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 KPROBES_ON_FTRACE 80 def_bool y 81 depends on KPROBES && HAVE_KPROBES_ON_FTRACE 82 depends on DYNAMIC_FTRACE_WITH_REGS 83 help 84 If function tracer is enabled and the arch supports full 85 passing of pt_regs to function tracing, then kprobes can 86 optimize on top of function tracing. 87 88config UPROBES 89 bool "Transparent user-space probes (EXPERIMENTAL)" 90 depends on UPROBE_EVENT && PERF_EVENTS 91 default n 92 select PERCPU_RWSEM 93 help 94 Uprobes is the user-space counterpart to kprobes: they 95 enable instrumentation applications (such as 'perf probe') 96 to establish unintrusive probes in user-space binaries and 97 libraries, by executing handler functions when the probes 98 are hit by user-space applications. 99 100 ( These probes come in the form of single-byte breakpoints, 101 managed by the kernel and kept transparent to the probed 102 application. ) 103 104 If in doubt, say "N". 105 106config HAVE_64BIT_ALIGNED_ACCESS 107 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS 108 help 109 Some architectures require 64 bit accesses to be 64 bit 110 aligned, which also requires structs containing 64 bit values 111 to be 64 bit aligned too. This includes some 32 bit 112 architectures which can do 64 bit accesses, as well as 64 bit 113 architectures without unaligned access. 114 115 This symbol should be selected by an architecture if 64 bit 116 accesses are required to be 64 bit aligned in this way even 117 though it is not a 64 bit architecture. 118 119 See Documentation/unaligned-memory-access.txt for more 120 information on the topic of unaligned memory accesses. 121 122config HAVE_EFFICIENT_UNALIGNED_ACCESS 123 bool 124 help 125 Some architectures are unable to perform unaligned accesses 126 without the use of get_unaligned/put_unaligned. Others are 127 unable to perform such accesses efficiently (e.g. trap on 128 unaligned access and require fixing it up in the exception 129 handler.) 130 131 This symbol should be selected by an architecture if it can 132 perform unaligned accesses efficiently to allow different 133 code paths to be selected for these cases. Some network 134 drivers, for example, could opt to not fix up alignment 135 problems with received packets if doing so would not help 136 much. 137 138 See Documentation/unaligned-memory-access.txt for more 139 information on the topic of unaligned memory accesses. 140 141config ARCH_USE_BUILTIN_BSWAP 142 bool 143 help 144 Modern versions of GCC (since 4.4) have builtin functions 145 for handling byte-swapping. Using these, instead of the old 146 inline assembler that the architecture code provides in the 147 __arch_bswapXX() macros, allows the compiler to see what's 148 happening and offers more opportunity for optimisation. In 149 particular, the compiler will be able to combine the byteswap 150 with a nearby load or store and use load-and-swap or 151 store-and-swap instructions if the architecture has them. It 152 should almost *never* result in code which is worse than the 153 hand-coded assembler in <asm/swab.h>. But just in case it 154 does, the use of the builtins is optional. 155 156 Any architecture with load-and-swap or store-and-swap 157 instructions should set this. And it shouldn't hurt to set it 158 on architectures that don't have such instructions. 159 160config KRETPROBES 161 def_bool y 162 depends on KPROBES && HAVE_KRETPROBES 163 164config USER_RETURN_NOTIFIER 165 bool 166 depends on HAVE_USER_RETURN_NOTIFIER 167 help 168 Provide a kernel-internal notification when a cpu is about to 169 switch to user mode. 170 171config HAVE_IOREMAP_PROT 172 bool 173 174config HAVE_KPROBES 175 bool 176 177config HAVE_KRETPROBES 178 bool 179 180config HAVE_OPTPROBES 181 bool 182 183config HAVE_KPROBES_ON_FTRACE 184 bool 185 186config HAVE_NMI_WATCHDOG 187 bool 188# 189# An arch should select this if it provides all these things: 190# 191# task_pt_regs() in asm/processor.h or asm/ptrace.h 192# arch_has_single_step() if there is hardware single-step support 193# arch_has_block_step() if there is hardware block-step support 194# asm/syscall.h supplying asm-generic/syscall.h interface 195# linux/regset.h user_regset interfaces 196# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 197# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 198# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 199# signal delivery calls tracehook_signal_handler() 200# 201config HAVE_ARCH_TRACEHOOK 202 bool 203 204config HAVE_DMA_ATTRS 205 bool 206 207config HAVE_DMA_CONTIGUOUS 208 bool 209 210config USE_GENERIC_SMP_HELPERS 211 bool 212 213config GENERIC_SMP_IDLE_THREAD 214 bool 215 216# Select if arch init_task initializer is different to init/init_task.c 217config ARCH_INIT_TASK 218 bool 219 220# Select if arch has its private alloc_task_struct() function 221config ARCH_TASK_STRUCT_ALLOCATOR 222 bool 223 224# Select if arch has its private alloc_thread_info() function 225config ARCH_THREAD_INFO_ALLOCATOR 226 bool 227 228config HAVE_REGS_AND_STACK_ACCESS_API 229 bool 230 help 231 This symbol should be selected by an architecure if it supports 232 the API needed to access registers and stack entries from pt_regs, 233 declared in asm/ptrace.h 234 For example the kprobes-based event tracer needs this API. 235 236config HAVE_CLK 237 bool 238 help 239 The <linux/clk.h> calls support software clock gating and 240 thus are a key power management tool on many systems. 241 242config HAVE_DMA_API_DEBUG 243 bool 244 245config HAVE_HW_BREAKPOINT 246 bool 247 depends on PERF_EVENTS 248 249config HAVE_MIXED_BREAKPOINTS_REGS 250 bool 251 depends on HAVE_HW_BREAKPOINT 252 help 253 Depending on the arch implementation of hardware breakpoints, 254 some of them have separate registers for data and instruction 255 breakpoints addresses, others have mixed registers to store 256 them but define the access type in a control register. 257 Select this option if your arch implements breakpoints under the 258 latter fashion. 259 260config HAVE_USER_RETURN_NOTIFIER 261 bool 262 263config HAVE_PERF_EVENTS_NMI 264 bool 265 help 266 System hardware can generate an NMI using the perf event 267 subsystem. Also has support for calculating CPU cycle events 268 to determine how many clock cycles in a given period. 269 270config HAVE_PERF_REGS 271 bool 272 help 273 Support selective register dumps for perf events. This includes 274 bit-mapping of each registers and a unique architecture id. 275 276config HAVE_PERF_USER_STACK_DUMP 277 bool 278 help 279 Support user stack dumps for perf event samples. This needs 280 access to the user stack pointer which is not unified across 281 architectures. 282 283config HAVE_ARCH_JUMP_LABEL 284 bool 285 286config HAVE_ARCH_MUTEX_CPU_RELAX 287 bool 288 289config HAVE_RCU_TABLE_FREE 290 bool 291 292config ARCH_HAVE_NMI_SAFE_CMPXCHG 293 bool 294 295config HAVE_ALIGNED_STRUCT_PAGE 296 bool 297 help 298 This makes sure that struct pages are double word aligned and that 299 e.g. the SLUB allocator can perform double word atomic operations 300 on a struct page for better performance. However selecting this 301 might increase the size of a struct page by a word. 302 303config HAVE_CMPXCHG_LOCAL 304 bool 305 306config HAVE_CMPXCHG_DOUBLE 307 bool 308 309config ARCH_WANT_IPC_PARSE_VERSION 310 bool 311 312config ARCH_WANT_COMPAT_IPC_PARSE_VERSION 313 bool 314 315config ARCH_WANT_OLD_COMPAT_IPC 316 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 317 bool 318 319config HAVE_ARCH_SECCOMP_FILTER 320 bool 321 help 322 An arch should select this symbol if it provides all of these things: 323 - syscall_get_arch() 324 - syscall_get_arguments() 325 - syscall_rollback() 326 - syscall_set_return_value() 327 - SIGSYS siginfo_t support 328 - secure_computing is called from a ptrace_event()-safe context 329 - secure_computing return value is checked and a return value of -1 330 results in the system call being skipped immediately. 331 332config SECCOMP_FILTER 333 def_bool y 334 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 335 help 336 Enable tasks to build secure computing environments defined 337 in terms of Berkeley Packet Filter programs which implement 338 task-defined system call filtering polices. 339 340 See Documentation/prctl/seccomp_filter.txt for details. 341 342config HAVE_CONTEXT_TRACKING 343 bool 344 help 345 Provide kernel/user boundaries probes necessary for subsystems 346 that need it, such as userspace RCU extended quiescent state. 347 Syscalls need to be wrapped inside user_exit()-user_enter() through 348 the slow path using TIF_NOHZ flag. Exceptions handlers must be 349 wrapped as well. Irqs are already protected inside 350 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on 351 irq exit still need to be protected. 352 353config HAVE_VIRT_CPU_ACCOUNTING 354 bool 355 356config HAVE_IRQ_TIME_ACCOUNTING 357 bool 358 help 359 Archs need to ensure they use a high enough resolution clock to 360 support irq time accounting and then call enable_sched_clock_irqtime(). 361 362config HAVE_ARCH_TRANSPARENT_HUGEPAGE 363 bool 364 365config HAVE_MOD_ARCH_SPECIFIC 366 bool 367 help 368 The arch uses struct mod_arch_specific to store data. Many arches 369 just need a simple module loader without arch specific data - those 370 should not enable this. 371 372config MODULES_USE_ELF_RELA 373 bool 374 help 375 Modules only use ELF RELA relocations. Modules with ELF REL 376 relocations will give an error. 377 378config MODULES_USE_ELF_REL 379 bool 380 help 381 Modules only use ELF REL relocations. Modules with ELF RELA 382 relocations will give an error. 383 384config HAVE_UNDERSCORE_SYMBOL_PREFIX 385 bool 386 help 387 Some architectures generate an _ in front of C symbols; things like 388 module loading and assembly files need to know about this. 389 390# 391# ABI hall of shame 392# 393config CLONE_BACKWARDS 394 bool 395 help 396 Architecture has tls passed as the 4th argument of clone(2), 397 not the 5th one. 398 399config CLONE_BACKWARDS2 400 bool 401 help 402 Architecture has the first two arguments of clone(2) swapped. 403 404config ODD_RT_SIGACTION 405 bool 406 help 407 Architecture has unusual rt_sigaction(2) arguments 408 409config OLD_SIGSUSPEND 410 bool 411 help 412 Architecture has old sigsuspend(2) syscall, of one-argument variety 413 414config OLD_SIGSUSPEND3 415 bool 416 help 417 Even weirder antique ABI - three-argument sigsuspend(2) 418 419config OLD_SIGACTION 420 bool 421 help 422 Architecture has old sigaction(2) syscall. Nope, not the same 423 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2), 424 but fairly different variant of sigaction(2), thanks to OSF/1 425 compatibility... 426 427config COMPAT_OLD_SIGACTION 428 bool 429 430source "kernel/gcov/Kconfig" 431