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KEXTLOAD(8)               BSD System Manager's Manual              KEXTLOAD(8)

     kextload -- loads, validates, and generates symbols for a kernel exten-
     sion (kext)

     kextload [-h] [ -v [0-6] | -q ] [-t] [-i | -I] [-x] [-z] [-e] [-c] [-D]
              [-k kernel_file] [-d extension] ...  [-r directory] ...  [ -l |
              -m | -n | -A | -a kext_id@address ] ...  [-s directory]
              [-p personality] ...  [-b -bundle_id] ...  [--] [extension] ...

     The kextload program is used to explicitly load kernel extensions
     (kexts), validate them to see that they can be loaded by other mecha-
     nisms, such as kextd(8), and to generate symbol files for debugging the
     kext in a running kernel.  In order to load a kext into the kernel
     kextload must be invoked as the superuser; for all other uses it can be
     invoked by any user.

     kextload is a formal interface for kext loading in the Darwin OS and in
     Mac OS X.  Software and installers can rely on its presence and invoke it
     in order to load kexts.

     kextload has many options, but most of them are rarely necessary.  See
     the EXAMPLES section for tips on common uses.  The arguments and options
     available are these:

              The pathname of a kext bundle to load or otherwise use.  Kexts
              can also be specified by CFBundleIdentifier with the -b option.

     -a kext_id@address
              Treat the kext whose CFBundleIdenfier is kext_id as being loaded
              at address when generating symbol files and not loading.  When
              generating symbols only, all dependencies must have known
              addresses.  Use this option repeatedly for every nonkernel
              dependency.  This option implies the use of the -n option. See
              also -A and -n.

     -A       When generating symbol files and not loading, look up all depen-
              dency kext addresses within the running kernel.  This option
              implies the use of the -n option. See also -a and -n.

     -b bundle_id
              Look up the kext whose CFBundleIdentifier is bundle_id within
              the set of known kexts and load it.  See the -d, -e, and -r
              options for more information.

     -c       Ignore any repository cache files and scan all kext bundles to
              gather information.  If this option is not given, kextload will
              attempt to use cache files and to create them if they are out of
              date or don't exist.

     -d extension
              Add extension to the set of known kexts for resolving dependen-
              cies.  This is useful for adding a single kext from a directory
              while excluding the others.  See the -e and -r options for more

     -D       Don't check the kernel for already loaded kexts when resolving
              dependencies.  This behavior is now the default and so this
              option is deprecated and redundant.  Note that this can result
              in load failures if a different version of a dependency is
              already loaded.  This option is relevant only when loading a
              kext into the kernel.  The -A option overrides this option as it
              must check the kernel for which kexts are loaded.

     -e       Don't use the contents of /System/Library/Extensions as the
              default repository of kexts.  If you use this option you will
              have to explicitly specify all dependencies of the kext being
              loaded or otherwise worked on using the -d and -r options.

     -h       Print a help message describing each option flag.

     -i       Interactive mode; pause at each stage of loading for user input
              to continue.  This allows for debugger setup when the kext needs
              to be debugged during its earliest stages of running.

     -I       (capital i) Interactive mode as -i for the specified kext and
              all of its dependencies.

     -k kernel_file
              Link against the given kernel_file (default is /mach).  Allowed
              only with the -n option to generate debug symbols.

     -l       Load and start the kext only; don't send I/O Kit personalities
              to the kernel to begin matching.  Matching may still occur if
              the personalities are present from an earlier load operation.
              You may want to use kextunload(8) before loading a kext with
              this option.

     -L       Same as -r (remains for backward compatibility).

     -m       Don't load the kext, but do send its personalities to the kernel
              to begin matching.  Use this option after you have loaded a
              driver with -l and after setting up the debugger.

     -n       Neither load the kext nor send personalities to the kernel.
              This option is for use when generating debug symbols only with
              the -s option, or when validating kexts with the -t option.  See
              also the -a and - A options.

     -p personality
              Send only the named personalities from the kext to the kernel.
              Repeat for each personality desired, or use the -i option to
              have kextload ask for each personality.

     -q       Quiet mode; print no informational or error messages.  This
              option excludes -v.  If kextload is run with -q in a way that
              might require user interaction, as with the -i and -I options,
              and some uses of -n, the program will silently exit with an
              error status.

     -r directory
              Use directory as a repository of kexts.  This adds to the set of
              known kexts for resolving dependencies or looking up by
              CFBundleIdentifier when using the -b option.  This is not recur-
              sive; only the directory's immediate contents are scanned.  See
              also the -c, -d, and -e options.

     -s directory
              Write all generated symbol files into directory.  The directory
              must already exist.  Symbol files are named after the CFBundleI-
              dentifier of each kexts with a .sym suffix appended.

     -t       Perform all possible tests on the named kext(s) and indicate
              whether the kext is loadable, or if not, what problems it has.
              Note that tests are performed in three stages, validation,
              authentication, and dependency resolution; a failure at any
              stage can make tests in further stages impossible.  Thus, a kext
              with validation failures may have unreported authentication
              problems or missing dependencies.

     -v [1-6]
              Verbose mode; print information about the kext scanning and
              loading process. Higher levels of verbosity include all lower
              levels.  The levels of verbose output are these:

              0    suppresses informational messages (errors are still
                   printed); see also -q

              1    prints basic kext scanning information

              2    prints basic load information

              3    prints detailed kext scanning information

              4    prints basic information on every kext encountered

              5    prints detailed information on every kext encountered

              6    prints detailed load information
              If -v is not specified only the essential information about the
              load operation is printed (such as whether the kext was already

              A kext can also specify verbose printing for just itself using
              the OSBundleDebugLevel top-level info dictionary property.  Its
              values are 1 and 2, for basic and detailed information, respec-

              This option excludes - q .

     -x       Run kextload in safe boot mode (indicating startup with the
              Shift key held down).  Kexts that don't specify a proper value
              for the OSBundleRequired info dictionary property, or those in
              which every personality contains a nonzero IOKitDebug property,
              will not load.  This option implies the use of the -c option.

     -z       Don't authenticate kexts.  This option is for convenience during
              development, and is allowed only for operations that don't actu-
              ally load a kext into the kernel (such as when generating sym-

     -Z       Don't try to resolve dependencies.  This option is allowed only
              when using the -n and -t options to test a kext for problems.
              It is not allowed with the -s option as generating symbols
              requires dependencies to be resolved.

     --       End of all options. Only kext names follow.

     Here are the common uses and usage patterns for kextload.

   Basic loading
     To load a kext you must run kextload as the superuser and supply a kext
     bundle name; no options are required:

               kextload TabletDriver.kext

     Alternatively, you can use the -b option to specify a kext by its

               kextload -b com.mycompany.driver.TabletDriver

     With no additional options kextload will look in /System/Library/Exten-
     sions for a kext with the given CFBundleIdentifier.  Adding repository
     directories with the -r option or individual kexts with the -d option
     expands the set of kexts that kextload looks among:

               kextload -r ${USER}/Library/Extensions TabletDriver.kext

     If you're modifying system startup to load a kext, be sure to check
     whether the system is starting up in safe boot mode (typically when the
     user presses the Shift key) and use the -x option to indicate this.  (The
     various rc files in /etc can simply use the $SafeBoot shell variable on
     the command line. It evaluates to an empty string during normal startup
     and "-x" during safe boot mode.)

   Validating Kexts
     The -t option causes kextload to perform all possible validation and
     authentication checks on the specified kexts and to attempt to resolve
     their dependencies.  If there are any problems with the specified kexts,
     kextload prints a list of the problems.

     The -t option is typically used with -n after a load failure to pinpoint
     a problem.  It can be used with any other set of options, however.

     If you want to validate a kext in isolation, as in a build environment
     where dependencies may not be available, you can use the -e and -Z
     options to omit the /System/Library/Extensions repository and to suppress
     dependency resolution, respectively:

               kextload -entZ PacketSniffer.kext

     Only validation and authentication checks will be performed.

   Generating Debug Symbols When Loading
     To generate a symbol file for use with gdb when loading a kext, use the
     -s option to specify a directory where symbol files will be written for
     the kext being loaded and all its dependencies.

               kextload -s ~/ksyms PacketSniffer.kext

   Generating Debug Symbols For an Already-Loaded Kext
     If you want to generate symbols for a kext that's already loaded, whether
     on the same system or on another, use the -s option along with the -n
     option.  Since in this case addresses must be known for the kext and all
     its dependencies, though, you must specify these.  If you don't indicate
     them on the command line, kextload will ask you for the load address of
     each kext needed.  Use kextstat(8) on the machine you're generating sym-
     bols for to get these addresses and enter them at each prompt.

               kextload -n -s ~/ksyms GrobbleEthernet.kext
               enter the hexadecimal load addresses for these modules:
               com.apple.iokit.IONetworkingFamily: 0x1001000

     Alternatively, if you know the CFBundleIdentifiers of all the kexts, you
     can use the -a option for each kext (you needn't specify -n when using
     the -a option):

               kextload -s ~/ksyms \
               -a com.apple.iokit.IONetworkingFamily@0x1001000 \
               -a com.apple.iokit.IOPCIFamily@0x1004000 \
               -a com.mycompany.driver.GrobbleEthernet@0x1007000 \

     Simplest of all, however, provided you can run kextload on the same
     machine as the loaded kext, is to use the -A option, which checks with
     the kernel for all loaded kexts and automatically gets their load

               kextload -s ~/ksyms -A GrobbleEthernet.kext

   Explicitly Specifying Dependencies
     Because kextload resolves dependencies automatically, it's possible that
     a kext other than the one you intend might get used as a dependency (such
     as when there are multiple versions, or if you're working on a new ver-
     sion of a kext that's already installed in /System/Library/Extensions).
     By default, when loading a kext into the kernel kextload checks which
     versions of possible dependencies are already loaded in order to assure a
     successful load.  When not loading, however, it always chooses the most
     recent versions of any dependencies.

     If you want to have complete control over the set of extensions used to
     resolve dependencies, use the -e, -d, and -r options.  The -e option
     excludes the standard /System/Library/Extensions folder, leaving the set
     of candidate extensions for dependency resolution entirely up to you.  To
     specify candidate dependencies you use either -d, which names a single
     kext as a candidate, or -r, which adds an entire directory of extensions.

               kextload -n -s ~/ksyms -e \
               -d /System/Library/Extensions/System.kext \
               -r ~/TestKexts -d JoystickSupport.kext JoystickDriver.kext

     Note also that if you use -e, you must supply some version of the Sys-
     tem.kext bundle in order to supply information about the kernel.  This
     should always match the kernel you're linking against, which is by
     default the installed kernel on the machine you're using kextload on; you
     can use the -k option to indicate a different kernel file.

   Debug-Loading an I/O Kit Driver
     If you need to debug an I/O Kit driver's early startup code, you must
     load the driver on the target machine without starting matching by using
     the -l option:

               kextload -l DiskController.kext

     Once you have done this, you can use the generated symbol file in your
     debug session to set breakpoints and then trigger matching by running
     kextload again on the target machine with the -m option:

               kextload -m DiskController.kext

     You may wish to use the -p option as well in order to send selected per-
     sonalities to the kernel.  Alternatively, you can use the -i option for
     the whole process, which causes kextload to pause just before loading any
     personalities and then to ask you for each personality whether that one
     should be sent to the kernel:

               kextload -i DiskController.kext

   Debug-Loading a non-I/O Kit Kext
     A non-I/O Kit kext doesn't have a personality-matching phase of loading;
     it just starts executing.  In order to debug a non-I/O Kit kext's startup
     code, you must use the -i or -I option, which pauses loading at each sig-
     nificant stage so that you can set up your debugging session as needed
     before proceeding.

     /System/Library/Extensions  The standard system repository of kernel
     directoryname.kextcache     A cache of all kext info dictionaries
                                 (plists) for a given directory

     kextload exits with a zero status upon success.  Upon failure, it prints
     an error message and continues processing any kexts if possible, then
     exits with a nonzero status.

     kextcache(8), kextd(8), kextstat(8), kextunload(8)

     Upon encountering a kext with validation errors, kextload typically
     prints an error message about that kext, even if it isn't involved in the
     load request.

Darwin                         February 22, 2002                        Darwin