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# SPDX-License-Identifier: GPL-2.0-only
menu "Kernel hacking"
menu "printk and dmesg options"
config PRINTK_TIME
bool "Show timing information on printks"
depends on PRINTK
help
Selecting this option causes time stamps of the printk()
messages to be added to the output of the syslog() system
call and at the console.
The timestamp is always recorded internally, and exported
to /dev/kmsg. This flag just specifies if the timestamp should
be included, not that the timestamp is recorded.
The behavior is also controlled by the kernel command line
parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
config PRINTK_CALLER
bool "Show caller information on printks"
depends on PRINTK
help
Selecting this option causes printk() to add a caller "thread id" (if
in task context) or a caller "processor id" (if not in task context)
to every message.
This option is intended for environments where multiple threads
concurrently call printk() for many times, for it is difficult to
interpret without knowing where these lines (or sometimes individual
line which was divided into multiple lines due to race) came from.
Since toggling after boot makes the code racy, currently there is
no option to enable/disable at the kernel command line parameter or
sysfs interface.
config STACKTRACE_BUILD_ID
bool "Show build ID information in stacktraces"
depends on PRINTK
help
Selecting this option adds build ID information for symbols in
stacktraces printed with the printk format '%p[SR]b'.
This option is intended for distros where debuginfo is not easily
accessible but can be downloaded given the build ID of the vmlinux or
kernel module where the function is located.
config CONSOLE_LOGLEVEL_DEFAULT
int "Default console loglevel (1-15)"
range 1 15
default "7"
help
Default loglevel to determine what will be printed on the console.
Setting a default here is equivalent to passing in loglevel=<x> in
the kernel bootargs. loglevel=<x> continues to override whatever
value is specified here as well.
Note: This does not affect the log level of un-prefixed printk()
usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
option.
config CONSOLE_LOGLEVEL_QUIET
int "quiet console loglevel (1-15)"
range 1 15
default "4"
help
loglevel to use when "quiet" is passed on the kernel commandline.
When "quiet" is passed on the kernel commandline this loglevel
will be used as the loglevel. IOW passing "quiet" will be the
equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
config MESSAGE_LOGLEVEL_DEFAULT
int "Default message log level (1-7)"
range 1 7
default "4"
help
Default log level for printk statements with no specified priority.
This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
that are auditing their logs closely may want to set it to a lower
priority.
Note: This does not affect what message level gets printed on the console
by default. To change that, use loglevel=<x> in the kernel bootargs,
or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
config BOOT_PRINTK_DELAY
bool "Delay each boot printk message by N milliseconds"
depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
help
This build option allows you to read kernel boot messages
by inserting a short delay after each one. The delay is
specified in milliseconds on the kernel command line,
using "boot_delay=N".
It is likely that you would also need to use "lpj=M" to preset
the "loops per jiffie" value.
See a previous boot log for the "lpj" value to use for your
system, and then set "lpj=M" before setting "boot_delay=N".
NOTE: Using this option may adversely affect SMP systems.
I.e., processors other than the first one may not boot up.
BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
what it believes to be lockup conditions.
config DYNAMIC_DEBUG
bool "Enable dynamic printk() support"
default n
depends on PRINTK
depends on (DEBUG_FS || PROC_FS)
select DYNAMIC_DEBUG_CORE
help
Compiles debug level messages into the kernel, which would not
otherwise be available at runtime. These messages can then be
enabled/disabled based on various levels of scope - per source file,
function, module, format string, and line number. This mechanism
implicitly compiles in all pr_debug() and dev_dbg() calls, which
enlarges the kernel text size by about 2%.
If a source file is compiled with DEBUG flag set, any
pr_debug() calls in it are enabled by default, but can be
disabled at runtime as below. Note that DEBUG flag is
turned on by many CONFIG_*DEBUG* options.
Usage:
Dynamic debugging is controlled via the 'dynamic_debug/control' file,
which is contained in the 'debugfs' filesystem or procfs.
Thus, the debugfs or procfs filesystem must first be mounted before
making use of this feature.
We refer the control file as: <debugfs>/dynamic_debug/control. This
file contains a list of the debug statements that can be enabled. The
format for each line of the file is:
filename:lineno [module]function flags format
filename : source file of the debug statement
lineno : line number of the debug statement
module : module that contains the debug statement
function : function that contains the debug statement
flags : '=p' means the line is turned 'on' for printing
format : the format used for the debug statement
From a live system:
nullarbor:~ # cat <debugfs>/dynamic_debug/control
# filename:lineno [module]function flags format
fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
Example usage:
// enable the message at line 1603 of file svcsock.c
nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
<debugfs>/dynamic_debug/control
// enable all the messages in file svcsock.c
nullarbor:~ # echo -n 'file svcsock.c +p' >
<debugfs>/dynamic_debug/control
// enable all the messages in the NFS server module
nullarbor:~ # echo -n 'module nfsd +p' >
<debugfs>/dynamic_debug/control
// enable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process +p' >
<debugfs>/dynamic_debug/control
// disable all 12 messages in the function svc_process()
nullarbor:~ # echo -n 'func svc_process -p' >
<debugfs>/dynamic_debug/control
See Documentation/admin-guide/dynamic-debug-howto.rst for additional
information.
config DYNAMIC_DEBUG_CORE
bool "Enable core function of dynamic debug support"
depends on PRINTK
depends on (DEBUG_FS || PROC_FS)
help
Enable core functional support of dynamic debug. It is useful
when you want to tie dynamic debug to your kernel modules with
DYNAMIC_DEBUG_MODULE defined for each of them, especially for
the case of embedded system where the kernel image size is
sensitive for people.
config SYMBOLIC_ERRNAME
bool "Support symbolic error names in printf"
default y if PRINTK
help
If you say Y here, the kernel's printf implementation will
be able to print symbolic error names such as ENOSPC instead
of the number 28. It makes the kernel image slightly larger
(about 3KB), but can make the kernel logs easier to read.
config DEBUG_BUGVERBOSE
bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
default y
help
Say Y here to make BUG() panics output the file name and line number
of the BUG call as well as the EIP and oops trace. This aids
debugging but costs about 70-100K of memory.
endmenu # "printk and dmesg options"
config DEBUG_KERNEL
bool "Kernel debugging"
help
Say Y here if you are developing drivers or trying to debug and
identify kernel problems.
config DEBUG_MISC
bool "Miscellaneous debug code"
default DEBUG_KERNEL
depends on DEBUG_KERNEL
help
Say Y here if you need to enable miscellaneous debug code that should
be under a more specific debug option but isn't.
menu "Compile-time checks and compiler options"
config DEBUG_INFO
bool
help
A kernel debug info option other than "None" has been selected
in the "Debug information" choice below, indicating that debug
information will be generated for build targets.
# Clang generates .uleb128 with label differences for DWARF v5, a feature that
# older binutils ports do not support when utilizing RISC-V style linker
# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
config AS_HAS_NON_CONST_ULEB128
def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
choice
prompt "Debug information"
depends on DEBUG_KERNEL
help
Selecting something other than "None" results in a kernel image
that will include debugging info resulting in a larger kernel image.
This adds debug symbols to the kernel and modules (gcc -g), and
is needed if you intend to use kernel crashdump or binary object
tools like crash, kgdb, LKCD, gdb, etc on the kernel.
Choose which version of DWARF debug info to emit. If unsure,
select "Toolchain default".
config DEBUG_INFO_NONE
bool "Disable debug information"
help
Do not build the kernel with debugging information, which will
result in a faster and smaller build.
config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
bool "Rely on the toolchain's implicit default DWARF version"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
help
The implicit default version of DWARF debug info produced by a
toolchain changes over time.
This can break consumers of the debug info that haven't upgraded to
support newer revisions, and prevent testing newer versions, but
those should be less common scenarios.
config DEBUG_INFO_DWARF4
bool "Generate DWARF Version 4 debuginfo"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
help
Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
if using clang without clang's integrated assembler, and gdb 7.0+.
If you have consumers of DWARF debug info that are not ready for
newer revisions of DWARF, you may wish to choose this or have your
config select this.
config DEBUG_INFO_DWARF5
bool "Generate DWARF Version 5 debuginfo"
select DEBUG_INFO
depends on !ARCH_HAS_BROKEN_DWARF5
depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
help
Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
5.0+ accepts the -gdwarf-5 flag but only had partial support for some
draft features until 7.0), and gdb 8.0+.
Changes to the structure of debug info in Version 5 allow for around
15-18% savings in resulting image and debug info section sizes as
compared to DWARF Version 4. DWARF Version 5 standardizes previous
extensions such as accelerators for symbol indexing and the format
for fission (.dwo/.dwp) files. Users may not want to select this
config if they rely on tooling that has not yet been updated to
support DWARF Version 5.
endchoice # "Debug information"
if DEBUG_INFO
config DEBUG_INFO_REDUCED
bool "Reduce debugging information"
help
If you say Y here gcc is instructed to generate less debugging
information for structure types. This means that tools that
need full debugging information (like kgdb or systemtap) won't
be happy. But if you merely need debugging information to
resolve line numbers there is no loss. Advantage is that
build directory object sizes shrink dramatically over a full
DEBUG_INFO build and compile times are reduced too.
Only works with newer gcc versions.
choice
prompt "Compressed Debug information"
help
Compress the resulting debug info. Results in smaller debug info sections,
but requires that consumers are able to decompress the results.
If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
config DEBUG_INFO_COMPRESSED_NONE
bool "Don't compress debug information"
help
Don't compress debug info sections.
config DEBUG_INFO_COMPRESSED_ZLIB
bool "Compress debugging information with zlib"
depends on $(cc-option,-gz=zlib)
depends on $(ld-option,--compress-debug-sections=zlib)
help
Compress the debug information using zlib. Requires GCC 5.0+ or Clang
5.0+, binutils 2.26+, and zlib.
Users of dpkg-deb via scripts/package/builddeb may find an increase in
size of their debug .deb packages with this config set, due to the
debug info being compressed with zlib, then the object files being
recompressed with a different compression scheme. But this is still
preferable to setting $KDEB_COMPRESS to "none" which would be even
larger.
config DEBUG_INFO_COMPRESSED_ZSTD
bool "Compress debugging information with zstd"
depends on $(cc-option,-gz=zstd)
depends on $(ld-option,--compress-debug-sections=zstd)
help
Compress the debug information using zstd. This may provide better
compression than zlib, for about the same time costs, but requires newer
toolchain support. Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
zstd.
endchoice # "Compressed Debug information"
config DEBUG_INFO_SPLIT
bool "Produce split debuginfo in .dwo files"
depends on $(cc-option,-gsplit-dwarf)
# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
# prior to 12.x:
# https://github.com/llvm/llvm-project/issues/56642
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
depends on !RISCV || GCC_VERSION >= 120000
help
Generate debug info into separate .dwo files. This significantly
reduces the build directory size for builds with DEBUG_INFO,
because it stores the information only once on disk in .dwo
files instead of multiple times in object files and executables.
In addition the debug information is also compressed.
Requires recent gcc (4.7+) and recent gdb/binutils.
Any tool that packages or reads debug information would need
to know about the .dwo files and include them.
Incompatible with older versions of ccache.
config DEBUG_INFO_BTF
bool "Generate BTF typeinfo"
depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
depends on BPF_SYSCALL
depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
# pahole uses elfutils, which does not have support for Hexagon relocations
depends on !HEXAGON
help
Generate deduplicated BTF type information from DWARF debug info.
Turning this on expects presence of pahole tool, which will convert
DWARF type info into equivalent deduplicated BTF type info.
config PAHOLE_HAS_SPLIT_BTF
def_bool PAHOLE_VERSION >= 119
config PAHOLE_HAS_BTF_TAG
def_bool PAHOLE_VERSION >= 123
depends on CC_IS_CLANG
help
Decide whether pahole emits btf_tag attributes (btf_type_tag and
btf_decl_tag) or not. Currently only clang compiler implements
these attributes, so make the config depend on CC_IS_CLANG.
config PAHOLE_HAS_LANG_EXCLUDE
def_bool PAHOLE_VERSION >= 124
help
Support for the --lang_exclude flag which makes pahole exclude
compilation units from the supplied language. Used in Kbuild to
omit Rust CUs which are not supported in version 1.24 of pahole,
otherwise it would emit malformed kernel and module binaries when
using DEBUG_INFO_BTF_MODULES.
config DEBUG_INFO_BTF_MODULES
def_bool y
depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
help
Generate compact split BTF type information for kernel modules.
config MODULE_ALLOW_BTF_MISMATCH
bool "Allow loading modules with non-matching BTF type info"
depends on DEBUG_INFO_BTF_MODULES
help
For modules whose split BTF does not match vmlinux, load without
BTF rather than refusing to load. The default behavior with
module BTF enabled is to reject modules with such mismatches;
this option will still load module BTF where possible but ignore
it when a mismatch is found.
config GDB_SCRIPTS
bool "Provide GDB scripts for kernel debugging"
help
This creates the required links to GDB helper scripts in the
build directory. If you load vmlinux into gdb, the helper
scripts will be automatically imported by gdb as well, and
additional functions are available to analyze a Linux kernel
instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
for further details.
endif # DEBUG_INFO
config FRAME_WARN
int "Warn for stack frames larger than"
range 0 8192
default 0 if KMSAN
default 2048 if GCC_PLUGIN_LATENT_ENTROPY
default 2048 if PARISC
default 1536 if (!64BIT && XTENSA)
default 1280 if KASAN && !64BIT
default 1024 if !64BIT
default 2048 if 64BIT
help
Tell the compiler to warn at build time for stack frames larger than this.
Setting this too low will cause a lot of warnings.
Setting it to 0 disables the warning.
config STRIP_ASM_SYMS
bool "Strip assembler-generated symbols during link"
default n
help
Strip internal assembler-generated symbols during a link (symbols
that look like '.Lxxx') so they don't pollute the output of
get_wchan() and suchlike.
config READABLE_ASM
bool "Generate readable assembler code"
depends on DEBUG_KERNEL
depends on CC_IS_GCC
help
Disable some compiler optimizations that tend to generate human unreadable
assembler output. This may make the kernel slightly slower, but it helps
to keep kernel developers who have to stare a lot at assembler listings
sane.
config HEADERS_INSTALL
bool "Install uapi headers to usr/include"
depends on !UML
help
This option will install uapi headers (headers exported to user-space)
into the usr/include directory for use during the kernel build.
This is unneeded for building the kernel itself, but needed for some
user-space program samples. It is also needed by some features such
as uapi header sanity checks.
config DEBUG_SECTION_MISMATCH
bool "Enable full Section mismatch analysis"
depends on CC_IS_GCC
help
The section mismatch analysis checks if there are illegal
references from one section to another section.
During linktime or runtime, some sections are dropped;
any use of code/data previously in these sections would
most likely result in an oops.
In the code, functions and variables are annotated with
__init,, etc. (see the full list in include/linux/init.h),
which results in the code/data being placed in specific sections.
The section mismatch analysis is always performed after a full
kernel build, and enabling this option causes the following
additional step to occur:
- Add the option -fno-inline-functions-called-once to gcc commands.
When inlining a function annotated with __init in a non-init
function, we would lose the section information and thus
the analysis would not catch the illegal reference.
This option tells gcc to inline less (but it does result in
a larger kernel).
config SECTION_MISMATCH_WARN_ONLY
bool "Make section mismatch errors non-fatal"
default y
help
If you say N here, the build process will fail if there are any
section mismatch, instead of just throwing warnings.
If unsure, say Y.
config DEBUG_FORCE_FUNCTION_ALIGN_64B
bool "Force all function address 64B aligned"
depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
select FUNCTION_ALIGNMENT_64B
help
There are cases that a commit from one domain changes the function
address alignment of other domains, and cause magic performance
bump (regression or improvement). Enable this option will help to
verify if the bump is caused by function alignment changes, while
it will slightly increase the kernel size and affect icache usage.
It is mainly for debug and performance tuning use.
#
# Select this config option from the architecture Kconfig, if it
# is preferred to always offer frame pointers as a config
# option on the architecture (regardless of KERNEL_DEBUG):
#
config ARCH_WANT_FRAME_POINTERS
bool
config FRAME_POINTER
bool "Compile the kernel with frame pointers"
depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
help
If you say Y here the resulting kernel image will be slightly
larger and slower, but it gives very useful debugging information
in case of kernel bugs. (precise oopses/stacktraces/warnings)
config OBJTOOL
bool
config STACK_VALIDATION
bool "Compile-time stack metadata validation"
depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
select OBJTOOL
default n
help
Validate frame pointer rules at compile-time. This helps ensure that
runtime stack traces are more reliable.
For more information, see
tools/objtool/Documentation/objtool.txt.
config NOINSTR_VALIDATION
bool
depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
select OBJTOOL
default y
config VMLINUX_MAP
bool "Generate vmlinux.map file when linking"
depends on EXPERT
help
Selecting this option will pass "-Map=vmlinux.map" to ld
when linking vmlinux. That file can be useful for verifying
and debugging magic section games, and for seeing which
pieces of code get eliminated with
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
config DEBUG_FORCE_WEAK_PER_CPU
bool "Force weak per-cpu definitions"
depends on DEBUG_KERNEL
help
s390 and alpha require percpu variables in modules to be
defined weak to work around addressing range issue which
puts the following two restrictions on percpu variable
definitions.
1. percpu symbols must be unique whether static or not
2. percpu variables can't be defined inside a function
To ensure that generic code follows the above rules, this
option forces all percpu variables to be defined as weak.
endmenu # "Compiler options"
menu "Generic Kernel Debugging Instruments"
config MAGIC_SYSRQ
bool "Magic SysRq key"
depends on !UML
help
If you say Y here, you will have some control over the system even
if the system crashes for example during kernel debugging (e.g., you
will be able to flush the buffer cache to disk, reboot the system
immediately or dump some status information). This is accomplished
by pressing various keys while holding SysRq (Alt+PrintScreen). It
also works on a serial console (on PC hardware at least), if you
send a BREAK and then within 5 seconds a command keypress. The
keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
Don't say Y unless you really know what this hack does.
config MAGIC_SYSRQ_DEFAULT_ENABLE
hex "Enable magic SysRq key functions by default"
depends on MAGIC_SYSRQ
default 0x1
help
Specifies which SysRq key functions are enabled by default.
This may be set to 1 or 0 to enable or disable them all, or
to a bitmask as described in Documentation/admin-guide/sysrq.rst.
config MAGIC_SYSRQ_SERIAL
bool "Enable magic SysRq key over serial"
depends on MAGIC_SYSRQ
default y
help
Many embedded boards have a disconnected TTL level serial which can
generate some garbage that can lead to spurious false sysrq detects.
This option allows you to decide whether you want to enable the
magic SysRq key.
config MAGIC_SYSRQ_SERIAL_SEQUENCE
string "Char sequence that enables magic SysRq over serial"
depends on MAGIC_SYSRQ_SERIAL
default ""
help
Specifies a sequence of characters that can follow BREAK to enable
SysRq on a serial console.
If unsure, leave an empty string and the option will not be enabled.
config DEBUG_FS
bool "Debug Filesystem"
help
debugfs is a virtual file system that kernel developers use to put
debugging files into. Enable this option to be able to read and
write to these files.
For detailed documentation on the debugfs API, see
Documentation/filesystems/.
If unsure, say N.
choice
prompt "Debugfs default access"
depends on DEBUG_FS
default DEBUG_FS_ALLOW_ALL
help
This selects the default access restrictions for debugfs.
It can be overridden with kernel command line option
debugfs=[on,no-mount,off]. The restrictions apply for API access
and filesystem registration.
config DEBUG_FS_ALLOW_ALL
bool "Access normal"
help
No restrictions apply. Both API and filesystem registration
is on. This is the normal default operation.
config DEBUG_FS_DISALLOW_MOUNT
bool "Do not register debugfs as filesystem"
help
The API is open but filesystem is not loaded. Clients can still do
their work and read with debug tools that do not need
debugfs filesystem.
config DEBUG_FS_ALLOW_NONE
bool "No access"
help
Access is off. Clients get -PERM when trying to create nodes in
debugfs tree and debugfs is not registered as a filesystem.
Client can then back-off or continue without debugfs access.
endchoice
source "lib/Kconfig.kgdb"
source "lib/Kconfig.ubsan"
source "lib/Kconfig.kcsan"
endmenu
menu "Networking Debugging"
source "net/Kconfig.debug"
endmenu # "Networking Debugging"
menu "Memory Debugging"
source "mm/Kconfig.debug"
config DEBUG_OBJECTS
bool "Debug object operations"
depends on DEBUG_KERNEL
help
If you say Y here, additional code will be inserted into the
kernel to track the life time of various objects and validate
the operations on those objects.
config DEBUG_OBJECTS_SELFTEST
bool "Debug objects selftest"
depends on DEBUG_OBJECTS
help
This enables the selftest of the object debug code.
config DEBUG_OBJECTS_FREE
bool "Debug objects in freed memory"
depends on DEBUG_OBJECTS
help
This enables checks whether a k/v free operation frees an area
which contains an object which has not been deactivated
properly. This can make kmalloc/kfree-intensive workloads
much slower.
config DEBUG_OBJECTS_TIMERS
bool "Debug timer objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
timer routines to track the life time of timer objects and
validate the timer operations.
config DEBUG_OBJECTS_WORK
bool "Debug work objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
work queue routines to track the life time of work objects and
validate the work operations.
config DEBUG_OBJECTS_RCU_HEAD
bool "Debug RCU callbacks objects"
depends on DEBUG_OBJECTS
help
Enable this to turn on debugging of RCU list heads (call_rcu() usage).
config DEBUG_OBJECTS_PERCPU_COUNTER
bool "Debug percpu counter objects"
depends on DEBUG_OBJECTS
help
If you say Y here, additional code will be inserted into the
percpu counter routines to track the life time of percpu counter
objects and validate the percpu counter operations.
config DEBUG_OBJECTS_ENABLE_DEFAULT
int "debug_objects bootup default value (0-1)"
range 0 1
default "1"
depends on DEBUG_OBJECTS
help
Debug objects boot parameter default value
config SHRINKER_DEBUG
bool "Enable shrinker debugging support"
depends on DEBUG_FS
help
Say Y to enable the shrinker debugfs interface which provides
visibility into the kernel memory shrinkers subsystem.
Disable it to avoid an extra memory footprint.
config DEBUG_STACK_USAGE
bool "Stack utilization instrumentation"
depends on DEBUG_KERNEL
help
Enables the display of the minimum amount of free stack which each
task has ever had available in the sysrq-T and sysrq-P debug output.
Also emits a message to dmesg when a process exits if that process
used more stack space than previously exiting processes.
This option will slow down process creation somewhat.
config SCHED_STACK_END_CHECK
bool "Detect stack corruption on calls to schedule()"
depends on DEBUG_KERNEL
default n
help
This option checks for a stack overrun on calls to schedule().
If the stack end location is found to be over written always panic as
the content of the corrupted region can no longer be trusted.
This is to ensure no erroneous behaviour occurs which could result in
data corruption or a sporadic crash at a later stage once the region
is examined. The runtime overhead introduced is minimal.
config ARCH_HAS_DEBUG_VM_PGTABLE
bool
help
An architecture should select this when it can successfully
build and run DEBUG_VM_PGTABLE.
config DEBUG_VM_IRQSOFF
def_bool DEBUG_VM && !PREEMPT_RT
config DEBUG_VM
bool "Debug VM"
depends on DEBUG_KERNEL
help
Enable this to turn on extended checks in the virtual-memory system
that may impact performance.
If unsure, say N.
config DEBUG_VM_SHOOT_LAZIES
bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
depends on DEBUG_VM
depends on MMU_LAZY_TLB_SHOOTDOWN
help
Enable additional IPIs that ensure lazy tlb mm references are removed
before the mm is freed.
If unsure, say N.
config DEBUG_VM_MAPLE_TREE
bool "Debug VM maple trees"
depends on DEBUG_VM
select DEBUG_MAPLE_TREE
help
Enable VM maple tree debugging information and extra validations.
If unsure, say N.
config DEBUG_VM_RB
bool "Debug VM red-black trees"
depends on DEBUG_VM
help
Enable VM red-black tree debugging information and extra validations.
If unsure, say N.
config DEBUG_VM_PGFLAGS
bool "Debug page-flags operations"
depends on DEBUG_VM
help
Enables extra validation on page flags operations.
If unsure, say N.
config DEBUG_VM_PGTABLE
bool "Debug arch page table for semantics compliance"
depends on MMU
depends on ARCH_HAS_DEBUG_VM_PGTABLE
default y if DEBUG_VM
help
This option provides a debug method which can be used to test
architecture page table helper functions on various platforms in
verifying if they comply with expected generic MM semantics. This
will help architecture code in making sure that any changes or
new additions of these helpers still conform to expected
semantics of the generic MM. Platforms will have to opt in for
this through ARCH_HAS_DEBUG_VM_PGTABLE.
If unsure, say N.
config ARCH_HAS_DEBUG_VIRTUAL
bool
config DEBUG_VIRTUAL
bool "Debug VM translations"
depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
help
Enable some costly sanity checks in virtual to page code. This can
catch mistakes with virt_to_page() and friends.
If unsure, say N.
config DEBUG_NOMMU_REGIONS
bool "Debug the global anon/private NOMMU mapping region tree"
depends on DEBUG_KERNEL && !MMU
help
This option causes the global tree of anonymous and private mapping
regions to be regularly checked for invalid topology.
config DEBUG_MEMORY_INIT
bool "Debug memory initialisation" if EXPERT
default !EXPERT
help
Enable this for additional checks during memory initialisation.
The sanity checks verify aspects of the VM such as the memory model
and other information provided by the architecture. Verbose
information will be printed at KERN_DEBUG loglevel depending
on the mminit_loglevel= command-line option.
If unsure, say Y
config MEMORY_NOTIFIER_ERROR_INJECT
tristate "Memory hotplug notifier error injection module"
depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
memory hotplug notifier chain callbacks. It is controlled through
debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject memory hotplug offline error (-12 == -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/memory
# echo -12 > actions/MEM_GOING_OFFLINE/error
# echo offline > /sys/devices/system/memory/memoryXXX/state
bash: echo: write error: Cannot allocate memory
To compile this code as a module, choose M here: the module will
be called memory-notifier-error-inject.
If unsure, say N.
config DEBUG_PER_CPU_MAPS
bool "Debug access to per_cpu maps"
depends on DEBUG_KERNEL
depends on SMP
help
Say Y to verify that the per_cpu map being accessed has
been set up. This adds a fair amount of code to kernel memory
and decreases performance.
Say N if unsure.
config DEBUG_KMAP_LOCAL
bool "Debug kmap_local temporary mappings"
depends on DEBUG_KERNEL && KMAP_LOCAL
help
This option enables additional error checking for the kmap_local
infrastructure. Disable for production use.
config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
bool
config DEBUG_KMAP_LOCAL_FORCE_MAP
bool "Enforce kmap_local temporary mappings"
depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
select KMAP_LOCAL
select DEBUG_KMAP_LOCAL
help
This option enforces temporary mappings through the kmap_local
mechanism for non-highmem pages and on non-highmem systems.
Disable this for production systems!
config DEBUG_HIGHMEM
bool "Highmem debugging"
depends on DEBUG_KERNEL && HIGHMEM
select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
select DEBUG_KMAP_LOCAL
help
This option enables additional error checking for high memory
systems. Disable for production systems.
config HAVE_DEBUG_STACKOVERFLOW
bool
config DEBUG_STACKOVERFLOW
bool "Check for stack overflows"
depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
help
Say Y here if you want to check for overflows of kernel, IRQ
and exception stacks (if your architecture uses them). This
option will show detailed messages if free stack space drops
below a certain limit.
These kinds of bugs usually occur when call-chains in the
kernel get too deep, especially when interrupts are
involved.
Use this in cases where you see apparently random memory
corruption, especially if it appears in 'struct thread_info'
If in doubt, say "N".
source "lib/Kconfig.kasan"
source "lib/Kconfig.kfence"
source "lib/Kconfig.kmsan"
endmenu # "Memory Debugging"
config DEBUG_SHIRQ
bool "Debug shared IRQ handlers"
depends on DEBUG_KERNEL
help
Enable this to generate a spurious interrupt just before a shared
interrupt handler is deregistered (generating one when registering
is currently disabled). Drivers need to handle this correctly. Some
don't and need to be caught.
menu "Debug Oops, Lockups and Hangs"
config PANIC_ON_OOPS
bool "Panic on Oops"
help
Say Y here to enable the kernel to panic when it oopses. This
has the same effect as setting oops=panic on the kernel command
line.
This feature is useful to ensure that the kernel does not do
anything erroneous after an oops which could result in data
corruption or other issues.
Say N if unsure.
config PANIC_ON_OOPS_VALUE
int
range 0 1
default 0 if !PANIC_ON_OOPS
default 1 if PANIC_ON_OOPS
config PANIC_TIMEOUT
int "panic timeout"
default 0
help
Set the timeout value (in seconds) until a reboot occurs when
the kernel panics. If n = 0, then we wait forever. A timeout
value n > 0 will wait n seconds before rebooting, while a timeout
value n < 0 will reboot immediately.
config LOCKUP_DETECTOR
bool
config SOFTLOCKUP_DETECTOR
bool "Detect Soft Lockups"
depends on DEBUG_KERNEL && !S390
select LOCKUP_DETECTOR
help
Say Y here to enable the kernel to act as a watchdog to detect
soft lockups.
Softlockups are bugs that cause the kernel to loop in kernel
mode for more than 20 seconds, without giving other tasks a
chance to run. The current stack trace is displayed upon
detection and the system will stay locked up.
config BOOTPARAM_SOFTLOCKUP_PANIC
bool "Panic (Reboot) On Soft Lockups"
depends on SOFTLOCKUP_DETECTOR
help
Say Y here to enable the kernel to panic on "soft lockups",
which are bugs that cause the kernel to loop in kernel
mode for more than 20 seconds (configurable using the watchdog_thresh
sysctl), without giving other tasks a chance to run.
The panic can be used in combination with panic_timeout,
to cause the system to reboot automatically after a
lockup has been detected. This feature is useful for
high-availability systems that have uptime guarantees and
where a lockup must be resolved ASAP.
Say N if unsure.
config HAVE_HARDLOCKUP_DETECTOR_BUDDY
bool
depends on SMP
default y
#
# Global switch whether to build a hardlockup detector at all. It is available
# only when the architecture supports at least one implementation. There are
# two exceptions. The hardlockup detector is never enabled on:
#
# s390: it reported many false positives there
#
# sparc64: has a custom implementation which is not using the common
# hardlockup command line options and sysctl interface.
#
config HARDLOCKUP_DETECTOR
bool "Detect Hard Lockups"
depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
imply HARDLOCKUP_DETECTOR_PERF
imply HARDLOCKUP_DETECTOR_BUDDY
imply HARDLOCKUP_DETECTOR_ARCH
select LOCKUP_DETECTOR
help
Say Y here to enable the kernel to act as a watchdog to detect
hard lockups.
Hardlockups are bugs that cause the CPU to loop in kernel mode
for more than 10 seconds, without letting other interrupts have a
chance to run. The current stack trace is displayed upon detection
and the system will stay locked up.
#
# Note that arch-specific variants are always preferred.
#
config HARDLOCKUP_DETECTOR_PREFER_BUDDY
bool "Prefer the buddy CPU hardlockup detector"
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
help
Say Y here to prefer the buddy hardlockup detector over the perf one.
With the buddy detector, each CPU uses its softlockup hrtimer
to check that the next CPU is processing hrtimer interrupts by
verifying that a counter is increasing.
This hardlockup detector is useful on systems that don't have
an arch-specific hardlockup detector or if resources needed
for the hardlockup detector are better used for other things.
config HARDLOCKUP_DETECTOR_PERF
bool
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
config HARDLOCKUP_DETECTOR_BUDDY
bool
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
config HARDLOCKUP_DETECTOR_ARCH
bool
depends on HARDLOCKUP_DETECTOR
depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
help
The arch-specific implementation of the hardlockup detector will
be used.
#
# Both the "perf" and "buddy" hardlockup detectors count hrtimer
# interrupts. This config enables functions managing this common code.
#
config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
bool
select SOFTLOCKUP_DETECTOR
#
# Enables a timestamp based low pass filter to compensate for perf based
# hard lockup detection which runs too fast due to turbo modes.
#
config HARDLOCKUP_CHECK_TIMESTAMP
bool
config BOOTPARAM_HARDLOCKUP_PANIC
bool "Panic (Reboot) On Hard Lockups"
depends on HARDLOCKUP_DETECTOR
help
Say Y here to enable the kernel to panic on "hard lockups",
which are bugs that cause the kernel to loop in kernel
mode with interrupts disabled for more than 10 seconds (configurable
using the watchdog_thresh sysctl).
Say N if unsure.
config DETECT_HUNG_TASK
bool "Detect Hung Tasks"
depends on DEBUG_KERNEL
default SOFTLOCKUP_DETECTOR
help
Say Y here to enable the kernel to detect "hung tasks",
which are bugs that cause the task to be stuck in
uninterruptible "D" state indefinitely.
When a hung task is detected, the kernel will print the
current stack trace (which you should report), but the
task will stay in uninterruptible state. If lockdep is
enabled then all held locks will also be reported. This
feature has negligible overhead.
config DEFAULT_HUNG_TASK_TIMEOUT
int "Default timeout for hung task detection (in seconds)"
depends on DETECT_HUNG_TASK
default 120
help
This option controls the default timeout (in seconds) used
to determine when a task has become non-responsive and should
be considered hung.
It can be adjusted at runtime via the kernel.hung_task_timeout_secs
sysctl or by writing a value to
/proc/sys/kernel/hung_task_timeout_secs.
A timeout of 0 disables the check. The default is two minutes.
Keeping the default should be fine in most cases.
config BOOTPARAM_HUNG_TASK_PANIC
bool "Panic (Reboot) On Hung Tasks"
depends on DETECT_HUNG_TASK
help
Say Y here to enable the kernel to panic on "hung tasks",
which are bugs that cause the kernel to leave a task stuck
in uninterruptible "D" state.
The panic can be used in combination with panic_timeout,
to cause the system to reboot automatically after a
hung task has been detected. This feature is useful for
high-availability systems that have uptime guarantees and
where a hung tasks must be resolved ASAP.
Say N if unsure.
config WQ_WATCHDOG
bool "Detect Workqueue Stalls"
depends on DEBUG_KERNEL
help
Say Y here to enable stall detection on workqueues. If a
worker pool doesn't make forward progress on a pending work
item for over a given amount of time, 30s by default, a
warning message is printed along with dump of workqueue
state. This can be configured through kernel parameter
"workqueue.watchdog_thresh" and its sysfs counterpart.
config WQ_CPU_INTENSIVE_REPORT
bool "Report per-cpu work items which hog CPU for too long"
depends on DEBUG_KERNEL
help
Say Y here to enable reporting of concurrency-managed per-cpu work
items that hog CPUs for longer than
workqueue.cpu_intensive_thresh_us. Workqueue automatically
detects and excludes them from concurrency management to prevent
them from stalling other per-cpu work items. Occassional
triggering may not necessarily indicate a problem. Repeated
triggering likely indicates that the work item should be switched
to use an unbound workqueue.
config TEST_LOCKUP
tristate "Test module to generate lockups"
depends on m
help
This builds the "test_lockup" module that helps to make sure
that watchdogs and lockup detectors are working properly.
Depending on module parameters it could emulate soft or hard
lockup, "hung task", or locking arbitrary lock for a long time.
Also it could generate series of lockups with cooling-down periods.
If unsure, say N.
endmenu # "Debug lockups and hangs"
menu "Scheduler Debugging"
config SCHED_DEBUG
bool "Collect scheduler debugging info"
depends on DEBUG_KERNEL && DEBUG_FS
default y
help
If you say Y here, the /sys/kernel/debug/sched file will be provided
that can help debug the scheduler. The runtime overhead of this
option is minimal.
config SCHED_INFO
bool
default n
config SCHEDSTATS
bool "Collect scheduler statistics"
depends on DEBUG_KERNEL && PROC_FS
select SCHED_INFO
help
If you say Y here, additional code will be inserted into the
scheduler and related routines to collect statistics about
scheduler behavior and provide them in /proc/schedstat. These
stats may be useful for both tuning and debugging the scheduler
If you aren't debugging the scheduler or trying to tune a specific
application, you can say N to avoid the very slight overhead
this adds.
endmenu
config DEBUG_TIMEKEEPING
bool "Enable extra timekeeping sanity checking"
help
This option will enable additional timekeeping sanity checks
which may be helpful when diagnosing issues where timekeeping
problems are suspected.
This may include checks in the timekeeping hotpaths, so this
option may have a (very small) performance impact to some
workloads.
If unsure, say N.
config DEBUG_PREEMPT
bool "Debug preemptible kernel"
depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
help
If you say Y here then the kernel will use a debug variant of the
commonly used smp_processor_id() function and will print warnings
if kernel code uses it in a preemption-unsafe way. Also, the kernel
will detect preemption count underflows.
This option has potential to introduce high runtime overhead,
depending on workload as it triggers debugging routines for each
this_cpu operation. It should only be used for debugging purposes.
menu "Lock Debugging (spinlocks, mutexes, etc...)"
config LOCK_DEBUGGING_SUPPORT
bool
depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
default y
config PROVE_LOCKING
bool "Lock debugging: prove locking correctness"
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select LOCKDEP
select DEBUG_SPINLOCK
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if RT_MUTEXES
select DEBUG_RWSEMS if !PREEMPT_RT
select DEBUG_WW_MUTEX_SLOWPATH
select DEBUG_LOCK_ALLOC
select PREEMPT_COUNT if !ARCH_NO_PREEMPT
select TRACE_IRQFLAGS
default n
help
This feature enables the kernel to prove that all locking
that occurs in the kernel runtime is mathematically
correct: that under no circumstance could an arbitrary (and
not yet triggered) combination of observed locking
sequences (on an arbitrary number of CPUs, running an
arbitrary number of tasks and interrupt contexts) cause a
deadlock.
In short, this feature enables the kernel to report locking
related deadlocks before they actually occur.
The proof does not depend on how hard and complex a
deadlock scenario would be to trigger: how many
participant CPUs, tasks and irq-contexts would be needed
for it to trigger. The proof also does not depend on
timing: if a race and a resulting deadlock is possible
theoretically (no matter how unlikely the race scenario
is), it will be proven so and will immediately be
reported by the kernel (once the event is observed that
makes the deadlock theoretically possible).
If a deadlock is impossible (i.e. the locking rules, as
observed by the kernel, are mathematically correct), the
kernel reports nothing.
NOTE: this feature can also be enabled for rwlocks, mutexes
and rwsems - in which case all dependencies between these
different locking variants are observed and mapped too, and
the proof of observed correctness is also maintained for an
arbitrary combination of these separate locking variants.
For more details, see Documentation/locking/lockdep-design.rst.
config PROVE_RAW_LOCK_NESTING
bool "Enable raw_spinlock - spinlock nesting checks"
depends on PROVE_LOCKING
default n
help
Enable the raw_spinlock vs. spinlock nesting checks which ensure
that the lock nesting rules for PREEMPT_RT enabled kernels are
not violated.
NOTE: There are known nesting problems. So if you enable this
option expect lockdep splats until these problems have been fully
addressed which is work in progress. This config switch allows to
identify and analyze these problems. It will be removed and the
check permanently enabled once the main issues have been fixed.
If unsure, select N.
config LOCK_STAT
bool "Lock usage statistics"
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select LOCKDEP
select DEBUG_SPINLOCK
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if RT_MUTEXES
select DEBUG_LOCK_ALLOC
default n
help
This feature enables tracking lock contention points
For more details, see Documentation/locking/lockstat.rst
This also enables lock events required by "perf lock",
subcommand of perf.
If you want to use "perf lock", you also need to turn on
CONFIG_EVENT_TRACING.
CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
(CONFIG_LOCKDEP defines "acquire" and "release" events.)
config DEBUG_RT_MUTEXES
bool "RT Mutex debugging, deadlock detection"
depends on DEBUG_KERNEL && RT_MUTEXES
help
This allows rt mutex semantics violations and rt mutex related
deadlocks (lockups) to be detected and reported automatically.
config DEBUG_SPINLOCK
bool "Spinlock and rw-lock debugging: basic checks"
depends on DEBUG_KERNEL
select UNINLINE_SPIN_UNLOCK
help
Say Y here and build SMP to catch missing spinlock initialization
and certain other kinds of spinlock errors commonly made. This is
best used in conjunction with the NMI watchdog so that spinlock
deadlocks are also debuggable.
config DEBUG_MUTEXES
bool "Mutex debugging: basic checks"
depends on DEBUG_KERNEL && !PREEMPT_RT
help
This feature allows mutex semantics violations to be detected and
reported.
config DEBUG_WW_MUTEX_SLOWPATH
bool "Wait/wound mutex debugging: Slowpath testing"
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select DEBUG_LOCK_ALLOC
select DEBUG_SPINLOCK
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if PREEMPT_RT
help
This feature enables slowpath testing for w/w mutex users by
injecting additional -EDEADLK wound/backoff cases. Together with
the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
will test all possible w/w mutex interface abuse with the
exception of simply not acquiring all the required locks.
Note that this feature can introduce significant overhead, so
it really should not be enabled in a production or distro kernel,
even a debug kernel. If you are a driver writer, enable it. If
you are a distro, do not.
config DEBUG_RWSEMS
bool "RW Semaphore debugging: basic checks"
depends on DEBUG_KERNEL && !PREEMPT_RT
help
This debugging feature allows mismatched rw semaphore locks
and unlocks to be detected and reported.
config DEBUG_LOCK_ALLOC
bool "Lock debugging: detect incorrect freeing of live locks"
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select DEBUG_SPINLOCK
select DEBUG_MUTEXES if !PREEMPT_RT
select DEBUG_RT_MUTEXES if RT_MUTEXES
select LOCKDEP
help
This feature will check whether any held lock (spinlock, rwlock,
mutex or rwsem) is incorrectly freed by the kernel, via any of the
memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
vfree(), etc.), whether a live lock is incorrectly reinitialized via
spin_lock_init()/mutex_init()/etc., or whether there is any lock
held during task exit.
config LOCKDEP
bool
depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
select STACKTRACE
select KALLSYMS
select KALLSYMS_ALL
config LOCKDEP_SMALL
bool
config LOCKDEP_BITS
int "Bitsize for MAX_LOCKDEP_ENTRIES"
depends on LOCKDEP && !LOCKDEP_SMALL
range 10 30
default 15
help
Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
config LOCKDEP_CHAINS_BITS
int "Bitsize for MAX_LOCKDEP_CHAINS"
depends on LOCKDEP && !LOCKDEP_SMALL
range 10 30
default 16
help
Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
config LOCKDEP_STACK_TRACE_BITS
int "Bitsize for MAX_STACK_TRACE_ENTRIES"
depends on LOCKDEP && !LOCKDEP_SMALL
range 10 30
default 19
help
Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
config LOCKDEP_STACK_TRACE_HASH_BITS
int "Bitsize for STACK_TRACE_HASH_SIZE"
depends on LOCKDEP && !LOCKDEP_SMALL
range 10 30
default 14
help
Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
config LOCKDEP_CIRCULAR_QUEUE_BITS
int "Bitsize for elements in circular_queue struct"
depends on LOCKDEP
range 10 30
default 12
help
Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
config DEBUG_LOCKDEP
bool "Lock dependency engine debugging"
depends on DEBUG_KERNEL && LOCKDEP
select DEBUG_IRQFLAGS
help
If you say Y here, the lock dependency engine will do
additional runtime checks to debug itself, at the price
of more runtime overhead.
config DEBUG_ATOMIC_SLEEP
bool "Sleep inside atomic section checking"
select PREEMPT_COUNT
depends on DEBUG_KERNEL
depends on !ARCH_NO_PREEMPT
help
If you say Y here, various routines which may sleep will become very
noisy if they are called inside atomic sections: when a spinlock is
held, inside an rcu read side critical section, inside preempt disabled
sections, inside an interrupt, etc...
config DEBUG_LOCKING_API_SELFTESTS
bool "Locking API boot-time self-tests"
depends on DEBUG_KERNEL
help
Say Y here if you want the kernel to run a short self-test during
bootup. The self-test checks whether common types of locking bugs
are detected by debugging mechanisms or not. (if you disable
lock debugging then those bugs won't be detected of course.)
The following locking APIs are covered: spinlocks, rwlocks,
mutexes and rwsems.
config LOCK_TORTURE_TEST
tristate "torture tests for locking"
depends on DEBUG_KERNEL
select TORTURE_TEST
help
This option provides a kernel module that runs torture tests
on kernel locking primitives. The kernel module may be built
after the fact on the running kernel to be tested, if desired.
Say Y here if you want kernel locking-primitive torture tests
to be built into the kernel.
Say M if you want these torture tests to build as a module.
Say N if you are unsure.
config WW_MUTEX_SELFTEST
tristate "Wait/wound mutex selftests"
help
This option provides a kernel module that runs tests on the
on the struct ww_mutex locking API.
It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
with this test harness.
Say M if you want these self tests to build as a module.
Say N if you are unsure.
config SCF_TORTURE_TEST
tristate "torture tests for smp_call_function*()"
depends on DEBUG_KERNEL
select TORTURE_TEST
help
This option provides a kernel module that runs torture tests
on the smp_call_function() family of primitives. The kernel
module may be built after the fact on the running kernel to
be tested, if desired.
config CSD_LOCK_WAIT_DEBUG
bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
depends on DEBUG_KERNEL
depends on 64BIT
default n
help
This option enables debug prints when CPUs are slow to respond
to the smp_call_function*() IPI wrappers. These debug prints
include the IPI handler function currently executing (if any)
and relevant stack traces.
config CSD_LOCK_WAIT_DEBUG_DEFAULT
bool "Default csd_lock_wait() debugging on at boot time"
depends on CSD_LOCK_WAIT_DEBUG
depends on 64BIT
default n
help
This option causes the csdlock_debug= kernel boot parameter to
default to 1 (basic debugging) instead of 0 (no debugging).
endmenu # lock debugging
config TRACE_IRQFLAGS
depends on TRACE_IRQFLAGS_SUPPORT
bool
help
Enables hooks to interrupt enabling and disabling for
either tracing or lock debugging.
config TRACE_IRQFLAGS_NMI
def_bool y
depends on TRACE_IRQFLAGS
depends on TRACE_IRQFLAGS_NMI_SUPPORT
config NMI_CHECK_CPU
bool "Debugging for CPUs failing to respond to backtrace requests"
depends on DEBUG_KERNEL
depends on X86
default n
help
Enables debug prints when a CPU fails to respond to a given
backtrace NMI. These prints provide some reasons why a CPU
might legitimately be failing to respond, for example, if it
is offline of if ignore_nmis is set.
config DEBUG_IRQFLAGS
bool "Debug IRQ flag manipulation"
help
Enables checks for potentially unsafe enabling or disabling of
interrupts, such as calling raw_local_irq_restore() when interrupts
are enabled.
config STACKTRACE
bool "Stack backtrace support"
depends on STACKTRACE_SUPPORT
help
This option causes the kernel to create a /proc/pid/stack for
every process, showing its current stack trace.
It is also used by various kernel debugging features that require
stack trace generation.
config WARN_ALL_UNSEEDED_RANDOM
bool "Warn for all uses of unseeded randomness"
default n
help
Some parts of the kernel contain bugs relating to their use of
cryptographically secure random numbers before it's actually possible
to generate those numbers securely. This setting ensures that these
flaws don't go unnoticed, by enabling a message, should this ever
occur. This will allow people with obscure setups to know when things
are going wrong, so that they might contact developers about fixing
it.
Unfortunately, on some models of some architectures getting
a fully seeded CRNG is extremely difficult, and so this can
result in dmesg getting spammed for a surprisingly long
time. This is really bad from a security perspective, and
so architecture maintainers really need to do what they can
to get the CRNG seeded sooner after the system is booted.
However, since users cannot do anything actionable to
address this, by default this option is disabled.
Say Y here if you want to receive warnings for all uses of
unseeded randomness. This will be of use primarily for
those developers interested in improving the security of
Linux kernels running on their architecture (or
subarchitecture).
config DEBUG_KOBJECT
bool "kobject debugging"
depends on DEBUG_KERNEL
help
If you say Y here, some extra kobject debugging messages will be sent
to the syslog.
config DEBUG_KOBJECT_RELEASE
bool "kobject release debugging"
depends on DEBUG_OBJECTS_TIMERS
help
kobjects are reference counted objects. This means that their
last reference count put is not predictable, and the kobject can
live on past the point at which a driver decides to drop its
initial reference to the kobject gained on allocation. An
example of this would be a struct device which has just been
unregistered.
However, some buggy drivers assume that after such an operation,
the memory backing the kobject can be immediately freed. This
goes completely against the principles of a refcounted object.
If you say Y here, the kernel will delay the release of kobjects
on the last reference count to improve the visibility of this
kind of kobject release bug.
config HAVE_DEBUG_BUGVERBOSE
bool
menu "Debug kernel data structures"
config DEBUG_LIST
bool "Debug linked list manipulation"
depends on DEBUG_KERNEL
select LIST_HARDENED
help
Enable this to turn on extended checks in the linked-list walking
routines.
This option trades better quality error reports for performance, and
is more suitable for kernel debugging. If you care about performance,
you should only enable CONFIG_LIST_HARDENED instead.
If unsure, say N.
config DEBUG_PLIST
bool "Debug priority linked list manipulation"
depends on DEBUG_KERNEL
help
Enable this to turn on extended checks in the priority-ordered
linked-list (plist) walking routines. This checks the entire
list multiple times during each manipulation.
If unsure, say N.
config DEBUG_SG
bool "Debug SG table operations"
depends on DEBUG_KERNEL
help
Enable this to turn on checks on scatter-gather tables. This can
help find problems with drivers that do not properly initialize
their sg tables.
If unsure, say N.
config DEBUG_NOTIFIERS
bool "Debug notifier call chains"
depends on DEBUG_KERNEL
help
Enable this to turn on sanity checking for notifier call chains.
This is most useful for kernel developers to make sure that
modules properly unregister themselves from notifier chains.
This is a relatively cheap check but if you care about maximum
performance, say N.
config DEBUG_CLOSURES
bool "Debug closures (bcache async widgits)"
depends on CLOSURES
select DEBUG_FS
help
Keeps all active closures in a linked list and provides a debugfs
interface to list them, which makes it possible to see asynchronous
operations that get stuck.
config DEBUG_MAPLE_TREE
bool "Debug maple trees"
depends on DEBUG_KERNEL
help
Enable maple tree debugging information and extra validations.
If unsure, say N.
endmenu
source "kernel/rcu/Kconfig.debug"
config DEBUG_WQ_FORCE_RR_CPU
bool "Force round-robin CPU selection for unbound work items"
depends on DEBUG_KERNEL
default n
help
Workqueue used to implicitly guarantee that work items queued
without explicit CPU specified are put on the local CPU. This
guarantee is no longer true and while local CPU is still
preferred work items may be put on foreign CPUs. Kernel
parameter "workqueue.debug_force_rr_cpu" is added to force
round-robin CPU selection to flush out usages which depend on the
now broken guarantee. This config option enables the debug
feature by default. When enabled, memory and cache locality will
be impacted.
config CPU_HOTPLUG_STATE_CONTROL
bool "Enable CPU hotplug state control"
depends on DEBUG_KERNEL
depends on HOTPLUG_CPU
default n
help
Allows to write steps between "offline" and "online" to the CPUs
sysfs target file so states can be stepped granular. This is a debug
option for now as the hotplug machinery cannot be stopped and
restarted at arbitrary points yet.
Say N if your are unsure.
config LATENCYTOP
bool "Latency measuring infrastructure"
depends on DEBUG_KERNEL
depends on STACKTRACE_SUPPORT
depends on PROC_FS
depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
select KALLSYMS
select KALLSYMS_ALL
select STACKTRACE
select SCHEDSTATS
help
Enable this option if you want to use the LatencyTOP tool
to find out which userspace is blocking on what kernel operations.
config DEBUG_CGROUP_REF
bool "Disable inlining of cgroup css reference count functions"
depends on DEBUG_KERNEL
depends on CGROUPS
depends on KPROBES
default n
help
Force cgroup css reference count functions to not be inlined so
that they can be kprobed for debugging.
source "kernel/trace/Kconfig"
config PROVIDE_OHCI1394_DMA_INIT
bool "Remote debugging over FireWire early on boot"
depends on PCI && X86
help
If you want to debug problems which hang or crash the kernel early
on boot and the crashing machine has a FireWire port, you can use
this feature to remotely access the memory of the crashed machine
over FireWire. This employs remote DMA as part of the OHCI1394
specification which is now the standard for FireWire controllers.
With remote DMA, you can monitor the printk buffer remotely using
firescope and access all memory below 4GB using fireproxy from gdb.
Even controlling a kernel debugger is possible using remote DMA.
Usage:
If ohci1394_dma=early is used as boot parameter, it will initialize
all OHCI1394 controllers which are found in the PCI config space.
As all changes to the FireWire bus such as enabling and disabling
devices cause a bus reset and thereby disable remote DMA for all
devices, be sure to have the cable plugged and FireWire enabled on
the debugging host before booting the debug target for debugging.
This code (~1k) is freed after boot. By then, the firewire stack
in charge of the OHCI-1394 controllers should be used instead.
See Documentation/core-api/debugging-via-ohci1394.rst for more information.
source "samples/Kconfig"
config ARCH_HAS_DEVMEM_IS_ALLOWED
bool
config STRICT_DEVMEM
bool "Filter access to /dev/mem"
depends on MMU && DEVMEM
depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
default y if PPC || X86 || ARM64
help
If this option is disabled, you allow userspace (root) access to all
of memory, including kernel and userspace memory. Accidental
access to this is obviously disastrous, but specific access can
be used by people debugging the kernel. Note that with PAT support
enabled, even in this case there are restrictions on /dev/mem
use due to the cache aliasing requirements.
If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
file only allows userspace access to PCI space and the BIOS code and
data regions. This is sufficient for dosemu and X and all common
users of /dev/mem.
If in doubt, say Y.
config IO_STRICT_DEVMEM
bool "Filter I/O access to /dev/mem"
depends on STRICT_DEVMEM
help
If this option is disabled, you allow userspace (root) access to all
io-memory regardless of whether a driver is actively using that
range. Accidental access to this is obviously disastrous, but
specific access can be used by people debugging kernel drivers.
If this option is switched on, the /dev/mem file only allows
userspace access to *idle* io-memory ranges (see /proc/iomem) This
may break traditional users of /dev/mem (dosemu, legacy X, etc...)
if the driver using a given range cannot be disabled.
If in doubt, say Y.
menu "$(SRCARCH) Debugging"
source "arch/$(SRCARCH)/Kconfig.debug"
endmenu
menu "Kernel Testing and Coverage"
source "lib/kunit/Kconfig"
config NOTIFIER_ERROR_INJECTION
tristate "Notifier error injection"
depends on DEBUG_KERNEL
select DEBUG_FS
help
This option provides the ability to inject artificial errors to
specified notifier chain callbacks. It is useful to test the error
handling of notifier call chain failures.
Say N if unsure.
config PM_NOTIFIER_ERROR_INJECT
tristate "PM notifier error injection module"
depends on PM && NOTIFIER_ERROR_INJECTION
default m if PM_DEBUG
help
This option provides the ability to inject artificial errors to
PM notifier chain callbacks. It is controlled through debugfs
interface /sys/kernel/debug/notifier-error-inject/pm
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject PM suspend error (-12 = -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/pm/
# echo -12 > actions/PM_SUSPEND_PREPARE/error
# echo mem > /sys/power/state
bash: echo: write error: Cannot allocate memory
To compile this code as a module, choose M here: the module will
be called pm-notifier-error-inject.
If unsure, say N.
config OF_RECONFIG_NOTIFIER_ERROR_INJECT
tristate "OF reconfig notifier error injection module"
depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
OF reconfig notifier chain callbacks. It is controlled
through debugfs interface under
/sys/kernel/debug/notifier-error-inject/OF-reconfig/
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
To compile this code as a module, choose M here: the module will
be called of-reconfig-notifier-error-inject.
If unsure, say N.
config NETDEV_NOTIFIER_ERROR_INJECT
tristate "Netdev notifier error injection module"
depends on NET && NOTIFIER_ERROR_INJECTION
help
This option provides the ability to inject artificial errors to
netdevice notifier chain callbacks. It is controlled through debugfs
interface /sys/kernel/debug/notifier-error-inject/netdev
If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".
Example: Inject netdevice mtu change error (-22 = -EINVAL)
# cd /sys/kernel/debug/notifier-error-inject/netdev
# echo -22 > actions/NETDEV_CHANGEMTU/error
# ip link set eth0 mtu 1024
RTNETLINK answers: Invalid argument
To compile this code as a module, choose M here: the module will
be called netdev-notifier-error-inject.
If unsure, say N.
config FUNCTION_ERROR_INJECTION
bool "Fault-injections of functions"
depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
help
Add fault injections into various functions that are annotated with
ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
value of these functions. This is useful to test error paths of code.
If unsure, say N
config FAULT_INJECTION
bool "Fault-injection framework"
depends on DEBUG_KERNEL
help
Provide fault-injection framework.
For more details, see Documentation/fault-injection/.
config FAILSLAB
bool "Fault-injection capability for kmalloc"
depends on FAULT_INJECTION
help
Provide fault-injection capability for kmalloc.
config FAIL_PAGE_ALLOC
bool "Fault-injection capability for alloc_pages()"
depends on FAULT_INJECTION
help
Provide fault-injection capability for alloc_pages().
config FAULT_INJECTION_USERCOPY
bool "Fault injection capability for usercopy functions"
depends on FAULT_INJECTION
help
Provides fault-injection capability to inject failures
in usercopy functions (copy_from_user(), get_user(), ...).
config FAIL_MAKE_REQUEST
bool "Fault-injection capability for disk IO"
depends on FAULT_INJECTION && BLOCK
help
Provide fault-injection capability for disk IO.
config FAIL_IO_TIMEOUT
bool "Fault-injection capability for faking disk interrupts"
depends on FAULT_INJECTION && BLOCK
help
Provide fault-injection capability on end IO handling. This
will make the block layer "forget" an interrupt as configured,
thus exercising the error handling.
Only works with drivers that use the generic timeout handling,
for others it won't do anything.
config FAIL_FUTEX
bool "Fault-injection capability for futexes"
select DEBUG_FS
depends on FAULT_INJECTION && FUTEX
help
Provide fault-injection capability for futexes.
config FAULT_INJECTION_DEBUG_FS
bool "Debugfs entries for fault-injection capabilities"
depends on FAULT_INJECTION && SYSFS && DEBUG_FS
help
Enable configuration of fault-injection capabilities via debugfs.
config FAIL_FUNCTION
bool "Fault-injection capability for functions"
depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
help
Provide function-based fault-injection capability.
This will allow you to override a specific function with a return
with given return value. As a result, function caller will see
an error value and have to handle it. This is useful to test the
error handling in various subsystems.
config FAIL_MMC_REQUEST
bool "Fault-injection capability for MMC IO"
depends on FAULT_INJECTION_DEBUG_FS && MMC
help
Provide fault-injection capability for MMC IO.
This will make the mmc core return data errors. This is
useful to test the error handling in the mmc block device
and to test how the mmc host driver handles retries from
the block device.
config FAIL_SUNRPC
bool "Fault-injection capability for SunRPC"
depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
help
Provide fault-injection capability for SunRPC and
its consumers.
config FAULT_INJECTION_CONFIGFS
bool "Configfs interface for fault-injection capabilities"
depends on FAULT_INJECTION
select CONFIGFS_FS
help
This option allows configfs-based drivers to dynamically configure
fault-injection via configfs. Each parameter for driver-specific
fault-injection can be made visible as a configfs attribute in a
configfs group.
config FAULT_INJECTION_STACKTRACE_FILTER
bool "stacktrace filter for fault-injection capabilities"
depends on FAULT_INJECTION
depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
select STACKTRACE
depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
help
Provide stacktrace filter for fault-injection capabilities
config ARCH_HAS_KCOV
bool
help
An architecture should select this when it can successfully
build and run with CONFIG_KCOV. This typically requires
disabling instrumentation for some early boot code.
config CC_HAS_SANCOV_TRACE_PC
def_bool $(cc-option,-fsanitize-coverage=trace-pc)
config KCOV
bool "Code coverage for fuzzing"
depends on ARCH_HAS_KCOV
depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
select DEBUG_FS
select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
select OBJTOOL if HAVE_NOINSTR_HACK
help
KCOV exposes kernel code coverage information in a form suitable
for coverage-guided fuzzing (randomized testing).
For more details, see Documentation/dev-tools/kcov.rst.
config KCOV_ENABLE_COMPARISONS
bool "Enable comparison operands collection by KCOV"
depends on KCOV
depends on $(cc-option,-fsanitize-coverage=trace-cmp)
help
KCOV also exposes operands of every comparison in the instrumented
code along with operand sizes and PCs of the comparison instructions.
These operands can be used by fuzzing engines to improve the quality
of fuzzing coverage.
config KCOV_INSTRUMENT_ALL
bool "Instrument all code by default"
depends on KCOV
default y
help
If you are doing generic system call fuzzing (like e.g. syzkaller),
then you will want to instrument the whole kernel and you should
say y here. If you are doing more targeted fuzzing (like e.g.
filesystem fuzzing with AFL) then you will want to enable coverage
for more specific subsets of files, and should say n here.
config KCOV_IRQ_AREA_SIZE
hex "Size of interrupt coverage collection area in words"
depends on KCOV
default 0x40000
help
KCOV uses preallocated per-cpu areas to collect coverage from
soft interrupts. This specifies the size of those areas in the
number of unsigned long words.
menuconfig RUNTIME_TESTING_MENU
bool "Runtime Testing"
def_bool y
if RUNTIME_TESTING_MENU
config TEST_DHRY
tristate "Dhrystone benchmark test"
help
Enable this to include the Dhrystone 2.1 benchmark. This test
calculates the number of Dhrystones per second, and the number of
DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
by 1757 (the number of Dhrystones per second obtained on the VAX
11/780, nominally a 1 MIPS machine).
To run the benchmark, it needs to be enabled explicitly, either from
the kernel command line (when built-in), or from userspace (when
built-in or modular.
Run once during kernel boot:
test_dhry.run
Set number of iterations from kernel command line:
test_dhry.iterations=<n>
Set number of iterations from userspace:
echo <n> > /sys/module/test_dhry/parameters/iterations
Trigger manual run from userspace:
echo y > /sys/module/test_dhry/parameters/run
If the number of iterations is <= 0, the test will devise a suitable
number of iterations (test runs for at least 2s) automatically.
This process takes ca. 4s.
If unsure, say N.
config LKDTM
tristate "Linux Kernel Dump Test Tool Module"
depends on DEBUG_FS
help
This module enables testing of the different dumping mechanisms by
inducing system failures at predefined crash points.
If you don't need it: say N
Choose M here to compile this code as a module. The module will be
called lkdtm.
Documentation on how to use the module can be found in
Documentation/fault-injection/provoke-crashes.rst
config CPUMASK_KUNIT_TEST
tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable to turn on cpumask tests, running at boot or module load time.
For more information on KUnit and unit tests in general, please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config TEST_LIST_SORT
tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable this to turn on 'list_sort()' function test. This test is
executed only once during system boot (so affects only boot time),
or at module load time.
If unsure, say N.
config TEST_MIN_HEAP
tristate "Min heap test"
depends on DEBUG_KERNEL || m
help
Enable this to turn on min heap function tests. This test is
executed only once during system boot (so affects only boot time),
or at module load time.
If unsure, say N.
config TEST_SORT
tristate "Array-based sort test" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This option enables the self-test function of 'sort()' at boot,
or at module load time.
If unsure, say N.
config TEST_DIV64
tristate "64bit/32bit division and modulo test"
depends on DEBUG_KERNEL || m
help
Enable this to turn on 'do_div()' function test. This test is
executed only once during system boot (so affects only boot time),
or at module load time.
If unsure, say N.
config TEST_IOV_ITER
tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
depends on KUNIT
depends on MMU
default KUNIT_ALL_TESTS
help
Enable this to turn on testing of the operation of the I/O iterator
(iov_iter). This test is executed only once during system boot (so
affects only boot time), or at module load time.
If unsure, say N.
config KPROBES_SANITY_TEST
tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
depends on DEBUG_KERNEL
depends on KPROBES
depends on KUNIT
select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
default KUNIT_ALL_TESTS
help
This option provides for testing basic kprobes functionality on
boot. Samples of kprobe and kretprobe are inserted and
verified for functionality.
Say N if you are unsure.
config FPROBE_SANITY_TEST
bool "Self test for fprobe"
depends on DEBUG_KERNEL
depends on FPROBE
depends on KUNIT=y
help
This option will enable testing the fprobe when the system boot.
A series of tests are made to verify that the fprobe is functioning
properly.
Say N if you are unsure.
config BACKTRACE_SELF_TEST
tristate "Self test for the backtrace code"
depends on DEBUG_KERNEL
help
This option provides a kernel module that can be used to test
the kernel stack backtrace code. This option is not useful
for distributions or general kernels, but only for kernel
developers working on architecture code.
Note that if you want to also test saved backtraces, you will
have to enable STACKTRACE as well.
Say N if you are unsure.
config TEST_REF_TRACKER
tristate "Self test for reference tracker"
depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
select REF_TRACKER
help
This option provides a kernel module performing tests
using reference tracker infrastructure.
Say N if you are unsure.
config RBTREE_TEST
tristate "Red-Black tree test"
depends on DEBUG_KERNEL
help
A benchmark measuring the performance of the rbtree library.
Also includes rbtree invariant checks.
config REED_SOLOMON_TEST
tristate "Reed-Solomon library test"
depends on DEBUG_KERNEL || m
select REED_SOLOMON
select REED_SOLOMON_ENC16
select REED_SOLOMON_DEC16
help
This option enables the self-test function of rslib at boot,
or at module load time.
If unsure, say N.
config INTERVAL_TREE_TEST
tristate "Interval tree test"
depends on DEBUG_KERNEL
select INTERVAL_TREE
help
A benchmark measuring the performance of the interval tree library
config PERCPU_TEST
tristate "Per cpu operations test"
depends on m && DEBUG_KERNEL
help
Enable this option to build test module which validates per-cpu
operations.
If unsure, say N.
config ATOMIC64_SELFTEST
tristate "Perform an atomic64_t self-test"
help
Enable this option to test the atomic64_t functions at boot or
at module load time.
If unsure, say N.
config ASYNC_RAID6_TEST
tristate "Self test for hardware accelerated raid6 recovery"
depends on ASYNC_RAID6_RECOV
select ASYNC_MEMCPY
help
This is a one-shot self test that permutes through the
recovery of all the possible two disk failure scenarios for a
N-disk array. Recovery is performed with the asynchronous
raid6 recovery routines, and will optionally use an offload
engine if one is available.
If unsure, say N.
config TEST_HEXDUMP
tristate "Test functions located in the hexdump module at runtime"
config STRING_KUNIT_TEST
tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
config STRING_HELPERS_KUNIT_TEST
tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
config TEST_KSTRTOX
tristate "Test kstrto*() family of functions at runtime"
config TEST_PRINTF
tristate "Test printf() family of functions at runtime"
config TEST_SCANF
tristate "Test scanf() family of functions at runtime"
config TEST_BITMAP
tristate "Test bitmap_*() family of functions at runtime"
help
Enable this option to test the bitmap functions at boot.
If unsure, say N.
config TEST_UUID
tristate "Test functions located in the uuid module at runtime"
config TEST_XARRAY
tristate "Test the XArray code at runtime"
config TEST_MAPLE_TREE
tristate "Test the Maple Tree code at runtime or module load"
help
Enable this option to test the maple tree code functions at boot, or
when the module is loaded. Enable "Debug Maple Trees" will enable
more verbose output on failures.
If unsure, say N.
config TEST_RHASHTABLE
tristate "Perform selftest on resizable hash table"
help
Enable this option to test the rhashtable functions at boot.
If unsure, say N.
config TEST_IDA
tristate "Perform selftest on IDA functions"
config TEST_PARMAN
tristate "Perform selftest on priority array manager"
depends on PARMAN
help
Enable this option to test priority array manager on boot
(or module load).
If unsure, say N.
config TEST_IRQ_TIMINGS
bool "IRQ timings selftest"
depends on IRQ_TIMINGS
help
Enable this option to test the irq timings code on boot.
If unsure, say N.
config TEST_LKM
tristate "Test module loading with 'hello world' module"
depends on m
help
This builds the "test_module" module that emits "Hello, world"
on printk when loaded. It is designed to be used for basic
evaluation of the module loading subsystem (for example when
validating module verification). It lacks any extra dependencies,
and will not normally be loaded by the system unless explicitly
requested by name.
If unsure, say N.
config TEST_BITOPS
tristate "Test module for compilation of bitops operations"
depends on m
help
This builds the "test_bitops" module that is much like the
TEST_LKM module except that it does a basic exercise of the
set/clear_bit macros and get_count_order/long to make sure there are
no compiler warnings from C=1 sparse checker or -Wextra
compilations. It has no dependencies and doesn't run or load unless
explicitly requested by name. for example: modprobe test_bitops.
If unsure, say N.
config TEST_VMALLOC
tristate "Test module for stress/performance analysis of vmalloc allocator"
default n
depends on MMU
depends on m
help
This builds the "test_vmalloc" module that should be used for
stress and performance analysis. So, any new change for vmalloc
subsystem can be evaluated from performance and stability point
of view.
If unsure, say N.
config TEST_USER_COPY
tristate "Test user/kernel boundary protections"
depends on m
help
This builds the "test_user_copy" module that runs sanity checks
on the copy_to/from_user infrastructure, making sure basic
user/kernel boundary testing is working. If it fails to load,
a regression has been detected in the user/kernel memory boundary
protections.
If unsure, say N.
config TEST_BPF
tristate "Test BPF filter functionality"
depends on m && NET
help
This builds the "test_bpf" module that runs various test vectors
against the BPF interpreter or BPF JIT compiler depending on the
current setting. This is in particular useful for BPF JIT compiler
development, but also to run regression tests against changes in
the interpreter code. It also enables test stubs for eBPF maps and
verifier used by user space verifier testsuite.
If unsure, say N.
config TEST_BLACKHOLE_DEV
tristate "Test blackhole netdev functionality"
depends on m && NET
help
This builds the "test_blackhole_dev" module that validates the
data path through this blackhole netdev.
If unsure, say N.
config FIND_BIT_BENCHMARK
tristate "Test find_bit functions"
help
This builds the "test_find_bit" module that measure find_*_bit()
functions performance.
If unsure, say N.
config TEST_FIRMWARE
tristate "Test firmware loading via userspace interface"
depends on FW_LOADER
help
This builds the "test_firmware" module that creates a userspace
interface for testing firmware loading. This can be used to
control the triggering of firmware loading without needing an
actual firmware-using device. The contents can be rechecked by
userspace.
If unsure, say N.
config TEST_SYSCTL
tristate "sysctl test driver"
depends on PROC_SYSCTL
help
This builds the "test_sysctl" module. This driver enables to test the
proc sysctl interfaces available to drivers safely without affecting
production knobs which might alter system functionality.
If unsure, say N.
config BITFIELD_KUNIT
tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable this option to test the bitfield functions at boot.
KUnit tests run during boot and output the results to the debug log
in TAP format (http://testanything.org/). Only useful for kernel devs
running the KUnit test harness, and not intended for inclusion into a
production build.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config CHECKSUM_KUNIT
tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable this option to test the checksum functions at boot.
KUnit tests run during boot and output the results to the debug log
in TAP format (http://testanything.org/). Only useful for kernel devs
running the KUnit test harness, and not intended for inclusion into a
production build.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config HASH_KUNIT_TEST
tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable this option to test the kernel's string (<linux/stringhash.h>), and
integer (<linux/hash.h>) hash functions on boot.
KUnit tests run during boot and output the results to the debug log
in TAP format (https://testanything.org/). Only useful for kernel devs
running the KUnit test harness, and not intended for inclusion into a
production build.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
This is intended to help people writing architecture-specific
optimized versions. If unsure, say N.
config RESOURCE_KUNIT_TEST
tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the resource API unit test.
Tests the logic of API provided by resource.c and ioport.h.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config SYSCTL_KUNIT_TEST
tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the proc sysctl unit test, which runs on boot.
Tests the API contract and implementation correctness of sysctl.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config LIST_KUNIT_TEST
tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the linked list KUnit test suite.
It tests that the API and basic functionality of the list_head type
and associated macros.
KUnit tests run during boot and output the results to the debug log
in TAP format (https://testanything.org/). Only useful for kernel devs
running the KUnit test harness, and not intended for inclusion into a
production build.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config HASHTABLE_KUNIT_TEST
tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the hashtable KUnit test suite.
It tests the basic functionality of the API defined in
include/linux/hashtable.h. For more information on KUnit and
unit tests in general please refer to the KUnit documentation
in Documentation/dev-tools/kunit/.
If unsure, say N.
config LINEAR_RANGES_TEST
tristate "KUnit test for linear_ranges"
depends on KUNIT
select LINEAR_RANGES
help
This builds the linear_ranges unit test, which runs on boot.
Tests the linear_ranges logic correctness.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config CMDLINE_KUNIT_TEST
tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the cmdline API unit test.
Tests the logic of API provided by cmdline.c.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config BITS_TEST
tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
This builds the bits unit test.
Tests the logic of macros defined in bits.h.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config SLUB_KUNIT_TEST
tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
depends on SLUB_DEBUG && KUNIT
default KUNIT_ALL_TESTS
help
This builds SLUB allocator unit test.
Tests SLUB cache debugging functionality.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config RATIONAL_KUNIT_TEST
tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
depends on KUNIT && RATIONAL
default KUNIT_ALL_TESTS
help
This builds the rational math unit test.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config MEMCPY_KUNIT_TEST
tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Builds unit tests for memcpy(), memmove(), and memset() functions.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config MEMCPY_SLOW_KUNIT_TEST
bool "Include exhaustive memcpy tests"
depends on MEMCPY_KUNIT_TEST
default y
help
Some memcpy tests are quite exhaustive in checking for overlaps
and bit ranges. These can be very slow, so they are split out
as a separate config, in case they need to be disabled.
Note this config option will be replaced by the use of KUnit test
attributes.
config IS_SIGNED_TYPE_KUNIT_TEST
tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Builds unit tests for the is_signed_type() macro.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config OVERFLOW_KUNIT_TEST
tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Builds unit tests for the check_*_overflow(), size_*(), allocation, and
related functions.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
config STACKINIT_KUNIT_TEST
tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Test if the kernel is zero-initializing stack variables and
padding. Coverage is controlled by compiler flags,
CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
config FORTIFY_KUNIT_TEST
tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Builds unit tests for checking internals of FORTIFY_SOURCE as used
by the str*() and mem*() family of functions. For testing runtime
traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
config HW_BREAKPOINT_KUNIT_TEST
bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
depends on HAVE_HW_BREAKPOINT
depends on KUNIT=y
default KUNIT_ALL_TESTS
help
Tests for hw_breakpoint constraints accounting.
If unsure, say N.
config STRCAT_KUNIT_TEST
tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
config STRSCPY_KUNIT_TEST
tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
config SIPHASH_KUNIT_TEST
tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
depends on KUNIT
default KUNIT_ALL_TESTS
help
Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
functions on boot (or module load).
This is intended to help people writing architecture-specific
optimized versions. If unsure, say N.
config TEST_UDELAY
tristate "udelay test driver"
help
This builds the "udelay_test" module that helps to make sure
that udelay() is working properly.
If unsure, say N.
config TEST_STATIC_KEYS
tristate "Test static keys"
depends on m
help
Test the static key interfaces.
If unsure, say N.
config TEST_DYNAMIC_DEBUG
tristate "Test DYNAMIC_DEBUG"
depends on DYNAMIC_DEBUG
help
This module registers a tracer callback to count enabled
pr_debugs in a 'do_debugging' function, then alters their
enablements, calls the function, and compares counts.
If unsure, say N.
config TEST_KMOD
tristate "kmod stress tester"
depends on m
depends on NETDEVICES && NET_CORE && INET # for TUN
depends on BLOCK
depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
select TEST_LKM
select XFS_FS
select TUN
select BTRFS_FS
help
Test the kernel's module loading mechanism: kmod. kmod implements
support to load modules using the Linux kernel's usermode helper.
This test provides a series of tests against kmod.
Although technically you can either build test_kmod as a module or
into the kernel we disallow building it into the kernel since
it stress tests request_module() and this will very likely cause
some issues by taking over precious threads available from other
module load requests, ultimately this could be fatal.
To run tests run:
tools/testing/selftests/kmod/kmod.sh --help
If unsure, say N.
config TEST_DEBUG_VIRTUAL
tristate "Test CONFIG_DEBUG_VIRTUAL feature"
depends on DEBUG_VIRTUAL
help
Test the kernel's ability to detect incorrect calls to
virt_to_phys() done against the non-linear part of the
kernel's virtual address map.
If unsure, say N.
config TEST_MEMCAT_P
tristate "Test memcat_p() helper function"
help
Test the memcat_p() helper for correctly merging two
pointer arrays together.
If unsure, say N.
config TEST_OBJAGG
tristate "Perform selftest on object aggreration manager"
default n
depends on OBJAGG
help
Enable this option to test object aggregation manager on boot
(or module load).
config TEST_MEMINIT
tristate "Test heap/page initialization"
help
Test if the kernel is zero-initializing heap and page allocations.
This can be useful to test init_on_alloc and init_on_free features.
If unsure, say N.
config TEST_HMM
tristate "Test HMM (Heterogeneous Memory Management)"
depends on TRANSPARENT_HUGEPAGE
depends on DEVICE_PRIVATE
select HMM_MIRROR
select MMU_NOTIFIER
help
This is a pseudo device driver solely for testing HMM.
Say M here if you want to build the HMM test module.
Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
If unsure, say N.
config TEST_FREE_PAGES
tristate "Test freeing pages"
help
Test that a memory leak does not occur due to a race between
freeing a block of pages and a speculative page reference.
Loading this module is safe if your kernel has the bug fixed.
If the bug is not fixed, it will leak gigabytes of memory and
probably OOM your system.
config TEST_FPU
tristate "Test floating point operations in kernel space"
depends on X86 && !KCOV_INSTRUMENT_ALL
help
Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
which will trigger a sequence of floating point operations. This is used
for self-testing floating point control register setting in
kernel_fpu_begin().
If unsure, say N.
config TEST_CLOCKSOURCE_WATCHDOG
tristate "Test clocksource watchdog in kernel space"
depends on CLOCKSOURCE_WATCHDOG
help
Enable this option to create a kernel module that will trigger
a test of the clocksource watchdog. This module may be loaded
via modprobe or insmod in which case it will run upon being
loaded, or it may be built in, in which case it will run
shortly after boot.
If unsure, say N.
config TEST_OBJPOOL
tristate "Test module for correctness and stress of objpool"
default n
depends on m && DEBUG_KERNEL
help
This builds the "test_objpool" module that should be used for
correctness verification and concurrent testings of objects
allocation and reclamation.
If unsure, say N.
endif # RUNTIME_TESTING_MENU
config ARCH_USE_MEMTEST
bool
help
An architecture should select this when it uses early_memtest()
during boot process.
config MEMTEST
bool "Memtest"
depends on ARCH_USE_MEMTEST
help
This option adds a kernel parameter 'memtest', which allows memtest
to be set and executed.
memtest=0, mean disabled; -- default
memtest=1, mean do 1 test pattern;
...
memtest=17, mean do 17 test patterns.
If you are unsure how to answer this question, answer N.
config HYPERV_TESTING
bool "Microsoft Hyper-V driver testing"
default n
depends on HYPERV && DEBUG_FS
help
Select this option to enable Hyper-V vmbus testing.
endmenu # "Kernel Testing and Coverage"
menu "Rust hacking"
config RUST_DEBUG_ASSERTIONS
bool "Debug assertions"
depends on RUST
help
Enables rustc's `-Cdebug-assertions` codegen option.
This flag lets you turn `cfg(debug_assertions)` conditional
compilation on or off. This can be used to enable extra debugging
code in development but not in production. For example, it controls
the behavior of the standard library's `debug_assert!` macro.
Note that this will apply to all Rust code, including `core`.
If unsure, say N.
config RUST_OVERFLOW_CHECKS
bool "Overflow checks"
default y
depends on RUST
help
Enables rustc's `-Coverflow-checks` codegen option.
This flag allows you to control the behavior of runtime integer
overflow. When overflow-checks are enabled, a Rust panic will occur
on overflow.
Note that this will apply to all Rust code, including `core`.
If unsure, say Y.
config RUST_BUILD_ASSERT_ALLOW
bool "Allow unoptimized build-time assertions"
depends on RUST
help
Controls how are `build_error!` and `build_assert!` handled during build.
If calls to them exist in the binary, it may indicate a violated invariant
or that the optimizer failed to verify the invariant during compilation.
This should not happen, thus by default the build is aborted. However,
as an escape hatch, you can choose Y here to ignore them during build
and let the check be carried at runtime (with `panic!` being called if
the check fails).
If unsure, say N.
config RUST_KERNEL_DOCTESTS
bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
depends on RUST && KUNIT=y
default KUNIT_ALL_TESTS
help
This builds the documentation tests of the `kernel` crate
as KUnit tests.
For more information on KUnit and unit tests in general,
please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.
endmenu # "Rust"
endmenu # Kernel hacking