1936 lines
65 KiB
Plaintext
1936 lines
65 KiB
Plaintext
menu "printk and dmesg options"
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config PRINTK_TIME
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bool "Show timing information on printks"
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depends on PRINTK
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help
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Selecting this option causes time stamps of the printk()
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messages to be added to the output of the syslog() system
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call and at the console.
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The timestamp is always recorded internally, and exported
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to /dev/kmsg. This flag just specifies if the timestamp should
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be included, not that the timestamp is recorded.
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The behavior is also controlled by the kernel command line
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parameter printk.time=1. See Documentation/kernel-parameters.txt
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config MESSAGE_LOGLEVEL_DEFAULT
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int "Default message log level (1-7)"
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range 1 7
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default "4"
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help
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Default log level for printk statements with no specified priority.
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This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
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that are auditing their logs closely may want to set it to a lower
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priority.
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config BOOT_PRINTK_DELAY
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bool "Delay each boot printk message by N milliseconds"
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depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
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help
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This build option allows you to read kernel boot messages
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by inserting a short delay after each one. The delay is
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specified in milliseconds on the kernel command line,
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using "boot_delay=N".
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It is likely that you would also need to use "lpj=M" to preset
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the "loops per jiffie" value.
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See a previous boot log for the "lpj" value to use for your
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system, and then set "lpj=M" before setting "boot_delay=N".
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NOTE: Using this option may adversely affect SMP systems.
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I.e., processors other than the first one may not boot up.
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BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
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what it believes to be lockup conditions.
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config DYNAMIC_DEBUG
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bool "Enable dynamic printk() support"
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default n
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depends on PRINTK
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depends on DEBUG_FS
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help
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Compiles debug level messages into the kernel, which would not
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otherwise be available at runtime. These messages can then be
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enabled/disabled based on various levels of scope - per source file,
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function, module, format string, and line number. This mechanism
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implicitly compiles in all pr_debug() and dev_dbg() calls, which
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enlarges the kernel text size by about 2%.
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If a source file is compiled with DEBUG flag set, any
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pr_debug() calls in it are enabled by default, but can be
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disabled at runtime as below. Note that DEBUG flag is
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turned on by many CONFIG_*DEBUG* options.
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Usage:
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Dynamic debugging is controlled via the 'dynamic_debug/control' file,
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which is contained in the 'debugfs' filesystem. Thus, the debugfs
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filesystem must first be mounted before making use of this feature.
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We refer the control file as: <debugfs>/dynamic_debug/control. This
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file contains a list of the debug statements that can be enabled. The
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format for each line of the file is:
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filename:lineno [module]function flags format
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filename : source file of the debug statement
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lineno : line number of the debug statement
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module : module that contains the debug statement
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function : function that contains the debug statement
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flags : '=p' means the line is turned 'on' for printing
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format : the format used for the debug statement
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From a live system:
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nullarbor:~ # cat <debugfs>/dynamic_debug/control
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# filename:lineno [module]function flags format
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fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
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fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
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fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
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Example usage:
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// enable the message at line 1603 of file svcsock.c
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nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
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<debugfs>/dynamic_debug/control
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// enable all the messages in file svcsock.c
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nullarbor:~ # echo -n 'file svcsock.c +p' >
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<debugfs>/dynamic_debug/control
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// enable all the messages in the NFS server module
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nullarbor:~ # echo -n 'module nfsd +p' >
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<debugfs>/dynamic_debug/control
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// enable all 12 messages in the function svc_process()
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nullarbor:~ # echo -n 'func svc_process +p' >
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<debugfs>/dynamic_debug/control
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// disable all 12 messages in the function svc_process()
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nullarbor:~ # echo -n 'func svc_process -p' >
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<debugfs>/dynamic_debug/control
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See Documentation/dynamic-debug-howto.txt for additional information.
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endmenu # "printk and dmesg options"
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menu "Compile-time checks and compiler options"
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config DEBUG_INFO
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bool "Compile the kernel with debug info"
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depends on DEBUG_KERNEL && !COMPILE_TEST
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help
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If you say Y here the resulting kernel image will include
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debugging info resulting in a larger kernel image.
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This adds debug symbols to the kernel and modules (gcc -g), and
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is needed if you intend to use kernel crashdump or binary object
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tools like crash, kgdb, LKCD, gdb, etc on the kernel.
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Say Y here only if you plan to debug the kernel.
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If unsure, say N.
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config DEBUG_INFO_REDUCED
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bool "Reduce debugging information"
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depends on DEBUG_INFO
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help
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If you say Y here gcc is instructed to generate less debugging
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information for structure types. This means that tools that
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need full debugging information (like kgdb or systemtap) won't
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be happy. But if you merely need debugging information to
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resolve line numbers there is no loss. Advantage is that
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build directory object sizes shrink dramatically over a full
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DEBUG_INFO build and compile times are reduced too.
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Only works with newer gcc versions.
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config DEBUG_INFO_SPLIT
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bool "Produce split debuginfo in .dwo files"
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depends on DEBUG_INFO
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help
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Generate debug info into separate .dwo files. This significantly
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reduces the build directory size for builds with DEBUG_INFO,
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because it stores the information only once on disk in .dwo
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files instead of multiple times in object files and executables.
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In addition the debug information is also compressed.
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Requires recent gcc (4.7+) and recent gdb/binutils.
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Any tool that packages or reads debug information would need
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to know about the .dwo files and include them.
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Incompatible with older versions of ccache.
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config DEBUG_INFO_DWARF4
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bool "Generate dwarf4 debuginfo"
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depends on DEBUG_INFO
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help
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Generate dwarf4 debug info. This requires recent versions
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of gcc and gdb. It makes the debug information larger.
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But it significantly improves the success of resolving
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variables in gdb on optimized code.
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config GDB_SCRIPTS
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bool "Provide GDB scripts for kernel debugging"
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depends on DEBUG_INFO
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help
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This creates the required links to GDB helper scripts in the
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build directory. If you load vmlinux into gdb, the helper
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scripts will be automatically imported by gdb as well, and
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additional functions are available to analyze a Linux kernel
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instance. See Documentation/gdb-kernel-debugging.txt for further
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details.
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config ENABLE_WARN_DEPRECATED
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bool "Enable __deprecated logic"
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default y
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help
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Enable the __deprecated logic in the kernel build.
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Disable this to suppress the "warning: 'foo' is deprecated
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(declared at kernel/power/somefile.c:1234)" messages.
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config ENABLE_MUST_CHECK
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bool "Enable __must_check logic"
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default y
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help
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Enable the __must_check logic in the kernel build. Disable this to
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suppress the "warning: ignoring return value of 'foo', declared with
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attribute warn_unused_result" messages.
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config FRAME_WARN
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int "Warn for stack frames larger than (needs gcc 4.4)"
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range 0 8192
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default 0 if KASAN
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default 1024 if !64BIT
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default 2048 if 64BIT
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help
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Tell gcc to warn at build time for stack frames larger than this.
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Setting this too low will cause a lot of warnings.
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Setting it to 0 disables the warning.
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Requires gcc 4.4
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config STRIP_ASM_SYMS
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bool "Strip assembler-generated symbols during link"
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default n
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help
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Strip internal assembler-generated symbols during a link (symbols
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that look like '.Lxxx') so they don't pollute the output of
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get_wchan() and suchlike.
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config READABLE_ASM
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bool "Generate readable assembler code"
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depends on DEBUG_KERNEL
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help
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Disable some compiler optimizations that tend to generate human unreadable
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assembler output. This may make the kernel slightly slower, but it helps
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to keep kernel developers who have to stare a lot at assembler listings
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sane.
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config UNUSED_SYMBOLS
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bool "Enable unused/obsolete exported symbols"
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default y if X86
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help
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Unused but exported symbols make the kernel needlessly bigger. For
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that reason most of these unused exports will soon be removed. This
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option is provided temporarily to provide a transition period in case
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some external kernel module needs one of these symbols anyway. If you
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encounter such a case in your module, consider if you are actually
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using the right API. (rationale: since nobody in the kernel is using
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this in a module, there is a pretty good chance it's actually the
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wrong interface to use). If you really need the symbol, please send a
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mail to the linux kernel mailing list mentioning the symbol and why
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you really need it, and what the merge plan to the mainline kernel for
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your module is.
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config PAGE_OWNER
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bool "Track page owner"
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depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
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select DEBUG_FS
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select STACKTRACE
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select PAGE_EXTENSION
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help
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This keeps track of what call chain is the owner of a page, may
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help to find bare alloc_page(s) leaks. Even if you include this
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feature on your build, it is disabled in default. You should pass
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"page_owner=on" to boot parameter in order to enable it. Eats
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a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
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for user-space helper.
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If unsure, say N.
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config DEBUG_FS
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bool "Debug Filesystem"
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help
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debugfs is a virtual file system that kernel developers use to put
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debugging files into. Enable this option to be able to read and
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write to these files.
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For detailed documentation on the debugfs API, see
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Documentation/DocBook/filesystems.
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If unsure, say N.
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config HEADERS_CHECK
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bool "Run 'make headers_check' when building vmlinux"
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depends on !UML
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help
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This option will extract the user-visible kernel headers whenever
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building the kernel, and will run basic sanity checks on them to
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ensure that exported files do not attempt to include files which
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were not exported, etc.
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If you're making modifications to header files which are
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relevant for userspace, say 'Y', and check the headers
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exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
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your build tree), to make sure they're suitable.
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config DEBUG_SECTION_MISMATCH
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bool "Enable full Section mismatch analysis"
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help
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The section mismatch analysis checks if there are illegal
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references from one section to another section.
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During linktime or runtime, some sections are dropped;
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any use of code/data previously in these sections would
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most likely result in an oops.
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In the code, functions and variables are annotated with
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__init,, etc. (see the full list in include/linux/init.h),
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which results in the code/data being placed in specific sections.
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The section mismatch analysis is always performed after a full
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kernel build, and enabling this option causes the following
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additional steps to occur:
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- Add the option -fno-inline-functions-called-once to gcc commands.
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When inlining a function annotated with __init in a non-init
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function, we would lose the section information and thus
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the analysis would not catch the illegal reference.
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This option tells gcc to inline less (but it does result in
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a larger kernel).
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- Run the section mismatch analysis for each module/built-in.o file.
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When we run the section mismatch analysis on vmlinux.o, we
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lose valueble information about where the mismatch was
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introduced.
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Running the analysis for each module/built-in.o file
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tells where the mismatch happens much closer to the
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source. The drawback is that the same mismatch is
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reported at least twice.
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- Enable verbose reporting from modpost in order to help resolve
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the section mismatches that are reported.
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config SECTION_MISMATCH_WARN_ONLY
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bool "Make section mismatch errors non-fatal"
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default y
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help
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If you say N here, the build process will fail if there are any
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section mismatch, instead of just throwing warnings.
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If unsure, say Y.
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#
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# Select this config option from the architecture Kconfig, if it
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# is preferred to always offer frame pointers as a config
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# option on the architecture (regardless of KERNEL_DEBUG):
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#
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config ARCH_WANT_FRAME_POINTERS
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bool
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help
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config FRAME_POINTER
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bool "Compile the kernel with frame pointers"
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depends on DEBUG_KERNEL && \
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(CRIS || M68K || FRV || UML || \
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AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
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ARCH_WANT_FRAME_POINTERS
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default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
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help
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If you say Y here the resulting kernel image will be slightly
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larger and slower, but it gives very useful debugging information
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in case of kernel bugs. (precise oopses/stacktraces/warnings)
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config DEBUG_FORCE_WEAK_PER_CPU
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bool "Force weak per-cpu definitions"
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depends on DEBUG_KERNEL
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help
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s390 and alpha require percpu variables in modules to be
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defined weak to work around addressing range issue which
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puts the following two restrictions on percpu variable
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definitions.
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1. percpu symbols must be unique whether static or not
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2. percpu variables can't be defined inside a function
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To ensure that generic code follows the above rules, this
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option forces all percpu variables to be defined as weak.
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endmenu # "Compiler options"
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config MAGIC_SYSRQ
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bool "Magic SysRq key"
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depends on !UML
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help
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If you say Y here, you will have some control over the system even
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if the system crashes for example during kernel debugging (e.g., you
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will be able to flush the buffer cache to disk, reboot the system
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immediately or dump some status information). This is accomplished
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by pressing various keys while holding SysRq (Alt+PrintScreen). It
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also works on a serial console (on PC hardware at least), if you
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send a BREAK and then within 5 seconds a command keypress. The
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keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
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unless you really know what this hack does.
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config MAGIC_SYSRQ_DEFAULT_ENABLE
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hex "Enable magic SysRq key functions by default"
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depends on MAGIC_SYSRQ
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default 0x1
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help
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Specifies which SysRq key functions are enabled by default.
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This may be set to 1 or 0 to enable or disable them all, or
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to a bitmask as described in Documentation/sysrq.txt.
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config DEBUG_KERNEL
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bool "Kernel debugging"
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help
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Say Y here if you are developing drivers or trying to debug and
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identify kernel problems.
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menu "Memory Debugging"
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source mm/Kconfig.debug
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config DEBUG_OBJECTS
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bool "Debug object operations"
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depends on DEBUG_KERNEL
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help
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If you say Y here, additional code will be inserted into the
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kernel to track the life time of various objects and validate
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the operations on those objects.
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config DEBUG_OBJECTS_SELFTEST
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bool "Debug objects selftest"
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depends on DEBUG_OBJECTS
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help
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This enables the selftest of the object debug code.
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config DEBUG_OBJECTS_FREE
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bool "Debug objects in freed memory"
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depends on DEBUG_OBJECTS
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help
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This enables checks whether a k/v free operation frees an area
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which contains an object which has not been deactivated
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properly. This can make kmalloc/kfree-intensive workloads
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much slower.
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config DEBUG_OBJECTS_TIMERS
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bool "Debug timer objects"
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depends on DEBUG_OBJECTS
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help
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If you say Y here, additional code will be inserted into the
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timer routines to track the life time of timer objects and
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validate the timer operations.
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config DEBUG_OBJECTS_WORK
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bool "Debug work objects"
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depends on DEBUG_OBJECTS
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help
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If you say Y here, additional code will be inserted into the
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work queue routines to track the life time of work objects and
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validate the work operations.
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config DEBUG_OBJECTS_RCU_HEAD
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bool "Debug RCU callbacks objects"
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depends on DEBUG_OBJECTS
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help
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Enable this to turn on debugging of RCU list heads (call_rcu() usage).
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config DEBUG_OBJECTS_PERCPU_COUNTER
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bool "Debug percpu counter objects"
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depends on DEBUG_OBJECTS
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help
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If you say Y here, additional code will be inserted into the
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percpu counter routines to track the life time of percpu counter
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objects and validate the percpu counter operations.
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config DEBUG_OBJECTS_ENABLE_DEFAULT
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int "debug_objects bootup default value (0-1)"
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range 0 1
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default "1"
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depends on DEBUG_OBJECTS
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help
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Debug objects boot parameter default value
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config DEBUG_SLAB
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bool "Debug slab memory allocations"
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depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
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help
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Say Y here to have the kernel do limited verification on memory
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allocation as well as poisoning memory on free to catch use of freed
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memory. This can make kmalloc/kfree-intensive workloads much slower.
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config DEBUG_SLAB_LEAK
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bool "Memory leak debugging"
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depends on DEBUG_SLAB
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config SLUB_DEBUG_ON
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bool "SLUB debugging on by default"
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depends on SLUB && SLUB_DEBUG && !KMEMCHECK
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default n
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help
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Boot with debugging on by default. SLUB boots by default with
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the runtime debug capabilities switched off. Enabling this is
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equivalent to specifying the "slub_debug" parameter on boot.
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There is no support for more fine grained debug control like
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possible with slub_debug=xxx. SLUB debugging may be switched
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off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
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"slub_debug=-".
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config SLUB_STATS
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default n
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bool "Enable SLUB performance statistics"
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depends on SLUB && SYSFS
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help
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SLUB statistics are useful to debug SLUBs allocation behavior in
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order find ways to optimize the allocator. This should never be
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enabled for production use since keeping statistics slows down
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the allocator by a few percentage points. The slabinfo command
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supports the determination of the most active slabs to figure
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out which slabs are relevant to a particular load.
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Try running: slabinfo -DA
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config HAVE_DEBUG_KMEMLEAK
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bool
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config DEBUG_KMEMLEAK
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bool "Kernel memory leak detector"
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depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
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select DEBUG_FS
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select STACKTRACE if STACKTRACE_SUPPORT
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select KALLSYMS
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select CRC32
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help
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Say Y here if you want to enable the memory leak
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detector. The memory allocation/freeing is traced in a way
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similar to the Boehm's conservative garbage collector, the
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difference being that the orphan objects are not freed but
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only shown in /sys/kernel/debug/kmemleak. Enabling this
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feature will introduce an overhead to memory
|
|
allocations. See Documentation/kmemleak.txt for more
|
|
details.
|
|
|
|
Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
|
|
of finding leaks due to the slab objects poisoning.
|
|
|
|
In order to access the kmemleak file, debugfs needs to be
|
|
mounted (usually at /sys/kernel/debug).
|
|
|
|
config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
|
|
int "Maximum kmemleak early log entries"
|
|
depends on DEBUG_KMEMLEAK
|
|
range 200 40000
|
|
default 400
|
|
help
|
|
Kmemleak must track all the memory allocations to avoid
|
|
reporting false positives. Since memory may be allocated or
|
|
freed before kmemleak is initialised, an early log buffer is
|
|
used to store these actions. If kmemleak reports "early log
|
|
buffer exceeded", please increase this value.
|
|
|
|
config DEBUG_KMEMLEAK_TEST
|
|
tristate "Simple test for the kernel memory leak detector"
|
|
depends on DEBUG_KMEMLEAK && m
|
|
help
|
|
This option enables a module that explicitly leaks memory.
|
|
|
|
If unsure, say N.
|
|
|
|
config DEBUG_KMEMLEAK_DEFAULT_OFF
|
|
bool "Default kmemleak to off"
|
|
depends on DEBUG_KMEMLEAK
|
|
help
|
|
Say Y here to disable kmemleak by default. It can then be enabled
|
|
on the command line via kmemleak=on.
|
|
|
|
config DEBUG_STACK_USAGE
|
|
bool "Stack utilization instrumentation"
|
|
depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
|
|
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.
|
|
|
|
This option will slow down process creation somewhat.
|
|
|
|
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_VMACACHE
|
|
bool "Debug VMA caching"
|
|
depends on DEBUG_VM
|
|
help
|
|
Enable this to turn on VMA caching debug information. Doing so
|
|
can cause significant overhead, so only enable it in non-production
|
|
environments.
|
|
|
|
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_VIRTUAL
|
|
bool "Debug VM translations"
|
|
depends on DEBUG_KERNEL && X86
|
|
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_SPARSE && 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_HIGHMEM
|
|
bool "Highmem debugging"
|
|
depends on DEBUG_KERNEL && HIGHMEM
|
|
help
|
|
This option enables additional error checking for high memory
|
|
systems. Disable for production systems.
|
|
|
|
config HAVE_DEBUG_STACKOVERFLOW
|
|
bool
|
|
|
|
config DEBUG_STACKOVERFLOW
|
|
bool "Check for stack overflows"
|
|
depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
|
|
---help---
|
|
Say Y here if you want to check for overflows of kernel, IRQ
|
|
and exception stacks (if your architecture uses them). This
|
|
option will show detailed messages if free stack space drops
|
|
below a certain limit.
|
|
|
|
These kinds of bugs usually occur when call-chains in the
|
|
kernel get too deep, especially when interrupts are
|
|
involved.
|
|
|
|
Use this in cases where you see apparently random memory
|
|
corruption, especially if it appears in 'struct thread_info'
|
|
|
|
If in doubt, say "N".
|
|
|
|
source "lib/Kconfig.kmemcheck"
|
|
|
|
source "lib/Kconfig.kasan"
|
|
|
|
endmenu # "Memory Debugging"
|
|
|
|
config DEBUG_SHIRQ
|
|
bool "Debug shared IRQ handlers"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to generate a spurious interrupt as soon as a shared
|
|
interrupt handler is registered, and just before one is deregistered.
|
|
Drivers ought to be able to handle interrupts coming in at those
|
|
points; some don't and need to be caught.
|
|
|
|
menu "Debug Lockups and Hangs"
|
|
|
|
config LOCKUP_DETECTOR
|
|
bool "Detect Hard and Soft Lockups"
|
|
depends on DEBUG_KERNEL && !S390
|
|
help
|
|
Say Y here to enable the kernel to act as a watchdog to detect
|
|
hard and 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.
|
|
|
|
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.
|
|
|
|
The overhead should be minimal. A periodic hrtimer runs to
|
|
generate interrupts and kick the watchdog task every 4 seconds.
|
|
An NMI is generated every 10 seconds or so to check for hardlockups.
|
|
|
|
The frequency of hrtimer and NMI events and the soft and hard lockup
|
|
thresholds can be controlled through the sysctl watchdog_thresh.
|
|
|
|
config HARDLOCKUP_DETECTOR
|
|
def_bool y
|
|
depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
|
|
depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
|
|
|
|
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 BOOTPARAM_HARDLOCKUP_PANIC_VALUE
|
|
int
|
|
depends on HARDLOCKUP_DETECTOR
|
|
range 0 1
|
|
default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
|
|
default 1 if BOOTPARAM_HARDLOCKUP_PANIC
|
|
|
|
config BOOTPARAM_SOFTLOCKUP_PANIC
|
|
bool "Panic (Reboot) On Soft Lockups"
|
|
depends on LOCKUP_DETECTOR
|
|
help
|
|
Say Y here to enable the kernel to panic on "soft lockups",
|
|
which are bugs that cause the kernel to loop in kernel
|
|
mode for more than 20 seconds (configurable using the watchdog_thresh
|
|
sysctl), without giving other tasks a chance to run.
|
|
|
|
The panic can be used in combination with panic_timeout,
|
|
to cause the system to reboot automatically after a
|
|
lockup has been detected. This feature is useful for
|
|
high-availability systems that have uptime guarantees and
|
|
where a lockup must be resolved ASAP.
|
|
|
|
Say N if unsure.
|
|
|
|
config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
|
|
int
|
|
depends on LOCKUP_DETECTOR
|
|
range 0 1
|
|
default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
|
|
default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
|
|
|
|
config DETECT_HUNG_TASK
|
|
bool "Detect Hung Tasks"
|
|
depends on DEBUG_KERNEL
|
|
default LOCKUP_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 indefinitiley.
|
|
|
|
When a hung task is detected, the kernel will print the
|
|
current stack trace (which you should report), but the
|
|
task will stay in uninterruptible state. If lockdep is
|
|
enabled then all held locks will also be reported. This
|
|
feature has negligible overhead.
|
|
|
|
config DEFAULT_HUNG_TASK_TIMEOUT
|
|
int "Default timeout for hung task detection (in seconds)"
|
|
depends on DETECT_HUNG_TASK
|
|
default 120
|
|
help
|
|
This option controls the default timeout (in seconds) used
|
|
to determine when a task has become non-responsive and should
|
|
be considered hung.
|
|
|
|
It can be adjusted at runtime via the kernel.hung_task_timeout_secs
|
|
sysctl or by writing a value to
|
|
/proc/sys/kernel/hung_task_timeout_secs.
|
|
|
|
A timeout of 0 disables the check. The default is two minutes.
|
|
Keeping the default should be fine in most cases.
|
|
|
|
config BOOTPARAM_HUNG_TASK_PANIC
|
|
bool "Panic (Reboot) On Hung Tasks"
|
|
depends on DETECT_HUNG_TASK
|
|
help
|
|
Say Y here to enable the kernel to panic on "hung tasks",
|
|
which are bugs that cause the kernel to leave a task stuck
|
|
in uninterruptible "D" state.
|
|
|
|
The panic can be used in combination with panic_timeout,
|
|
to cause the system to reboot automatically after a
|
|
hung task has been detected. This feature is useful for
|
|
high-availability systems that have uptime guarantees and
|
|
where a hung tasks must be resolved ASAP.
|
|
|
|
Say N if unsure.
|
|
|
|
config BOOTPARAM_HUNG_TASK_PANIC_VALUE
|
|
int
|
|
depends on DETECT_HUNG_TASK
|
|
range 0 1
|
|
default 0 if !BOOTPARAM_HUNG_TASK_PANIC
|
|
default 1 if BOOTPARAM_HUNG_TASK_PANIC
|
|
|
|
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.
|
|
|
|
endmenu # "Debug lockups and hangs"
|
|
|
|
config PANIC_ON_OOPS
|
|
bool "Panic on Oops"
|
|
help
|
|
Say Y here to enable the kernel to panic when it oopses. This
|
|
has the same effect as setting oops=panic on the kernel command
|
|
line.
|
|
|
|
This feature is useful to ensure that the kernel does not do
|
|
anything erroneous after an oops which could result in data
|
|
corruption or other issues.
|
|
|
|
Say N if unsure.
|
|
|
|
config PANIC_ON_OOPS_VALUE
|
|
int
|
|
range 0 1
|
|
default 0 if !PANIC_ON_OOPS
|
|
default 1 if PANIC_ON_OOPS
|
|
|
|
config PANIC_TIMEOUT
|
|
int "panic timeout"
|
|
default 0
|
|
help
|
|
Set the timeout value (in seconds) until a reboot occurs when the
|
|
the kernel panics. If n = 0, then we wait forever. A timeout
|
|
value n > 0 will wait n seconds before rebooting, while a timeout
|
|
value n < 0 will reboot immediately.
|
|
|
|
config SCHED_DEBUG
|
|
bool "Collect scheduler debugging info"
|
|
depends on DEBUG_KERNEL && PROC_FS
|
|
default y
|
|
help
|
|
If you say Y here, the /proc/sched_debug file will be provided
|
|
that can help debug the scheduler. The runtime overhead of this
|
|
option is minimal.
|
|
|
|
config SCHED_INFO
|
|
bool
|
|
default n
|
|
|
|
config SCHEDSTATS
|
|
bool "Collect scheduler statistics"
|
|
depends on DEBUG_KERNEL && PROC_FS
|
|
select SCHED_INFO
|
|
help
|
|
If you say Y here, additional code will be inserted into the
|
|
scheduler and related routines to collect statistics about
|
|
scheduler behavior and provide them in /proc/schedstat. These
|
|
stats may be useful for both tuning and debugging the scheduler
|
|
If you aren't debugging the scheduler or trying to tune a specific
|
|
application, you can say N to avoid the very slight overhead
|
|
this adds.
|
|
|
|
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 DEBUG_TIMEKEEPING
|
|
bool "Enable extra timekeeping sanity checking"
|
|
help
|
|
This option will enable additional timekeeping sanity checks
|
|
which may be helpful when diagnosing issues where timekeeping
|
|
problems are suspected.
|
|
|
|
This may include checks in the timekeeping hotpaths, so this
|
|
option may have a (very small) performance impact to some
|
|
workloads.
|
|
|
|
If unsure, say N.
|
|
|
|
config TIMER_STATS
|
|
bool "Collect kernel timers statistics"
|
|
depends on DEBUG_KERNEL && PROC_FS
|
|
help
|
|
If you say Y here, additional code will be inserted into the
|
|
timer routines to collect statistics about kernel timers being
|
|
reprogrammed. The statistics can be read from /proc/timer_stats.
|
|
The statistics collection is started by writing 1 to /proc/timer_stats,
|
|
writing 0 stops it. This feature is useful to collect information
|
|
about timer usage patterns in kernel and userspace. This feature
|
|
is lightweight if enabled in the kernel config but not activated
|
|
(it defaults to deactivated on bootup and will only be activated
|
|
if some application like powertop activates it explicitly).
|
|
|
|
config DEBUG_PREEMPT
|
|
bool "Debug preemptible kernel"
|
|
depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
|
|
default y
|
|
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.
|
|
|
|
menu "Lock Debugging (spinlocks, mutexes, etc...)"
|
|
|
|
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
|
|
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 && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select DEBUG_LOCK_ALLOC
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_MUTEXES
|
|
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_LOCK_ALLOC
|
|
bool "Lock debugging: detect incorrect freeing of live locks"
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_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 PROVE_LOCKING
|
|
bool "Lock debugging: prove locking correctness"
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select LOCKDEP
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_MUTEXES
|
|
select DEBUG_LOCK_ALLOC
|
|
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.txt.
|
|
|
|
config LOCKDEP
|
|
bool
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select STACKTRACE
|
|
select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
|
|
select KALLSYMS
|
|
select KALLSYMS_ALL
|
|
|
|
config LOCK_STAT
|
|
bool "Lock usage statistics"
|
|
depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
|
|
select LOCKDEP
|
|
select DEBUG_SPINLOCK
|
|
select DEBUG_MUTEXES
|
|
select DEBUG_LOCK_ALLOC
|
|
default n
|
|
help
|
|
This feature enables tracking lock contention points
|
|
|
|
For more details, see Documentation/locking/lockstat.txt
|
|
|
|
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_LOCKDEP
|
|
bool "Lock dependency engine debugging"
|
|
depends on DEBUG_KERNEL && LOCKDEP
|
|
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
|
|
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 wont 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
|
|
default n
|
|
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.
|
|
|
|
endmenu # lock debugging
|
|
|
|
config TRACE_IRQFLAGS
|
|
bool
|
|
help
|
|
Enables hooks to interrupt enabling and disabling for
|
|
either tracing or lock debugging.
|
|
|
|
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 it's
|
|
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
|
|
|
|
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_LIST
|
|
bool "Debug linked list manipulation"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to turn on extended checks in the linked-list
|
|
walking routines.
|
|
|
|
If unsure, say N.
|
|
|
|
config DEBUG_PI_LIST
|
|
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_CREDENTIALS
|
|
bool "Debug credential management"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to turn on some debug checking for credential
|
|
management. The additional code keeps track of the number of
|
|
pointers from task_structs to any given cred struct, and checks to
|
|
see that this number never exceeds the usage count of the cred
|
|
struct.
|
|
|
|
Furthermore, if SELinux is enabled, this also checks that the
|
|
security pointer in the cred struct is never seen to be invalid.
|
|
|
|
If unsure, say N.
|
|
|
|
menu "RCU Debugging"
|
|
|
|
config PROVE_RCU
|
|
def_bool PROVE_LOCKING
|
|
|
|
config PROVE_RCU_REPEATEDLY
|
|
bool "RCU debugging: don't disable PROVE_RCU on first splat"
|
|
depends on PROVE_RCU
|
|
default n
|
|
help
|
|
By itself, PROVE_RCU will disable checking upon issuing the
|
|
first warning (or "splat"). This feature prevents such
|
|
disabling, allowing multiple RCU-lockdep warnings to be printed
|
|
on a single reboot.
|
|
|
|
Say Y to allow multiple RCU-lockdep warnings per boot.
|
|
|
|
Say N if you are unsure.
|
|
|
|
config SPARSE_RCU_POINTER
|
|
bool "RCU debugging: sparse-based checks for pointer usage"
|
|
default n
|
|
help
|
|
This feature enables the __rcu sparse annotation for
|
|
RCU-protected pointers. This annotation will cause sparse
|
|
to flag any non-RCU used of annotated pointers. This can be
|
|
helpful when debugging RCU usage. Please note that this feature
|
|
is not intended to enforce code cleanliness; it is instead merely
|
|
a debugging aid.
|
|
|
|
Say Y to make sparse flag questionable use of RCU-protected pointers
|
|
|
|
Say N if you are unsure.
|
|
|
|
config TORTURE_TEST
|
|
tristate
|
|
default n
|
|
|
|
config RCU_TORTURE_TEST
|
|
tristate "torture tests for RCU"
|
|
depends on DEBUG_KERNEL
|
|
select TORTURE_TEST
|
|
select SRCU
|
|
select TASKS_RCU
|
|
default n
|
|
help
|
|
This option provides a kernel module that runs torture tests
|
|
on the RCU infrastructure. The kernel module may be built
|
|
after the fact on the running kernel to be tested, if desired.
|
|
|
|
Say Y here if you want RCU torture tests to be built into
|
|
the kernel.
|
|
Say M if you want the RCU torture tests to build as a module.
|
|
Say N if you are unsure.
|
|
|
|
config RCU_TORTURE_TEST_RUNNABLE
|
|
bool "torture tests for RCU runnable by default"
|
|
depends on RCU_TORTURE_TEST = y
|
|
default n
|
|
help
|
|
This option provides a way to build the RCU torture tests
|
|
directly into the kernel without them starting up at boot
|
|
time. You can use /proc/sys/kernel/rcutorture_runnable
|
|
to manually override this setting. This /proc file is
|
|
available only when the RCU torture tests have been built
|
|
into the kernel.
|
|
|
|
Say Y here if you want the RCU torture tests to start during
|
|
boot (you probably don't).
|
|
Say N here if you want the RCU torture tests to start only
|
|
after being manually enabled via /proc.
|
|
|
|
config RCU_TORTURE_TEST_SLOW_PREINIT
|
|
bool "Slow down RCU grace-period pre-initialization to expose races"
|
|
depends on RCU_TORTURE_TEST
|
|
help
|
|
This option delays grace-period pre-initialization (the
|
|
propagation of CPU-hotplug changes up the rcu_node combining
|
|
tree) for a few jiffies between initializing each pair of
|
|
consecutive rcu_node structures. This helps to expose races
|
|
involving grace-period pre-initialization, in other words, it
|
|
makes your kernel less stable. It can also greatly increase
|
|
grace-period latency, especially on systems with large numbers
|
|
of CPUs. This is useful when torture-testing RCU, but in
|
|
almost no other circumstance.
|
|
|
|
Say Y here if you want your system to crash and hang more often.
|
|
Say N if you want a sane system.
|
|
|
|
config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
|
|
int "How much to slow down RCU grace-period pre-initialization"
|
|
range 0 5
|
|
default 3
|
|
depends on RCU_TORTURE_TEST_SLOW_PREINIT
|
|
help
|
|
This option specifies the number of jiffies to wait between
|
|
each rcu_node structure pre-initialization step.
|
|
|
|
config RCU_TORTURE_TEST_SLOW_INIT
|
|
bool "Slow down RCU grace-period initialization to expose races"
|
|
depends on RCU_TORTURE_TEST
|
|
help
|
|
This option delays grace-period initialization for a few
|
|
jiffies between initializing each pair of consecutive
|
|
rcu_node structures. This helps to expose races involving
|
|
grace-period initialization, in other words, it makes your
|
|
kernel less stable. It can also greatly increase grace-period
|
|
latency, especially on systems with large numbers of CPUs.
|
|
This is useful when torture-testing RCU, but in almost no
|
|
other circumstance.
|
|
|
|
Say Y here if you want your system to crash and hang more often.
|
|
Say N if you want a sane system.
|
|
|
|
config RCU_TORTURE_TEST_SLOW_INIT_DELAY
|
|
int "How much to slow down RCU grace-period initialization"
|
|
range 0 5
|
|
default 3
|
|
depends on RCU_TORTURE_TEST_SLOW_INIT
|
|
help
|
|
This option specifies the number of jiffies to wait between
|
|
each rcu_node structure initialization.
|
|
|
|
config RCU_TORTURE_TEST_SLOW_CLEANUP
|
|
bool "Slow down RCU grace-period cleanup to expose races"
|
|
depends on RCU_TORTURE_TEST
|
|
help
|
|
This option delays grace-period cleanup for a few jiffies
|
|
between cleaning up each pair of consecutive rcu_node
|
|
structures. This helps to expose races involving grace-period
|
|
cleanup, in other words, it makes your kernel less stable.
|
|
It can also greatly increase grace-period latency, especially
|
|
on systems with large numbers of CPUs. This is useful when
|
|
torture-testing RCU, but in almost no other circumstance.
|
|
|
|
Say Y here if you want your system to crash and hang more often.
|
|
Say N if you want a sane system.
|
|
|
|
config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
|
|
int "How much to slow down RCU grace-period cleanup"
|
|
range 0 5
|
|
default 3
|
|
depends on RCU_TORTURE_TEST_SLOW_CLEANUP
|
|
help
|
|
This option specifies the number of jiffies to wait between
|
|
each rcu_node structure cleanup operation.
|
|
|
|
config RCU_CPU_STALL_TIMEOUT
|
|
int "RCU CPU stall timeout in seconds"
|
|
depends on RCU_STALL_COMMON
|
|
range 3 300
|
|
default 21
|
|
help
|
|
If a given RCU grace period extends more than the specified
|
|
number of seconds, a CPU stall warning is printed. If the
|
|
RCU grace period persists, additional CPU stall warnings are
|
|
printed at more widely spaced intervals.
|
|
|
|
config RCU_TRACE
|
|
bool "Enable tracing for RCU"
|
|
depends on DEBUG_KERNEL
|
|
select TRACE_CLOCK
|
|
help
|
|
This option provides tracing in RCU which presents stats
|
|
in debugfs for debugging RCU implementation.
|
|
|
|
Say Y here if you want to enable RCU tracing
|
|
Say N if you are unsure.
|
|
|
|
config RCU_EQS_DEBUG
|
|
bool "Provide debugging asserts for adding NO_HZ support to an arch"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
This option provides consistency checks in RCU's handling of
|
|
NO_HZ. These checks have proven quite helpful in detecting
|
|
bugs in arch-specific NO_HZ code.
|
|
|
|
Say N here if you need ultimate kernel/user switch latencies
|
|
Say Y if you are unsure
|
|
|
|
endmenu # "RCU Debugging"
|
|
|
|
config DEBUG_BLOCK_EXT_DEVT
|
|
bool "Force extended block device numbers and spread them"
|
|
depends on DEBUG_KERNEL
|
|
depends on BLOCK
|
|
default n
|
|
help
|
|
BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
|
|
SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
|
|
YOU ARE DOING. Distros, please enable this and fix whatever
|
|
is broken.
|
|
|
|
Conventionally, block device numbers are allocated from
|
|
predetermined contiguous area. However, extended block area
|
|
may introduce non-contiguous block device numbers. This
|
|
option forces most block device numbers to be allocated from
|
|
the extended space and spreads them to discover kernel or
|
|
userland code paths which assume predetermined contiguous
|
|
device number allocation.
|
|
|
|
Note that turning on this debug option shuffles all the
|
|
device numbers for all IDE and SCSI devices including libata
|
|
ones, so root partition specified using device number
|
|
directly (via rdev or root=MAJ:MIN) won't work anymore.
|
|
Textual device names (root=/dev/sdXn) will continue to work.
|
|
|
|
Say N if you are unsure.
|
|
|
|
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 CPU_NOTIFIER_ERROR_INJECT
|
|
tristate "CPU notifier error injection module"
|
|
depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
|
|
help
|
|
This option provides a kernel module that can be used to test
|
|
the error handling of the cpu notifiers by injecting artificial
|
|
errors to CPU notifier chain callbacks. It is controlled through
|
|
debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
|
|
|
|
If the notifier call chain should be failed with some events
|
|
notified, write the error code to "actions/<notifier event>/error".
|
|
|
|
Example: Inject CPU offline error (-1 == -EPERM)
|
|
|
|
# cd /sys/kernel/debug/notifier-error-inject/cpu
|
|
# echo -1 > actions/CPU_DOWN_PREPARE/error
|
|
# echo 0 > /sys/devices/system/cpu/cpu1/online
|
|
bash: echo: write error: Operation not permitted
|
|
|
|
To compile this code as a module, choose M here: the module will
|
|
be called cpu-notifier-error-inject.
|
|
|
|
If unsure, say N.
|
|
|
|
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 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
|
|
depends on SLAB || SLUB
|
|
help
|
|
Provide fault-injection capability for kmalloc.
|
|
|
|
config FAIL_PAGE_ALLOC
|
|
bool "Fault-injection capabilitiy for alloc_pages()"
|
|
depends on FAULT_INJECTION
|
|
help
|
|
Provide fault-injection capability for alloc_pages().
|
|
|
|
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 wont do anything.
|
|
|
|
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_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 FAULT_INJECTION_STACKTRACE_FILTER
|
|
bool "stacktrace filter for fault-injection capabilities"
|
|
depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
|
|
depends on !X86_64
|
|
select STACKTRACE
|
|
select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
|
|
help
|
|
Provide stacktrace filter for fault-injection capabilities
|
|
|
|
config LATENCYTOP
|
|
bool "Latency measuring infrastructure"
|
|
depends on DEBUG_KERNEL
|
|
depends on STACKTRACE_SUPPORT
|
|
depends on PROC_FS
|
|
select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
|
|
select KALLSYMS
|
|
select KALLSYMS_ALL
|
|
select STACKTRACE
|
|
select SCHEDSTATS
|
|
select SCHED_DEBUG
|
|
help
|
|
Enable this option if you want to use the LatencyTOP tool
|
|
to find out which userspace is blocking on what kernel operations.
|
|
|
|
config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
|
|
bool
|
|
|
|
config DEBUG_STRICT_USER_COPY_CHECKS
|
|
bool "Strict user copy size checks"
|
|
depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
|
|
depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
|
|
help
|
|
Enabling this option turns a certain set of sanity checks for user
|
|
copy operations into compile time failures.
|
|
|
|
The copy_from_user() etc checks are there to help test if there
|
|
are sufficient security checks on the length argument of
|
|
the copy operation, by having gcc prove that the argument is
|
|
within bounds.
|
|
|
|
If unsure, say N.
|
|
|
|
source kernel/trace/Kconfig
|
|
|
|
menu "Runtime Testing"
|
|
|
|
config LKDTM
|
|
tristate "Linux Kernel Dump Test Tool Module"
|
|
depends on DEBUG_FS
|
|
depends on BLOCK
|
|
default n
|
|
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.txt
|
|
|
|
config TEST_LIST_SORT
|
|
bool "Linked list sorting test"
|
|
depends on DEBUG_KERNEL
|
|
help
|
|
Enable this to turn on 'list_sort()' function test. This test is
|
|
executed only once during system boot, so affects only boot time.
|
|
|
|
If unsure, say N.
|
|
|
|
config KPROBES_SANITY_TEST
|
|
bool "Kprobes sanity tests"
|
|
depends on DEBUG_KERNEL
|
|
depends on KPROBES
|
|
default n
|
|
help
|
|
This option provides for testing basic kprobes functionality on
|
|
boot. A sample kprobe, jprobe and kretprobe are inserted and
|
|
verified for functionality.
|
|
|
|
Say N if you are unsure.
|
|
|
|
config BACKTRACE_SELF_TEST
|
|
tristate "Self test for the backtrace code"
|
|
depends on DEBUG_KERNEL
|
|
default n
|
|
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 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 INTERVAL_TREE_TEST
|
|
tristate "Interval tree test"
|
|
depends on m && 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
|
|
bool "Perform an atomic64_t self-test at boot"
|
|
help
|
|
Enable this option to test the atomic64_t functions at boot.
|
|
|
|
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 TEST_STRING_HELPERS
|
|
tristate "Test functions located in the string_helpers module at runtime"
|
|
|
|
config TEST_KSTRTOX
|
|
tristate "Test kstrto*() family of functions at runtime"
|
|
|
|
config TEST_PRINTF
|
|
tristate "Test printf() family of functions at runtime"
|
|
|
|
config TEST_RHASHTABLE
|
|
tristate "Perform selftest on resizable hash table"
|
|
default n
|
|
help
|
|
Enable this option to test the rhashtable functions at boot.
|
|
|
|
If unsure, say N.
|
|
|
|
endmenu # runtime tests
|
|
|
|
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/debugging-via-ohci1394.txt for more information.
|
|
|
|
config BUILD_DOCSRC
|
|
bool "Build targets in Documentation/ tree"
|
|
depends on HEADERS_CHECK
|
|
help
|
|
This option attempts to build objects from the source files in the
|
|
kernel Documentation/ tree.
|
|
|
|
Say N if you are unsure.
|
|
|
|
config DMA_API_DEBUG
|
|
bool "Enable debugging of DMA-API usage"
|
|
depends on HAVE_DMA_API_DEBUG
|
|
help
|
|
Enable this option to debug the use of the DMA API by device drivers.
|
|
With this option you will be able to detect common bugs in device
|
|
drivers like double-freeing of DMA mappings or freeing mappings that
|
|
were never allocated.
|
|
|
|
This also attempts to catch cases where a page owned by DMA is
|
|
accessed by the cpu in a way that could cause data corruption. For
|
|
example, this enables cow_user_page() to check that the source page is
|
|
not undergoing DMA.
|
|
|
|
This option causes a performance degradation. Use only if you want to
|
|
debug device drivers and dma interactions.
|
|
|
|
If unsure, say N.
|
|
|
|
config TEST_LKM
|
|
tristate "Test module loading with 'hello world' module"
|
|
default n
|
|
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_USER_COPY
|
|
tristate "Test user/kernel boundary protections"
|
|
default n
|
|
depends on m
|
|
help
|
|
This builds the "test_user_copy" module that runs sanity checks
|
|
on the copy_to/from_user infrastructure, making sure basic
|
|
user/kernel boundary testing is working. If it fails to load,
|
|
a regression has been detected in the user/kernel memory boundary
|
|
protections.
|
|
|
|
If unsure, say N.
|
|
|
|
config TEST_BPF
|
|
tristate "Test BPF filter functionality"
|
|
default n
|
|
depends on m && NET
|
|
help
|
|
This builds the "test_bpf" module that runs various test vectors
|
|
against the BPF interpreter or BPF JIT compiler depending on the
|
|
current setting. This is in particular useful for BPF JIT compiler
|
|
development, but also to run regression tests against changes in
|
|
the interpreter code. It also enables test stubs for eBPF maps and
|
|
verifier used by user space verifier testsuite.
|
|
|
|
If unsure, say N.
|
|
|
|
config TEST_FIRMWARE
|
|
tristate "Test firmware loading via userspace interface"
|
|
default n
|
|
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_UDELAY
|
|
tristate "udelay test driver"
|
|
default n
|
|
help
|
|
This builds the "udelay_test" module that helps to make sure
|
|
that udelay() is working properly.
|
|
|
|
If unsure, say N.
|
|
|
|
config MEMTEST
|
|
bool "Memtest"
|
|
depends on HAVE_MEMBLOCK
|
|
---help---
|
|
This option adds a kernel parameter 'memtest', which allows memtest
|
|
to be set.
|
|
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 TEST_STATIC_KEYS
|
|
tristate "Test static keys"
|
|
default n
|
|
depends on m
|
|
help
|
|
Test the static key interfaces.
|
|
|
|
If unsure, say N.
|
|
|
|
source "samples/Kconfig"
|
|
|
|
source "lib/Kconfig.kgdb"
|
|
|
|
source "lib/Kconfig.ubsan"
|
|
|
|
config ARCH_HAS_DEVMEM_IS_ALLOWED
|
|
bool
|
|
|
|
config STRICT_DEVMEM
|
|
bool "Filter access to /dev/mem"
|
|
depends on MMU
|
|
depends on ARCH_HAS_DEVMEM_IS_ALLOWED
|
|
default y if TILE || PPC
|
|
---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.
|