:: RootR ::  Hosting Order Map Login   Secure Inter-Network Operations  
 
kexec(8) - phpMan

Command: man perldoc info search(apropos)  


kexec(8)                                   User Manuals                                  kexec(8)



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 cur‐
       rently  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 architec‐
       ture) 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.

       Insert the command-line parameters that must  be  passed  to  the  new  kernel  into  com‐
       mand-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.

       It's also possible to invoke kexec without an option parameter. In that case, kexec  loads
       the  specified kernel and then invokes shutdown(8).  If the shutdown scripts of your Linux
       distribution support kexec-based rebooting, they then call kexec -e just  before  actually
       rebooting  the machine. That way, the machine does a clean shutdown including all shutdown
       scripts.


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
       -d (--debug)
              Enable debugging messages.

       -e (--exec)
              Run the currently loaded kernel. Note that it will reboot into  the  loaded  kernel
              without calling shutdown(8).

       -f (--force)
              Force  an  immediate  kexec  call, do not call shutdown(8) (contrary to the default
              action without any option parameter). This option performs the  same  actions  like
              executing -l and -e in one call.

       -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. If a capture kernel is being unloaded then
              specify -p with -u.

       -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.

       --entry=addr
              Specify the jump back address. (0 means it's not jump back or preserve context)

       --load-preserve-context
              Load the new kernel and preserve context of current kernel during kexec.

       --load-jump-back-helper
              Load a helper image to jump back to original kernel.

       --reuseinitrd
              Reuse initrd from first boot.



SUPPORTED KERNEL FILE TYPES AND OPTIONS
       Beoboot-x86

              --args-elf
                     Pass ELF boot notes.

              --args-linux
                     Pass Linux kernel style options.

              --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.

              --reuse-cmdline
                     Use the command line from the running system. When a panic kernel is loaded,
                     it strips the crashkernel parameter automatically. The BOOT_IMAGE  parameter
                     is also stripped.

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

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

       bzImage-x86

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

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

              --reuse-cmdline
                     Use the command line from the running system. When a panic kernel is loaded,
                     it strips the crashkernel parameter automatically. The BOOT_IMAGE  parameter
                     is also stripped.

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

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

              --real-mode
                     Use real-mode entry point.

       multiboot-x86

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

              --reuse-cmdline
                     Use the command line from the running system. When a panic kernel is loaded,
                     it strips the crashkernel parameter automatically. The BOOT_IMAGE  parameter
                     is also stripped.

              --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.



Linux                                       April 2006                                   kexec(8)


/man
rootr.net - man pages