1# 2# General architecture dependent options 3# 4 5config OPROFILE 6 tristate "OProfile system profiling" 7 depends on PROFILING 8 depends on HAVE_OPROFILE 9 select RING_BUFFER 10 select RING_BUFFER_ALLOW_SWAP 11 help 12 OProfile is a profiling system capable of profiling the 13 whole system, include the kernel, kernel modules, libraries, 14 and applications. 15 16 If unsure, say N. 17 18config OPROFILE_EVENT_MULTIPLEX 19 bool "OProfile multiplexing support (EXPERIMENTAL)" 20 default n 21 depends on OPROFILE && X86 22 help 23 The number of hardware counters is limited. The multiplexing 24 feature enables OProfile to gather more events than counters 25 are provided by the hardware. This is realized by switching 26 between events at an user specified time interval. 27 28 If unsure, say N. 29 30config HAVE_OPROFILE 31 bool 32 33config OPROFILE_NMI_TIMER 34 def_bool y 35 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI 36 37config KPROBES 38 bool "Kprobes" 39 depends on MODULES 40 depends on HAVE_KPROBES 41 select KALLSYMS 42 help 43 Kprobes allows you to trap at almost any kernel address and 44 execute a callback function. register_kprobe() establishes 45 a probepoint and specifies the callback. Kprobes is useful 46 for kernel debugging, non-intrusive instrumentation and testing. 47 If in doubt, say "N". 48 49config JUMP_LABEL 50 bool "Optimize very unlikely/likely branches" 51 depends on HAVE_ARCH_JUMP_LABEL 52 help 53 This option enables a transparent branch optimization that 54 makes certain almost-always-true or almost-always-false branch 55 conditions even cheaper to execute within the kernel. 56 57 Certain performance-sensitive kernel code, such as trace points, 58 scheduler functionality, networking code and KVM have such 59 branches and include support for this optimization technique. 60 61 If it is detected that the compiler has support for "asm goto", 62 the kernel will compile such branches with just a nop 63 instruction. When the condition flag is toggled to true, the 64 nop will be converted to a jump instruction to execute the 65 conditional block of instructions. 66 67 This technique lowers overhead and stress on the branch prediction 68 of the processor and generally makes the kernel faster. The update 69 of the condition is slower, but those are always very rare. 70 71 ( On 32-bit x86, the necessary options added to the compiler 72 flags may increase the size of the kernel slightly. ) 73 74config OPTPROBES 75 def_bool y 76 depends on KPROBES && HAVE_OPTPROBES 77 depends on !PREEMPT 78 79config HAVE_EFFICIENT_UNALIGNED_ACCESS 80 bool 81 help 82 Some architectures are unable to perform unaligned accesses 83 without the use of get_unaligned/put_unaligned. Others are 84 unable to perform such accesses efficiently (e.g. trap on 85 unaligned access and require fixing it up in the exception 86 handler.) 87 88 This symbol should be selected by an architecture if it can 89 perform unaligned accesses efficiently to allow different 90 code paths to be selected for these cases. Some network 91 drivers, for example, could opt to not fix up alignment 92 problems with received packets if doing so would not help 93 much. 94 95 See Documentation/unaligned-memory-access.txt for more 96 information on the topic of unaligned memory accesses. 97 98config HAVE_SYSCALL_WRAPPERS 99 bool 100 101config KRETPROBES 102 def_bool y 103 depends on KPROBES && HAVE_KRETPROBES 104 105config USER_RETURN_NOTIFIER 106 bool 107 depends on HAVE_USER_RETURN_NOTIFIER 108 help 109 Provide a kernel-internal notification when a cpu is about to 110 switch to user mode. 111 112config HAVE_IOREMAP_PROT 113 bool 114 115config HAVE_KPROBES 116 bool 117 118config HAVE_KRETPROBES 119 bool 120 121config HAVE_OPTPROBES 122 bool 123# 124# An arch should select this if it provides all these things: 125# 126# task_pt_regs() in asm/processor.h or asm/ptrace.h 127# arch_has_single_step() if there is hardware single-step support 128# arch_has_block_step() if there is hardware block-step support 129# asm/syscall.h supplying asm-generic/syscall.h interface 130# linux/regset.h user_regset interfaces 131# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 132# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 133# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 134# signal delivery calls tracehook_signal_handler() 135# 136config HAVE_ARCH_TRACEHOOK 137 bool 138 139config HAVE_DMA_ATTRS 140 bool 141 142config USE_GENERIC_SMP_HELPERS 143 bool 144 145config HAVE_REGS_AND_STACK_ACCESS_API 146 bool 147 help 148 This symbol should be selected by an architecure if it supports 149 the API needed to access registers and stack entries from pt_regs, 150 declared in asm/ptrace.h 151 For example the kprobes-based event tracer needs this API. 152 153config HAVE_CLK 154 bool 155 help 156 The <linux/clk.h> calls support software clock gating and 157 thus are a key power management tool on many systems. 158 159config HAVE_DMA_API_DEBUG 160 bool 161 162config HAVE_HW_BREAKPOINT 163 bool 164 depends on PERF_EVENTS 165 166config HAVE_MIXED_BREAKPOINTS_REGS 167 bool 168 depends on HAVE_HW_BREAKPOINT 169 help 170 Depending on the arch implementation of hardware breakpoints, 171 some of them have separate registers for data and instruction 172 breakpoints addresses, others have mixed registers to store 173 them but define the access type in a control register. 174 Select this option if your arch implements breakpoints under the 175 latter fashion. 176 177config HAVE_USER_RETURN_NOTIFIER 178 bool 179 180config HAVE_PERF_EVENTS_NMI 181 bool 182 help 183 System hardware can generate an NMI using the perf event 184 subsystem. Also has support for calculating CPU cycle events 185 to determine how many clock cycles in a given period. 186 187config HAVE_ARCH_JUMP_LABEL 188 bool 189 190config HAVE_ARCH_MUTEX_CPU_RELAX 191 bool 192 193config HAVE_RCU_TABLE_FREE 194 bool 195 196config ARCH_HAVE_NMI_SAFE_CMPXCHG 197 bool 198 199config HAVE_ALIGNED_STRUCT_PAGE 200 bool 201 help 202 This makes sure that struct pages are double word aligned and that 203 e.g. the SLUB allocator can perform double word atomic operations 204 on a struct page for better performance. However selecting this 205 might increase the size of a struct page by a word. 206 207config HAVE_CMPXCHG_LOCAL 208 bool 209 210config HAVE_CMPXCHG_DOUBLE 211 bool 212 213source "kernel/gcov/Kconfig" 214