KEXTCACHE(8)

NAME
kextcache - creates or updates kext caches

SYNOPSIS
kextcache [-a arch] [-c kernel_cache_filename] [-e] [-F] [-h] [-k] [-K kernel_filename] [-l | -L] [-m mkext_filename] [-n | -N] [-r] [-s | -S] [-t] [-v [1-6]] [-z] [kext_or_directory] ...
kextcache [-f] -u os_volume

DESCRIPTION
The kextcache program creates or updates kext caches, which are used to speed up kext loading operations and to prepare kexts for inclusion in such media as device ROM. It is invoked automatically as needed to rebuild the system caches, and can be used manually to build kext archives to be stored in device ROM.

NOTE: Kernel extension installers should not use this program to update caches. Instead they should merely touch(1) the /System/Library/Extensions directory after they have finished, which will cause the system to update all necessary kernel extension caches.

There are three kinds of kext cache. The first is the mkext cache, which contains the info dictionaries and binary files for an arbitrary set of kexts. Mkext caches are used during early system startup to load drivers essential to mounting the root filesystem and providing basic hardware services. They're also used to package drivers in device ROM. To create an mkext cache use the -m option.

The second type of cache is the kext repository cache, which contains the info dictionaries for all the kexts in a single repository directory, including their plugins, in a file with a .kextcache extension. A repository cache speeds the startup of tools such as kextload(8) and kextd(8). A repository cache must exist alongside its repository directory for the kext tools to find and use it. The kext tools normally build or update repository caches as needed. To create or update a kext cache use the -k option.

The third type of cache is the kernel cache, which contains the kernel code, linked kext code, and info dictionaries for an arbitrary set of kexts. Having the kernel code and kexts already linked speeds the startup of tools such as kextload(8) and kextd(8). To create or update a kernel cache use the -c option.

kextcache accepts these arguments and options:

kext_or_directory
    A kext bundle or a repository directory containing kexts to add to the cache. When using the -m option only, any number may be specified. When using the -k option, only a single directory may be named.

-a arch
    Include in an mkext archive only kexts whose executable files contain code for the given arch, stripping the binaries before inclusion. If multiple -a options are used, a multi-architecture file will be created containing an embedded mkext archive for each of the specified architectures.

-c kernel_cache_filename
    The name of the kernel cache file to create. If none is specified, a cache file is created in the /System/Library/Caches/com.apple.kernelcaches/ folder.

-e  This option is a convenience to update the mkext cache for the /System/Library/Extensions folder.

-F  Fork a child process and exit immediately. This allows a cache update during system startup to continue without delaying startup.

-f  Used with -u to specify that everything should be updated regardless of "bootstamp" information.

-h  Extended usage statement

-k  Create or update the kext cache for any repository directories specified.

-K kernel_filename
    The name of the kernel file to use as the base of a kernel cache file (default is /mach_kernel).

-l  Specifies that for directory arguments, only extensions required for local disk boot be included in an mkext cache. Kexts explicitly named on the command line are included unconditionally; to apply this restriction to all kexts, use the -L option. May be combined with the -n, -N, -s, or -S options to archive network-root and safe boot extensions as well.

-L  Specifies that only extensions required for local disk boot be included in an mkext cache. To apply this restriction only to repository directories, use the -l option. May be combined with the -n, -N, -s, or -S options to archive network-root and safe boot extensions as well.

-m mkext_filename
    The name of the mkext cache file to create.

-n  Specifies that for directory arguments, only extensions required for network boot be included in an mkext cache. Kexts explicitly named on the command line are included unconditionally; to apply this restriction to all kexts, use the -N option. May be combined with the -l, -L, -s, or -S options to archive local-root and safe boot extensions as well.

-N  Specifies that only extensions required for network boot be included in an mkext cache. To apply this restriction only to repository directories, use the -n option. May be combined with the -l, -L, -s, or -S options to archive local-root and safe boot extensions as well.

-r  Include all kexts that have been loaded by the machine running this command during this boot. This include kexts loaded and later unloaded.

-s  Specifies that for directory arguments, only extensions required for safe boot be included in an mkext cache. Kexts explicitly named on the command line are included unconditionally; to apply this restriction to all kexts, use the -S option. May be combined with the -l, -L, -n, or -N options to archive local- and network-root extensions as well.

-S  Specifies that only extensions required for safe boot be included in an mkext cache. To apply this restriction only to repository directories, use the -s option. May be combined with the -l, -L, -n, or -N options to archive local- and network-root extensions as well.

-t  Perform all possible tests on the named kext(s) and indicate whether the kext is loadable (and therefore eligible for inclusion in the cache), 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.

-u os_volume
    Update boot caches and any helper partitions associated with os_volume. The mkext is always updated. By default, only caches which have changed since the last update are copied to the helper partitions. See also -f. OS volumes without /usr/standalone/bootcaches.plist are ignored (success is returned).

-v [1-6]
    Verbose mode; print information about the kext scanning and loading process. Higher levels of verbosity include all lower levels. With this program only verbose levels 1-3 are useful. The levels of verbose output are these:

    1   prints basic kext scanning and archiving information

    2   prints basic compression information

    3   prints detailed kext scanning information; also uncompresses mkext cache entries to make sure they do so without error

    4   prints basic information on every kext encountered

    5   prints detailed information on every kext encountered

    6   prints detailed load information (not applicable)

    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, respectively.

-z  Don't authenticate kexts. This option is for convenience in building archive and cache files. Mkext archives and kext repository caches must have proper ownership (root:wheel) and permissions (0644) in order to be used by the system.

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

DIAGNOSTICS
kextcache exits with a zero status upon success. Upon failure, it prints an error message and exits with a nonzero status. When the -F option is used, however, kextcache exits with a nonzero status only if the fork(2) operation fails.

SEE ALSO
kextd(8), kextload(8), kextstat(8), kextunload(8)

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