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1#
2# General architecture dependent options
3#
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4
5config OPROFILE
b309a294 6 tristate "OProfile system profiling"
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7 depends on PROFILING
8 depends on HAVE_OPROFILE
d69d59f4 9 select RING_BUFFER
9a5963eb 10 select RING_BUFFER_ALLOW_SWAP
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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
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JY
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
125e5645 30config HAVE_OPROFILE
9ba16087 31 bool
125e5645 32
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33config OPROFILE_NMI_TIMER
34 def_bool y
35 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
36
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37config KPROBES
38 bool "Kprobes"
05ed160e 39 depends on MODULES
125e5645 40 depends on HAVE_KPROBES
05ed160e 41 select KALLSYMS
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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
45f81b1c 49config JUMP_LABEL
c5905afb 50 bool "Optimize very unlikely/likely branches"
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51 depends on HAVE_ARCH_JUMP_LABEL
52 help
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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
45f81b1c 61 If it is detected that the compiler has support for "asm goto",
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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.
45f81b1c 70
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71 ( On 32-bit x86, the necessary options added to the compiler
72 flags may increase the size of the kernel slightly. )
45f81b1c 73
afd66255 74config OPTPROBES
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75 def_bool y
76 depends on KPROBES && HAVE_OPTPROBES
afd66255 77 depends on !PREEMPT
afd66255 78
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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
2b144498 88config UPROBES
7b2d81d4 89 bool "Transparent user-space probes (EXPERIMENTAL)"
ec83db0f 90 depends on UPROBE_EVENT && PERF_EVENTS
2b144498 91 default n
22b361d1 92 select PERCPU_RWSEM
2b144498 93 help
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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. )
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103
104 If in doubt, say "N".
105
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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
58340a07 122config HAVE_EFFICIENT_UNALIGNED_ACCESS
9ba16087 123 bool
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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
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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
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160config KRETPROBES
161 def_bool y
162 depends on KPROBES && HAVE_KRETPROBES
163
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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
28b2ee20 171config HAVE_IOREMAP_PROT
9ba16087 172 bool
28b2ee20 173
125e5645 174config HAVE_KPROBES
9ba16087 175 bool
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176
177config HAVE_KRETPROBES
9ba16087 178 bool
74bc7cee 179
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180config HAVE_OPTPROBES
181 bool
d314d74c 182
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183config HAVE_KPROBES_ON_FTRACE
184 bool
185
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186config HAVE_NMI_WATCHDOG
187 bool
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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
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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
9ba16087 202 bool
1f5a4ad9 203
74bc7cee 204config HAVE_DMA_ATTRS
9ba16087 205 bool
3d442233 206
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207config HAVE_DMA_CONTIGUOUS
208 bool
209
3d442233 210config USE_GENERIC_SMP_HELPERS
9ba16087 211 bool
9483a578 212
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213config GENERIC_SMP_IDLE_THREAD
214 bool
215
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216config GENERIC_IDLE_POLL_SETUP
217 bool
218
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219# Select if arch init_task initializer is different to init/init_task.c
220config ARCH_INIT_TASK
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221 bool
222
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223# Select if arch has its private alloc_task_struct() function
224config ARCH_TASK_STRUCT_ALLOCATOR
225 bool
226
227# Select if arch has its private alloc_thread_info() function
228config ARCH_THREAD_INFO_ALLOCATOR
229 bool
230
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231config HAVE_REGS_AND_STACK_ACCESS_API
232 bool
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233 help
234 This symbol should be selected by an architecure if it supports
235 the API needed to access registers and stack entries from pt_regs,
236 declared in asm/ptrace.h
237 For example the kprobes-based event tracer needs this API.
f850c30c 238
9483a578 239config HAVE_CLK
9ba16087 240 bool
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241 help
242 The <linux/clk.h> calls support software clock gating and
243 thus are a key power management tool on many systems.
244
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245config HAVE_DMA_API_DEBUG
246 bool
36cd3c9f 247
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248config HAVE_HW_BREAKPOINT
249 bool
99e8c5a3 250 depends on PERF_EVENTS
62a038d3 251
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252config HAVE_MIXED_BREAKPOINTS_REGS
253 bool
254 depends on HAVE_HW_BREAKPOINT
255 help
256 Depending on the arch implementation of hardware breakpoints,
257 some of them have separate registers for data and instruction
258 breakpoints addresses, others have mixed registers to store
259 them but define the access type in a control register.
260 Select this option if your arch implements breakpoints under the
261 latter fashion.
262
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263config HAVE_USER_RETURN_NOTIFIER
264 bool
a1922ed6 265
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266config HAVE_PERF_EVENTS_NMI
267 bool
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268 help
269 System hardware can generate an NMI using the perf event
270 subsystem. Also has support for calculating CPU cycle events
271 to determine how many clock cycles in a given period.
c01d4323 272
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273config HAVE_PERF_REGS
274 bool
275 help
276 Support selective register dumps for perf events. This includes
277 bit-mapping of each registers and a unique architecture id.
278
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279config HAVE_PERF_USER_STACK_DUMP
280 bool
281 help
282 Support user stack dumps for perf event samples. This needs
283 access to the user stack pointer which is not unified across
284 architectures.
285
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286config HAVE_ARCH_JUMP_LABEL
287 bool
288
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289config HAVE_ARCH_MUTEX_CPU_RELAX
290 bool
291
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292config HAVE_RCU_TABLE_FREE
293 bool
294
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295config ARCH_HAVE_NMI_SAFE_CMPXCHG
296 bool
297
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298config HAVE_ALIGNED_STRUCT_PAGE
299 bool
300 help
301 This makes sure that struct pages are double word aligned and that
302 e.g. the SLUB allocator can perform double word atomic operations
303 on a struct page for better performance. However selecting this
304 might increase the size of a struct page by a word.
305
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306config HAVE_CMPXCHG_LOCAL
307 bool
308
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309config HAVE_CMPXCHG_DOUBLE
310 bool
311
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312config ARCH_WANT_IPC_PARSE_VERSION
313 bool
314
315config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
316 bool
317
48b25c43 318config ARCH_WANT_OLD_COMPAT_IPC
c1d7e01d 319 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
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320 bool
321
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322config HAVE_ARCH_SECCOMP_FILTER
323 bool
324 help
fb0fadf9 325 An arch should select this symbol if it provides all of these things:
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326 - syscall_get_arch()
327 - syscall_get_arguments()
328 - syscall_rollback()
329 - syscall_set_return_value()
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330 - SIGSYS siginfo_t support
331 - secure_computing is called from a ptrace_event()-safe context
332 - secure_computing return value is checked and a return value of -1
333 results in the system call being skipped immediately.
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334
335config SECCOMP_FILTER
336 def_bool y
337 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
338 help
339 Enable tasks to build secure computing environments defined
340 in terms of Berkeley Packet Filter programs which implement
341 task-defined system call filtering polices.
342
343 See Documentation/prctl/seccomp_filter.txt for details.
344
91d1aa43 345config HAVE_CONTEXT_TRACKING
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346 bool
347 help
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348 Provide kernel/user boundaries probes necessary for subsystems
349 that need it, such as userspace RCU extended quiescent state.
350 Syscalls need to be wrapped inside user_exit()-user_enter() through
351 the slow path using TIF_NOHZ flag. Exceptions handlers must be
352 wrapped as well. Irqs are already protected inside
353 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
354 irq exit still need to be protected.
2b1d5024 355
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356config HAVE_VIRT_CPU_ACCOUNTING
357 bool
358
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FW
359config HAVE_IRQ_TIME_ACCOUNTING
360 bool
361 help
362 Archs need to ensure they use a high enough resolution clock to
363 support irq time accounting and then call enable_sched_clock_irqtime().
364
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365config HAVE_ARCH_TRANSPARENT_HUGEPAGE
366 bool
367
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368config HAVE_MOD_ARCH_SPECIFIC
369 bool
370 help
371 The arch uses struct mod_arch_specific to store data. Many arches
372 just need a simple module loader without arch specific data - those
373 should not enable this.
374
375config MODULES_USE_ELF_RELA
376 bool
377 help
378 Modules only use ELF RELA relocations. Modules with ELF REL
379 relocations will give an error.
380
381config MODULES_USE_ELF_REL
382 bool
383 help
384 Modules only use ELF REL relocations. Modules with ELF RELA
385 relocations will give an error.
386
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387config HAVE_UNDERSCORE_SYMBOL_PREFIX
388 bool
389 help
390 Some architectures generate an _ in front of C symbols; things like
391 module loading and assembly files need to know about this.
392
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393#
394# ABI hall of shame
395#
396config CLONE_BACKWARDS
397 bool
398 help
399 Architecture has tls passed as the 4th argument of clone(2),
400 not the 5th one.
401
402config CLONE_BACKWARDS2
403 bool
404 help
405 Architecture has the first two arguments of clone(2) swapped.
406
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407config ODD_RT_SIGACTION
408 bool
409 help
410 Architecture has unusual rt_sigaction(2) arguments
411
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412config OLD_SIGSUSPEND
413 bool
414 help
415 Architecture has old sigsuspend(2) syscall, of one-argument variety
416
417config OLD_SIGSUSPEND3
418 bool
419 help
420 Even weirder antique ABI - three-argument sigsuspend(2)
421
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AV
422config OLD_SIGACTION
423 bool
424 help
425 Architecture has old sigaction(2) syscall. Nope, not the same
426 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
427 but fairly different variant of sigaction(2), thanks to OSF/1
428 compatibility...
429
430config COMPAT_OLD_SIGACTION
431 bool
432
2521f2c2 433source "kernel/gcov/Kconfig"