1 2config 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 12config 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 26config DEBUG_KERNEL 27 bool "Kernel debugging" 28 help 29 Say Y here if you are developing drivers or trying to debug and 30 identify kernel problems. 31 32config LOG_BUF_SHIFT 33 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL 34 range 12 21 35 default 17 if S390 36 default 16 if X86_NUMAQ || IA64 37 default 15 if SMP 38 default 14 39 help 40 Select kernel log buffer size as a power of 2. 41 Defaults and Examples: 42 17 => 128 KB for S/390 43 16 => 64 KB for x86 NUMAQ or IA-64 44 15 => 32 KB for SMP 45 14 => 16 KB for uniprocessor 46 13 => 8 KB 47 12 => 4 KB 48 49config DETECT_SOFTLOCKUP 50 bool "Detect Soft Lockups" 51 depends on DEBUG_KERNEL 52 default y 53 help 54 Say Y here to enable the kernel to detect "soft lockups", 55 which are bugs that cause the kernel to loop in kernel 56 mode for more than 10 seconds, without giving other tasks a 57 chance to run. 58 59 When a soft-lockup is detected, the kernel will print the 60 current stack trace (which you should report), but the 61 system will stay locked up. This feature has negligible 62 overhead. 63 64 (Note that "hard lockups" are separate type of bugs that 65 can be detected via the NMI-watchdog, on platforms that 66 support it.) 67 68config SCHEDSTATS 69 bool "Collect scheduler statistics" 70 depends on DEBUG_KERNEL && PROC_FS 71 help 72 If you say Y here, additional code will be inserted into the 73 scheduler and related routines to collect statistics about 74 scheduler behavior and provide them in /proc/schedstat. These 75 stats may be useful for both tuning and debugging the scheduler 76 If you aren't debugging the scheduler or trying to tune a specific 77 application, you can say N to avoid the very slight overhead 78 this adds. 79 80config DEBUG_SLAB 81 bool "Debug slab memory allocations" 82 depends on DEBUG_KERNEL && SLAB 83 help 84 Say Y here to have the kernel do limited verification on memory 85 allocation as well as poisoning memory on free to catch use of freed 86 memory. This can make kmalloc/kfree-intensive workloads much slower. 87 88config DEBUG_SLAB_LEAK 89 bool "Memory leak debugging" 90 depends on DEBUG_SLAB 91 92config DEBUG_PREEMPT 93 bool "Debug preemptible kernel" 94 depends on DEBUG_KERNEL && PREEMPT 95 default y 96 help 97 If you say Y here then the kernel will use a debug variant of the 98 commonly used smp_processor_id() function and will print warnings 99 if kernel code uses it in a preemption-unsafe way. Also, the kernel 100 will detect preemption count underflows. 101 102config DEBUG_MUTEXES 103 bool "Mutex debugging, deadlock detection" 104 default n 105 depends on DEBUG_KERNEL 106 help 107 This allows mutex semantics violations and mutex related deadlocks 108 (lockups) to be detected and reported automatically. 109 110config DEBUG_SPINLOCK 111 bool "Spinlock debugging" 112 depends on DEBUG_KERNEL 113 help 114 Say Y here and build SMP to catch missing spinlock initialization 115 and certain other kinds of spinlock errors commonly made. This is 116 best used in conjunction with the NMI watchdog so that spinlock 117 deadlocks are also debuggable. 118 119config DEBUG_SPINLOCK_SLEEP 120 bool "Sleep-inside-spinlock checking" 121 depends on DEBUG_KERNEL 122 help 123 If you say Y here, various routines which may sleep will become very 124 noisy if they are called with a spinlock held. 125 126config DEBUG_KOBJECT 127 bool "kobject debugging" 128 depends on DEBUG_KERNEL 129 help 130 If you say Y here, some extra kobject debugging messages will be sent 131 to the syslog. 132 133config DEBUG_HIGHMEM 134 bool "Highmem debugging" 135 depends on DEBUG_KERNEL && HIGHMEM 136 help 137 This options enables addition error checking for high memory systems. 138 Disable for production systems. 139 140config DEBUG_BUGVERBOSE 141 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 142 depends on BUG 143 depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV 144 default !EMBEDDED 145 help 146 Say Y here to make BUG() panics output the file name and line number 147 of the BUG call as well as the EIP and oops trace. This aids 148 debugging but costs about 70-100K of memory. 149 150config DEBUG_INFO 151 bool "Compile the kernel with debug info" 152 depends on DEBUG_KERNEL 153 help 154 If you say Y here the resulting kernel image will include 155 debugging info resulting in a larger kernel image. 156 Say Y here only if you plan to debug the kernel. 157 158 If unsure, say N. 159 160config DEBUG_FS 161 bool "Debug Filesystem" 162 depends on SYSFS 163 help 164 debugfs is a virtual file system that kernel developers use to put 165 debugging files into. Enable this option to be able to read and 166 write to these files. 167 168 If unsure, say N. 169 170config DEBUG_VM 171 bool "Debug VM" 172 depends on DEBUG_KERNEL 173 help 174 Enable this to turn on extended checks in the virtual-memory system 175 that may impact performance. 176 177 If unsure, say N. 178 179config FRAME_POINTER 180 bool "Compile the kernel with frame pointers" 181 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML) 182 default y if DEBUG_INFO && UML 183 help 184 If you say Y here the resulting kernel image will be slightly larger 185 and slower, but it might give very useful debugging information on 186 some architectures or if you use external debuggers. 187 If you don't debug the kernel, you can say N. 188 189config UNWIND_INFO 190 bool "Compile the kernel with frame unwind information" 191 depends on !IA64 192 depends on !MODULES || !(MIPS || PARISC || PPC || SUPERH || V850) 193 help 194 If you say Y here the resulting kernel image will be slightly larger 195 but not slower, and it will give very useful debugging information. 196 If you don't debug the kernel, you can say N, but we may not be able 197 to solve problems without frame unwind information or frame pointers. 198 199config FORCED_INLINING 200 bool "Force gcc to inline functions marked 'inline'" 201 depends on DEBUG_KERNEL 202 default y 203 help 204 This option determines if the kernel forces gcc to inline the functions 205 developers have marked 'inline'. Doing so takes away freedom from gcc to 206 do what it thinks is best, which is desirable for the gcc 3.x series of 207 compilers. The gcc 4.x series have a rewritten inlining algorithm and 208 disabling this option will generate a smaller kernel there. Hopefully 209 this algorithm is so good that allowing gcc4 to make the decision can 210 become the default in the future, until then this option is there to 211 test gcc for this. 212 213config RCU_TORTURE_TEST 214 tristate "torture tests for RCU" 215 depends on DEBUG_KERNEL 216 default n 217 help 218 This option provides a kernel module that runs torture tests 219 on the RCU infrastructure. The kernel module may be built 220 after the fact on the running kernel to be tested, if desired. 221 222 Say Y here if you want RCU torture tests to start automatically 223 at boot time (you probably don't). 224 Say M if you want the RCU torture tests to build as a module. 225 Say N if you are unsure. 226