Ubuntu Manpage: pxe-kexec - Read PXE configuration file and kexec entries

NAME

       pxe-kexec - Read PXE configuration file and kexec entries

SYNOPSIS

       pxe-kexec [options] [tftp_server]

DESCRIPTION

Overview
pxe-kexec is a tool that fetches PXE configuration from a TFTP server, reads that PXE
configuration file, prompts the user for an boot entry, downloads the specified kernel and
initrd and finally tries to boot the kernel.

The normal process to boot with kexec(8) is that pxe-kexec loads the kernel and invokes
reboot(8). The shutdown script of the Linux distribution then executes "kexec -e" at the
very end. That is not implemented everywhere. Therefore, pxe-kexec has a whitelist of
Linux distributions that support reboot with kexec. If the distribution is not on that
whitelist, the program quits with a warning. To bypass that warning, please use the
"--igore-whitelist" parameter. You can also use the "--force" parameter to execute "kexec
-e" to immediately boot the selected kernel, without invoking shutdown(8)/reboot(8).

pxe-kexec meant to be used in an environment where pre-defined PXE configurations exist
but the user wants to use kexec(8) instead of rebooting.

Normally, the tftp_server must be specified as first argument. If there's no TFTP server
specified, pxe-kexec looks in the DHCP info file for the DHCP server and uses this one as
TFTP server. This only works when the TFTP server is running on the same machine as the
DHCP server.

==> Please also read the section called "Update Info" <==

Whitelist
As mentioned previously, a whitelist of Linux distributions that support kexec-based
rebooting is maintained. Currently following distributions are on the whitelist:

• openSUSE, starting with version 11.0

• Ubuntu, starting with version 9.04

• Red Hat Enterprise Linux and CentOS, starting with version 5.3

• Fedora Linux, starting with version 11

• ARCH Linux

Don't hesitate to send the author an email to add the distribution to the whitelist.
Please include the output of "pxe-kexec --print-distribution" in that mail.

OPTIONS

Following options can be specified:

-h | --help
Prints a short help.

-v | --version
Prints the version number to standard output.

-f | --force
Immediately load the kernel without invoking reboot(8). This does not execute
shutdown scripts, i.e. does not terminate daemons, network connections etc.

-L | --load-only
When that option is specified, the new kernel is only loaded. No reboot is
triggered and "kexec -e" is also not executed.

-w | --ignore-whitelist
Don't check if the detected Linux distribution is on the whitelist of distributions
that have kexec(8) in their shutdown script. Please don't use that parameter
without letting the author know which distribution you use and how to detect that
distribution. Then the distribution can be added to the whitelist and other users
profit from that experience.

-l label | --label label
Specifies the label that should be booted. Use that option if you already know
which label you want to boot. This option implies "--quiet".

-i | --interface netif
Uses netif instead of the first (non-loopback and up) interface that is found.
Example: "eth5".

-n | --noconfirm
Don't ask the user for confirmation before booting an entry. Use that option with
care!

-Y | --dry-run
Don't execute call to kexec and don't switch the virtual console before running
"kexec -e". Instead, print the information which program would be executed with
which arguments to standard error.

-q | --quiet
Don't display the PXE messages that are added in the PXE configuration with the say
keyword. Also don't display messages which PXE configuration files the downloader
tries to fetch.

-p | --print-distribution
Only prints the detected Linux distribution and exits. For example:

Type : Ubuntu
Name : Ubuntu
Release : 9.04
Codename : jaunty
Description : Ubuntu 9.04

This option is very useful if your distribution is not on the whitelist of Linux
distributions that support kexec(8) in the reboot scripts and you want to create a
bugreport.

This command does not require root privileges.

-D | --debug
Enable debugging output. That's good for finding (and fixing!) bugs.

-d | --nodelete
Keep downloaded files.

-F | --ftp
Always use FTP instead of TFTP. Useful for servers that share TFTP root and FTP
root. (Passive) FTP has the advantage that it passes firewalls better than TFTP.

UPDATE INFO

Updating from 0.1.x to 0.2
Compared to version 0.1.x, the syntax has changed:

• The default label must now be set with the -l label option instead of the 2nd
argument. Example:

% pxe-kexec mydhcp.mydomain.com SLES10-install-auto

is now

% pxe-kexec -l SLES10-install-auto mydhcp.mydomain.com

• pxe-kexec now uses the reboot mechanism by default: The kernel is loaded, then the
reboot is triggered and the reboot script of the Linux distribution finally boots
the kernel. This has the advantage of a clear shutdown.

The program keeps a database of Linux distributions that support kexec-based
reboot. If the currently active distribution is not on the whitelist, an error is
printed. (That whitelist can be ignored with "--ignore-whitelist".)

• To use the previous behaviour, i.e. just execute "kexec -e" in pxe-kexec at the
end, you can still use the "--force" parameter. Example:

% pxe-kexec mydhcp.mydomain.com

is now

% pxe-kexec --force mydhcp.mydomain.com

• If you want to have the old "dry-run" behaviour back, which in fact only missed the
last "kexec -e" step, you can use the option "--load-only". Example:

% pxe-kexec --dry-run mydhcp.mydomain.com

is now

% pxe-kexec --load-only mydhcp.mydomain.com

EXAMPLES

       pxe-kexec mydhcp.mydomain.com
              Try to fetch the PXE configuration from mydhcp.mydomain.com, display the say
              messages from that configuration, prompt for an entry, letting the user confirm
              that entry and finally load that entry via kexec(8) and reboot via reboot(8).

              This only works if you distribution supports kexec-based rebooting, i.e.  it is in
              the internal whitelist.

       pxe-kexec -n mydhcp.mydomain.com
              Same as the previous example, but omit the final confirmation step.

       pxe-kexec -l SLES10-install-auto mydhcp.mydomain.com
              Same as the first example, but don't prompt the user for the label to boot.
              Directly boot the SLES10-install-auto label, but letting the user confirm that he
              really wants to boot this!

       pxe-kexec -n -l SLES10-install-auto mydhcp.mydomain.com
              Same as the previous example, but without confirmation.

       pxe-kexec -f mydhcp.mydomain.com
              Same as the first example, but execute "kexec -e" at the end instead of invoking
              reboot(8).

       pxe-kexec -l mydhcp.mydomain.com
              Same as the first example, but don't trigger a reboot. Instead, the kernel is just
              loaded. If your distribution supports kexec-based rebooting, the kernel will be
              loaded on next reboot. You can also run "kexec -e" manually at any time.

AUTHOR

       The pxe-kexec program and documentation has been written by Bernhard Walle
       <bernhard@bwalle.de>.

BUGS

       This program has no bugs. If you find a feature that should be removed, please report to
       <bernhard@bwalle.de> if you don't want to create an account.

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

UPDATE INFO

EXAMPLES

AUTHOR

BUGS

SEE ALSO