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