SYSLINUX
Encyclopedia
The SYSLINUX Project is a suite of lightweight IBM PC
MBR
bootloaders for starting up computer
s with the Linux kernel
. It is the work of H. Peter Anvin, and consists of several separate systems, the best-known of which is ISOLINUX.
s, or other lightweight boot systems. ISOLINUX is generally used by Linux Live CD
s and bootable install CDs.
A minor complication is involved when booting from CD-ROM. The El Torito standard
allows for booting in two different modes:
Floppy emulation mode: the boot information is stored in an image file of a FAT
-formatted floppy disk, which is loaded from the CD and then behaves as a virtual floppy disk. This mode uses SYSLINUX.
No emulation mode: the boot information is stored directly on the CD (not in a floppy image). This mode uses ISOLINUX.
To have this choice is sometimes useful, since ISOLINUX is vulnerable to BIOS
bugs; for that reason, it's handy to be able to boot using SYSLINUX. This mostly affects computers built before about 1999, and, in fact, for modern computers no emulation mode is generally the more reliable method.
The use of SYSLINUX for the creation of Live USBs is growing, though, and allowing the creation of distributions like Slax
that allow users to try Linux with complete interactivity and persistent changes without needing to install it on their hard disk.
compliant ROM
on a network card. The PXE environment uses DHCP
or BOOTP
to enable basic TCP/IP networking, then downloads a bootstrap
program via TFTP
. This bootstrap program loads and configures a kernel according to directives that are also downloaded from the TFTP server.
Typically, PXELINUX is used for Linux installations from a central network server or for booting diskless workstations.
or GRUB
.
Since Syslinux 4, EXTLINUX has been merged with SYSLINUX.
This tool is a Syslinux com32 module that displays low-level information for any x86 compatible system. It provides both a command-line interface and a semi-graphical menu mode for browsing.
HDT is available as com32 file, a bootable ISO, a 2.88MB floppy disk.
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...
MBR
Master boot record
A master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...
bootloaders for starting up computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
s with the Linux kernel
Linux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
. It is the work of H. Peter Anvin, and consists of several separate systems, the best-known of which is ISOLINUX.
List
- The original SYSLINUX, used for booting from FATFile Allocation TableFile Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
filesystems (such as floppy disks and USB drives). - ISOLINUX, used for booting from CD-ROMCD-ROMA CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....
ISO 9660ISO 9660ISO 9660, also referred to as CDFS by some hardware and software providers, is a file system standard published by the International Organization for Standardization for optical disc media....
filesystems. - PXELINUX, used for booting from a network server using the Preboot Execution EnvironmentPreboot Execution EnvironmentThe Preboot eXecution Environment is an environment to boot computers using a network interface independently of data storage devices or installed operating systems.PXE was introduced as part of the Wired for Management framework by Intel and is described in the specification The Preboot...
(PXE) system. - EXTLINUX, used to boot from LinuxLinuxLinux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
ext2Ext2The ext2 or second extended filesystem is a file system for the Linux kernel. It was initially designed by Rémy Card as a replacement for the extended file system ....
/ext3Ext3The ext3 or third extended filesystem is a journaled file system that is commonly used by the Linux kernel. It is the default file system for many popular Linux distributions, including Debian...
/ext4Ext4The ext4 or fourth extended filesystem is a journaling file system for Linux, developed as the successor to ext3.It was born as a series of backward compatible extensions to ext3, many of them originally developed by Cluster File Systems for the Lustre file system between 2003 and 2006, meant to...
or btrfsBtrfsBtrfs is a GPL-licensed copy-on-write file system for Linux.Development began at Oracle Corporation in 2007....
filesystems. - MEMDISK, used to boot older operating systems like MS-DOSMS-DOSMS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
from these media. - Two separate menu systems.
- A development environment for additional modules.
SYSLINUX and ISOLINUX
SYSLINUX is not normally used for booting full Linux installations since Linux is not normally installed on FAT filesystems. Instead, it is often used for boot or rescue floppy discs, Live USBLive USB
A live USB is a USB flash drive or a USB external hard disk drive containing a full operating system that can be booted. Live USBs are closely related to live CDs, but sometimes have the ability to persistently save settings and permanently install software packages back onto the USB device...
s, or other lightweight boot systems. ISOLINUX is generally used by Linux Live CD
Live CD
A live CD, live DVD, or live disc is a CD or DVD containing a bootable computer operating system. Live CDs are unique in that they have the ability to run a complete, modern operating system on a computer lacking mutable secondary storage, such as a hard disk drive...
s and bootable install CDs.
A minor complication is involved when booting from CD-ROM. The El Torito standard
El Torito (CD-ROM standard)
The El Torito Bootable CD Specification is an extension to the ISO 9660 CD-ROM specification. It is designed to allow a computer to boot from a CD-ROM...
allows for booting in two different modes:
Floppy emulation mode: the boot information is stored in an image file of a FAT
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
-formatted floppy disk, which is loaded from the CD and then behaves as a virtual floppy disk. This mode uses SYSLINUX.
No emulation mode: the boot information is stored directly on the CD (not in a floppy image). This mode uses ISOLINUX.
To have this choice is sometimes useful, since ISOLINUX is vulnerable to BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
bugs; for that reason, it's handy to be able to boot using SYSLINUX. This mostly affects computers built before about 1999, and, in fact, for modern computers no emulation mode is generally the more reliable method.
The use of SYSLINUX for the creation of Live USBs is growing, though, and allowing the creation of distributions like Slax
SLAX
Slax is a LiveCD Linux distribution based on Slackware and is currently being developed by Tomáš Matějíček. Packages can be selected in a website where users can build a custom Slax iso image. Slax slogan refers to the software as a "Pocket Operating System"...
that allow users to try Linux with complete interactivity and persistent changes without needing to install it on their hard disk.
PXELINUX
PXELINUX is used in conjunction with a PXEPreboot Execution Environment
The Preboot eXecution Environment is an environment to boot computers using a network interface independently of data storage devices or installed operating systems.PXE was introduced as part of the Wired for Management framework by Intel and is described in the specification The Preboot...
compliant ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
on a network card. The PXE environment uses DHCP
Dynamic Host Configuration Protocol
The Dynamic Host Configuration Protocol is a network configuration protocol for hosts on Internet Protocol networks. Computers that are connected to IP networks must be configured before they can communicate with other hosts. The most essential information needed is an IP address, and a default...
or BOOTP
BOOTP
In computer networking, the Bootstrap Protocol, or BOOTP, is a network protocol used by a network client to obtain an IP address from a configuration server. The BOOTP protocol was originally defined in RFC 951....
to enable basic TCP/IP networking, then downloads a bootstrap
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
program via TFTP
Trivial File Transfer Protocol
Trivial File Transfer Protocol is a file transfer protocol known for its simplicity. It is generally used forautomated transfer of configuration or boot files between machines in a local environment....
. This bootstrap program loads and configures a kernel according to directives that are also downloaded from the TFTP server.
Typically, PXELINUX is used for Linux installations from a central network server or for booting diskless workstations.
EXTLINUX
EXTLINUX is typically used as a general-purpose bootloader, similar to LILOLILO (boot loader)
LILO is a generic boot loader for Linux.-Overview:LILO does not depend on a specific file system, and can boot an operating system from floppy disks and hard disks. One of up to sixteen different images can be selected at boot time. Various parameters, such as the root device, can be set...
or GRUB
GNU GRUB
GNU GRUB is a boot loader package from the GNU Project. GRUB is the reference implementation of the Multiboot Specification, which provides a user the choice to boot one of multiple operating systems installed on a computer or select a specific kernel configuration available on a particular...
.
Since Syslinux 4, EXTLINUX has been merged with SYSLINUX.
Hardware Detection Tool (HDT)
Since the 3.74 release, the Syslinux project hosts the Hardware Detection Tool (HDT) project.This tool is a Syslinux com32 module that displays low-level information for any x86 compatible system. It provides both a command-line interface and a semi-graphical menu mode for browsing.
HDT is available as com32 file, a bootable ISO, a 2.88MB floppy disk.
External links
- SYSLINUX website
- Download site
- Joseph's Site - PXELinux - Notes on getting it working
- Syslinux's dedicated com32/hdt directory