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 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_PREEMPT 89 bool "Debug preemptible kernel" 90 depends on DEBUG_KERNEL && PREEMPT 91 default y 92 help 93 If you say Y here then the kernel will use a debug variant of the 94 commonly used smp_processor_id() function and will print warnings 95 if kernel code uses it in a preemption-unsafe way. Also, the kernel 96 will detect preemption count underflows. 97 98config DEBUG_MUTEXES 99 bool "Mutex debugging, deadlock detection" 100 default y 101 depends on DEBUG_KERNEL 102 help 103 This allows mutex semantics violations and mutex related deadlocks 104 (lockups) to be detected and reported automatically. 105 106config DEBUG_SPINLOCK 107 bool "Spinlock debugging" 108 depends on DEBUG_KERNEL 109 help 110 Say Y here and build SMP to catch missing spinlock initialization 111 and certain other kinds of spinlock errors commonly made. This is 112 best used in conjunction with the NMI watchdog so that spinlock 113 deadlocks are also debuggable. 114 115config DEBUG_SPINLOCK_SLEEP 116 bool "Sleep-inside-spinlock checking" 117 depends on DEBUG_KERNEL 118 help 119 If you say Y here, various routines which may sleep will become very 120 noisy if they are called with a spinlock held. 121 122config DEBUG_KOBJECT 123 bool "kobject debugging" 124 depends on DEBUG_KERNEL 125 help 126 If you say Y here, some extra kobject debugging messages will be sent 127 to the syslog. 128 129config DEBUG_HIGHMEM 130 bool "Highmem debugging" 131 depends on DEBUG_KERNEL && HIGHMEM 132 help 133 This options enables addition error checking for high memory systems. 134 Disable for production systems. 135 136config DEBUG_BUGVERBOSE 137 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 138 depends on BUG 139 depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV 140 default !EMBEDDED 141 help 142 Say Y here to make BUG() panics output the file name and line number 143 of the BUG call as well as the EIP and oops trace. This aids 144 debugging but costs about 70-100K of memory. 145 146config DEBUG_INFO 147 bool "Compile the kernel with debug info" 148 depends on DEBUG_KERNEL 149 help 150 If you say Y here the resulting kernel image will include 151 debugging info resulting in a larger kernel image. 152 Say Y here only if you plan to debug the kernel. 153 154 If unsure, say N. 155 156config DEBUG_IOREMAP 157 bool "Enable ioremap() debugging" 158 depends on DEBUG_KERNEL && PARISC 159 help 160 Enabling this option will cause the kernel to distinguish between 161 ioremapped and physical addresses. It will print a backtrace (at 162 most one every 10 seconds), hopefully allowing you to see which 163 drivers need work. Fixing all these problems is a prerequisite 164 for turning on USE_HPPA_IOREMAP. The warnings are harmless; 165 the kernel has enough information to fix the broken drivers 166 automatically, but we'd like to make it more efficient by not 167 having to do that. 168 169config DEBUG_FS 170 bool "Debug Filesystem" 171 depends on DEBUG_KERNEL && SYSFS 172 help 173 debugfs is a virtual file system that kernel developers use to put 174 debugging files into. Enable this option to be able to read and 175 write to these files. 176 177 If unsure, say N. 178 179config DEBUG_VM 180 bool "Debug VM" 181 depends on DEBUG_KERNEL 182 help 183 Enable this to turn on extended checks in the virtual-memory system 184 that may impact performance. 185 186 If unsure, say N. 187 188config FRAME_POINTER 189 bool "Compile the kernel with frame pointers" 190 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML) 191 default y if DEBUG_INFO && UML 192 help 193 If you say Y here the resulting kernel image will be slightly larger 194 and slower, but it might give very useful debugging information on 195 some architectures or if you use external debuggers. 196 If you don't debug the kernel, you can say N. 197 198config FORCED_INLINING 199 bool "Force gcc to inline functions marked 'inline'" 200 depends on DEBUG_KERNEL 201 default y 202 help 203 This option determines if the kernel forces gcc to inline the functions 204 developers have marked 'inline'. Doing so takes away freedom from gcc to 205 do what it thinks is best, which is desirable for the gcc 3.x series of 206 compilers. The gcc 4.x series have a rewritten inlining algorithm and 207 disabling this option will generate a smaller kernel there. Hopefully 208 this algorithm is so good that allowing gcc4 to make the decision can 209 become the default in the future, until then this option is there to 210 test gcc for this. 211 212config RCU_TORTURE_TEST 213 tristate "torture tests for RCU" 214 depends on DEBUG_KERNEL 215 default n 216 help 217 This option provides a kernel module that runs torture tests 218 on the RCU infrastructure. The kernel module may be built 219 after the fact on the running kernel to be tested, if desired. 220 221 Say Y here if you want RCU torture tests to start automatically 222 at boot time (you probably don't). 223 Say M if you want the RCU torture tests to build as a module. 224 Say N if you are unsure. 225