|  |  | 
|  | config PRINTK_TIME | 
|  | bool "Show timing information on printks" | 
|  | depends on PRINTK | 
|  | help | 
|  | Selecting this option causes timing information to be | 
|  | included in printk output.  This allows you to measure | 
|  | the interval between kernel operations, including bootup | 
|  | operations.  This is useful for identifying long delays | 
|  | in kernel startup. | 
|  |  | 
|  | config ENABLE_WARN_DEPRECATED | 
|  | bool "Enable __deprecated logic" | 
|  | default y | 
|  | help | 
|  | Enable the __deprecated logic in the kernel build. | 
|  | Disable this to suppress the "warning: 'foo' is deprecated | 
|  | (declared at kernel/power/somefile.c:1234)" messages. | 
|  |  | 
|  | config ENABLE_MUST_CHECK | 
|  | bool "Enable __must_check logic" | 
|  | default y | 
|  | help | 
|  | Enable the __must_check logic in the kernel build.  Disable this to | 
|  | suppress the "warning: ignoring return value of 'foo', declared with | 
|  | attribute warn_unused_result" messages. | 
|  |  | 
|  | config FRAME_WARN | 
|  | int "Warn for stack frames larger than (needs gcc 4.4)" | 
|  | range 0 8192 | 
|  | default 1024 if !64BIT | 
|  | default 2048 if 64BIT | 
|  | help | 
|  | Tell gcc to warn at build time for stack frames larger than this. | 
|  | Setting this too low will cause a lot of warnings. | 
|  | Setting it to 0 disables the warning. | 
|  | Requires gcc 4.4 | 
|  |  | 
|  | config MAGIC_SYSRQ | 
|  | bool "Magic SysRq key" | 
|  | depends on !UML | 
|  | help | 
|  | If you say Y here, you will have some control over the system even | 
|  | if the system crashes for example during kernel debugging (e.g., you | 
|  | will be able to flush the buffer cache to disk, reboot the system | 
|  | immediately or dump some status information). This is accomplished | 
|  | by pressing various keys while holding SysRq (Alt+PrintScreen). It | 
|  | also works on a serial console (on PC hardware at least), if you | 
|  | send a BREAK and then within 5 seconds a command keypress. The | 
|  | keys are documented in <file:Documentation/sysrq.txt>. Don't say Y | 
|  | unless you really know what this hack does. | 
|  |  | 
|  | config UNUSED_SYMBOLS | 
|  | bool "Enable unused/obsolete exported symbols" | 
|  | default y if X86 | 
|  | help | 
|  | Unused but exported symbols make the kernel needlessly bigger.  For | 
|  | that reason most of these unused exports will soon be removed.  This | 
|  | option is provided temporarily to provide a transition period in case | 
|  | some external kernel module needs one of these symbols anyway. If you | 
|  | encounter such a case in your module, consider if you are actually | 
|  | using the right API.  (rationale: since nobody in the kernel is using | 
|  | this in a module, there is a pretty good chance it's actually the | 
|  | wrong interface to use).  If you really need the symbol, please send a | 
|  | mail to the linux kernel mailing list mentioning the symbol and why | 
|  | you really need it, and what the merge plan to the mainline kernel for | 
|  | your module is. | 
|  |  | 
|  | config DEBUG_FS | 
|  | bool "Debug Filesystem" | 
|  | depends on SYSFS | 
|  | help | 
|  | debugfs is a virtual file system that kernel developers use to put | 
|  | debugging files into.  Enable this option to be able to read and | 
|  | write to these files. | 
|  |  | 
|  | For detailed documentation on the debugfs API, see | 
|  | Documentation/DocBook/filesystems. | 
|  |  | 
|  | If unsure, say N. | 
|  |  | 
|  | config HEADERS_CHECK | 
|  | bool "Run 'make headers_check' when building vmlinux" | 
|  | depends on !UML | 
|  | help | 
|  | This option will extract the user-visible kernel headers whenever | 
|  | building the kernel, and will run basic sanity checks on them to | 
|  | ensure that exported files do not attempt to include files which | 
|  | were not exported, etc. | 
|  |  | 
|  | If you're making modifications to header files which are | 
|  | relevant for userspace, say 'Y', and check the headers | 
|  | exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in | 
|  | your build tree), to make sure they're suitable. | 
|  |  | 
|  | config DEBUG_SECTION_MISMATCH | 
|  | bool "Enable full Section mismatch analysis" | 
|  | depends on UNDEFINED | 
|  | # This option is on purpose disabled for now. | 
|  | # It will be enabled when we are down to a resonable number | 
|  | # of section mismatch warnings (< 10 for an allyesconfig build) | 
|  | help | 
|  | The section mismatch analysis checks if there are illegal | 
|  | references from one section to another section. | 
|  | Linux will during link or during runtime drop some sections | 
|  | and any use of code/data previously in these sections will | 
|  | most likely result in an oops. | 
|  | In the code functions and variables are annotated with | 
|  | __init, __devinit etc. (see full list in include/linux/init.h) | 
|  | which results in the code/data being placed in specific sections. | 
|  | The section mismatch analysis is always done after a full | 
|  | kernel build but enabling this option will in addition | 
|  | do the following: | 
|  | - Add the option -fno-inline-functions-called-once to gcc | 
|  | When inlining a function annotated __init in a non-init | 
|  | function we would lose the section information and thus | 
|  | the analysis would not catch the illegal reference. | 
|  | This option tells gcc to inline less but will also | 
|  | result in a larger kernel. | 
|  | - Run the section mismatch analysis for each module/built-in.o | 
|  | When we run the section mismatch analysis on vmlinux.o we | 
|  | lose valueble information about where the mismatch was | 
|  | introduced. | 
|  | Running the analysis for each module/built-in.o file | 
|  | will tell where the mismatch happens much closer to the | 
|  | source. The drawback is that we will report the same | 
|  | mismatch at least twice. | 
|  | - Enable verbose reporting from modpost to help solving | 
|  | the section mismatches reported. | 
|  |  | 
|  | config DEBUG_KERNEL | 
|  | bool "Kernel debugging" | 
|  | help | 
|  | Say Y here if you are developing drivers or trying to debug and | 
|  | identify kernel problems. | 
|  |  | 
|  | config DEBUG_SHIRQ | 
|  | bool "Debug shared IRQ handlers" | 
|  | depends on DEBUG_KERNEL && GENERIC_HARDIRQS | 
|  | 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. | 
|  |  | 
|  | config DETECT_SOFTLOCKUP | 
|  | bool "Detect Soft Lockups" | 
|  | depends on DEBUG_KERNEL && !S390 | 
|  | default y | 
|  | help | 
|  | Say Y here to enable the kernel to detect "soft lockups", | 
|  | which are bugs that cause the kernel to loop in kernel | 
|  | mode for more than 60 seconds, without giving other tasks a | 
|  | chance to run. | 
|  |  | 
|  | When a soft-lockup is detected, the kernel will print the | 
|  | current stack trace (which you should report), but the | 
|  | system will stay locked up. This feature has negligible | 
|  | overhead. | 
|  |  | 
|  | (Note that "hard lockups" are separate type of bugs that | 
|  | can be detected via the NMI-watchdog, on platforms that | 
|  | support it.) | 
|  |  | 
|  | config BOOTPARAM_SOFTLOCKUP_PANIC | 
|  | bool "Panic (Reboot) On Soft Lockups" | 
|  | depends on DETECT_SOFTLOCKUP | 
|  | 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 60 seconds, 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 DETECT_SOFTLOCKUP | 
|  | range 0 1 | 
|  | default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC | 
|  | default 1 if BOOTPARAM_SOFTLOCKUP_PANIC | 
|  |  | 
|  | 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 SCHEDSTATS | 
|  | bool "Collect scheduler statistics" | 
|  | depends on DEBUG_KERNEL && PROC_FS | 
|  | 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 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_OBJECTS | 
|  | bool "Debug object operations" | 
|  | depends on DEBUG_KERNEL | 
|  | help | 
|  | If you say Y here, additional code will be inserted into the | 
|  | kernel to track the life time of various objects and validate | 
|  | the operations on those objects. | 
|  |  | 
|  | config DEBUG_OBJECTS_SELFTEST | 
|  | bool "Debug objects selftest" | 
|  | depends on DEBUG_OBJECTS | 
|  | help | 
|  | This enables the selftest of the object debug code. | 
|  |  | 
|  | config DEBUG_OBJECTS_FREE | 
|  | bool "Debug objects in freed memory" | 
|  | depends on DEBUG_OBJECTS | 
|  | help | 
|  | This enables checks whether a k/v free operation frees an area | 
|  | which contains an object which has not been deactivated | 
|  | properly. This can make kmalloc/kfree-intensive workloads | 
|  | much slower. | 
|  |  | 
|  | config DEBUG_OBJECTS_TIMERS | 
|  | bool "Debug timer objects" | 
|  | depends on DEBUG_OBJECTS | 
|  | help | 
|  | If you say Y here, additional code will be inserted into the | 
|  | timer routines to track the life time of timer objects and | 
|  | validate the timer operations. | 
|  |  | 
|  | config DEBUG_SLAB | 
|  | bool "Debug slab memory allocations" | 
|  | depends on DEBUG_KERNEL && SLAB | 
|  | help | 
|  | Say Y here to have the kernel do limited verification on memory | 
|  | allocation as well as poisoning memory on free to catch use of freed | 
|  | memory. This can make kmalloc/kfree-intensive workloads much slower. | 
|  |  | 
|  | config DEBUG_SLAB_LEAK | 
|  | bool "Memory leak debugging" | 
|  | depends on DEBUG_SLAB | 
|  |  | 
|  | config SLUB_DEBUG_ON | 
|  | bool "SLUB debugging on by default" | 
|  | depends on SLUB && SLUB_DEBUG | 
|  | default n | 
|  | help | 
|  | Boot with debugging on by default. SLUB boots by default with | 
|  | the runtime debug capabilities switched off. Enabling this is | 
|  | equivalent to specifying the "slub_debug" parameter on boot. | 
|  | There is no support for more fine grained debug control like | 
|  | possible with slub_debug=xxx. SLUB debugging may be switched | 
|  | off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying | 
|  | "slub_debug=-". | 
|  |  | 
|  | config SLUB_STATS | 
|  | default n | 
|  | bool "Enable SLUB performance statistics" | 
|  | depends on SLUB && SLUB_DEBUG && SYSFS | 
|  | help | 
|  | SLUB statistics are useful to debug SLUBs allocation behavior in | 
|  | order find ways to optimize the allocator. This should never be | 
|  | enabled for production use since keeping statistics slows down | 
|  | the allocator by a few percentage points. The slabinfo command | 
|  | supports the determination of the most active slabs to figure | 
|  | out which slabs are relevant to a particular load. | 
|  | Try running: slabinfo -DA | 
|  |  | 
|  | config DEBUG_PREEMPT | 
|  | bool "Debug preemptible kernel" | 
|  | depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64) | 
|  | 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. | 
|  |  | 
|  | 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_PI_LIST | 
|  | bool | 
|  | default y | 
|  | depends on DEBUG_RT_MUTEXES | 
|  |  | 
|  | config RT_MUTEX_TESTER | 
|  | bool "Built-in scriptable tester for rt-mutexes" | 
|  | depends on DEBUG_KERNEL && RT_MUTEXES | 
|  | help | 
|  | This option enables a rt-mutex tester. | 
|  |  | 
|  | config DEBUG_SPINLOCK | 
|  | bool "Spinlock and rw-lock debugging: basic checks" | 
|  | depends on DEBUG_KERNEL | 
|  | 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_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 | 
|  | 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/lockdep-design.txt. | 
|  |  | 
|  | config LOCKDEP | 
|  | bool | 
|  | depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT | 
|  | select STACKTRACE | 
|  | select FRAME_POINTER if !X86 && !MIPS && !PPC | 
|  | 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/lockstat.txt | 
|  |  | 
|  | 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 TRACE_IRQFLAGS | 
|  | depends on DEBUG_KERNEL | 
|  | bool | 
|  | default y | 
|  | depends on TRACE_IRQFLAGS_SUPPORT | 
|  | depends on PROVE_LOCKING | 
|  |  | 
|  | config DEBUG_SPINLOCK_SLEEP | 
|  | bool "Spinlock debugging: sleep-inside-spinlock checking" | 
|  | depends on DEBUG_KERNEL | 
|  | help | 
|  | If you say Y here, various routines which may sleep will become very | 
|  | noisy if they are called with a spinlock held. | 
|  |  | 
|  | 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 STACKTRACE | 
|  | bool | 
|  | depends on STACKTRACE_SUPPORT | 
|  |  | 
|  | 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_HIGHMEM | 
|  | bool "Highmem debugging" | 
|  | depends on DEBUG_KERNEL && HIGHMEM | 
|  | help | 
|  | This options enables addition error checking for high memory systems. | 
|  | Disable for production systems. | 
|  |  | 
|  | config DEBUG_BUGVERBOSE | 
|  | bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED | 
|  | depends on BUG | 
|  | depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \ | 
|  | FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 | 
|  | default !EMBEDDED | 
|  | 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_INFO | 
|  | bool "Compile the kernel with debug info" | 
|  | depends on DEBUG_KERNEL | 
|  | help | 
|  | If you say Y here the resulting kernel image will include | 
|  | debugging info resulting in a larger kernel image. | 
|  | This adds debug symbols to the kernel and modules (gcc -g), and | 
|  | is needed if you intend to use kernel crashdump or binary object | 
|  | tools like crash, kgdb, LKCD, gdb, etc on the kernel. | 
|  | Say Y here only if you plan to debug the kernel. | 
|  |  | 
|  | If unsure, say N. | 
|  |  | 
|  | 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_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_WRITECOUNT | 
|  | bool "Debug filesystem writers count" | 
|  | depends on DEBUG_KERNEL | 
|  | help | 
|  | Enable this to catch wrong use of the writers count in struct | 
|  | vfsmount.  This will increase the size of each file struct by | 
|  | 32 bits. | 
|  |  | 
|  | If unsure, say N. | 
|  |  | 
|  | config DEBUG_MEMORY_INIT | 
|  | bool "Debug memory initialisation" if EMBEDDED | 
|  | default !EMBEDDED | 
|  | 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 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_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 FRAME_POINTER | 
|  | bool "Compile the kernel with frame pointers" | 
|  | depends on DEBUG_KERNEL && \ | 
|  | (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \ | 
|  | AVR32 || SUPERH || BLACKFIN || MN10300) | 
|  | default y if DEBUG_INFO && UML | 
|  | help | 
|  | If you say Y here the resulting kernel image will be slightly larger | 
|  | and slower, but it might give very useful debugging information on | 
|  | some architectures or if you use external debuggers. | 
|  | If you don't debug the kernel, you can say N. | 
|  |  | 
|  | config BOOT_PRINTK_DELAY | 
|  | bool "Delay each boot printk message by N milliseconds" | 
|  | depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY | 
|  | help | 
|  | This build option allows you to read kernel boot messages | 
|  | by inserting a short delay after each one.  The delay is | 
|  | specified in milliseconds on the kernel command line, | 
|  | using "boot_delay=N". | 
|  |  | 
|  | It is likely that you would also need to use "lpj=M" to preset | 
|  | the "loops per jiffie" value. | 
|  | See a previous boot log for the "lpj" value to use for your | 
|  | system, and then set "lpj=M" before setting "boot_delay=N". | 
|  | NOTE:  Using this option may adversely affect SMP systems. | 
|  | I.e., processors other than the first one may not boot up. | 
|  | BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect | 
|  | what it believes to be lockup conditions. | 
|  |  | 
|  | config RCU_TORTURE_TEST | 
|  | tristate "torture tests for RCU" | 
|  | depends on DEBUG_KERNEL | 
|  | 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_CPU_STALL_DETECTOR | 
|  | bool "Check for stalled CPUs delaying RCU grace periods" | 
|  | depends on CLASSIC_RCU | 
|  | default n | 
|  | help | 
|  | This option causes RCU to printk information on which | 
|  | CPUs are delaying the current grace period, but only when | 
|  | the grace period extends for excessive time periods. | 
|  |  | 
|  | Say Y if you want RCU to perform such checks. | 
|  |  | 
|  | Say N if you are unsure. | 
|  |  | 
|  | 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 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 LKDTM | 
|  | tristate "Linux Kernel Dump Test Tool Module" | 
|  | depends on DEBUG_KERNEL | 
|  | depends on KPROBES | 
|  | 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 | 
|  | drivers/misc/lkdtm.c | 
|  |  | 
|  | config FAULT_INJECTION | 
|  | bool "Fault-injection framework" | 
|  | depends on DEBUG_KERNEL | 
|  | help | 
|  | Provide fault-injection framework. | 
|  | For more details, see Documentation/fault-injection/. | 
|  |  | 
|  | config FAILSLAB | 
|  | bool "Fault-injection capability for kmalloc" | 
|  | depends on FAULT_INJECTION | 
|  | help | 
|  | Provide fault-injection capability for kmalloc. | 
|  |  | 
|  | config FAIL_PAGE_ALLOC | 
|  | bool "Fault-injection 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 "Faul-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 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 !PPC | 
|  | help | 
|  | Provide stacktrace filter for fault-injection capabilities | 
|  |  | 
|  | config LATENCYTOP | 
|  | bool "Latency measuring infrastructure" | 
|  | select FRAME_POINTER if !MIPS && !PPC | 
|  | select KALLSYMS | 
|  | select KALLSYMS_ALL | 
|  | select STACKTRACE | 
|  | select SCHEDSTATS | 
|  | select SCHED_DEBUG | 
|  | depends on HAVE_LATENCYTOP_SUPPORT | 
|  | help | 
|  | Enable this option if you want to use the LatencyTOP tool | 
|  | to find out which userspace is blocking on what kernel operations. | 
|  |  | 
|  | config SYSCTL_SYSCALL_CHECK | 
|  | bool "Sysctl checks" | 
|  | depends on SYSCTL_SYSCALL | 
|  | ---help--- | 
|  | sys_sysctl uses binary paths that have been found challenging | 
|  | to properly maintain and use. This enables checks that help | 
|  | you to keep things correct. | 
|  |  | 
|  | source kernel/trace/Kconfig | 
|  |  | 
|  | config PROVIDE_OHCI1394_DMA_INIT | 
|  | bool "Remote debugging over FireWire early on boot" | 
|  | depends on PCI && X86 | 
|  | help | 
|  | If you want to debug problems which hang or crash the kernel early | 
|  | on boot and the crashing machine has a FireWire port, you can use | 
|  | this feature to remotely access the memory of the crashed machine | 
|  | over FireWire. This employs remote DMA as part of the OHCI1394 | 
|  | specification which is now the standard for FireWire controllers. | 
|  |  | 
|  | With remote DMA, you can monitor the printk buffer remotely using | 
|  | firescope and access all memory below 4GB using fireproxy from gdb. | 
|  | Even controlling a kernel debugger is possible using remote DMA. | 
|  |  | 
|  | Usage: | 
|  |  | 
|  | If ohci1394_dma=early is used as boot parameter, it will initialize | 
|  | all OHCI1394 controllers which are found in the PCI config space. | 
|  |  | 
|  | As all changes to the FireWire bus such as enabling and disabling | 
|  | devices cause a bus reset and thereby disable remote DMA for all | 
|  | devices, be sure to have the cable plugged and FireWire enabled on | 
|  | the debugging host before booting the debug target for debugging. | 
|  |  | 
|  | This code (~1k) is freed after boot. By then, the firewire stack | 
|  | in charge of the OHCI-1394 controllers should be used instead. | 
|  |  | 
|  | See Documentation/debugging-via-ohci1394.txt for more information. | 
|  |  | 
|  | config FIREWIRE_OHCI_REMOTE_DMA | 
|  | bool "Remote debugging over FireWire with firewire-ohci" | 
|  | depends on FIREWIRE_OHCI | 
|  | help | 
|  | This option lets you use the FireWire bus for remote debugging | 
|  | with help of the firewire-ohci driver. It enables unfiltered | 
|  | remote DMA in firewire-ohci. | 
|  | See Documentation/debugging-via-ohci1394.txt for more information. | 
|  |  | 
|  | If unsure, say N. | 
|  |  | 
|  | menuconfig 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 DYNAMIC_PRINTK_DEBUG | 
|  | bool "Enable dynamic printk() call support" | 
|  | default n | 
|  | depends on PRINTK | 
|  | select PRINTK_DEBUG | 
|  | help | 
|  |  | 
|  | Compiles debug level messages into the kernel, which would not | 
|  | otherwise be available at runtime. These messages can then be | 
|  | enabled/disabled on a per module basis. This mechanism implicitly | 
|  | enables all pr_debug() and dev_dbg() calls. The impact of this | 
|  | compile option is a larger kernel text size of about 2%. | 
|  |  | 
|  | Usage: | 
|  |  | 
|  | Dynamic debugging is controlled by the debugfs file, | 
|  | dynamic_printk/modules. This file contains a list of the modules that | 
|  | can be enabled. The format of the file is the module name, followed | 
|  | by a set of flags that can be enabled. The first flag is always the | 
|  | 'enabled' flag. For example: | 
|  |  | 
|  | <module_name> <enabled=0/1> | 
|  | . | 
|  | . | 
|  | . | 
|  |  | 
|  | <module_name> : Name of the module in which the debug call resides | 
|  | <enabled=0/1> : whether the messages are enabled or not | 
|  |  | 
|  | From a live system: | 
|  |  | 
|  | snd_hda_intel enabled=0 | 
|  | fixup enabled=0 | 
|  | driver enabled=0 | 
|  |  | 
|  | Enable a module: | 
|  |  | 
|  | $echo "set enabled=1 <module_name>" > dynamic_printk/modules | 
|  |  | 
|  | Disable a module: | 
|  |  | 
|  | $echo "set enabled=0 <module_name>" > dynamic_printk/modules | 
|  |  | 
|  | Enable all modules: | 
|  |  | 
|  | $echo "set enabled=1 all" > dynamic_printk/modules | 
|  |  | 
|  | Disable all modules: | 
|  |  | 
|  | $echo "set enabled=0 all" > dynamic_printk/modules | 
|  |  | 
|  | Finally, passing "dynamic_printk" at the command line enables | 
|  | debugging for all modules. This mode can be turned off via the above | 
|  | disable command. | 
|  |  | 
|  | source "samples/Kconfig" | 
|  |  | 
|  | source "lib/Kconfig.kgdb" |