KEXTCACHE(8) BSD System Manager's Manual KEXTCACHE(8)NAMEkextcache — create kext cache files
SYNOPSISkextcache mkext_option [filename] [options] [--] kext_or_directory ...
kextcache-prelinked-kernel filename [options] [--]
[kext_or_directory ...]
kextcache-system-prelinked-kernel [options] [--] [kext_or_directory ...]
kextcache-system-caches [options]
kextcache-update-volume os_volume [options]
DESCRIPTION
The kextcache program creates kext caches, which speed up kext loading
operations. It is invoked automatically as needed to rebuild system
caches.
Caution: Incorrect use of kextcache can render a volume incapable of
startup. Installers and administrators should not use this program to
update system kext caches. Instead they should run touch(1) on the
/System/Library/Extensions/ directory of the installation target volume
after they have finished, which invalidates the existing caches and
causes the system to update all necessary kext caches. kextcache-update-volume can be used to wait for this process to complete. See
“Apple Developer Technical Q&A QA1319: Installing an I/O Kit Kext Without
Rebooting” for information on updating kext caches on prior releases of
Mac OS X.
kextcache creates several kinds of kext caches. The first is the pre‐
linked kernel (also known as a “kernelcache”), which contains the kernel
code and the essential files (info dictionary and executable) for an
arbitrary set of kexts, with kext executables linked for their run-time
locations. A prelinked kernel speeds early system startup by collecting
these many files in one place for the booter to locate, and by having
each kext linked in place and ready to start as needed. To create or
update a prelinked kernel, use the -prelinked-kernel or
-system-prelinked-kernel option.
Other kext caches collect specific data from the info dictionaries of
kexts. There are many individual caches for specific subsets of data;
they care collectively called system info caches. These caches are used
to optimize disk I/O when working with kexts during late system startup
and beyond. To update the system kext info caches for the root volume,
use the -system-caches option.
The last type of kext cache is the mkext cache, which contains the essen‐
tial files (info dictionary and executable) for an arbitrary set of
kexts; executables are unrelocated. Mkext is a legacy format that was
used on prior releases of Mac OS X. To create an mkext cache, use one of
the -mkext, -mkext1, or -mkext2 options, with appropriate filtering
options, described below.
PRIMARY OPTIONS
You must specify one of these options to have kextcache do anything:
-c [filename], -prelinked-kernel [filename]
Create a prelinked kernel. filename is required unless this
option is the last argument. If this option is the last argu‐
ment and no filename is given, the startup prelinked kernel for
the system is created. See -all-loaded.
-system-prelinked-kernel
This option is a convenience to update the prelinked kernel used
for startup on the root volume, with all kexts in /Sys‐
tem/Library/Extensions and /Library/Extensions that have been
loaded to date. This option implies -all-loaded.
-system-caches
Rebuild the info caches for system kexts on the root volume.
-u os_volume, -update-volume os_volume
Rebuild out-of-date caches and update any helper partitions
associated with os_volume.
os_volume/System/Library/Caches/com.apple.bootstamps/ is used to
track whether any helper partitions are up to date. See
-caches-only and -force.
Which caches are rebuilt depends on the Mac OS X release
installed on os_volume. If kextcache cannot find or make sense
of os_volume/usr/standalone/bootcaches.plist the volume is
treated as if no caches need updating: success is returned.
-U os_volume
A special exit code is returned if any updates were needed. -U
should only be used by the system during startup.
-m filename, -mkext filename
Create an mkext of the latest supported format.
-mkext1 filename
Create an mkext of format 1, used on Mac OS X versions 10.5
(Leopard) and earlier.
-mkext2 filename
Create an mkext of format 2, used on Mac OS X version 10.6 (Snow
Leopard).
-e, -system-mkext
This option is provided for legacy compatibility, and is simply
an alias to -system-prelinked-kernel.
PRELINKED KERNEL AND MKEXT FILTERING OPTIONS
These options restrict which kexts are included in a prelinked kernel or
mkext. The options -arch and -bundle-id select kexts by supported archi‐
tecture and bundle identifier; the remaining filtering options select
kexts based on the value of their OSBundleRequired property. If these
options are specified, the cache will contain only kexts whose
OSBundleRequired property matches any of these options, or whose
OSBundleRequired property is “Root” or “Console”.
A prelinked kernel or mkext cache intended for a startup from a local
disk should be created with the -local-root option, while a cache
intended for startup from the network should be created with the
-network-root option. When creating a prelinked kernel, if the
-all-loaded option is specified, kexts requested by the kernel are always
included regardless of these filtering options.
-a arch, -arch arch
Include in an mkext or prelinked kernel only kexts loadable on
arch, thinning executables to that architecture before inclu‐
sion. Multiple architectures are allowed; in this case a multi-
architecture file is created containing an embedded cache for
each of the specified architectures. If no architectures are
specified, a default set of architectures supported by the cur‐
rent Mac OS X version is used (Mac OS X 10.6 and later).
-b identifier, -bundle-id identifier
Find the kext whose CFBundleIdentifier is identifier amongst
known kexts and repository directories and include it in the
mkext or prelinked kernel. The kext of the highest CFBundleVer‐
sion with the given identifier is used; in the case of version
ties, the last such kext specified on the command line is used.
This option may be specified multiple times; if so, the speci‐
fied bundle identifiers select a subset from all named reposito‐
ries and kexts, to which the remaining filters described in this
section are then applied.
-l, -local-root
Specifies that for directory arguments, only extensions required
for local disk boot be included in a cache. Kexts explicitly
indicated by name or identifier are included unconditionally; to
apply this filter to all kexts, use the -local-root-all option.
-L, -local-root-all
Specifies that only extensions required for local disk boot be
included in a cache, regardless of whether they are from a
repository directory or are explicitly indicated by name or
identifier. To apply this restriction only to kexts from repos‐
itory directories, use the -local-root option.
-n, -network-root
Specifies that for directory arguments, only extensions required
for network disk boot be included in a cache. Kexts explicitly
indicated by name or identifier are included unconditionally; to
apply this filter to all kexts, use the -network-root-all
option.
-N, -network-root-all
Specifies that only extensions required for network disk boot be
included in a cache, regardless of whether they are from a
repository directory or are explicitly indicated by name or
identifier. To apply this restriction only to kexts from repos‐
itory directories, use the -network-root option.
-s, -safe-boot
Specifies that for directory arguments, only extensions required
for safe boot be included in a cache. Kexts explicitly indi‐
cated by name or identifier are included unconditionally; to
apply this filter to all kexts, use the -safe-boot-all option.
-S, -safe-boot-all
Specifies that only extensions required for safe boot be
included in a cache, regardless of whether they are from a
repository directory or are explicitly indicated by name or
identifier. To apply this restriction only to kexts from repos‐
itory directories, use the -safe-boot option.
OTHER OPTIONS AND ARGUMENTS
kext_or_directory
A kext bundle or a repository directory containing kexts to con‐
sider for inclusion in an mkext or prelinked kernel. The fil‐
tering options described under “PRELINKED KERNEL AND MKEXT
FILTERING OPTIONS” select the individual kexts to be included in
the archive. If no filtering options are specified, then all
kexts named as arguments are included (this is probably not what
you want).
-caches-only
With -update-volume, skips updating any helper partitions even
if they appear out of to date.
-f, -force
With -update-volume, rebuilds any helper partitions even if they
appear up to date. If this version of kextcache does not under‐
stand bootcaches.plist well enough to be able to update the
helpers, exit with EX_OSFILE (72).
-Installer
With -update-volume, implies -force while making helper parti‐
tion updates optional.
-F Run in low-priority mode, as when forked and executed by
kextd(8). (This used to actually fork, but no longer does, as
kextd(8) handles the forking.)
-h, -help
Print a help message describing each option flag and exit with a
success result, regardless of any other options on the command
line.
-K kernel_filename, -kernel kernel_filename
The name of the kernel file to use as the base of a prelinked
kernel file (the default is /mach_kernel).
-q, -quiet
Quiet mode; print no informational or error messages.
-r, -all-loaded
When creating a prelinked kernel, include all kexts in /Sys‐
tem/Library/Extensions and /Library/Extensions that have been
loaded by the machine running this command during this startup
session. This include kexts loaded and later unloaded.
-compressed
Compress the mkext or prelinked kernel (enabled by default).
-uncompressed
Do not compress the mkext or prelinked kernel. If specified as
the only other argument with -c, uncompresses an existing pre‐
linked kernel file in place.
-symbols symbol_directory
Generate symbols for every kext in the prelinked kernel and save
them in symbol_directory. The directory must already exist.
Symbol files are named after the CFBundleIdentifier of each kext
with a .sym suffix attached.
-t, -print-diagnostics
If a kext has validation, authentication, or dependency resolu‐
tion problems, print them. Note that tests are performed in
three stages: validation, authentication, and dependency resolu‐
tion; 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 [0-6 | 0x####], -verbose [0-6 | 0x####]
Verbose mode; print information about program operation. Higher
levels of verbosity include all lower levels. By default
kextcache prints only warnings and errors. You can specify a
level from 0-6, or a hexadecimal log specification (as described
in kext_logging(8)). The levels of verbose output are:
0 Print only errors (that is, suppress warnings); see
also -quiet.
1 (or none) Print basic information about program operation.
2 Print basic information about program progress and
files created.
3 Print information about individual kexts; for exam‐
ple, when a kext is added to or omitted from an ar‐
chive.
4 Print information about compression and architec‐
tures processed.
5 Print debug-level information about internal opera‐
tions.
6 Identical to level 5 for kextcache.
Unlike in other kext tools, the -verbose flag in kextcache
applies to all kexts (that is, it turns on hexadecimal bit 0x8
by default). See kext_logging(8) for more information on ver‐
bose logging.
-volume-root path
When creating caches for a volume other than the root volume,
remove path from the beginning of absolute kext paths stored in
the cache file. This ensures that the kext paths stored in the
kernel are accurate when the caches are used for startup with
that volume.
-z, -no-authenticate
Don't authenticate kexts. This option is for convenience in
building cache files. Caches used for startup 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.
FILES
/System/Library/Extensions/
The standard system repository of kernel extensions.
/Library/Extensions/
The standard repository of non Apple kernel extensions.
/System/Library/Caches/com.apple.kext.caches/
Contains all kext caches for a Mac OS X 10.6 system: prelinked kernel,
mkext, and system kext info caches.
/mach_kernel
The default kernel file.
/usr/standalone/bootcaches.plist
Describes specific kext cache files for a Mac OS X volume.
/System/Library/Caches/com.apple.bootstamps/
Contains timestamp information about kext caches.
DIAGNOSTICSkextcache exits with a zero status upon success. Upon failure, it prints
an error message and exits with a nonzero status.
BUGS
Many single-letter options are inconsistent in meaning with (or directly
contradictory to) the same letter options in other kext tools.
SEE ALSOmkextunpack(8), kext_logging(8), kextd(8), kextload(8), kextutil(8),
kextstat(8), kextunload(8)Darwin November 14, 2012 Darwin
