[Fastboot] [RFC] - Kexec man page

[David Wilder]

Attached is a replacement man page for kexec.   Please let me know what 
you think.
Included is a html version for easy viewing.
Thanks.--
David Wilder
IBM Linux Technology Center
Beaverton, Oregon, USA 
[EMAIL PROTECTED]
(503)578-3789

.\" Process this file with
.\" groff -man -Tascii kexec.8
.\"
.TH kexec 8 "April 2006" Linux "User Manuals"
.SH NAME
kexec \- directly boot into a new kernel
.SH SYNOPSIS
.B /sbin/kexec
.B [-v (\-\-version)] [-f (\-\-force)] [-x (\-\-no-ifdown)] [-l (\-\-load)] [-p (\-\-load-panic)] [-u (\-\-unload)] [-e (\-\-exec)] [-t (\-\-type)]
.BI [\-\-mem\-min= addr ]
.BI [\-\-mem\-max= addr ] 

.SH DESCRIPTION
.B kexec
is a system call that enables you to load and boot into another
kernel from the currently running kernel.
.B kexec
performs the function of the boot loader from within the kernel. The
primary difference between a standard system boot and a
.B kexec
boot is that the hardware initialization normally performed by the BIOS
or firmware (depending on architecture) is not performed during a
.B kexec
boot. This has the effect of reducing the time required for a reboot.
.PP
Make sure you have selected
.B CONFIG_KEXEC=y
when configuring the kernel. The
.B CONFIG_KEXEC
option enables the
.B kexec
system call.
.SH USAGE
Using
.B kexec
consists of

.RS
(1) loading the kernel to be rebooted to into memory, and
.RE
.RS
(2) actually rebooting to the pre-loaded kernel.
.RE
.PP
To load a kernel, the syntax is as follows:

.RS
.B kexec
.RI \-l\  kernel-image
.RI "\-\-append=" command\-line\-options 
.RI "\-\-initrd=" initrd\-image
.RE

where
.I kernel\-image
is the kernel file that you intend to reboot to.
.PP
Note: Compressed kernel images such as bzImage are not supported by
.BR kexec .
Use the uncompressed vmlinux.
.PP
Insert the command-line parameters that must be passed to the new
kernel into
.IR command\-line\-options .
Passing the exact contents of /proc/cmdline into
.I command\-line\-options
is the safest way to ensure that correct values are passed to the
rebooting kernel.
.PP
The optional
.I initrd-image
is the initrd image to be used during boot.
.PP

.SH EXAMPLE
.PP
For example, if the kernel image you want to reboot to is
.BR /boot/vmlinux ,
the contents of /proc/cmdline is
.BR "root\=/dev/hda1" ,
and the path to the initrd is
.BR /boot/initrd ,
then you would use the following command to load the kernel:

.RS
.B kexec
.RB \-l\  /boot/vmlinux
.RB "\-\-append=" "root=/dev/hda1" "\ \-\-initrd=" /boot/initrd
.RE
.PP
After this kernel is loaded, it can be booted to at any time using the
command:

.RS
.BR kexec \ \-e
.RE

.SH OPTIONS
.TP
.B \-e\ (\-\-exec)
Run the currently loaded kernel.
.TP
.B \-f\ (\-\-force)
Force an immediate
.B kexec
call, do not call shutdown.
.TP
.B \-h\ (\-\-help)
Open a help file for
.BR kexec .
.TP
.BI \-l\ (\-\-load) \ kernel
Load the specified
.I kernel
into the current kernel.
.TP
.B \-p\ (\-\-load\-panic)
Load the new kernel for use on panic.
.TP
.BI \-t\ (\-\-type= type )
Specify that the new kernel is of this
.I type.
.TP
.B \-u\ (\-\-unload)
Unload the current
.B kexec
target kernel.
.TP
.B \-v\ (\-\-version)
Return the version number of the installed utility.
.TP
.B \-x\ (\-\-no\-ifdown)
Shut down the running kernel, but restore the interface on reload. (If
this option is used, it must be specified last.)
.TP
.BI \-\-mem\-min= addr
Specify the lowest memory address
.I addr
to load code into.
.TP
.BI \-\-mem\-max= addr
Specify the highest memory address
.I addr
to load code into.

.SH SUPPORTED KERNEL FILE TYPES AND OPTIONS
.B Beoboot-x86
.RS
.TP
.B \-\-args\-elf
Pass ELF boot notes.
.TP
.B \-\-args\-linux
Pass Linux kernel style options.
.TP
.B \-d \ (\-\-debug)
Enable debugging messages.
.TP
.B \-\-real\-mode
Use the kernel's real mode entry point.
.RE
.PP
.B elf-x86
.RS
.TP
.BI \-\-append= string
Append
.I string
to the kernel command line.
.TP
.BI \-\-command\-line= string
Set the kernel command line to
.IR string .
.TP
.BI \-\-initrd= file
Use
.I file
as the kernel's initial ramdisk.
.TP
.BI \-\-ramdisk= file
Use
.I file
as the kernel's initial ramdisk.
.RE
.PP
.B multiboot-x86
.RS
.TP
.BI \-\-command\-line= string
Set the kernel command line to
.IR string .
.TP
.BI \-\-module= "mod arg1 arg2 ..."
Load module
.I mod
with command-line arguments
.I "arg1 arg2 ..."
This parameter can be specified multiple times.
.RE

.SH ARCHITECTURE OPTIONS
.TP
.B \-\-console\-serial
Enable the serial console.
.TP
.B \-\-console\-vga
Enable the VGA console.
.TP
.B \-\-elf32\-core\-headers
Prepare core headers in ELF32 format.
.TP
.B \-\-elf64\-core\-headers
Prepare core headers in ELF64 format.
.TP
.B \-\-reset\-vga
Attempt to reset a standard VGA device.
.TP
.BI \-\-serial= port
Specify the serial
.I port
for debug output.
.TP
.BI \-\-serial\-baud= baud_rate
Specify the
.I baud rate
of the serial port.
Title: Manpage of kexec
Content-type: text/html


kexec
Section: User Manuals (8)Updated: April 2006Index
Return to Main Contents

 
NAME

kexec - directly boot into a new kernel
 
SYNOPSIS

/sbin/kexec

[-v (--version)] [-f (--force)] [-x (--no-ifdown)] [-l (--load)] [-p (--load-panic)] [-u (--unload)] [-e (--exec)] [-t (--type)]

[--mem-min=addr]

[--mem-max=addr]


 
DESCRIPTION

kexec

is a system call that enables you to load and boot into another
kernel from the currently running kernel.
kexec

performs the function of the boot loader from within the kernel. The
primary difference between a standard system boot and a
kexec

boot is that the hardware initialization normally performed by the BIOS
or firmware (depending on architecture) is not performed during a
kexec

boot. This has the effect of reducing the time required for a reboot.


Make sure you have selected
CONFIG_KEXEC=y

when configuring the kernel. The
CONFIG_KEXEC

option enables the
kexec

system call.
 
USAGE

Using
kexec

consists of


(1) loading the kernel to be rebooted to into memory, and



(2) actually rebooting to the pre-loaded kernel.




To load a kernel, the syntax is as follows:


kexec

-l kernel-image

--append=command-line-options

--initrd=initrd-image




where
kernel-image

is the kernel file that you intend to reboot to.


Note: Compressed kernel images such as bzImage are not supported by
kexec.

Use the uncompressed vmlinux.


Insert the command-line parameters that must be passed to the new
kernel into
command-line-options.

Passing the exact contents of /proc/cmdline into
command-line-options

is the safest way to ensure that correct values are passed to the
rebooting kernel.


The optional
initrd-image

is the initrd image to be used during boot.



 
EXAMPLE



For example, if the kernel image you want to reboot to is
/boot/vmlinux,

the contents of /proc/cmdline is
root=/dev/hda1,

and the path to the initrd is
/boot/initrd,

then you would use the following command to load the kernel:


kexec

-l /boot/vmlinux

--append=root=/dev/hda1 --initrd=/boot/initrd





After this kernel is loaded, it can be booted to at any time using the
command:


kexec -e




 
OPTIONS


-e (--exec)


Run the currently loaded kernel.
-f (--force)


Force an immediate
kexec

call, do not call shutdown.
-h (--help)


Open a help file for
kexec.

-l (--load) kernel


Load the specified
kernel

into the current kernel.
-p (--load-panic)


Load the new kernel for use on panic.
-t (--type=type)


Specify that the new kernel is of this
type.

-u (--unload)


Unload the current
kexec

target kernel.
-v (--version)


Return the version number of the installed utility.
-x (--no-ifdown)


Shut down the running kernel, but restore the interface on reload. (If
this option is used, it must be specified last.)
--mem-min=addr


Specify the lowest memory address
addr

to load code into.
--mem-max=addr


Specify the highest memory address
addr

to load code into.


 
SUPPORTED KERNEL FILE TYPES AND OPTIONS

Beoboot-x86



--args-elf


Pass ELF boot notes.
--args-linux


Pass Linux kernel style options.
-d  (--debug)


Enable debugging messages.
--real-mode


Use the kernel's real mode entry point.





elf-x86



--append=string


Append
string

to the kernel command line.
--command-line=string


Set the kernel command line to
string.

--initrd=file


Use
file

as the kernel's initial ramdisk.
--ramdisk=file


Use
file

as the kernel's initial ramdisk.





multiboot-x86



--command-line=string


Set the kernel command line to
string.

--module=mod arg1 arg2 ...


Load module
mod

with command-line arguments
arg1 arg2 ...

This parameter can be specified multiple times.




 
ARCHITECTURE OPTIONS


--console-serial


Enable the serial console.
--console-vga


Enable the VGA console.
--elf32-core-headers


Prepare core headers in ELF32 format.
--elf64-core-headers


Prepare core headers in ELF64 format.
--reset-vga


Attempt to reset a standard VGA device.
--serial=port


Specify the serial
port

for debug output.
--serial-baud=baud_rate


Specify the
baud rate

of the serial port.




 Index

NAME
SYNOPSIS
DESCRIPTION
USAGE
EXAMPLE
OPTIONS
SUPPORTED KERNEL FILE TYPES AND OPTIONS
ARCHITECTURE OPTIONS


This document was created by
man2html,
using the manual pages.
Time: 22:35:57 GMT, April 28, 2006


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