kconfig(5)kconfig(5)NAMEkconfig - introduction to kernel configuration commands
HP-UX contains a set of commands used to view and modify the configura‐
tion of the HP-UX kernel. The commands are:
Operations on complete kernel configurations
Operations on kernel modules
Operations on kernel tunable parameters ("tunables")
Retrieves pathnames of kernel files
Searches and displays the kernel configuration log file
Builds a kernel configuration from a system file
The set of data that controls the behavior and content of the HP-UX
kernel is called a kernel configuration. System administrators may
save any number of kernel configurations, and may load any one of them
at any time. A kernel configuration consists of module usage choices
made using and tunable values chosen using
By default, these commands affect the state of the currently running
system. When these commands are given a option, they instead affect
the saved kernel configuration named config.
The currently running kernel configuration can be saved using A saved
configuration can be loaded using This causes the state of the running
system to be changed to match the saved configuration. A saved config‐
uration can be marked for use when the system is next booted, by using
This makes no change to the state of the running system, but causes the
specified saved configuration to be loaded when the system is rebooted.
Saved kernel configuration names must start with a letter; contain only
letters, digits, and underscores (_); and be at most 32 characters in
length. The names are case-distinct.
The system maintains a saved configuration called which can be used to
recover from configuration errors. Depending on the selected backup
behavior, the system can automatically save the currently running con‐
figuration to immediately before making any requested change to the
configuration. The backup behavior is set using the option to the or
commands. The recognized backup behaviors are:
Always update the
configuration before making a change.
configuration before making the current change. For
subsequent changes, ask whether to update it.
Do not update the
configuration before making the current change. For
subsequent changes, ask whether to update it.
configuration before changes.
These behaviors can be abbreviated to one letter. For compatibil‐
ity with previous releases, is accepted as an alias for and is
accepted as an alias for These aliases will be removed in a future
After each boot, the default backup behavior is to ask whether to
update the configuration before each change. Changes made noninterac‐
tively assume a "no" response.
Dynamic and Static Changes
By default, the kernel configuration tools will apply configuration
changes to the currently running system, causing an immediate change in
their behavior. System administrators can override this default by
specifying the option to changes made using the or commands. This
option causes the change(s) to be held until the system is rebooted.
HP recommends that this option be used only when the next reboot is
expected to happen soon. If the reboot doesn't happen for months after
the change, the change could come as an unwelcome surprise to an admin‐
istrator who had forgotten the request.
Some configuration changes cannot be applied without a reboot. These
changes will be held until the system is rebooted even if the option is
not specified. In these cases, a warning message will be printed.
If multiple configuration changes are requested in a single invocation
of one of the kernel configuration commands, and any one of those
changes requires a reboot, all of the requested changes will be held
until the system is rebooted. In particular, if a saved kernel config‐
uration is loaded using and that configuration cannot be used without a
reboot, the state of the running system is not changed and the speci‐
fied kernel configuration is marked to be used at next boot.
If a change to a configuration is being held until next boot, and a
subsequent change to the same configuration setting is made with imme‐
diate effect, the immediate change will take precedence. The first
change will not take effect at next boot. A warning will be printed in
Changes that replace the entire currently running configuration, such
as (import), (load), or (nextboot), cause any changes being held for
next boot to be discarded.
Changes that are made to the currently running system are retained when
the system is rebooted. They remain in effect until changed, or until
a saved kernel configuration is loaded.
When the system is booted, the administrator may specify the name of a
saved kernel configuration on the boot command line (see hpux(1M) and
hpux.efi(1M)). If so, that kernel configuration will be loaded during
If no kernel configuration is specified on the boot command line, the
system will look for any kernel configuration that had been marked for
use at next boot (via a or command). If any such configuration is
found, that configuration will be loaded during boot.
If no kernel configuration is specified on the boot command line, and
none is marked for use at next boot, the system will boot using the
same configuration that was in use before the reboot. If the configu‐
ration had any changes that were being held for reboot, either because
they could not be applied without a reboot or because the option was
used, those changes will be applied during the boot process.
If the kernel configuration fails to boot properly, recovery can be
attempted by booting the configuration and/or booting with the "fail‐
safe boot" flag on systems, on PA-RISC systems). See hpux(1M) and
hpux.efi(1M) for details.
Users of past releases of HP-UX may be used to keeping kernel configu‐
ration choices in a text file called Such a file is known as a "system
file". A system file is automatically maintained for the currently
running kernel configuration. This file can be found at System files
are also automatically maintained for each saved kernel configuration.
These files can be found at where config is the name of the saved con‐
figuration. Any time a kernel configuration (saved or current) is
changed using one of the kernel configuration commands, the correspond‐
ing system file automatically gets rewritten to reflect the change.
System files can also be generated on demand for any configuration
using The format of a system file is described in system(4).
It is possible to make configuration changes by modifying a system file
in a text editor and then running This command will read the system
file and modify the appropriate kernel configuration to match the con‐
tents of the system file. can also read a system file and modify a
kernel configuration. It is retained for compatibility with previous
releases of HP-UX.
Note: Some configuration changes can be made without using one of the
kernel configuration commands (for example, by calling the or
system calls directly). In these cases, the system files are
not automatically updated. Be sure to update them manually, or
re-create them using before using them.
Note: Avoid putting comments in a system file. System files get re-
created every time a kernel configuration change is made, and
comments are not preserved in this process.
System files can be useful for propagating kernel configurations to
other systems. To do so, use to export a configuration to a system
file on a source machine. Move the file to one or more target machines
and use to import the system file into a configuration on the target.
The target machines must have the same kernel filesets installed, or
the import operation may fail. The flag can be used to ensure that the
target machine has exactly the same versions of kernel filesets
If there are changes to the currently running kernel configuration that
are being held for reboot, those changes are reflected in the system
The kernel configuration commands maintain a log file that describes
all kernel configuration changes. This log file is located at The com‐
mand can be used to search and view the log file, or to make entries
that don't correspond to configuration changes.
When making a configuration change using any of the commands, you can
specify a comment option. The commands will include the specified com‐
ment in the log file entry describing the change. Note that the com‐
ment usually must be quoted to avoid interpretation by the shell.
Some configuration changes can be made without using the kernel config‐
uration commands. No log file entries are made for such changes.
The format of the log file may be changed without notice. Programs
must use the command to retrieve entries from the file rather than
attempting to parse the file format.
All error, warning, and note messages printed by the kernel configura‐
tion commands are numbered. For aesthetic reasons, the message numbers
are not usually displayed. To enable display of the message numbers,
set the environment variable to 1.
Most of the kernel configuration commands produce tabular output
describing the details of a configuration. Such output may be attrac‐
tive for humans, but can be difficult for scripts and applications to
parse. Also, the tabular output format can change at any time: for
example, between different types of systems or between releases of HP-
For these reasons, each of the kernel configuration commands that pro‐
duce such output accept a option, which changes the output format. The
format is designed to be easy to parse, and is guaranteed not to
change. HP will not support applications and scripts which parse the
output of the kernel configuration commands unless they use the option.
The option must be followed by a comma-separated list of field names.
Each kernel configuration command supports a different set of field
names; refer to the man page for the command for a list. The field
names must appear in a single argument, so there should be no spaces
anywhere in the list. For example,
The kernel configuration command will produce output that consists of a
series of lines describing one object, a blank line, a series of lines
describing the next object, a blank line, and so on until all objects
are described. Each line in the series consists of a field name, a
single tab character (ASCII 9), and the value of that field for the
object being described. The lines occur in the same order as
requested. So the above command might produce this output:
Some fields may occur multiple times within an object, or may not occur
at all. This will be noted in the description of the field. For exam‐
ple, the command
might produce this output:
This shows that has no dependencies, but is dependent on two other mod‐
New fields may be added at any time, but they will not be included in
the output unless specified in a option. Fields will not be removed.
In rare cases, future developments may render a field meaningless. In
these cases, the field name will still be accepted but the correspond‐
ing lines will be omitted from the output.
SEE ALSOhpux(1M), hpux.efi(1M), kclog(1M), kcmodule(1M), kconfig(1M),
kcpath(1M), kctune(1M), mk_kernel(1M), modload(2), settune(2), sys‐