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 kconfig(5)                                                       kconfig(5)

 NAME    [Toc]    [Back]
      kconfig - introduction to kernel configuration commands

 DESCRIPTION    [Toc]    [Back]
      HP-UX contains a set of commands used to view and modify the
      configuration of the HP-UX kernel.  The commands are:

           kconfig       Operations on complete kernel configurations

           kcmodule      Operations on kernel modules

           kctune        Operations on kernel tunable parameters

           kcpath        Retrieves pathnames of kernel files

           kclog         Searches and displays the kernel configuration log

           mk_kernel     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 kcmodul

      By default, these commands affect the state of the currently running
      system.  When these commands are given a -c config option, they
      instead affect the saved kernel configuration named config.

      The currently running kernel configuration can be saved using kconfig
      -s.  A saved configuration can be loaded using kconfig -l.  This
      causes the state of the running system to be changed to match the
      saved configuration.  A saved configuration can be marked for use when
      the system is next booted, by using kconfig -n.  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.  (See Boot
      Behavior, below.)

      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.

    Backup Configuration    [Toc]    [Back]
      The system maintains a saved configuration called backup, which can be
      used to recover from configuration errors.  The system automatically
      saves the currently running configuration to backup immediately before
      making any requested change to the configuration.  This behavior can
      be disabled using the -K option on the command line when a change is

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 kconfig(5)                                                       kconfig(5)


      The first update of the backup configuration after the system boots is
      treated specially, since it will overwrite the backup of the
      configuration that was running before the reboot.  Any time the backup
      configuration dates to before the time the system booted, the command
      making the configuration change will ask for confirmation before
      replacing it.  (If the command is running non-interactively, the
      answer is assumed to be "no".)  This behavior can be overridden by
      specifying the -B (update the backup) or -K (don't update the backup)
      flags on the command line for the change.

    Dynamic and Static Changes    [Toc]    [Back]
      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 -h option to any of the 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
      administrator 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 -h
      option is not specified.  In these cases, a warning message will be

      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
      configuration is loaded using kconfig -l, and that configuration
      cannot be used without a reboot, the state of the running system is
      not changed and the specified 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
      immediate effect, the immediate change will take precedence.  The
      first change will not take effect at next boot.  A warning will be
      printed in these situations.

      Changes that replace the entire currently running configuration, such
      as kconfig -i (import), kconfig -l (load), or kconfig -n (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.

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 kconfig(5)                                                       kconfig(5)

    Boot Behavior    [Toc]    [Back]
      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 boot.

      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 kconfig -n, kconfig -l, or kconfig -i
      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
      configuration had any changes that were being held for reboot, either
      because they could not be applied without a reboot or because the -h
      option was used, those changes will be applied during the boot

      If the kernel configuration fails to boot properly, recovery can be
      attempted by booting the backup configuration and/or booting with the
      "failsafe boot" flag (-tm on Itanium(R)-based systems, -f0x40000 on
      PA-RISC systems).  See hpux(1M) and hpux.efi(1M) for details.

 SYSTEM FILES    [Toc]    [Back]
      Users of past releases of HP-UX may be used to keeping kernel
      configuration choices in a text file called /stand/system.  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 /stand/system.  System files are also automatically
      maintained for each saved kernel configuration.  These files can be
      found at /stand/config/system, where config is the name of the saved
      configuration.  Any time a kernel configuration (saved or current) is
      changed using one of the kernel configuration commands, the
      corresponding system file automatically gets rewritten to reflect the
      change.  System files can also be generated on demand for any
      configuration set using kconfig -e.  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 kconfig -i.  This command will
      read the system file and modify the appropriate kernel configuration
      to match the contents of the system file.  (mk_kernel(1M) 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
              settune(2) or modload(2) system calls directly).  In these
              cases, the system files are not automatically updated.  Be

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 kconfig(5)                                                       kconfig(5)

              sure to update them manually, or re-create them using kconfig
              -e, 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 kconfig -e to export a configuration set
      to a system file on a source machine.  Move the file to one or more
      target machines and use kconfig -i to import the system file into a
      configuration set on the target.  The target machines must have the
      same kernel filesets installed, or the import operation may fail.  The
      -V flag can be used to ensure that the target machine has exactly the
      same versions of kernel filesets installed.

      If there are changes to the currently running kernel configuration
      that are being held for reboot, those changes are reflected in the
      system file /stand/system.

 LOG FILE    [Toc]    [Back]
      The kernel configuration commands maintain a log file that describes
      all kernel configuration changes.  This log file is located at
      /var/adm/kc.log.  The kclog command can be used to search and view the
      log file, or to make entries that don't correspond to configuration

      When making a configuration change using any of the commands, you can
      specify a -C comment option.  The commands will include the specified
      comment in the log file entry describing the change.  Note that the
      comment usually must be quoted to avoid interpretation by the shell.
      kconfig -i and mk_kernel will include in the log file any comments
      that they remove from a system file.

      Some configuration changes can be made without using the kernel
      configuration commands.  No log file entries are made for such

      The format of the log file may be changed without notice.  Programs
      must use the kclog command to retrieve entries from the file rather
      than attempting to parse the file format.

 PARSING OUTPUT    [Toc]    [Back]
      Most of the kernel configuration commands produce tabular output
      describing the details of a configuration.  Such output may be
      attractive 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-UX.

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 kconfig(5)                                                       kconfig(5)

      For these reasons, each of the kernel configuration commands that
      produce such output accept a -P option, which changes the output
      format.  The -P 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 -P option.

      The -P 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,

           kcmodule -P name,state,desc

      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:

          name    module1
          state   loaded
          desc    This is the first sample module.

          name    module2
          state   unused
          desc    This is a different sample module.

      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 example, the command

           kcmodule -P name,state,depend

      might produce this output:

          name    module1
          state   loaded

          name    module2
          state   unused
          depend  module1
          depend  module4

      This shows that module1 has no dependencies, but module2 is dependent
      on two other modules.

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 kconfig(5)                                                       kconfig(5)

      New fields may be added at any time, but they will not be included in
      the output unless specified in a -P 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 corresponding lines will be omitted from the output.

 SEE ALSO    [Toc]    [Back]
      hpux(1M), hpux.efi(1M), kclog(1M), kcmodule(1M), kconfig(1M),
      kcpath(1M), kctune(1M), mk_kernel(1M), system(4).

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[ Back ]
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