kextutil.8

.Dd November 14, 2012 
.Os Darwin
.Dt KEXTUTIL 8
.Sh NAME
.Nm kextutil
.Nd load, diagnose problems with, and generate symbols for kernel extensions (kexts)
.Sh SYNOPSIS
.Nm
.Op Ar options
.Op Fl -
.Op Ar kext
.Li \&.\|.\|.
.Sh DESCRIPTION
The
.Nm
program is used to explicitly load kernel extensions (kexts),
diagnose problems with kexts,
and to generate symbol files for debugging kexts.
In order to load a kext into the kernel
.Nm
must run as the superuser;
for all other uses it can run as any user.
.Pp
.Nm
is the developer utility for kext loading in the Darwin OS and
in Mac OS X.
Software and installers should use
.Xr kextload 8
instead of this program.
.Pp
The arguments and options available are these:
.Bl -tag -width -indent
.It Ar kext
The pathname of a kext bundle to load or otherwise use.
Kexts can also be specified by CFBundleIdentifier with the
.Fl bundle-id
option.
.It Fl a Ar identifier@address , Fl address Ar identifier@address
Treat the kext whose CFBundleIdenfier is
.Ar identifier
as being loaded at
.Ar address
when generating symbol files and not loading.
When generating symbols,
any dependencies with unspecified addresses are skipped.
Use this option repeatedly to name every nonkernel dependency
for which you want symbols.
This option implies the use of the
.Fl no-load
option. See also
.Fl use-load-addresses
and
.Fl no-load .
.It Fl arch
Use the specified architecture for generating symbols
and performing tests.
If loading into the kernel or getting load addresses from the kernel,
the specified arch must match that of the running kernel.
.It Fl A , Fl use-load-addresses
When generating symbol files and not loading,
look up all dependency kext addresses within the running kernel.
This option implies the use of the
.Fl no-load
option. See also
.Fl address
and
.Fl no-load .
.It Fl b Ar identifier , Fl bundle-id Ar identifier
Look up the kext whose CFBundleIdentifier is
.Ar identifier
within the set of known kexts and load it.
The kext of the highest CFBundleVersion with the given identifier is used;
in the case of version ties,
the last such kext specified on the command line is used.
See the
.Fl dependency ,
.Fl no-system-extensions ,
and
.Fl repository
options for more information.
.It Fl c , Fl no-caches
Ignore any repository cache files and scan all kext bundles
to gather information.
If this option is not given,
.Nm
attempts to use cache files and (when running as root) to create them
if they are out of date or don't exist.
.It Fl d Ar kext , Fl dependency Ar kext
Add
.Ar kext
and its plugins to the set of known kexts for resolving dependencies.
This is useful for adding a single kext from a directory.
See
.Dq Explicitly Specifying Dependencies
for more information, as well as the
.Fl no-system-extensions
and
.Fl repository
options.
.It Fl e , Fl no-system-extensions
Don't use the contents of
.Pa /System/Library/Extensions/
or 
.Pa /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
.Fl dependency
and
.Fl repository
options.
See
.Dq Explicitly Specifying Dependencies
for more information.
.It Fl h , Fl help
Print a help message describing each option flag and exit with a success result,
regardless of any other options on the command line.
.It Fl i , interactive
Interactive mode; pause after loading each specified kext and
wait for user input to start the kext and
send its personalities to the kernel.
This allows for debugger setup when the kext needs
to be debugged during its earliest stages of running.
.It Fl I , Fl interactive-all
Interactive mode, as described above,
for each specified kext and all of their dependencies.
.It Fl k Ar kernel_file , Fl kernel Ar kernel_file
Link against the given
.Ar kernel_file .
Allowed only with the
.Fl no-load
option to generate debug symbols.
By default
.Nm
attempts to get link symbols from the kernel at /System/Library/Kernels/kernel.
.It Fl l , Fl load-only
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
.Xr kextunload 8
before loading a kext with this option.
.It Fl m , Fl match-only
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
.Fl load-only
and after setting up the debugger.
.It Fl n , Fl no-load
Neither load the kext nor send personalities to the kernel.
This option is for use when generating debug symbols only
with the
.Fl symbols
option,
or when diagnosing kexts with the
.Fl print-diagnostics
option.
For convenience in development, this option implies the
.Fl no-authentication
option.
See also the
.Fl address
and
.Fl use-load-addresses
options.
.It Fl p Ar personality , Fl personality Ar personality
Send only the named personalities from the kext to the
kernel. Repeat for each personality desired, or use the
.Fl interactive
option to have
.Nm
ask for each personality.
.It Fl q , Fl quiet
Quiet mode; print no informational or error messages.
If
.Nm
is run with
.Fl quiet
in a way that might require user interaction,
as with the
.Fl interactive
and
.Fl interactive-all
options,
and some uses of
.Fl no-load ,
the program silently exits with an error status.
.It Fl r Ar directory , Fl repository Ar directory
Use
.Ar 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
.Fl bundle-id
option.
This is not recursive; only the directory's immediate
contents (and their plugins) are scanned.
See
.Dq Explicitly Specifying Dependencies
for more information, as well as the
.Fl dependency
and
.Fl no-system-extensions
options.
.It Fl s Ar directory , Fl symbols Ar directory
Write all generated symbol files into
.Ar directory .
The directory must already exist.
Symbol files are named after the CFBundleIdentifier
of each kext with a
.Pa .sym
suffix appended.
.It Fl t , Fl print-diagnostics
Perform all possible tests on the specified kexts,
even with options that implicitly disable some tests,
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.
.It Fl v Li [ 0-6 | 0x#### Ns Li ] , Fl verbose Li [ 0-6 | 0x#### Ns Li ]
Verbose mode; print information about program operation.
Higher levels of verbosity include all lower levels.
By default
.Nm
prints only warnings and errors.
You can specify a level from 0-6,
or a hexadecimal log specification
(as described in
.Xr kext_logging 8 Ns No ).
The levels of verbose output are:
.Bl -tag -width "1 (or none)"
.It 0
Print only errors (that is, suppress warnings); see also
.Fl quiet .
.It 1 (or none)
Print basic information about program operation.
.It 2
Print basic information about the link/load operation.
.It 3
Print more information about user-kernel interaction, link/load operation,
and processing of I/O Kit Personalities.
.It 4
Print detailed information about module start and C++ class construction.
.It 5
Print internal debug information, including checks for loaded kexts.
.It 6
Identical to level 5 but for all kexts read by the program.
.El
.Pp
To ease debug loading of kexts,
the verbose levels 1-6 in
.Nm
implicitly set the
OSBundleEnableKextLogging
property for each kext specified on the command line to true.
See
.Xr kext_logging 8
for more information on verbose logging.
.It Fl x , Fl safe-boot
Run
.Nm
as if 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 will not load.
This option implies the use of the
.Fl no-caches
option.
.Pp
Note that if the system has actually started up in safe boot mode,
this option is redundant.
There is no way to simulate non-safe boot mode
for a system running in safe boot mode.
.It Fl z , Fl no-authentication
Don't authenticate kexts.
This option is for convenience during development,
and is allowed only for operations
that don't actually load a kext
into the kernel (such as when generating symbols).
.It Fl Z , Fl no-resolve-dependencies
Don't try to resolve dependencies.
This option is allowed only when using the
.Fl no-load
and
.Fl print-diagnostics
options to test a kext for problems.
It is not allowed with the
.Fl symbols
option as generating symbols requires dependencies to be resolved.
.It Fl -
End of all options. Only kext names follow.
.El
.Sh EXAMPLES
Here are the common uses and usage patterns for
.Nm .
.Ss Basic Loading
To load a kext you must run
.Nm
as the superuser and supply a kext bundle name;
no options are required:
.Bd -literal -offset indent
kextutil TabletDriver.kext
.Ed
.Pp
Alternatively, you can use the
.Fl bundle-id
.Li ( Ns Fl b Ns Li )
option to specify a kext by its CFBundleIdentifier:
.Bd -literal -offset indent
kextutil -b com.mycompany.driver.TabletDriver
.Ed
.Pp
With no additional options
.Nm
looks in
.Pa /System/Library/Extensions/
and
.Pa /Library/Extensions/
for a kext
with the given CFBundleIdentifier.
Adding repository directories with the
.Fl repository
.Li ( Ns Fl r Ns Li )
option or individual kexts with the
.Fl dependency
.Li ( Ns Fl d Ns Li )
option expands the set of kexts that
.Nm
looks among:
.Bd -literal -offset indent
kextutil -r ${USER}/Library/Extensions TabletDriver.kext
.Ed
.Ss Diagnosing Kexts
.Nm
prints diagnostic information about kexts by default,
but some options cause certain tests to be skipped.
The ensure that all tests are performed,
use the
.Fl print-diagnostics
.Li ( Ns Fl t Ns Li )
option.
.Pp
The
.Fl print-diagnostics
option is typically used with
.Fl no-load
.Li ( Ns Fl n Ns Li )
after a load failure to pinpoint a problem.
It can be used with any other set of options, however.
.Pp
If you want to validate a kext in isolation,
as in a build environment where dependencies may not be available,
you can use the
.Fl no-system-extensions
.Li ( Ns Fl e Ns Li )
and
.Fl no-resolve-dependencies
.Li ( Ns Fl Z Ns Li )
options to omit the
.Pa /System/Library/Extensions/
and
.Pa /Library/Extensions/
repositories
and to suppress dependency resolution, respectively:
.Bd -literal -offset indent
kextutil -entZ PacketSniffer.kext
.Ed
.Pp
Only validation and authentication checks are performed.
.Ss Generating Debug Symbols When Loading
To generate a symbol file for use with gdb when loading a kext,
use the
.Fl symbols
.Li ( Ns Fl s Ns Li )
option to specify a directory where symbol files will be written
for the kext being loaded and all its dependencies.
.Bd -literal -offset indent
kextutil -s ~/ksyms PacketSniffer.kext
.Ed
.Pp
.Ss 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
.Fl symbols
.Li ( Ns Fl s Ns Li )
option along with the
.Fl no-load
.Li ( Ns Fl n Ns Li )
option.
Since in this case addresses must be known for the kext and
all its dependencies, though, you must specify them.
If you don't indicate them on the command line,
.Nm
asks for the load address of each kext needed.
To get these addresses you can use
.Xr kextstat 8
on the machine you're generating symbols for,
the
.Xr showallkmods
.Xr gdb 1
macro defined by the
.Pa kgmacros
file in the Kernel Development Kit,
or consult a panic backtrace.
.Bd -literal -offset indent
kextutil -n -s ~/ksyms GrobbleEthernet.kext
enter the hexadecimal load addresses for these modules:
com.apple.iokit.IONetworkingFamily: 0x1001000
\&.\|.\|.
.Ed
.Pp
Alternatively, if you know the CFBundleIdentifiers
of all the kexts, you can use the
.Fl address
.Li ( Ns Fl a Ns Li )
option for each kext (you needn't specify
.Fl no-load
when using the
.Fl address
option):
.Bd -literal -offset indent
kextutil -s ~/ksyms \\
    -a com.apple.iokit.IONetworkingFamily@0x1001000 \\
    -a com.apple.iokit.IOPCIFamily@0x1004000 \\
    -a com.mycompany.driver.GrobbleEthernet@0x1007000 \\
    GrobbleEthernet.kext
.Ed
.Pp
Simplest of all, however, provided you can run
.Nm
on the same machine as the loaded kext,
is to use the
.Fl use-load-addresses
.Li ( Ns Fl A Ns Li )
option, which checks with the kernel for all loaded
kexts and automatically gets their load addresses.
.Bd -literal -offset indent
kextutil -s ~/ksyms -A GrobbleEthernet.kext
.Ed
.Pp
.Ss Explicitly Specifying Dependencies
Because
.Nm
resolves dependencies automatically,
it's possible that a kext other than the one you
intend might get used as a dependency
(as when there are multiple copies of the same version,
or if you're working with a different version of a kext
that's already in
.Pa /System/Library/Extensions/ Ns ).
By default, when loading a kext into the kernel,
.Nm
checks which versions of possible dependencies are already
loaded in order to assure a successful load.
When not loading and not using
.Fl use-load-addresses ,
however, it always chooses the highest
versions of any dependencies,
and in the case of a tie it chooses from kexts
specified on the command line using the
.Fl dependency
or
.Fl repository
options,
or as command line arguments (in decreasing order of priority).
.Pp
For precise control over the set of extensions
used to resolve dependencies,
use the
.Fl no-system-extensions
.Li ( Ns Fl e Ns Li )
option along with the
.Fl dependency
.Li ( Ns Fl d Ns Li ),
and
.Fl repository
.Li ( Ns Fl r Ns Li )
options.
The
.Fl no-system-extensions
option excludes the standard
.Pa /System/Library/Extensions/
and 
.Pa /Library/Extensions/
directories,
leaving the set of candidate extensions for dependency resolution
entirely up to you.
To specify candidate dependencies you use either
.Fl dependency
.Li ( Ns Fl d Ns Li ),
which names a single kext as a candidate, or
.Fl repository
.Li ( Ns Fl r Ns Li ),
which adds an entire directory of extensions.
.Bd -literal -offset indent
kextutil -n -s ~/ksyms -e \\
    -d /System/Library/Extensions/System.kext \\
    -r ~/TestKexts -d JoystickSupport.kext JoystickDriver.kext
.Ed
.Pp
Note also that if you use
.Fl no-system-extensions
.Li ( Ns Fl e Ns Li ),
you must supply at least some version of
.Pa System.kext
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
.Nm
on; you can use the
.Fl kernel
.Li ( Ns Fl k Ns Li )
option to specify a different kernel file.
You may also need to explicitly specify other library or family kexts.
.Ss Debug Loading an I/O Kit Driver
Pure I/O Kit driver kexts have empty module-start routines,
but trigger matching and driver instance creation on load.
If you need to debug an I/O Kit driver's early startup code,
you can load the driver on the target machine without starting matching
by using the
.Fl load-only
.Li ( Ns Fl l Ns Li )
option:
.Bd -literal -offset indent
kextutil -l DiskController.kext
.Ed
.Pp
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
.Nm
again on the target machine with the
.Fl match-only
.Li ( Ns Fl m Ns Li )
option:
.Bd -literal -offset indent
kextutil -m DiskController.kext
.Ed
.Pp
You may wish to use the
.Fl personality
.Li ( Ns Fl p Ns Li )
option as well in order to send selected personalities to the kernel.
Alternatively, you can use the
.Fl interactive
.Li ( Ns Fl i Ns Li )
option for the whole process, which causes
.Nm
to pause just before loading any personalities and then
to ask you for each personality whether that one should be sent to the kernel:
.Bd -literal -offset indent
kextutil -i DiskController.kext
DiskController.kext appears to be loadable (not including linkage
for on-disk libraries).
Load DiskController.kext and its dependencies into the kernel [Y/n]? y
Loading DiskController.kext.
DiskController.kext successfully loaded (or already loaded).

DiskController.kext and its dependencies are now loaded,
but not started (unless they were already running).
You may now set breakpoints in the debugger before starting them.

start DiskController.kext [Y/n]? y
DiskController.kext started.
send personalities for DiskController.kext [Y/n]? y
send personality Test Match Personality [Y/n]? y
.Ed
.Pp
.Ss Debug Loading a Kext with a Module-Start Routine
In order to debug a kext's module-start routine, you must
use the
.Fl interactive
.Li ( Ns Fl i Ns Li )
or
.Fl interactive-all
.Li ( Ns Fl I Ns Li )
option, which pause after loading and before calling the module-start function,
so that you can set up your debugging session as needed before proceeding.
.Sh FILES
.Bl -tag -width "/System/Library/Extensions/" -compact
.It Pa /System/Library/Extensions/
The standard system repository of kernel extensions.
.It Pa /Library/Extensions/
The standard repository of non Apple kernel extensions.
.It Pa /System/Library/Caches/com.apple.kext.caches/*
Contains all kext caches for a Mac OS X 10.6 (Snow Leopard) system: prelinked kernel,
mkext, and system kext info caches.
.It Pa /System/Library/Kernels/kernel
The default kernel file.
.El
.Sh DIAGNOSTICS
.Nm
exits with a zero status upon success.
Upon failure, it prints an error message
and continues processing remaining kexts if possible,
then exits with a nonzero status.
.Pp
For a kext to be loadable, it must be valid, authentic,
have all dependencies met
(that is, all dependencies must be found and loadable).
A valid kext has a well formed bundle, info dictionary, and executable.
An authentic kext's component files are owned by root:wheel,
with permissions nonwritable by group and other.
If your kext fails to load, try using the
.Fl print-diagnostics
.Li ( Ns Fl t Ns Li )
option to print diagnostics related to validation and authentication.
.Sh BUGS
Many single-letter options are inconsistent in meaning
with (or directly contradictory to) the same letter options
in other kext tools.
.Sh SEE ALSO 
.Xr kextcache 8 ,
.Xr kextd 8 ,
.Xr kextload 8 ,
.Xr kextstat 8 ,
.Xr kextunload 8 ,
.Xr kext_logging 8