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 UPROBES 80 bool "Transparent user-space probes (EXPERIMENTAL)" 81 depends on UPROBE_EVENT && PERF_EVENTS 82 default n 83 select PERCPU_RWSEM 84 help 85 Uprobes is the user-space counterpart to kprobes: they 86 enable instrumentation applications (such as 'perf probe') 87 to establish unintrusive probes in user-space binaries and 88 libraries, by executing handler functions when the probes 89 are hit by user-space applications. 90 91 ( These probes come in the form of single-byte breakpoints, 92 managed by the kernel and kept transparent to the probed 93 application. ) 94 95 If in doubt, say "N". 96 97config HAVE_EFFICIENT_UNALIGNED_ACCESS 98 bool 99 help 100 Some architectures are unable to perform unaligned accesses 101 without the use of get_unaligned/put_unaligned. Others are 102 unable to perform such accesses efficiently (e.g. trap on 103 unaligned access and require fixing it up in the exception 104 handler.) 105 106 This symbol should be selected by an architecture if it can 107 perform unaligned accesses efficiently to allow different 108 code paths to be selected for these cases. Some network 109 drivers, for example, could opt to not fix up alignment 110 problems with received packets if doing so would not help 111 much. 112 113 See Documentation/unaligned-memory-access.txt for more 114 information on the topic of unaligned memory accesses. 115 116config HAVE_SYSCALL_WRAPPERS 117 bool 118 119config KRETPROBES 120 def_bool y 121 depends on KPROBES && HAVE_KRETPROBES 122 123config USER_RETURN_NOTIFIER 124 bool 125 depends on HAVE_USER_RETURN_NOTIFIER 126 help 127 Provide a kernel-internal notification when a cpu is about to 128 switch to user mode. 129 130config HAVE_IOREMAP_PROT 131 bool 132 133config HAVE_KPROBES 134 bool 135 136config HAVE_KRETPROBES 137 bool 138 139config HAVE_OPTPROBES 140 bool 141 142config HAVE_NMI_WATCHDOG 143 bool 144# 145# An arch should select this if it provides all these things: 146# 147# task_pt_regs() in asm/processor.h or asm/ptrace.h 148# arch_has_single_step() if there is hardware single-step support 149# arch_has_block_step() if there is hardware block-step support 150# asm/syscall.h supplying asm-generic/syscall.h interface 151# linux/regset.h user_regset interfaces 152# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 153# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 154# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 155# signal delivery calls tracehook_signal_handler() 156# 157config HAVE_ARCH_TRACEHOOK 158 bool 159 160config HAVE_DMA_ATTRS 161 bool 162 163config HAVE_DMA_CONTIGUOUS 164 bool 165 166config USE_GENERIC_SMP_HELPERS 167 bool 168 169config GENERIC_SMP_IDLE_THREAD 170 bool 171 172# Select if arch init_task initializer is different to init/init_task.c 173config ARCH_INIT_TASK 174 bool 175 176# Select if arch has its private alloc_task_struct() function 177config ARCH_TASK_STRUCT_ALLOCATOR 178 bool 179 180# Select if arch has its private alloc_thread_info() function 181config ARCH_THREAD_INFO_ALLOCATOR 182 bool 183 184config HAVE_REGS_AND_STACK_ACCESS_API 185 bool 186 help 187 This symbol should be selected by an architecure if it supports 188 the API needed to access registers and stack entries from pt_regs, 189 declared in asm/ptrace.h 190 For example the kprobes-based event tracer needs this API. 191 192config HAVE_CLK 193 bool 194 help 195 The <linux/clk.h> calls support software clock gating and 196 thus are a key power management tool on many systems. 197 198config HAVE_DMA_API_DEBUG 199 bool 200 201config HAVE_HW_BREAKPOINT 202 bool 203 depends on PERF_EVENTS 204 205config HAVE_MIXED_BREAKPOINTS_REGS 206 bool 207 depends on HAVE_HW_BREAKPOINT 208 help 209 Depending on the arch implementation of hardware breakpoints, 210 some of them have separate registers for data and instruction 211 breakpoints addresses, others have mixed registers to store 212 them but define the access type in a control register. 213 Select this option if your arch implements breakpoints under the 214 latter fashion. 215 216config HAVE_USER_RETURN_NOTIFIER 217 bool 218 219config HAVE_PERF_EVENTS_NMI 220 bool 221 help 222 System hardware can generate an NMI using the perf event 223 subsystem. Also has support for calculating CPU cycle events 224 to determine how many clock cycles in a given period. 225 226config HAVE_PERF_REGS 227 bool 228 help 229 Support selective register dumps for perf events. This includes 230 bit-mapping of each registers and a unique architecture id. 231 232config HAVE_PERF_USER_STACK_DUMP 233 bool 234 help 235 Support user stack dumps for perf event samples. This needs 236 access to the user stack pointer which is not unified across 237 architectures. 238 239config HAVE_ARCH_JUMP_LABEL 240 bool 241 242config HAVE_ARCH_MUTEX_CPU_RELAX 243 bool 244 245config HAVE_RCU_TABLE_FREE 246 bool 247 248config ARCH_HAVE_NMI_SAFE_CMPXCHG 249 bool 250 251config HAVE_ALIGNED_STRUCT_PAGE 252 bool 253 help 254 This makes sure that struct pages are double word aligned and that 255 e.g. the SLUB allocator can perform double word atomic operations 256 on a struct page for better performance. However selecting this 257 might increase the size of a struct page by a word. 258 259config HAVE_CMPXCHG_LOCAL 260 bool 261 262config HAVE_CMPXCHG_DOUBLE 263 bool 264 265config ARCH_WANT_IPC_PARSE_VERSION 266 bool 267 268config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 269 bool 270 271config ARCH_WANT_OLD_COMPAT_IPC 272 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 273 bool 274 275config GENERIC_KERNEL_THREAD 276 bool 277 278config GENERIC_KERNEL_EXECVE 279 bool 280 281config HAVE_ARCH_SECCOMP_FILTER 282 bool 283 help 284 An arch should select this symbol if it provides all of these things: 285 - syscall_get_arch() 286 - syscall_get_arguments() 287 - syscall_rollback() 288 - syscall_set_return_value() 289 - SIGSYS siginfo_t support 290 - secure_computing is called from a ptrace_event()-safe context 291 - secure_computing return value is checked and a return value of -1 292 results in the system call being skipped immediately. 293 294config SECCOMP_FILTER 295 def_bool y 296 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 297 help 298 Enable tasks to build secure computing environments defined 299 in terms of Berkeley Packet Filter programs which implement 300 task-defined system call filtering polices. 301 302 See Documentation/prctl/seccomp_filter.txt for details. 303 304config HAVE_CONTEXT_TRACKING 305 bool 306 help 307 Provide kernel/user boundaries probes necessary for subsystems 308 that need it, such as userspace RCU extended quiescent state. 309 Syscalls need to be wrapped inside user_exit()-user_enter() through 310 the slow path using TIF_NOHZ flag. Exceptions handlers must be 311 wrapped as well. Irqs are already protected inside 312 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 313 irq exit still need to be protected. 314 315config HAVE_VIRT_CPU_ACCOUNTING 316 bool 317 318config HAVE_IRQ_TIME_ACCOUNTING 319 bool 320 help 321 Archs need to ensure they use a high enough resolution clock to 322 support irq time accounting and then call enable_sched_clock_irqtime(). 323 324config HAVE_ARCH_TRANSPARENT_HUGEPAGE 325 bool 326 327config HAVE_MOD_ARCH_SPECIFIC 328 bool 329 help 330 The arch uses struct mod_arch_specific to store data. Many arches 331 just need a simple module loader without arch specific data - those 332 should not enable this. 333 334config MODULES_USE_ELF_RELA 335 bool 336 help 337 Modules only use ELF RELA relocations. Modules with ELF REL 338 relocations will give an error. 339 340config MODULES_USE_ELF_REL 341 bool 342 help 343 Modules only use ELF REL relocations. Modules with ELF RELA 344 relocations will give an error. 345 346# 347# ABI hall of shame 348# 349config CLONE_BACKWARDS 350 bool 351 help 352 Architecture has tls passed as the 4th argument of clone(2), 353 not the 5th one. 354 355config CLONE_BACKWARDS2 356 bool 357 help 358 Architecture has the first two arguments of clone(2) swapped. 359 360source "kernel/gcov/Kconfig" 361