关于SYSLINUX的一些重要描述摘录

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The SYSLINUX suite contains the following boot loaders ("derivatives"), for their respective boot media:

SYSLINUX - MS-DOS/Windows FAT filesystem

PXELINUX - PXE network booting

ISOLINUX - ISO9660 CD-ROM

EXTLINUX - Linux ext2/ext3 filesystem

For historical reasons, some of the sections in this document applies to the FAT loader only

Options

These are the options common to all versions of Syslinux:

-s Safe, slow, stupid; uses simpler code that boots better

-f Force installing

These are only in the Windows version:

-m Mbr; install a bootable MBR sector to the beginning of the drive.

-a Active; marks the partition used active (=bootable)

CREATING A BOOTABLE LINUX FLOPPY

In order to create a bootable Linux floppy using SYSLINUX, prepare a normal MS-DOS formatted floppy. Copy one or more Linux kernel files to it, then execute the DOS command:

syslinux [-sfma][-d directory] a:

(or whichever drive letter is appropriate; the [] meaning optional.)

Use "syslinux.com" (in the dos subdirectory of the distribution) for plain DOS (MS-DOS, DR-DOS, PC-DOS, FreeDOS...) or Win9x/ME.

Use "syslinux.exe" (in the win32 subdirectory of the distribution) for WinNT/2000/XP.

Under Linux, execute the command:

syslinux [-sf][-d directory][-o offset] /dev/fd0

(or, again, whichever device is the correct one.)

This will alter the boot sector on the disk and copy a file named LDLINUX.SYS into its root directory (or a subdirectory, if the -d option is specified.)

The -s option, if given, will install a "safe, slow and stupid" version of SYSLINUX. This version may work on some very buggy BIOSes on which SYSLINUX would otherwise fail. If you find a machine on which the -s option is required to make it boot reliably, please send as much info about your machine as you can, and include the failure mode.

The -o option is used with a disk image file and specifies the byte offset of the filesystem image in the file.

For the DOS and Windows installers, the -m and -a options can be used on hard drives to write a Master Boot Record (MBR), and to mark the specific partition active.

On boot time, by default, the kernel will be loaded from the image named LINUX on the boot floppy. This default can be changed, see the section on the SYSLINUX config file.

If the Shift or Alt keys are held down during boot, or the Caps or Scroll locks are set, SYSLINUX will display a LILO-style "boot:" prompt. The user can then type a kernel file name followed by any kernel parameters. The SYSLINUX loader does not need to know about the kernel file in advance; all that is required is that it is a file located in the root directory on the disk.

There are two versions of the Linux installer; one in the "mtools" directory which requires no special privilege (other than write permission to the device where you are installing) but requires the mtools program suite to be available, and one in the "unix" directory which requires root privilege.

CONFIGURATION FILE

All the configurable defaults in SYSLINUX can be changed by putting a file called "syslinux.cfg" in the root directory of the boot disk.

This is a text file in either UNIX or DOS format, containing one or more of the following items (case is insensitive for keywords; uppercase is used here to indicate that a word should be typed verbatim):

Starting with version 3.35, the configuration file can also be in either the /boot/syslinux or /syslinux directories (searched in that order.) If that is the case, then all filenames are assumed to be relative to that same directory, unless preceded with a slash or backslash.

All options here applies to PXELINUX, ISOLINUX and EXTLINUX as well as SYSLINUX unless otherwise noted. See the respective .txt files.

# comment

A comment line. The whitespace after the hash mark is mandatory.

INCLUDE filename

Inserts the contents of another file at this point in the configuration file. Files can currently be nested up to 16 levels deep, but it is not guaranteed that more than 8 levels will be supported in the future.

DEFAULT kernel options...

Sets the default command line. If SYSLINUX boots automatically, it will act just as if the entries after DEFAULT had been typed in at the "boot:" prompt.

If no configuration file is present, or no DEFAULT entry is present in the config file, the default is "linux auto".

NOTE: Earlier versions of SYSLINUX used to automatically append the string "auto" to whatever the user specified using the DEFAULT command. As of version 1.54, this is no longer true, as it caused problems when using a shell as a substitute for "init." You may want to include this option manually.

APPEND options...

Add one or more options to the kernel command line. These are added both for automatic and manual boots. The options are added at the very beginning of the kernel command line, usually permitting explicitly entered kernel options to override them. This is the equivalent of the LILO "append" option.

IPAPPEND flag_val [PXELINUX only]

The IPAPPEND option is available only on PXELINUX. The flag_val is an OR of the following

1: indicates that an option of the following format should be generated and added to the kernel command line:

ip=<client-ip>:<boot-server-ip>:<gw-ip>:<netmask>

... based on the input from the DHCP/BOOTP or PXE boot server.

THE USE OF THIS OPTION IS NOT RECOMMENDED. If you have to use it, it is probably an indication that your network configuration is broken. Using just "ip=dhcp" on the kernel command line is a preferrable option, or, better yet, run dhcpcd/dhclient, from an initrd if necessary.

2: indicates that an option of the following format should be generated and added to the kernel command line:

BOOTIF=<hardware-address-of-boot-interface>

... in dash-separated hexadecimal with leading hardware type

(same as for the configuration file; see pxelinux.txt.)

This allows an initrd program to determine from which interface the system booted.

LABEL label

KERNEL image

APPEND options...

IPAPPEND flag_val [PXELINUX only]

Indicates that if "label" is entered as the kernel to boot, SYSLINUX should instead boot "image", and the specified APPEND and IPAPPEND options should be used instead of the ones specified in the global section of the file (before the first LABEL command.) The default for "image" is the same as "label", and if no APPEND is given the default is to use the global entry (if any).

Starting with version 3.62, the number of LABEL statements is virtually unlimited.

Note that LILO uses the syntax:

image = mykernel

label = mylabel

append = "myoptions"

... whereas SYSLINUX uses the syntax:

label mylabel

kernel mykernel

append myoptions

Note: The "kernel" doesn‘t have to be a Linux kernel; it can be a boot sector or a COMBOOT file (see below.)

Since version 3.32 label names are no longer mangled into DOS format (for SYSLINUX.)

The following commands are available after a LABEL statement:

LINUX image - Linux kernel image (default)

BOOT image - Bootstrap program (.bs, .bin)

BSS image - BSS image (.bss)

PXE image - PXE Network Bootstrap Program (.0)

FDIMAGE image - Floppy disk image (.img)

COMBOOT image - COMBOOT program (.com, .cbt)

COM32 image - COM32 program (.c32)

CONFIG image - New configuration file

Using one of these keywords instead of KERNEL forces the filetype, regardless of the filename.

CONFIG means restart the boot loader using a different configuration file.

APPEND -

Append nothing. APPEND with a single hyphen as argument in a LABEL section can be used to override a global APPEND.

LOCALBOOT type [ISOLINUX, PXELINUX]

On PXELINUX, specifying "LOCALBOOT 0" instead of a "KERNEL" option means invoking this particular label will cause a local disk boot instead of booting a kernel.

The argument 0 means perform a normal boot. The argument 4 will perform a local boot with the Universal Network Driver Interface (UNDI) driver still resident in memory. Finally, the argument 5 will perform a local boot with the entire PXE stack, including the UNDI driver, still resident in memory. All other values are undefined. If you don‘t know what the UNDI or PXE stacks are, don‘t worry -- you don‘t want them, just specify 0.

On ISOLINUX, the "type" specifies the local drive number to boot from; 0x00 is the primary floppy drive and 0x80 is the primary hard drive. The special value -1 causes ISOLINUX to report failure to the BIOS, which, on recent BIOSes, should mean that the next boot device in the boot sequence should be activated.

INITRD initrd_file

Starting with version 3.71, an initrd can be specified in a separate statement (INITRD) instead of as part of the APPEND statement; this functionally appends "initrd=initrd_file" to the kernel command line.

PROMPT flag_val

If flag_val is 0, display the boot: prompt only if the Shift or Alt key is pressed, or Caps Lock or Scroll lock is set (this is the default). If flag_val is 1, always display the boot: prompt.