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 DEBUG_KERNEL 13 bool "Kernel debugging" 14 help 15 Say Y here if you are developing drivers or trying to debug and 16 identify kernel problems. 17 18config MAGIC_SYSRQ 19 bool "Magic SysRq key" 20 depends on DEBUG_KERNEL && !UML 21 help 22 If you say Y here, you will have some control over the system even 23 if the system crashes for example during kernel debugging (e.g., you 24 will be able to flush the buffer cache to disk, reboot the system 25 immediately or dump some status information). This is accomplished 26 by pressing various keys while holding SysRq (Alt+PrintScreen). It 27 also works on a serial console (on PC hardware at least), if you 28 send a BREAK and then within 5 seconds a command keypress. The 29 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y 30 unless you really know what this hack does. 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 ARCH_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 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_SPINLOCK 99 bool "Spinlock debugging" 100 depends on DEBUG_KERNEL 101 help 102 Say Y here and build SMP to catch missing spinlock initialization 103 and certain other kinds of spinlock errors commonly made. This is 104 best used in conjunction with the NMI watchdog so that spinlock 105 deadlocks are also debuggable. 106 107config DEBUG_SPINLOCK_SLEEP 108 bool "Sleep-inside-spinlock checking" 109 depends on DEBUG_KERNEL 110 help 111 If you say Y here, various routines which may sleep will become very 112 noisy if they are called with a spinlock held. 113 114config DEBUG_KOBJECT 115 bool "kobject debugging" 116 depends on DEBUG_KERNEL 117 help 118 If you say Y here, some extra kobject debugging messages will be sent 119 to the syslog. 120 121config DEBUG_HIGHMEM 122 bool "Highmem debugging" 123 depends on DEBUG_KERNEL && HIGHMEM 124 help 125 This options enables addition error checking for high memory systems. 126 Disable for production systems. 127 128config DEBUG_BUGVERBOSE 129 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED 130 depends on BUG 131 depends on ARM || ARM26 || M32R || M68K || SPARC32 || SPARC64 || (X86 && !X86_64) || FRV 132 default !EMBEDDED 133 help 134 Say Y here to make BUG() panics output the file name and line number 135 of the BUG call as well as the EIP and oops trace. This aids 136 debugging but costs about 70-100K of memory. 137 138config DEBUG_INFO 139 bool "Compile the kernel with debug info" 140 depends on DEBUG_KERNEL 141 help 142 If you say Y here the resulting kernel image will include 143 debugging info resulting in a larger kernel image. 144 Say Y here only if you plan to debug the kernel. 145 146 If unsure, say N. 147 148config DEBUG_IOREMAP 149 bool "Enable ioremap() debugging" 150 depends on DEBUG_KERNEL && PARISC 151 help 152 Enabling this option will cause the kernel to distinguish between 153 ioremapped and physical addresses. It will print a backtrace (at 154 most one every 10 seconds), hopefully allowing you to see which 155 drivers need work. Fixing all these problems is a prerequisite 156 for turning on USE_HPPA_IOREMAP. The warnings are harmless; 157 the kernel has enough information to fix the broken drivers 158 automatically, but we'd like to make it more efficient by not 159 having to do that. 160 161config DEBUG_FS 162 bool "Debug Filesystem" 163 depends on DEBUG_KERNEL && SYSFS 164 help 165 debugfs is a virtual file system that kernel developers use to put 166 debugging files into. Enable this option to be able to read and 167 write to these files. 168 169 If unsure, say N. 170 171config FRAME_POINTER 172 bool "Compile the kernel with frame pointers" 173 depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML) 174 default y if DEBUG_INFO && UML 175 help 176 If you say Y here the resulting kernel image will be slightly larger 177 and slower, but it might give very useful debugging information 178 on some architectures or you use external debuggers. 179 If you don't debug the kernel, you can say N. 180 181