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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 PRINTK_EXECUTION_CTX
- bool
- depends on PRINTK
- help
- This option extends struct printk_info to include extra execution
- context in printk, such as task name and CPU number from where the
- message originated. This is useful for correlating printk messages
- with specific execution contexts.
- This is automatically enabled when a console driver that supports
- execution context is selected.
- 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 jiffy" 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.
- config DEBUG_BUGVERBOSE_DETAILED
- bool "Verbose WARN_ON_ONCE() reporting (adds 100K)" if DEBUG_BUGVERBOSE
- help
- Say Y here to make WARN_ON_ONCE() output the condition string of the
- warning, in addition to the file name and line number.
- This helps debugging, but costs about 100K of memory.
- Say N if unsure.
- 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 || (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.
- Users of dpkg-deb via debian/rules 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 or DPKG_DEB_COMPRESSOR_TYPE 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 type information"
- depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
- depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
- depends on BPF_SYSCALL
- depends on PAHOLE_VERSION >= 122
- # 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 requires pahole v1.22 or later, which will convert
- DWARF type info into equivalent deduplicated BTF type info.
- 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
- bool "Generate BTF type information for kernel modules"
- default y
- depends on DEBUG_INFO_BTF && MODULES
- 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/process/debugging/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 !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"
- 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. 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,
- __initdata, and so on (see the full list in include/linux/init.h).
- This directs the toolchain to place code/data in specific sections.
- The section mismatch analysis is always performed after a full
- kernel build, and enabling this option causes the option
- -fno-inline-functions-called-once to be added to gcc commands.
- However, 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 OBJTOOL_WERROR
- bool "Upgrade objtool warnings to errors"
- depends on OBJTOOL && !COMPILE_TEST
- help
- Fail the build on objtool warnings.
- Objtool warnings can indicate kernel instability, including boot
- failures. This option is highly recommended.
- If unsure, say Y.
- 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 BUILTIN_MODULE_RANGES
- bool "Generate address range information for builtin modules"
- depends on !LTO
- depends on VMLINUX_MAP
- help
- When modules are built into the kernel, there will be no module name
- associated with its symbols in /proc/kallsyms. Tracers may want to
- identify symbols by module name and symbol name regardless of whether
- the module is configured as loadable or not.
- This option generates modules.builtin.ranges in the build tree with
- offset ranges (per ELF section) for the module(s) they belong to.
- It also records an anchor symbol to determine the load address of the
- section.
- 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.
- config WARN_CONTEXT_ANALYSIS
- bool "Compiler context-analysis warnings"
- depends on CC_IS_CLANG && CLANG_VERSION >= 220100
- # Branch profiling re-defines "if", which messes with the compiler's
- # ability to analyze __cond_acquires(..), resulting in false positives.
- depends on !TRACE_BRANCH_PROFILING
- default y
- help
- Context Analysis is a language extension, which enables statically
- checking that required contexts are active (or inactive) by acquiring
- and releasing user-definable "context locks".
- Clang's name of the feature is "Thread Safety Analysis". Requires
- Clang 22.1.0 or later.
- Produces warnings by default. Select CONFIG_WERROR if you wish to
- turn these warnings into errors.
- For more details, see Documentation/dev-tools/context-analysis.rst.
- config WARN_CONTEXT_ANALYSIS_ALL
- bool "Enable context analysis for all source files"
- depends on WARN_CONTEXT_ANALYSIS
- depends on EXPERT && !COMPILE_TEST
- help
- Enable tree-wide context analysis. This is likely to produce a
- large number of false positives - enable at your own risk.
- If unsure, say N.
- 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,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_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 PREEMPT_COUNT || !DEFERRED_STRUCT_PAGE_INIT
- 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_VFS
- bool "Debug VFS"
- depends on DEBUG_KERNEL
- help
- Enable this to turn on extended checks in the VFS layer that may impact
- performance.
- If unsure, say N.
- 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".
- config CODE_TAGGING
- bool
- select KALLSYMS
- config MEM_ALLOC_PROFILING
- bool "Enable memory allocation profiling"
- default n
- depends on MMU
- depends on PROC_FS
- depends on !DEBUG_FORCE_WEAK_PER_CPU
- select CODE_TAGGING
- select PAGE_EXTENSION
- select SLAB_OBJ_EXT
- help
- Track allocation source code and record total allocation size
- initiated at that code location. The mechanism can be used to track
- memory leaks with a low performance and memory impact.
- config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
- bool "Enable memory allocation profiling by default"
- default y
- depends on MEM_ALLOC_PROFILING
- config MEM_ALLOC_PROFILING_DEBUG
- bool "Memory allocation profiler debugging"
- default n
- depends on MEM_ALLOC_PROFILING
- select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
- help
- Adds warnings with helpful error messages for memory allocation
- profiling.
- 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_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. This setting can be overridden
- with the kernel command line option panic=, and from userspace via
- /proc/sys/kernel/panic.
- 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 SOFTLOCKUP_DETECTOR_INTR_STORM
- bool "Detect Interrupt Storm in Soft Lockups"
- depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
- select GENERIC_IRQ_STAT_SNAPSHOT
- default y if NR_CPUS <= 128
- help
- Say Y here to enable the kernel to detect interrupt storm
- during "soft lockups".
- "soft lockups" can be caused by a variety of reasons. If one is
- caused by an interrupt storm, then the storming interrupts will not
- be on the callstack. To detect this case, it is necessary to report
- the CPU stats and the interrupt counts during the "soft lockups".
- config BOOTPARAM_SOFTLOCKUP_PANIC
- int "Panic (Reboot) On Soft Lockups"
- depends on SOFTLOCKUP_DETECTOR
- default 0
- help
- Set to a non-zero value N to enable the kernel to panic on "soft
- lockups", which are bugs that cause the kernel to loop in kernel
- mode for more than (N * 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 0 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
- int "Number of hung tasks to trigger kernel panic"
- depends on DETECT_HUNG_TASK
- default 0
- help
- When set to a non-zero value, a kernel panic will be triggered
- if the number of hung tasks found during a single scan reaches
- this value.
- 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 0 if unsure.
- config DETECT_HUNG_TASK_BLOCKER
- bool "Dump Hung Tasks Blocker"
- depends on DETECT_HUNG_TASK
- depends on !PREEMPT_RT
- default y
- help
- Say Y here to show the blocker task's stacktrace who acquires
- the mutex lock which "hung tasks" are waiting.
- This will add overhead a bit but shows suspicious tasks and
- call trace if it comes from waiting a mutex.
- 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 BOOTPARAM_WQ_STALL_PANIC
- int "Panic on Nth workqueue stall"
- default 0
- range 0 100
- depends on WQ_WATCHDOG
- help
- Set the number of workqueue stalls to trigger a kernel panic.
- A workqueue stall occurs when a worker pool doesn't make forward
- progress on a pending work item for over 30 seconds (configurable
- using the workqueue.watchdog_thresh parameter).
- If n = 0, the kernel will not panic on stall. If n > 0, the kernel
- will panic after n stall warnings.
- The panic can be used in combination with panic_timeout,
- to cause the system to reboot automatically after a
- stall has been detected. This feature is useful for
- high-availability systems that have uptime guarantees and
- where a stall must be resolved ASAP.
- This setting can be overridden at runtime via the
- workqueue.panic_on_stall kernel parameter.
- 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_INFO
- bool
- default n
- config SCHEDSTATS
- bool "Collect scheduler statistics"
- depends on 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_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.
- config DEBUG_ATOMIC
- bool "Debug atomic variables"
- depends on DEBUG_KERNEL
- help
- If you say Y here then the kernel will add a runtime alignment check
- to atomic accesses. Useful for architectures that do not have trap on
- mis-aligned access.
- This option has potentially significant overhead.
- config DEBUG_ATOMIC_LARGEST_ALIGN
- bool "Check alignment only up to __aligned_largest"
- depends on DEBUG_ATOMIC
- help
- If you say Y here then the check for natural alignment of
- atomic accesses will be constrained to the compiler's largest
- alignment for scalar types.
- 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" if !ARCH_SUPPORTS_RT
- depends on PROVE_LOCKING
- default y if ARCH_SUPPORTS_RT
- help
- Enable the raw_spinlock vs. spinlock nesting checks which ensure
- that the lock nesting rules for PREEMPT_RT enabled kernels are
- not violated.
- 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 "Size for MAX_LOCKDEP_ENTRIES (as Nth power of 2)"
- depends on LOCKDEP && !LOCKDEP_SMALL
- range 10 24
- default 15
- help
- Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
- config LOCKDEP_CHAINS_BITS
- int "Size for MAX_LOCKDEP_CHAINS (as Nth power of 2)"
- depends on LOCKDEP && !LOCKDEP_SMALL
- range 10 21
- default 16
- help
- Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
- config LOCKDEP_STACK_TRACE_BITS
- int "Size for MAX_STACK_TRACE_ENTRIES (as Nth power of 2)"
- depends on LOCKDEP && !LOCKDEP_SMALL
- range 10 26
- 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 "Size for STACK_TRACE_HASH_SIZE (as Nth power of 2)"
- depends on LOCKDEP && !LOCKDEP_SMALL
- range 10 26
- default 14
- help
- Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
- config LOCKDEP_CIRCULAR_QUEUE_BITS
- int "Size for elements in circular_queue struct (as Nth power of 2)"
- depends on LOCKDEP
- range 10 26
- 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 SMP
- 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 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 || S390
- 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 FAIL_SKB_REALLOC
- bool "Fault-injection capability forcing skb to reallocate"
- depends on FAULT_INJECTION_DEBUG_FS
- help
- Provide fault-injection capability that forces the skb to be
- reallocated, catching possible invalid pointers to the skb.
- For more information, check
- Documentation/fault-injection/fault-injection.rst
- 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 KCOV
- bool "Code coverage for fuzzing"
- depends on ARCH_HAS_KCOV
- depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
- GCC_VERSION >= 120000 || CC_IS_CLANG
- select DEBUG_FS
- 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.
- config KCOV_SELFTEST
- bool "Perform short selftests on boot"
- depends on KCOV
- help
- Run short KCOV coverage collection selftests on boot.
- On test failure, causes the kernel to panic. Recommended to be
- enabled, ensuring critical functionality works as intended.
- menuconfig RUNTIME_TESTING_MENU
- bool "Runtime Testing"
- default 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_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_MULDIV64
- tristate "mul_u64_u64_div_u64() test"
- depends on DEBUG_KERNEL || m
- help
- Enable this to turn on 'mul_u64_u64_div_u64()' 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 PRINTF_KUNIT_TEST
- tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- Enable this option to test the printf functions at runtime.
- If unsure, say N.
- config SCANF_KUNIT_TEST
- tristate "KUnit test scanf() family of functions at runtime" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- Enable this option to test the scanf functions at runtime.
- If unsure, say N.
- config SEQ_BUF_KUNIT_TEST
- tristate "KUnit test for seq_buf" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds unit tests for the seq_buf library.
- If unsure, say N.
- 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 FFS_KUNIT_TEST
- tristate "KUnit test ffs-family functions at runtime" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds KUnit tests for ffs-family bit manipulation functions
- including ffs(), __ffs(), fls(), __fls(), fls64(), and __ffs64().
- These tests validate mathematical correctness, edge case handling,
- and cross-architecture consistency of bit scanning functions.
- For more information on KUnit and unit tests in general,
- please refer to Documentation/dev-tools/kunit/.
- config TEST_KSTRTOX
- tristate "Test kstrto*() 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_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_MISC_MINOR
- bool "miscdevice KUnit test" if !KUNIT_ALL_TESTS
- depends on KUNIT=y
- default KUNIT_ALL_TESTS
- help
- Kunit test for miscdevice API, specially its behavior in respect to
- static and dynamic minor numbers.
- 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 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_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"
- 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
- 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_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 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 FIND_BIT_BENCHMARK_RUST
- tristate "Test find_bit functions in Rust"
- depends on RUST
- help
- This builds the "find_bit_benchmark_rust" module. It is a micro
- benchmark that measures the performance of Rust functions that
- correspond to the find_*_bit() operations in C. It follows the
- FIND_BIT_BENCHMARK closely but will in general not yield same
- numbers due to extra bounds checks and overhead of foreign
- function calls.
- 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 BITOPS_KUNIT
- tristate "KUnit test for bitops" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test for the bitops library
- which provides functions for bit operations.
- Note that this is derived from the original test_bitops module.
- For micro-benchmarks and compiler warning checks, enable TEST_BITOPS.
- 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 UTIL_MACROS_KUNIT
- tristate "KUnit test util_macros.h functions at runtime" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- Enable this option to test the util_macros.h function 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
- select GET_FREE_REGION
- 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 KFIFO_KUNIT_TEST
- tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds the generic FIFO implementation KUnit test suite.
- It tests that the API and basic functionality of the kfifo type
- and associated macros.
- 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 LIST_PRIVATE_KUNIT_TEST
- tristate "KUnit Test for Kernel Private Linked-list structures" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds the KUnit test for the private linked-list primitives
- defined in include/linux/list_private.h.
- These primitives allow manipulation of list_head members that are
- marked as private and require special accessors (ACCESS_PRIVATE)
- to strip qualifiers or handle encapsulation.
- 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 CONTEXT_ANALYSIS_TEST
- bool "Compiler context-analysis warnings test"
- depends on EXPERT
- help
- This builds the test for compiler-based context analysis. The test
- does not add executable code to the kernel, but is meant to test that
- common patterns supported by the analysis do not result in false
- positive warnings.
- When adding support for new context locks, it is strongly recommended
- to add supported patterns to this test.
- If unsure, say N.
- config LIVEUPDATE_TEST
- bool "Live Update Kernel Test"
- default n
- depends on LIVEUPDATE
- help
- Enable a built-in kernel test module for the Live Update
- Orchestrator.
- This module validates the File-Lifecycle-Bound subsystem by
- registering a set of mock FLB objects with any real file handlers
- that support live update (such as the memfd handler).
- When live update operations are performed, this test module will
- output messages to the kernel log (dmesg), confirming that its
- registration and various callback functions (preserve, retrieve,
- finish, etc.) are being invoked correctly.
- This is a debugging and regression testing tool for developers
- working on the Live Update subsystem. It should not be enabled in
- production kernels.
- 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 BASE64_KUNIT
- tristate "KUnit test for base64 decoding and encoding" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds the base64 unit tests.
- The tests cover the encoding and decoding logic of Base64 functions
- in the kernel.
- In addition to correctness checks, simple performance benchmarks
- for both encoding and decoding are also included.
- 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 bit functions and macros" 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 MIN_HEAP_KUNIT_TEST
- tristate "Min heap test" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the min heap library
- which provides functions for creating and managing min heaps.
- The test suite checks the functionality of the min heap library.
- If unsure, say N
- 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 RANDSTRUCT_KUNIT_TEST
- tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which
- randomizes structure layouts.
- 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 or CONFIG_INIT_STACK_ALL_ZERO.
- 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 LONGEST_SYM_KUNIT_TEST
- tristate "Test the longest symbol possible" if !KUNIT_ALL_TESTS
- depends on KUNIT && KPROBES
- depends on !PREFIX_SYMBOLS && !CFI && !GCOV_KERNEL
- default KUNIT_ALL_TESTS
- help
- Tests the longest symbol possible
- If unsure, say N.
- 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 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 USERCOPY_KUNIT_TEST
- tristate "KUnit Test for user/kernel boundary protections"
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds the "usercopy_kunit" module that runs sanity checks
- on the copy_to/from_user infrastructure, making sure basic
- user/kernel boundary testing is working.
- config BLACKHOLE_DEV_KUNIT_TEST
- tristate "Test blackhole netdev functionality" if !KUNIT_ALL_TESTS
- depends on NET
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds the "blackhole_dev_kunit" module that validates the
- data path through this blackhole netdev.
- 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
- select TEST_LKM
- 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_RUNTIME
- bool
- config TEST_RUNTIME_MODULE
- bool
- config TEST_KALLSYMS
- tristate "module kallsyms find_symbol() test"
- depends on m
- select TEST_RUNTIME
- select TEST_RUNTIME_MODULE
- select TEST_KALLSYMS_A
- select TEST_KALLSYMS_B
- select TEST_KALLSYMS_C
- select TEST_KALLSYMS_D
- help
- This allows us to stress test find_symbol() through the kallsyms
- used to place symbols on the kernel ELF kallsyms and modules kallsyms
- where we place kernel symbols such as exported symbols.
- We have four test modules:
- A: has KALLSYSMS_NUMSYMS exported symbols
- B: uses one of A's symbols
- C: adds KALLSYMS_SCALE_FACTOR * KALLSYSMS_NUMSYMS exported
- D: adds 2 * the symbols than C
- We stress test find_symbol() through two means:
- 1) Upon load of B it will trigger simplify_symbols() to look for the
- one symbol it uses from the module A with tons of symbols. This is an
- indirect way for us to have B call resolve_symbol_wait() upon module
- load. This will eventually call find_symbol() which will eventually
- try to find the symbols used with find_exported_symbol_in_section().
- find_exported_symbol_in_section() uses bsearch() so a binary search
- for each symbol. Binary search will at worst be O(log(n)) so the
- larger TEST_MODULE_KALLSYSMS the worse the search.
- 2) The selftests should load C first, before B. Upon B's load towards
- the end right before we call module B's init routine we get
- complete_formation() called on the module. That will first check
- for duplicate symbols with the call to verify_exported_symbols().
- That is when we'll force iteration on module C's insane symbol list.
- Since it has 10 * KALLSYMS_NUMSYMS it means we can first test
- just loading B without C. The amount of time it takes to load C Vs
- B can give us an idea of the impact growth of the symbol space and
- give us projection. Module A only uses one symbol from B so to allow
- this scaling in module C to be proportional, if it used more symbols
- then the first test would be doing more and increasing just the
- search space would be slightly different. The last module, module D
- will just increase the search space by twice the number of symbols in
- C so to allow for full projects.
- tools/testing/selftests/module/find_symbol.sh
- The current defaults will incur a build delay of about 7 minutes
- on an x86_64 with only 8 cores. Enable this only if you want to
- stress test find_symbol() with thousands of symbols. At the same
- time this is also useful to test building modules with thousands of
- symbols, and if BTF is enabled this also stress tests adding BTF
- information for each module. Currently enabling many more symbols
- will segfault the build system.
- If unsure, say N.
- if TEST_KALLSYMS
- config TEST_KALLSYMS_A
- tristate
- depends on m
- config TEST_KALLSYMS_B
- tristate
- depends on m
- config TEST_KALLSYMS_C
- tristate
- depends on m
- config TEST_KALLSYMS_D
- tristate
- depends on m
- choice
- prompt "Kallsym test range"
- default TEST_KALLSYMS_LARGE
- help
- Selecting something other than "Fast" will enable tests which slow
- down the build and may crash your build.
- config TEST_KALLSYMS_FAST
- bool "Fast builds"
- help
- You won't really be testing kallsysms, so this just helps fast builds
- when allmodconfig is used..
- config TEST_KALLSYMS_LARGE
- bool "Enable testing kallsyms with large exports"
- help
- This will enable larger number of symbols. This will slow down
- your build considerably.
- config TEST_KALLSYMS_MAX
- bool "Known kallsysms limits"
- help
- This will enable exports to the point we know we'll start crashing
- builds.
- endchoice
- config TEST_KALLSYMS_NUMSYMS
- int "test kallsyms number of symbols"
- range 2 10000
- default 2 if TEST_KALLSYMS_FAST
- default 100 if TEST_KALLSYMS_LARGE
- default 10000 if TEST_KALLSYMS_MAX
- help
- The number of symbols to create on TEST_KALLSYMS_A, only one of which
- module TEST_KALLSYMS_B will use. This also will be used
- for how many symbols TEST_KALLSYMS_C will have, scaled up by
- TEST_KALLSYMS_SCALE_FACTOR. Note that setting this to 10,000 will
- trigger a segfault today, don't use anything close to it unless
- you are aware that this should not be used for automated build tests.
- config TEST_KALLSYMS_SCALE_FACTOR
- int "test kallsyms scale factor"
- default 8
- help
- How many more unusued symbols will TEST_KALLSYSMS_C have than
- TEST_KALLSYMS_A. If 8, then module C will have 8 * syms
- than module A. Then TEST_KALLSYMS_D will have double the amount
- of symbols than C so to allow projections.
- endif # TEST_KALLSYMS
- 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 ARCH_HAS_KERNEL_FPU_SUPPORT && !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.
- config TEST_KEXEC_HANDOVER
- bool "Test for Kexec HandOver"
- default n
- depends on KEXEC_HANDOVER
- help
- This option enables test for Kexec HandOver (KHO).
- The test consists of two parts: saving kernel data before kexec and
- restoring the data after kexec and verifying that it was properly
- handed over. This test module creates and saves data on the boot of
- the first kernel and restores and verifies the data on the boot of
- kexec'ed kernel.
- For detailed documentation about KHO, see Documentation/core-api/kho.
- To run the test run:
- tools/testing/selftests/kho/vmtest.sh -h
- If unsure, say N.
- config RATELIMIT_KUNIT_TEST
- tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This builds the "test_ratelimit" module that should be used
- for correctness verification and concurrent testings of rate
- limiting.
- If unsure, say N.
- config UUID_KUNIT_TEST
- tristate "KUnit test for UUID" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the uuid library,
- which provides functions for generating and parsing UUID and GUID.
- The test suite checks parsing of UUID and GUID strings.
- If unsure, say N.
- config INT_POW_KUNIT_TEST
- tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the int_pow function,
- which performs integer exponentiation. The test suite is designed to
- verify that the implementation of int_pow correctly computes the power
- of a given base raised to a given exponent.
- Enabling this option will include tests that check various scenarios
- and edge cases to ensure the accuracy and reliability of the exponentiation
- function.
- If unsure, say N
- config INT_SQRT_KUNIT_TEST
- tristate "Integer square root test" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the int_sqrt() function,
- which performs square root calculation. The test suite checks
- various scenarios, including edge cases, to ensure correctness.
- Enabling this option will include tests that check various scenarios
- and edge cases to ensure the accuracy and reliability of the square root
- function.
- If unsure, say N
- config INT_LOG_KUNIT_TEST
- tristate "Integer log (int_log) test" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the int_log library, which
- provides two functions to compute the integer logarithm in base 2 and
- base 10, called respectively as intlog2 and intlog10.
- If unsure, say N
- config GCD_KUNIT_TEST
- tristate "Greatest common divisor test" if !KUNIT_ALL_TESTS
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the gcd() function,
- which computes the greatest common divisor of two numbers.
- This test suite verifies the correctness of gcd() across various
- scenarios, including edge cases.
- If unsure, say N
- config PRIME_NUMBERS_KUNIT_TEST
- tristate "Prime number generator test" if !KUNIT_ALL_TESTS
- depends on KUNIT
- depends on PRIME_NUMBERS
- default KUNIT_ALL_TESTS
- help
- This option enables the KUnit test suite for the {is,next}_prime_number
- functions.
- Enabling this option will include tests that compare the prime number
- generator functions against a brute force implementation.
- If unsure, say N
- config GLOB_KUNIT_TEST
- tristate "Glob matching test" if !KUNIT_ALL_TESTS
- depends on GLOB
- depends on KUNIT
- default KUNIT_ALL_TESTS
- help
- Enable this option to test the glob functions at runtime.
- This test suite verifies the correctness of glob_match() across various
- scenarios, including edge cases.
- 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 `build_error!` and `build_assert!` are handled during the 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
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