lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         help
   5           Selecting this option causes timing information to be
   6           included in printk output.  This allows you to measure
   7           the interval between kernel operations, including bootup
   8           operations.  This is useful for identifying long delays
   9           in kernel startup.
  10
  11 config ENABLE_MUST_CHECK
  12         bool "Enable __must_check logic"
  13         default y
  14         help
  15           Enable the __must_check logic in the kernel build.  Disable this to
  16           suppress the "warning: ignoring return value of 'foo', declared with
  17           attribute warn_unused_result" messages.
  18
  19 config MAGIC_SYSRQ
  20         bool "Magic SysRq key"
  21         depends on !UML
  22         help
  23           If you say Y here, you will have some control over the system even
  24           if the system crashes for example during kernel debugging (e.g., you
  25           will be able to flush the buffer cache to disk, reboot the system
  26           immediately or dump some status information). This is accomplished
  27           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  28           also works on a serial console (on PC hardware at least), if you
  29           send a BREAK and then within 5 seconds a command keypress. The
  30           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  31           unless you really know what this hack does.
  32
  33 config UNUSED_SYMBOLS
  34         bool "Enable unused/obsolete exported symbols"
  35         default y if X86
  36         help
  37           Unused but exported symbols make the kernel needlessly bigger.  For
  38           that reason most of these unused exports will soon be removed.  This
  39           option is provided temporarily to provide a transition period in case
  40           some external kernel module needs one of these symbols anyway. If you
  41           encounter such a case in your module, consider if you are actually
  42           using the right API.  (rationale: since nobody in the kernel is using
  43           this in a module, there is a pretty good chance it's actually the
  44           wrong interface to use).  If you really need the symbol, please send a
  45           mail to the linux kernel mailing list mentioning the symbol and why
  46           you really need it, and what the merge plan to the mainline kernel for
  47           your module is.
  48
  49 config DEBUG_KERNEL
  50         bool "Kernel debugging"
  51         help
  52           Say Y here if you are developing drivers or trying to debug and
  53           identify kernel problems.
  54
  55 config LOG_BUF_SHIFT
  56         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
  57         range 12 21
  58         default 17 if S390 || LOCKDEP
  59         default 16 if X86_NUMAQ || IA64
  60         default 15 if SMP
  61         default 14
  62         help
  63           Select kernel log buffer size as a power of 2.
  64           Defaults and Examples:
  65                      17 => 128 KB for S/390
  66                      16 => 64 KB for x86 NUMAQ or IA-64
  67                      15 => 32 KB for SMP
  68                      14 => 16 KB for uniprocessor
  69                      13 =>  8 KB
  70                      12 =>  4 KB
  71
  72 config DETECT_SOFTLOCKUP
  73         bool "Detect Soft Lockups"
  74         depends on DEBUG_KERNEL && !S390
  75         default y
  76         help
  77           Say Y here to enable the kernel to detect "soft lockups",
  78           which are bugs that cause the kernel to loop in kernel
  79           mode for more than 10 seconds, without giving other tasks a
  80           chance to run.
  81
  82           When a soft-lockup is detected, the kernel will print the
  83           current stack trace (which you should report), but the
  84           system will stay locked up. This feature has negligible
  85           overhead.
  86
  87           (Note that "hard lockups" are separate type of bugs that
  88            can be detected via the NMI-watchdog, on platforms that
  89            support it.)
  90
  91 config SCHEDSTATS
  92         bool "Collect scheduler statistics"
  93         depends on DEBUG_KERNEL && PROC_FS
  94         help
  95           If you say Y here, additional code will be inserted into the
  96           scheduler and related routines to collect statistics about
  97           scheduler behavior and provide them in /proc/schedstat.  These
  98           stats may be useful for both tuning and debugging the scheduler
  99           If you aren't debugging the scheduler or trying to tune a specific
 100           application, you can say N to avoid the very slight overhead
 101           this adds.
 102
 103 config DEBUG_SLAB
 104         bool "Debug slab memory allocations"
 105         depends on DEBUG_KERNEL && SLAB
 106         help
 107           Say Y here to have the kernel do limited verification on memory
 108           allocation as well as poisoning memory on free to catch use of freed
 109           memory. This can make kmalloc/kfree-intensive workloads much slower.
 110
 111 config DEBUG_SLAB_LEAK
 112         bool "Memory leak debugging"
 113         depends on DEBUG_SLAB
 114
 115 config DEBUG_PREEMPT
 116         bool "Debug preemptible kernel"
 117         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 118         default y
 119         help
 120           If you say Y here then the kernel will use a debug variant of the
 121           commonly used smp_processor_id() function and will print warnings
 122           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 123           will detect preemption count underflows.
 124
 125 config DEBUG_RT_MUTEXES
 126         bool "RT Mutex debugging, deadlock detection"
 127         depends on DEBUG_KERNEL && RT_MUTEXES
 128         help
 129          This allows rt mutex semantics violations and rt mutex related
 130          deadlocks (lockups) to be detected and reported automatically.
 131
 132 config DEBUG_PI_LIST
 133         bool
 134         default y
 135         depends on DEBUG_RT_MUTEXES
 136
 137 config RT_MUTEX_TESTER
 138         bool "Built-in scriptable tester for rt-mutexes"
 139         depends on DEBUG_KERNEL && RT_MUTEXES
 140         help
 141           This option enables a rt-mutex tester.
 142
 143 config DEBUG_SPINLOCK
 144         bool "Spinlock and rw-lock debugging: basic checks"
 145         depends on DEBUG_KERNEL
 146         help
 147           Say Y here and build SMP to catch missing spinlock initialization
 148           and certain other kinds of spinlock errors commonly made.  This is
 149           best used in conjunction with the NMI watchdog so that spinlock
 150           deadlocks are also debuggable.
 151
 152 config DEBUG_MUTEXES
 153         bool "Mutex debugging: basic checks"
 154         depends on DEBUG_KERNEL
 155         help
 156          This feature allows mutex semantics violations to be detected and
 157          reported.
 158
 159 config DEBUG_RWSEMS
 160         bool "RW-sem debugging: basic checks"
 161         depends on DEBUG_KERNEL
 162         help
 163          This feature allows read-write semaphore semantics violations to
 164          be detected and reported.
 165
 166 config DEBUG_LOCK_ALLOC
 167         bool "Lock debugging: detect incorrect freeing of live locks"
 168         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 169         select DEBUG_SPINLOCK
 170         select DEBUG_MUTEXES
 171         select DEBUG_RWSEMS
 172         select LOCKDEP
 173         help
 174          This feature will check whether any held lock (spinlock, rwlock,
 175          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 176          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 177          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 178          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 179          held during task exit.
 180
 181 config PROVE_LOCKING
 182         bool "Lock debugging: prove locking correctness"
 183         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 184         select LOCKDEP
 185         select DEBUG_SPINLOCK
 186         select DEBUG_MUTEXES
 187         select DEBUG_RWSEMS
 188         select DEBUG_LOCK_ALLOC
 189         default n
 190         help
 191          This feature enables the kernel to prove that all locking
 192          that occurs in the kernel runtime is mathematically
 193          correct: that under no circumstance could an arbitrary (and
 194          not yet triggered) combination of observed locking
 195          sequences (on an arbitrary number of CPUs, running an
 196          arbitrary number of tasks and interrupt contexts) cause a
 197          deadlock.
 198
 199          In short, this feature enables the kernel to report locking
 200          related deadlocks before they actually occur.
 201
 202          The proof does not depend on how hard and complex a
 203          deadlock scenario would be to trigger: how many
 204          participant CPUs, tasks and irq-contexts would be needed
 205          for it to trigger. The proof also does not depend on
 206          timing: if a race and a resulting deadlock is possible
 207          theoretically (no matter how unlikely the race scenario
 208          is), it will be proven so and will immediately be
 209          reported by the kernel (once the event is observed that
 210          makes the deadlock theoretically possible).
 211
 212          If a deadlock is impossible (i.e. the locking rules, as
 213          observed by the kernel, are mathematically correct), the
 214          kernel reports nothing.
 215
 216          NOTE: this feature can also be enabled for rwlocks, mutexes
 217          and rwsems - in which case all dependencies between these
 218          different locking variants are observed and mapped too, and
 219          the proof of observed correctness is also maintained for an
 220          arbitrary combination of these separate locking variants.
 221
 222          For more details, see Documentation/lockdep-design.txt.
 223
 224 config LOCKDEP
 225         bool
 226         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 227         select STACKTRACE
 228         select FRAME_POINTER if !X86
 229         select KALLSYMS
 230         select KALLSYMS_ALL
 231
 232 config DEBUG_LOCKDEP
 233         bool "Lock dependency engine debugging"
 234         depends on DEBUG_KERNEL && LOCKDEP
 235         help
 236           If you say Y here, the lock dependency engine will do
 237           additional runtime checks to debug itself, at the price
 238           of more runtime overhead.
 239
 240 config TRACE_IRQFLAGS
 241         depends on DEBUG_KERNEL
 242         bool
 243         default y
 244         depends on TRACE_IRQFLAGS_SUPPORT
 245         depends on PROVE_LOCKING
 246
 247 config DEBUG_SPINLOCK_SLEEP
 248         bool "Spinlock debugging: sleep-inside-spinlock checking"
 249         depends on DEBUG_KERNEL
 250         help
 251           If you say Y here, various routines which may sleep will become very
 252           noisy if they are called with a spinlock held.
 253
 254 config DEBUG_LOCKING_API_SELFTESTS
 255         bool "Locking API boot-time self-tests"
 256         depends on DEBUG_KERNEL
 257         help
 258           Say Y here if you want the kernel to run a short self-test during
 259           bootup. The self-test checks whether common types of locking bugs
 260           are detected by debugging mechanisms or not. (if you disable
 261           lock debugging then those bugs wont be detected of course.)
 262           The following locking APIs are covered: spinlocks, rwlocks,
 263           mutexes and rwsems.
 264
 265 config STACKTRACE
 266         bool
 267         depends on DEBUG_KERNEL
 268         depends on STACKTRACE_SUPPORT
 269
 270 config DEBUG_KOBJECT
 271         bool "kobject debugging"
 272         depends on DEBUG_KERNEL
 273         help
 274           If you say Y here, some extra kobject debugging messages will be sent
 275           to the syslog.
 276
 277 config DEBUG_HIGHMEM
 278         bool "Highmem debugging"
 279         depends on DEBUG_KERNEL && HIGHMEM
 280         help
 281           This options enables addition error checking for high memory systems.
 282           Disable for production systems.
 283
 284 config DEBUG_BUGVERBOSE
 285         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 286         depends on BUG
 287         depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV || SUPERH
 288         default !EMBEDDED
 289         help
 290           Say Y here to make BUG() panics output the file name and line number
 291           of the BUG call as well as the EIP and oops trace.  This aids
 292           debugging but costs about 70-100K of memory.
 293
 294 config DEBUG_INFO
 295         bool "Compile the kernel with debug info"
 296         depends on DEBUG_KERNEL
 297         help
 298           If you say Y here the resulting kernel image will include
 299           debugging info resulting in a larger kernel image.
 300           Say Y here only if you plan to debug the kernel.
 301
 302           If unsure, say N.
 303
 304 config DEBUG_FS
 305         bool "Debug Filesystem"
 306         depends on SYSFS
 307         help
 308           debugfs is a virtual file system that kernel developers use to put
 309           debugging files into.  Enable this option to be able to read and
 310           write to these files.
 311
 312           If unsure, say N.
 313
 314 config DEBUG_VM
 315         bool "Debug VM"
 316         depends on DEBUG_KERNEL
 317         help
 318           Enable this to turn on extended checks in the virtual-memory system
 319           that may impact performance.
 320
 321           If unsure, say N.
 322
 323 config DEBUG_LIST
 324         bool "Debug linked list manipulation"
 325         depends on DEBUG_KERNEL
 326         help
 327           Enable this to turn on extended checks in the linked-list
 328           walking routines.
 329
 330           If unsure, say N.
 331
 332 config FRAME_POINTER
 333         bool "Compile the kernel with frame pointers"
 334         depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH)
 335         default y if DEBUG_INFO && UML
 336         help
 337           If you say Y here the resulting kernel image will be slightly larger
 338           and slower, but it might give very useful debugging information on
 339           some architectures or if you use external debuggers.
 340           If you don't debug the kernel, you can say N.
 341
 342 config UNWIND_INFO
 343         bool "Compile the kernel with frame unwind information"
 344         depends on !IA64 && !PARISC
 345         depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
 346         help
 347           If you say Y here the resulting kernel image will be slightly larger
 348           but not slower, and it will give very useful debugging information.
 349           If you don't debug the kernel, you can say N, but we may not be able
 350           to solve problems without frame unwind information or frame pointers.
 351
 352 config STACK_UNWIND
 353         bool "Stack unwind support"
 354         depends on UNWIND_INFO
 355         depends on X86
 356         help
 357           This enables more precise stack traces, omitting all unrelated
 358           occurrences of pointers into kernel code from the dump.
 359
 360 config FORCED_INLINING
 361         bool "Force gcc to inline functions marked 'inline'"
 362         depends on DEBUG_KERNEL
 363         default y
 364         help
 365           This option determines if the kernel forces gcc to inline the functions
 366           developers have marked 'inline'. Doing so takes away freedom from gcc to
 367           do what it thinks is best, which is desirable for the gcc 3.x series of
 368           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 369           disabling this option will generate a smaller kernel there. Hopefully
 370           this algorithm is so good that allowing gcc4 to make the decision can
 371           become the default in the future, until then this option is there to
 372           test gcc for this.
 373
 374 config HEADERS_CHECK
 375         bool "Run 'make headers_check' when building vmlinux"
 376         help
 377           This option will extract the user-visible kernel headers whenever
 378           building the kernel, and will run basic sanity checks on them to
 379           ensure that exported files do not attempt to include files which
 380           were not exported, etc.
 381
 382           If you're making modifications to header files which are
 383           relevant for userspace, say 'Y', and check the headers
 384           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 385           your build tree), to make sure they're suitable.
 386
 387 config RCU_TORTURE_TEST
 388         tristate "torture tests for RCU"
 389         depends on DEBUG_KERNEL
 390         default n
 391         help
 392           This option provides a kernel module that runs torture tests
 393           on the RCU infrastructure.  The kernel module may be built
 394           after the fact on the running kernel to be tested, if desired.
 395
 396           Say Y here if you want RCU torture tests to start automatically
 397           at boot time (you probably don't).
 398           Say M if you want the RCU torture tests to build as a module.
 399           Say N if you are unsure.
 400
 401 config LKDTM
 402         tristate "Linux Kernel Dump Test Tool Module"
 403         depends on KPROBES
 404         default n
 405         help
 406         This module enables testing of the different dumping mechanisms by
 407         inducing system failures at predefined crash points.
 408         If you don't need it: say N
 409         Choose M here to compile this code as a module. The module will be
 410         called lkdtm.
 411
 412         Documentation on how to use the module can be found in
 413         drivers/misc/lkdtm.c