk. Next, use {{ic|cfdisk}} to delete the {{ic|/boot}} partition, and recreate it.  This time it should begin at the proper sector, '''63'''. Now mount your partitions and {{ic|chroot}} into your mounted system, as described in the beginners guide. Restore {{ic|/boot}} with the command
If you get this message, check if the partition that contains {{ic|/boot}} has the boot flag enabled. If the flag is enabled, then perhaps this partition starts at sector 1 rather than sector 63 or 2048.  Check this with fdisk -l.  If it starts at sector 1, you can move the partition(s) with gparted from a rescue disk. Or, if you have a separate boot partition, you can back up /boot with  
+
  # cp -a /boot.bak/* /boot
  cp -a /boot /boot.bak
+
Check if {{ic|/etc/fstab}} is correct, run:
and then boot up with the arch install disk. Next, use cfdisk to delete the /boot partition, and recreate it.  This time it should begin at the proper sector, 63. Now mount your partitions and chroot into your mounted system, as described in the beginners guide. Restore /boot with the command
+
  # syslinux-install_update -iam
  cp -a /boot.bak/* /boot
+
Check if /etc/fstab is correct.  Then run
+
  /usr/sbin/syslinux-install_update -iam
+
 
and reboot.
 
and reboot.
  
===Windows boots up! No Syslinux!===
+
=== Windows boots up, ignoring Syslinux ===
 
'''Solution:''' Make sure the partition that contains {{ic|/boot}} has the boot flag enabled. Also, make sure the boot flag is not enabled on the Windows partition. See the installation section above.
 
'''Solution:''' Make sure the partition that contains {{ic|/boot}} has the boot flag enabled. Also, make sure the boot flag is not enabled on the Windows partition. See the installation section above.
  
The MBR that comes with syslinux looks for the first active partition that has the boot flag set. The Windows partition was likely found first and had the boot flag set. If you wanted, you could use the MBR that Windows or MS-DOS fdisk provides.
+
The MBR that comes with Syslinux looks for the first active partition that has the boot flag set. The Windows partition was likely found first and had the boot flag set. If you wanted, you could use the MBR that Windows or MS-DOS {{ic|fdisk}} provides.
  
===Menu entries do nothing===
+
=== Menu entries do nothing ===
You select a menu entry and it does nothing, it just "refreshes" the menu. This usually means that you have an error in your {{ic|syslinux.cfg}} file. Hit {{Keypress|Tab}} to edit your boot parameters. Alternatively, press {{Keypress|Esc}} and type in the LABEL of your boot entry (e.g. ''arch'').
+
You select a menu entry and it does nothing, it just ''"refreshes"'' the menu. This usually means that you have an error in your {{ic|syslinux.cfg}} file. Hit {{Keypress|Tab}} to edit your boot parameters. Alternatively, press {{Keypress|Esc}} and type in the {{ic|LABEL}} of your boot entry (e.g. ''arch'').
  
===Cannot remove ldlinux.sys===
+
=== Cannot remove ldlinux.sys ===
  
 
The {{ic|ldlinux.sys}} file has the immutable attribute set, which prevents it from being deleted or overwritten. This is because the sector location of the file must not change or else Syslinux has to be reinstalled. To remove it, run:
 
The {{ic|ldlinux.sys}} file has the immutable attribute set, which prevents it from being deleted or overwritten. This is because the sector location of the file must not change or else Syslinux has to be reinstalled. To remove it, run:
 
 
  # chattr -i /boot/syslinux/ldlinux.sys
 
  # chattr -i /boot/syslinux/ldlinux.sys
 
  # rm /boot/syslinux/ldlinux.sys
 
  # rm /boot/syslinux/ldlinux.sys
  
===A white block on the upper left corner appears when a kernel is loaded with modesetting on in early stage and when using vesamenu===
+
=== White block in upper left corner when using vesamenu ===
'''Brain0''' said:
+
Problem:
''As of linux-3.0, the modesetting driver tries to keep the current contents of the screen after changing the resolution (at least it does so with my Intel, when having syslinux in text mode). It seems that this goes wrong when combined with the vesamenu module in syslinux (the white block is actually an attempt to keep the syslinux menu, but the driver fails to capture the picture from vesa graphics mode).''
+
''As of linux-3.0, the modesetting driver tries to keep the current contents of the screen after changing the resolution (at least it does so with my Intel, when having Syslinux in text mode). It seems that this goes wrong when combined with the vesamenu module in Syslinux (the white block is actually an attempt to keep the Syslinux menu, but the driver fails to capture the picture from vesa graphics mode).''
 
+
If you have a custom resolution and a vesamenu with early modesetting, try to append the following in {{ic|syslinux.cfg}} to remove the white block and continue in graphics mode:
+
  
 +
If you have a custom resolution and a {{ic|vesamenu}} with early modesetting, try to append the following in {{ic|syslinux.cfg}} to remove the white block and continue in graphics mode:
 
  APPEND root=/dev/sda6 ro 5 '''vga=current''' quiet splash
 
  APPEND root=/dev/sda6 ro 5 '''vga=current''' quiet splash
  
 
== See also ==
 
== See also ==
* [http://www.syslinux.org The Syslinux Project]'s web site.
+
* [http://www.syslinux.org Official Website]
 +
* [http://www.josephn.net/scrapbook/pxelinux_stuff PXELinux configuration]

Revision as of 16:13, 25 December 2012

Summary help replacing me
Describes installing and configuring Syslinux, a collection of bootloaders.
Overview
Template:Boot process overview

Merge-arrows-2.pngThis article or section is a candidate for merging with Network_Installation_Guide#Pxelinux.Merge-arrows-2.png

Notes: No mention of PXE capability in this article (Discuss in Talk:Syslinux#)
Syslinux is a collection of boot loaders capable of booting from hard drives, CDs, and over the network via PXE. It supports the FAT, ext2, ext3, ext4, and Btrfs file systems.
Note: Since Syslinux 4, Extlinux and Syslinux are the same thing.
Note: Syslinux UEFI support is present in version 6.00-preXX and is currently of alpha quality. See UEFI_Bootloaders#SYSLINUX for more info.

Syslinux Boot Process

  1. Load MBR. At boot, the computer loads the MBR (/usr/lib/syslinux/mbr.bin).
  2. Search active partition. The MBR looks for the partition that is marked as active (boot flag).
  3. Execute volume boot record. Once found, the volume boot record (VBR) will be executed. In the case of ext2/3/4 and FAT12/16/32, the starting sector of ldlinux.sys is hard-coded into the VBR.
  4. Execute ldlinux.sys. The VBR will execute (ldlinux.sys). Therefore, if the location of ldlinux.sys changes, Syslinux will no longer boot. (In the case of Btrfs, the above method will not work since files move around resulting in the sector location of ldlinux.sys changing. Therefore, the entire Syslinux code needs to be stored outside the filesystem. The code is stored in the sectors following the VBR.)
  5. Search configuration file. Once Syslinux is fully loaded, it looks for a configuration file, either extlinux.conf or syslinux.cfg.
  6. Load configuration. If one is found, the configuration file is loaded. If no configuration file is found, you will be given a Syslinux prompt.

Installation

Install syslinux from the official repositories.

Automatic Install

The syslinux-install_update script will install Syslinux, copy/symlink *.c32 modules to /boot/syslinux, set the boot flag and install the boot code in the MBR. It can handle MBR and GPT disks along with software RAID.

1. If you use a separate boot partition make sure that it is mounted. Check with lsblk; if you don't see a /boot mountpoint, mount it before you go any further.
2. Run syslinux-install_update with flags: -i (install the files), -a (mark the partition active with the boot flag), -m (install the MBR boot code):
# syslinux-install_update -i -a -m
3. Edit /boot/syslinux/syslinux.cfg.
Note: For this to work with GPT, the gptfdisk package is needed as the backend for setting the boot flag.

Manual Install

Note: If you are unsure of which partition table you are using (MBR or GPT), you are likely using the MBR partition table. Most of the time GPT will create a special MBR-style partition (type 0xEE) using the whole disk which will be displayed with the following command:
# fdisk -l /dev/sda

or alternatively:

# sgdisk -p /dev/sda

will show "GPT: not present" if it is not a GPT disk.

Note: If you are trying to rescue an installed system with a live CD, be sure to chroot into it before executing these commands. If you do not chroot first, you must prepend all file paths (not /dev/ paths) with the mount point.

Your boot partition, on which you plan to install Syslinux, must contain a FAT, ext2, ext3, ext4, or Btrfs file system. You should install it on a mounted directory, not a /dev/sdXY device. You do not have to install it on the root directory of a file system, e.g., with device /dev/sda1 mounted on /boot you can install Syslinux in the syslinux directory:

# mkdir /boot/syslinux
# extlinux --install /boot/syslinux 

MBR Partition Table

Template:Box

Next you need to mark your boot partition active in your partition table. Applications capable of doing this include fdisk, cfdisk, sfdisk, parted/gparted. It should look like this:

# fdisk -l /dev/sda
[...]
  Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      104447       51200   83  Linux
/dev/sda2          104448   625142447   312519000   83  Linux

Install the MBR:

# dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/mbr.bin of=/dev/sda

An alternate MBR which Syslinux provides is: altmbr.bin. This MBR does not scan for bootable partitions; instead, the last byte of the MBR is set to a value indicating which partition to boot from. Here is an example of how altmbr.bin can be copied into position:

# printf '\x5' | cat /usr/lib/syslinux/altmbr.bin - | dd bs=440 count=1 iflag=fullblock conv=notrunc of=/dev/sda

In this case, a single byte of value 5 is appended to the contents of altmbr.bin and the resulting 440 bytes are written to the MBR on device sda. Syslinux was installed on the first logical partition (/dev/sda5) of the disk.

GUID Partition Table aka GPT

Template:Box

Bit 2 of the attributes for the /boot partition needs to be set.

# sgdisk /dev/sda --attributes=1:set:2

This would toggle the attribute legacy BIOS bootable on partition 1. To check:

# sgdisk /dev/sda --attributes=1:show
1:2:1 (legacy BIOS bootable)

Install the MBR:

# dd bs=440 conv=notrunc count=1 if=/usr/lib/syslinux/gptmbr.bin of=/dev/sda

Rebooting

When you reboot your system now, you will have a Syslinux prompt. To automatically boot your system or get a boot menu, you still need to create a configuration file.

Configuration

The Syslinux configuration file, syslinux.cfg, should be created in the same directory where you installed Syslinux. In our case, /boot/syslinux/.

The bootloader will look for either syslinux.cfg (preferred) or extlinux.conf

Tip:
  • Instead of LINUX, the keyword KERNEL can also be used. KERNEL tries to detect the type of the file, while LINUX always expects a Linux kernel.
  • TIMEOUT value is in units of 1/10 of a second.

Examples

Basic Config

This is a simple configuration file that will show a boot: prompt and automatically boot after 5 seconds.

Note: The partition in question needs to be whatever you have as / (root), not /boot.

Configuration:

/boot/syslinux/syslinux.cfg
 PROMPT 1
 TIMEOUT 50
 DEFAULT arch
 
 LABEL arch
         LINUX ../vmlinuz-linux
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux.img
 
 LABEL archfallback
         LINUX ../vmlinuz-linux
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux-fallback.img

If you want to boot directly without seeing a prompt, set PROMPT to 0.

If you want to use UUID for persistent device naming instead of device names, change the APPEND line to your equivalent UUID of the root partition:

APPEND root=UUID=978e3e81-8048-4ae1-8a06-aa727458e8ff ro

If you use encryption LUKS change the APPEND line to use your encrypted volume:

APPEND root=/dev/mapper/<group>-<name> cryptdevice=/dev/sda2:<name> ro

If you are using software RAID using mdadm, change the APPEND line to accommodate your RAID arrays. As an example the following accommodates three RAID 1 array's and sets the appropriate one as root:

APPEND root=/dev/md1 ro md=0,/dev/sda2,/dev/sdb2 md=1,/dev/sda3,/dev/sdb3 md=2,/dev/sda4,/dev/sdb4

Text Boot menu

Syslinux also allows you to use a boot menu. To use it, copy the menu COM32 module to your Syslinux directory:

# cp /usr/lib/syslinux/menu.c32 /boot/syslinux/

If /boot is in the same partition as /usr, a symlink will also work:

# ln -s /usr/lib/syslinux/menu.c32 /boot/syslinux/

Configuration:

/boot/syslinux/syslinux.cfg
 UI menu.c32
 PROMPT 0
 
 MENU TITLE Boot Menu
 TIMEOUT 50
 DEFAULT arch
 
 LABEL arch
         MENU LABEL Arch Linux
         LINUX ../vmlinuz-linux
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux.img
 
 LABEL archfallback
         MENU LABEL Arch Linux Fallback
         LINUX ../vmlinuz-linux
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux-fallback.img

For more details about the menu system, see the Syslinux documentation.

Graphical Boot menu

Syslinux also allows you to use a graphical boot menu. To use it, copy the vesamenu COM32 module to your Syslinux folder:

# cp /usr/lib/syslinux/vesamenu.c32 /boot/syslinux/

If /boot is the same partition as /, a symlink will also work:

# ln -s /usr/lib/syslinux/vesamenu.c32 /boot/syslinux/

This config uses the same menu design as the Arch Install CD. The background file can be found there too.

Configuration:

/boot/syslinux/syslinux.cfg
 UI vesamenu.c32
 DEFAULT arch
 PROMPT 0
 MENU TITLE Boot Menu
 MENU BACKGROUND splash.png
 TIMEOUT 50
 
 MENU WIDTH 78
 MENU MARGIN 4
 MENU ROWS 5
 MENU VSHIFT 10
 MENU TIMEOUTROW 13
 MENU TABMSGROW 11
 MENU CMDLINEROW 11
 MENU HELPMSGROW 16
 MENU HELPMSGENDROW 29
 
 # Refer to http://www.syslinux.org/wiki/index.php/Comboot/menu.c32
 
 MENU COLOR border       30;44   #40ffffff #a0000000 std
 MENU COLOR title        1;36;44 #9033ccff #a0000000 std
 MENU COLOR sel          7;37;40 #e0ffffff #20ffffff all
 MENU COLOR unsel        37;44   #50ffffff #a0000000 std
 MENU COLOR help         37;40   #c0ffffff #a0000000 std
 MENU COLOR timeout_msg  37;40   #80ffffff #00000000 std
 MENU COLOR timeout      1;37;40 #c0ffffff #00000000 std
 MENU COLOR msg07        37;40   #90ffffff #a0000000 std
 MENU COLOR tabmsg       31;40   #30ffffff #00000000 std
 
 
 LABEL arch
         MENU LABEL Arch Linux
         LINUX ../vmlinuz-linux
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux.img
 
 
 LABEL archfallback
         MENU LABEL Arch Linux Fallback
         LINUX ../vmlinuz-linux
         APPEND root=/dev/sda2 ro
         INITRD ../initramfs-linux-fallback.img

Since Syslinux 3.84, vesamenu.c32 supports the MENU RESOLUTION $WIDTH $HEIGHT directive. To use it, insert MENU RESOLUTION 1440 900 into your config for a 1440x900 resolution. The background picture has to have exactly the right resolution, however, as Syslinux will otherwise refuse to load the menu.

Auto Boot

If you don't want to see the Syslinux menu at all, comment out all UI commands and make sure there is a DEFAULT set in your syslinux.cfg.

Chainloading

If you want to chainload other operating systems (such as Windows) or boot loaders, copy (or symlink) the chain.c32 module to the Syslinux directory (for details, see the instructions in the previous section). Then create a section in the configuration file:

/boot/syslinux/syslinux.cfg
...
 LABEL windows
         MENU LABEL Windows
         COM32 chain.c32
         APPEND hd0 3
...

hd0 3 is the third partition on the first BIOS drive - drives are counted from zero, but partitions are counted from one.

If you are unsure about which drive your BIOS thinks is "first", you can instead use the MBR identifier, or if you are using GPT, the filesystem labels. To use the MBR identifier, run the command

# fdisk -l /dev/sdb
 Disk /dev/sdb: 128.0 GB, 128035676160 bytes 
 255 heads, 63 sectors/track, 15566 cylinders, total 250069680 sectors
 Units = sectors of 1 * 512 = 512 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disk identifier: 0xf00f1fd3
  
 Device Boot      Start         End      Blocks   Id  System
 /dev/sdb1            2048     4196351     2097152    7  HPFS/NTFS/exFAT
 /dev/sdb2         4196352   250066943   122935296    7  HPFS/NTFS/exFAT

replacing /dev/sdb with the drive you wish to chainload. Using the hexadecimal number under Disk identifier: 0xf00f1fd3 in this case, the syntax in syslinux.cfg is

/boot/syslinux/syslinux.cfg
...
 LABEL windows
         MENU LABEL Windows
         COM32 chain.c32
         APPEND mbr:0xf00f1fd3
...

For more details about chainloading, see the Syslinux wiki.

If you have GRUB installed on the same partition, you can chainload it by using:

/boot/syslinux/syslinux.cfg
...
 LABEL grub2
        MENU LABEL Grub2
        COM32 chain.c32
        append file=../grub/boot.img
...

This may be required for booting from ISO images.

Chainloading other Linux systems

Chainloading another bootloader such as Windows' is pretty obvious, as there is a definite bootloader to chain to. But with Syslinux, it is only able to load files residing on the same partition as the configuration file. Thus, if you have another version of Linux on a separate partition, without a shared /boot, it becomes necessary to employ Extlinux. Essentially, Extlinux can be installed on the partition superblock and be called as a separate bootloader from the MBR installed by Syslinux. Extlinux is part of the Syslinux project and is included with the syslinux package.

The following instructions assume you have Syslinux installed already. These instructions will also assume that the typical Arch Linux configuration path of /boot/syslinux is being used and the chainloaded / is on /dev/sda3.

From a booted Linux (likely the partition that Syslinux is set up to boot), mount the other root partition to your desired mount point. In this example this will be /mnt. Also, if a separate /boot partition is used on the second operating system, that will also need to be mounted. The example assumes this is /dev/sda2.

# mount /dev/sda3 /mnt
# mount /dev/sda2 /mnt/boot (only necessary for separate /boot)

Install Extlinux and copy necessary *.c32 files

# extlinux -i /mnt/boot/syslinux
# cp /usr/lib/syslinux/{chain,menu}.c32 /mnt/boot/syslinux

Create /mnt/boot/syslinux/syslinux.cfg. Below is an example:

/boot/syslinux/syslinux.cfg on /dev/sda3
timeout 10

ui menu.c32


label Other Linux
    linux /boot/vmlinuz-linux
    initrd /boot/initramfs-linux.img
    append root=/dev/sda3 ro quiet


label MAIN
    com32 chain.c32
    append hd0 0

taken from Djgera's user wiki page.

Using memtest

Install memtest86+ from the official repositories.

Use this LABEL section to launch memtest:

/boot/syslinux/syslinux.cfg
...
 LABEL memtest
         MENU LABEL Memtest86+
         LINUX ../memtest86+/memtest.bin
...

HDT

HDT (Hardware Detection Tool) displays hardware information. Like before, the .c32 file has to be copied or symlinked from /boot/syslinux/. For PCI info, either copy or symlink /usr/share/hwdata/pci.ids to /boot/syslinux/pci.ids and add the following to your configuration file:

/boot/syslinux/syslinux.cfg
 LABEL hdt
         MENU LABEL Hardware Info
         COM32 hdt.c32

Reboot and power off

Use the following sections to reboot or power off your machine:

/boot/syslinux/syslinux.cfg
 LABEL reboot
         MENU LABEL Reboot
         COM32 reboot.c32
 
 LABEL poweroff
         MENU LABEL Power Off
         COMBOOT poweroff.com

Clear Menu

To clear the screen when exiting the menu, add the following line:

/boot/syslinux/syslinux.cfg
 MENU CLEAR

Keyboard remapping

If you often have to edit your boot parameters, you might want to remap your keyboard layout. This allows you to enter "=", "/" and other characters easily on a non-US keyboard.

First you have to create a compatible keymap (for example a German one):

# cp /usr/share/kbd/keymaps/i386/qwerty/us.map.gz ./
# cp /usr/share/kbd/keymaps/i386/qwertz/de.map.gz ./
# gunzip {de,us}.map.gz
# mv de.{,k}map
# mv us.{,k}map
# keytab-lilo de > de.ktl

Copy de.ktl as root to /boot/syslinux/ and set ownership to root:

# chown root:root /boot/syslinux/de.ktl

Now edit syslinux.conf and add:

/boot/syslinux/syslinux.cfg
 KBDMAP de.ktl

Hiding the menu

Use the option:

/boot/syslinux/syslinux.cfg
 MENU HIDDEN

to hide the menu while displaying only the timeout. Press any key to bring up the menu.

Troubleshooting

Using the Syslinux prompt

You can type in the LABEL name of the entry that you want to boot (as per your syslinux.cfg). If you used the example configurations, just type:

boot: arch

If you get an error that the configuration file could not be loaded, you can pass your needed boot parameters, e.g.:

boot: ../vmlinuz-linux root=/dev/sda2 ro initrd=../initramfs-linux.img

If you do not have access to boot: in ramfs, and therefore temporarily unable to boot kernel again,

1. Create a temporary directory, in order to mount your root partition (if it does not exist already):
 # mkdir -p /new_root
2. Mount / under /new_root (in case /boot/ is on the same partition, otherwise you will need to mount them both):
Note: If /boot is on its own ext2 partition then busybox cannot mount it.
 # mount /dev/sd[a-z][1-9] /new_root
3. Use vim and edit syslinux.cfg again to suit your needs and save file.
4. Reboot.

No Default or UI found on some computers

Certain motherboard manufacturers have less compatibility for booting from USB devices than others. While an ext4 formatted USB drive may boot on a more recent computer, some computers may hang if the boot partition containing the kernel and initrd are not on a FAT16 partition. To prevent an older machine from loading ldlinux and failing to read syslinux.cfg, use cfdisk to create a FAT16 partition (<=2GB) and format using dosfstools:

# mkfs.msdos -F 16 /dev/sda1

then install and configure Syslinux.

Missing Operating System

If you get this message, check if the partition that contains /boot has the boot flag enabled. If the flag is enabled, then perhaps this partition starts at sector 1 rather than sector 63 or 2048. Check this with fdisk -l. If it starts at sector 1, you can move the partition(s) with gparted from a rescue disk. Or, if you have a separate boot partition, you can back up /boot with

# cp -a /boot /boot.bak

and then boot up with the Arch install disk. Next, use cfdisk to delete the /boot partition, and recreate it. This time it should begin at the proper sector, 63. Now mount your partitions and chroot into your mounted system, as described in the beginners guide. Restore /boot with the command

# cp -a /boot.bak/* /boot

Check if /etc/fstab is correct, run:

# syslinux-install_update -iam

and reboot.

Windows boots up, ignoring Syslinux

Solution: Make sure the partition that contains /boot has the boot flag enabled. Also, make sure the boot flag is not enabled on the Windows partition. See the installation section above.

The MBR that comes with Syslinux looks for the first active partition that has the boot flag set. The Windows partition was likely found first and had the boot flag set. If you wanted, you could use the MBR that Windows or MS-DOS fdisk provides.

Menu entries do nothing

You select a menu entry and it does nothing, it just "refreshes" the menu. This usually means that you have an error in your syslinux.cfg file. Hit Template:Keypress to edit your boot parameters. Alternatively, press Template:Keypress and type in the LABEL of your boot entry (e.g. arch).

Cannot remove ldlinux.sys

The ldlinux.sys file has the immutable attribute set, which prevents it from being deleted or overwritten. This is because the sector location of the file must not change or else Syslinux has to be reinstalled. To remove it, run:

# chattr -i /boot/syslinux/ldlinux.sys
# rm /boot/syslinux/ldlinux.sys

White block in upper left corner when using vesamenu

Problem: As of linux-3.0, the modesetting driver tries to keep the current contents of the screen after changing the resolution (at least it does so with my Intel, when having Syslinux in text mode). It seems that this goes wrong when combined with the vesamenu module in Syslinux (the white block is actually an attempt to keep the Syslinux menu, but the driver fails to capture the picture from vesa graphics mode).

If you have a custom resolution and a vesamenu with early modesetting, try to append the following in syslinux.cfg to remove the white block and continue in graphics mode:

APPEND root=/dev/sda6 ro 5 vga=current quiet splash

See also