knl8

Usage

Options

[--kernel=]image

Selects the kernel image file of interest.

-f=flaglist --flags=flaglist

Specifies the kernel flags to be set. Currently, only RO is implemented, which specifies that the root file system is to be mounted read-only by default. However, for compatibility with future additions, flags of the format Xn are also accepted, where n is in the range from 0 to 15 inclusive, and these will set the appropriate flag.

An option of None is also implemented to indicate that no flags should be set, but if used, the None option must be the only option specified.

--help

Displays a help screen, then exits.

--noram

Specifies that no ramdisk should be created by default.

This option is incompatible with the --prompt and --ram parameters.

-p --prompt

Specifies that a ramdisk should be created by default, and that the kernel should prompt for the relevant disk before loading the ramdisk image from disk.

This option is incompatible with the --noram option.

--ram=offset

Specifies that a ramdisk should be created by default, and the offset in the disk to the start of the ramdisk image. This offset may not exceed 8191 blocks.

This option is incompatible with the --noram option.

-r=device --root=device

Specifies the default device to mount as the file system root. The device can be specified as described in the DEVICES section (below), or can be specified as NFS to indicate that the file system root is remote NFS mounted.

-s=device --swap=device

Specifies the default device to mount as a swap partition. See the DEVICES section (below) for further details.

--version

Displays the program version, then exits.

-v=mode --video=mode

Specifies the default video mode. See the VIDEO MODES section (below) for further details.

Overview

In a bootable image for the Linux kernel, there are several pairs of bytes which specify various kernel options, located at the following offsets:

 496  1F0  Reserved
 498  1F2  Root flags
 500  1F4  Reserved
 502  1F6  Swap Device
 504  1F8  RAM Disk Parameters
 506  1FA  VGA Mode
 508  1FC  Root Device
 510  1FE  Boot Signature

knl will change or display these values.

Devices

Valid values for the device specification in the --root and --swap options are as follows:

/dev/aztcd           /dev/aztcd[1-255]
                     /dev/cdouble[0-127]
                     /dev/double[0-127]
                     /dev/fd[0-3]
/dev/flash           /dev/flash[1-7]
/dev/gscd            /dev/gscd[1-255]
/dev/hd[a-h]         /dev/hd[a-h][1-63]
/dev/hitcd           /dev/hitcd[1-255]
/dev/mcd             /dev/mcd[1-255]
/dev/optcd           /dev/optcd[1-255]
/dev/ram             /dev/ram[0-7]
/dev/rflash          /dev/rflash[1-7]
/dev/rom             /dev/rom[1-7]
/dev/rrom            /dev/rrom[1-7]
/dev/scd             /dev/scd[1-255]
/dev/sd[a-g]         /dev/sd[a-g][1-15]
/dev/sjcd            /dev/sjcd[1-255]
/dev/sonycd          /dev/sonycd[1-255]
/dev/xda             /dev/xda[1-63]
/dev/xdb             /dev/xdb[1-63]

In addition to the options listed above, /dev/ramdisc and /dev/ramdisk are synonyms for /dev/ram0 and, additionally, Boot can be used to specify the boot device. The /dev/ part is optional in each case (but must NOT be prefixed to the Boot option).

In addition to the above, a general method of specifying ANY block device by its major and minor numbers has been implemented. To specify a device that is not specifically supported (or indeed one that is supported, if it comes to that), specify Mode-X.Y where X is the relevant major number, and Y is the appropriate minor number.

Kernel image selection

Typical values for the --kernel option, which specifies a bootable Linux kernel image, are as follows:

/boot/vmlinuz
/boot/vmlinuz.test
/vmlinux
/vmlinux.test
/vmunix
/vmunix.test
/dev/fd0
/dev/fd1

Any other file on the disk can be specified and, providing it satisfies the (admittedly rather basic) criteria for being a kernel image file, it will be accepted as such.

Video modes

Valid values for the --video option are as follows:

Ask  = Prompt for the video mode to use
EVGA = Extended VGA (80x50)
VGA  = Standard VGA (80x25)
  0  = Mode selected by choosing '0' at the prompt.
  1  = Mode selected by choosing '1' at the prompt.
  2  = Mode selected by choosing '2' at the prompt.
  n  = Mode selected by choosing 'n' at the prompt.

Valid numeric arguments are in the range from 0 to 65499 inclusive.

Errors

The following errorlevels may be reported:

When using lilo

If LILO is used, knl is no longer needed for setting the root device and the video mode since these parameters that knl modifies can be set from the LILO prompt during a boot.
However, knl is still needed at this time for setting the RAM disk parameters. Users are encouraged to find the LILO documentation for more information, and to use LILO when booting their systems.