| config PRINTK_TIME | |
| bool "Show timing information on printks" | |
| 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_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 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_KERNEL | |
| bool "Kernel debugging" | |
| help | |
| Say Y here if you are developing drivers or trying to debug and | |
| identify kernel problems. | |
| config LOG_BUF_SHIFT | |
| int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL | |
| range 12 21 | |
| default 17 if S390 || LOCKDEP | |
| default 16 if X86_NUMAQ || IA64 | |
| default 15 if SMP | |
| default 14 | |
| help | |
| Select kernel log buffer size as a power of 2. | |
| Defaults and Examples: | |
| 17 => 128 KB for S/390 | |
| 16 => 64 KB for x86 NUMAQ or IA-64 | |
| 15 => 32 KB for SMP | |
| 14 => 16 KB for uniprocessor | |
| 13 => 8 KB | |
| 12 => 4 KB | |
| 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 10 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 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 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 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. | |
| 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_RWSEMS | |
| bool "RW-sem debugging: basic checks" | |
| depends on DEBUG_KERNEL | |
| help | |
| This feature allows read-write semaphore 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 DEBUG_RWSEMS | |
| 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_RWSEMS | |
| 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 | |
| select KALLSYMS | |
| select KALLSYMS_ALL | |
| 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 DEBUG_KERNEL | |
| 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 || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV || SUPERH | |
| 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. | |
| Say Y here only if you plan to debug the kernel. | |
| If unsure, say N. | |
| 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. | |
| 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_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 FRAME_POINTER | |
| bool "Compile the kernel with frame pointers" | |
| depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH) | |
| 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 UNWIND_INFO | |
| bool "Compile the kernel with frame unwind information" | |
| depends on !IA64 && !PARISC && !ARM | |
| depends on !MODULES || !(MIPS || PPC || SUPERH || V850) | |
| help | |
| If you say Y here the resulting kernel image will be slightly larger | |
| but not slower, and it will give very useful debugging information. | |
| If you don't debug the kernel, you can say N, but we may not be able | |
| to solve problems without frame unwind information or frame pointers. | |
| config STACK_UNWIND | |
| bool "Stack unwind support" | |
| depends on UNWIND_INFO | |
| depends on X86 | |
| help | |
| This enables more precise stack traces, omitting all unrelated | |
| occurrences of pointers into kernel code from the dump. | |
| config FORCED_INLINING | |
| bool "Force gcc to inline functions marked 'inline'" | |
| depends on DEBUG_KERNEL | |
| default y | |
| help | |
| This option determines if the kernel forces gcc to inline the functions | |
| developers have marked 'inline'. Doing so takes away freedom from gcc to | |
| do what it thinks is best, which is desirable for the gcc 3.x series of | |
| compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
| disabling this option will generate a smaller kernel there. Hopefully | |
| this algorithm is so good that allowing gcc4 to make the decision can | |
| become the default in the future, until then this option is there to | |
| test gcc for this. | |
| 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 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 start automatically | |
| at boot time (you probably don't). | |
| Say M if you want the RCU torture tests to build as a module. | |
| Say N if you are unsure. | |
| config LKDTM | |
| tristate "Linux Kernel Dump Test Tool Module" | |
| depends on KPROBES | |
| 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 |