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1#
2# General architecture dependent options
3#
125e5645 4
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5config KEXEC_CORE
6 bool
7
125e5645 8config OPROFILE
b309a294 9 tristate "OProfile system profiling"
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10 depends on PROFILING
11 depends on HAVE_OPROFILE
d69d59f4 12 select RING_BUFFER
9a5963eb 13 select RING_BUFFER_ALLOW_SWAP
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14 help
15 OProfile is a profiling system capable of profiling the
16 whole system, include the kernel, kernel modules, libraries,
17 and applications.
18
19 If unsure, say N.
20
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JY
21config OPROFILE_EVENT_MULTIPLEX
22 bool "OProfile multiplexing support (EXPERIMENTAL)"
23 default n
24 depends on OPROFILE && X86
25 help
26 The number of hardware counters is limited. The multiplexing
27 feature enables OProfile to gather more events than counters
28 are provided by the hardware. This is realized by switching
29 between events at an user specified time interval.
30
31 If unsure, say N.
32
125e5645 33config HAVE_OPROFILE
9ba16087 34 bool
125e5645 35
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36config OPROFILE_NMI_TIMER
37 def_bool y
af9feebe 38 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
dcfce4a0 39
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40config KPROBES
41 bool "Kprobes"
05ed160e 42 depends on MODULES
125e5645 43 depends on HAVE_KPROBES
05ed160e 44 select KALLSYMS
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45 help
46 Kprobes allows you to trap at almost any kernel address and
47 execute a callback function. register_kprobe() establishes
48 a probepoint and specifies the callback. Kprobes is useful
49 for kernel debugging, non-intrusive instrumentation and testing.
50 If in doubt, say "N".
51
45f81b1c 52config JUMP_LABEL
c5905afb 53 bool "Optimize very unlikely/likely branches"
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54 depends on HAVE_ARCH_JUMP_LABEL
55 help
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56 This option enables a transparent branch optimization that
57 makes certain almost-always-true or almost-always-false branch
58 conditions even cheaper to execute within the kernel.
59
60 Certain performance-sensitive kernel code, such as trace points,
61 scheduler functionality, networking code and KVM have such
62 branches and include support for this optimization technique.
63
45f81b1c 64 If it is detected that the compiler has support for "asm goto",
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65 the kernel will compile such branches with just a nop
66 instruction. When the condition flag is toggled to true, the
67 nop will be converted to a jump instruction to execute the
68 conditional block of instructions.
69
70 This technique lowers overhead and stress on the branch prediction
71 of the processor and generally makes the kernel faster. The update
72 of the condition is slower, but those are always very rare.
45f81b1c 73
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74 ( On 32-bit x86, the necessary options added to the compiler
75 flags may increase the size of the kernel slightly. )
45f81b1c 76
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77config STATIC_KEYS_SELFTEST
78 bool "Static key selftest"
79 depends on JUMP_LABEL
80 help
81 Boot time self-test of the branch patching code.
82
afd66255 83config OPTPROBES
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84 def_bool y
85 depends on KPROBES && HAVE_OPTPROBES
afd66255 86 depends on !PREEMPT
afd66255 87
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88config KPROBES_ON_FTRACE
89 def_bool y
90 depends on KPROBES && HAVE_KPROBES_ON_FTRACE
91 depends on DYNAMIC_FTRACE_WITH_REGS
92 help
93 If function tracer is enabled and the arch supports full
94 passing of pt_regs to function tracing, then kprobes can
95 optimize on top of function tracing.
96
2b144498 97config UPROBES
09294e31 98 def_bool n
2b144498 99 help
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100 Uprobes is the user-space counterpart to kprobes: they
101 enable instrumentation applications (such as 'perf probe')
102 to establish unintrusive probes in user-space binaries and
103 libraries, by executing handler functions when the probes
104 are hit by user-space applications.
105
106 ( These probes come in the form of single-byte breakpoints,
107 managed by the kernel and kept transparent to the probed
108 application. )
2b144498 109
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110config HAVE_64BIT_ALIGNED_ACCESS
111 def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
112 help
113 Some architectures require 64 bit accesses to be 64 bit
114 aligned, which also requires structs containing 64 bit values
115 to be 64 bit aligned too. This includes some 32 bit
116 architectures which can do 64 bit accesses, as well as 64 bit
117 architectures without unaligned access.
118
119 This symbol should be selected by an architecture if 64 bit
120 accesses are required to be 64 bit aligned in this way even
121 though it is not a 64 bit architecture.
122
123 See Documentation/unaligned-memory-access.txt for more
124 information on the topic of unaligned memory accesses.
125
58340a07 126config HAVE_EFFICIENT_UNALIGNED_ACCESS
9ba16087 127 bool
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128 help
129 Some architectures are unable to perform unaligned accesses
130 without the use of get_unaligned/put_unaligned. Others are
131 unable to perform such accesses efficiently (e.g. trap on
132 unaligned access and require fixing it up in the exception
133 handler.)
134
135 This symbol should be selected by an architecture if it can
136 perform unaligned accesses efficiently to allow different
137 code paths to be selected for these cases. Some network
138 drivers, for example, could opt to not fix up alignment
139 problems with received packets if doing so would not help
140 much.
141
142 See Documentation/unaligned-memory-access.txt for more
143 information on the topic of unaligned memory accesses.
144
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145config ARCH_USE_BUILTIN_BSWAP
146 bool
147 help
148 Modern versions of GCC (since 4.4) have builtin functions
149 for handling byte-swapping. Using these, instead of the old
150 inline assembler that the architecture code provides in the
151 __arch_bswapXX() macros, allows the compiler to see what's
152 happening and offers more opportunity for optimisation. In
153 particular, the compiler will be able to combine the byteswap
154 with a nearby load or store and use load-and-swap or
155 store-and-swap instructions if the architecture has them. It
156 should almost *never* result in code which is worse than the
157 hand-coded assembler in <asm/swab.h>. But just in case it
158 does, the use of the builtins is optional.
159
160 Any architecture with load-and-swap or store-and-swap
161 instructions should set this. And it shouldn't hurt to set it
162 on architectures that don't have such instructions.
163
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164config KRETPROBES
165 def_bool y
166 depends on KPROBES && HAVE_KRETPROBES
167
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168config USER_RETURN_NOTIFIER
169 bool
170 depends on HAVE_USER_RETURN_NOTIFIER
171 help
172 Provide a kernel-internal notification when a cpu is about to
173 switch to user mode.
174
28b2ee20 175config HAVE_IOREMAP_PROT
9ba16087 176 bool
28b2ee20 177
125e5645 178config HAVE_KPROBES
9ba16087 179 bool
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180
181config HAVE_KRETPROBES
9ba16087 182 bool
74bc7cee 183
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184config HAVE_OPTPROBES
185 bool
d314d74c 186
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187config HAVE_KPROBES_ON_FTRACE
188 bool
189
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190config HAVE_NMI_WATCHDOG
191 bool
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192#
193# An arch should select this if it provides all these things:
194#
195# task_pt_regs() in asm/processor.h or asm/ptrace.h
196# arch_has_single_step() if there is hardware single-step support
197# arch_has_block_step() if there is hardware block-step support
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198# asm/syscall.h supplying asm-generic/syscall.h interface
199# linux/regset.h user_regset interfaces
200# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
201# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
202# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
203# signal delivery calls tracehook_signal_handler()
204#
205config HAVE_ARCH_TRACEHOOK
9ba16087 206 bool
1f5a4ad9 207
74bc7cee 208config HAVE_DMA_ATTRS
9ba16087 209 bool
3d442233 210
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211config HAVE_DMA_CONTIGUOUS
212 bool
213
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214config GENERIC_SMP_IDLE_THREAD
215 bool
216
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217config GENERIC_IDLE_POLL_SETUP
218 bool
219
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220# Select if arch init_task initializer is different to init/init_task.c
221config ARCH_INIT_TASK
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222 bool
223
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224# Select if arch has its private alloc_task_struct() function
225config ARCH_TASK_STRUCT_ALLOCATOR
226 bool
227
228# Select if arch has its private alloc_thread_info() function
229config ARCH_THREAD_INFO_ALLOCATOR
230 bool
231
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232# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
233config ARCH_WANTS_DYNAMIC_TASK_STRUCT
234 bool
235
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236config HAVE_REGS_AND_STACK_ACCESS_API
237 bool
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238 help
239 This symbol should be selected by an architecure if it supports
240 the API needed to access registers and stack entries from pt_regs,
241 declared in asm/ptrace.h
242 For example the kprobes-based event tracer needs this API.
f850c30c 243
9483a578 244config HAVE_CLK
9ba16087 245 bool
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246 help
247 The <linux/clk.h> calls support software clock gating and
248 thus are a key power management tool on many systems.
249
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250config HAVE_DMA_API_DEBUG
251 bool
36cd3c9f 252
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253config HAVE_HW_BREAKPOINT
254 bool
99e8c5a3 255 depends on PERF_EVENTS
62a038d3 256
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257config HAVE_MIXED_BREAKPOINTS_REGS
258 bool
259 depends on HAVE_HW_BREAKPOINT
260 help
261 Depending on the arch implementation of hardware breakpoints,
262 some of them have separate registers for data and instruction
263 breakpoints addresses, others have mixed registers to store
264 them but define the access type in a control register.
265 Select this option if your arch implements breakpoints under the
266 latter fashion.
267
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268config HAVE_USER_RETURN_NOTIFIER
269 bool
a1922ed6 270
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271config HAVE_PERF_EVENTS_NMI
272 bool
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273 help
274 System hardware can generate an NMI using the perf event
275 subsystem. Also has support for calculating CPU cycle events
276 to determine how many clock cycles in a given period.
c01d4323 277
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278config HAVE_PERF_REGS
279 bool
280 help
281 Support selective register dumps for perf events. This includes
282 bit-mapping of each registers and a unique architecture id.
283
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284config HAVE_PERF_USER_STACK_DUMP
285 bool
286 help
287 Support user stack dumps for perf event samples. This needs
288 access to the user stack pointer which is not unified across
289 architectures.
290
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291config HAVE_ARCH_JUMP_LABEL
292 bool
293
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294config HAVE_RCU_TABLE_FREE
295 bool
296
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297config ARCH_HAVE_NMI_SAFE_CMPXCHG
298 bool
299
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300config HAVE_ALIGNED_STRUCT_PAGE
301 bool
302 help
303 This makes sure that struct pages are double word aligned and that
304 e.g. the SLUB allocator can perform double word atomic operations
305 on a struct page for better performance. However selecting this
306 might increase the size of a struct page by a word.
307
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308config HAVE_CMPXCHG_LOCAL
309 bool
310
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311config HAVE_CMPXCHG_DOUBLE
312 bool
313
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314config ARCH_WANT_IPC_PARSE_VERSION
315 bool
316
317config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
318 bool
319
48b25c43 320config ARCH_WANT_OLD_COMPAT_IPC
c1d7e01d 321 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
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322 bool
323
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324config HAVE_ARCH_SECCOMP_FILTER
325 bool
326 help
fb0fadf9 327 An arch should select this symbol if it provides all of these things:
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328 - syscall_get_arch()
329 - syscall_get_arguments()
330 - syscall_rollback()
331 - syscall_set_return_value()
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332 - SIGSYS siginfo_t support
333 - secure_computing is called from a ptrace_event()-safe context
334 - secure_computing return value is checked and a return value of -1
335 results in the system call being skipped immediately.
48dc92b9 336 - seccomp syscall wired up
e2cfabdf 337
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338 For best performance, an arch should use seccomp_phase1 and
339 seccomp_phase2 directly. It should call seccomp_phase1 for all
340 syscalls if TIF_SECCOMP is set, but seccomp_phase1 does not
341 need to be called from a ptrace-safe context. It must then
342 call seccomp_phase2 if seccomp_phase1 returns anything other
343 than SECCOMP_PHASE1_OK or SECCOMP_PHASE1_SKIP.
344
345 As an additional optimization, an arch may provide seccomp_data
346 directly to seccomp_phase1; this avoids multiple calls
347 to the syscall_xyz helpers for every syscall.
348
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349config SECCOMP_FILTER
350 def_bool y
351 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
352 help
353 Enable tasks to build secure computing environments defined
354 in terms of Berkeley Packet Filter programs which implement
355 task-defined system call filtering polices.
356
357 See Documentation/prctl/seccomp_filter.txt for details.
358
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359config HAVE_CC_STACKPROTECTOR
360 bool
361 help
362 An arch should select this symbol if:
363 - its compiler supports the -fstack-protector option
364 - it has implemented a stack canary (e.g. __stack_chk_guard)
365
366config CC_STACKPROTECTOR
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367 def_bool n
368 help
369 Set when a stack-protector mode is enabled, so that the build
370 can enable kernel-side support for the GCC feature.
371
372choice
373 prompt "Stack Protector buffer overflow detection"
19952a92 374 depends on HAVE_CC_STACKPROTECTOR
8779657d 375 default CC_STACKPROTECTOR_NONE
19952a92 376 help
8779657d 377 This option turns on the "stack-protector" GCC feature. This
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378 feature puts, at the beginning of functions, a canary value on
379 the stack just before the return address, and validates
380 the value just before actually returning. Stack based buffer
381 overflows (that need to overwrite this return address) now also
382 overwrite the canary, which gets detected and the attack is then
383 neutralized via a kernel panic.
384
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385config CC_STACKPROTECTOR_NONE
386 bool "None"
387 help
388 Disable "stack-protector" GCC feature.
389
390config CC_STACKPROTECTOR_REGULAR
391 bool "Regular"
392 select CC_STACKPROTECTOR
393 help
394 Functions will have the stack-protector canary logic added if they
395 have an 8-byte or larger character array on the stack.
396
19952a92 397 This feature requires gcc version 4.2 or above, or a distribution
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398 gcc with the feature backported ("-fstack-protector").
399
400 On an x86 "defconfig" build, this feature adds canary checks to
401 about 3% of all kernel functions, which increases kernel code size
402 by about 0.3%.
403
404config CC_STACKPROTECTOR_STRONG
405 bool "Strong"
406 select CC_STACKPROTECTOR
407 help
408 Functions will have the stack-protector canary logic added in any
409 of the following conditions:
410
411 - local variable's address used as part of the right hand side of an
412 assignment or function argument
413 - local variable is an array (or union containing an array),
414 regardless of array type or length
415 - uses register local variables
416
417 This feature requires gcc version 4.9 or above, or a distribution
418 gcc with the feature backported ("-fstack-protector-strong").
419
420 On an x86 "defconfig" build, this feature adds canary checks to
421 about 20% of all kernel functions, which increases the kernel code
422 size by about 2%.
423
424endchoice
19952a92 425
91d1aa43 426config HAVE_CONTEXT_TRACKING
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427 bool
428 help
91d1aa43
FW
429 Provide kernel/user boundaries probes necessary for subsystems
430 that need it, such as userspace RCU extended quiescent state.
431 Syscalls need to be wrapped inside user_exit()-user_enter() through
432 the slow path using TIF_NOHZ flag. Exceptions handlers must be
433 wrapped as well. Irqs are already protected inside
434 rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
435 irq exit still need to be protected.
2b1d5024 436
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437config HAVE_VIRT_CPU_ACCOUNTING
438 bool
439
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440config HAVE_VIRT_CPU_ACCOUNTING_GEN
441 bool
442 default y if 64BIT
443 help
444 With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
445 Before enabling this option, arch code must be audited
446 to ensure there are no races in concurrent read/write of
447 cputime_t. For example, reading/writing 64-bit cputime_t on
448 some 32-bit arches may require multiple accesses, so proper
449 locking is needed to protect against concurrent accesses.
450
451
fdf9c356
FW
452config HAVE_IRQ_TIME_ACCOUNTING
453 bool
454 help
455 Archs need to ensure they use a high enough resolution clock to
456 support irq time accounting and then call enable_sched_clock_irqtime().
457
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458config HAVE_ARCH_TRANSPARENT_HUGEPAGE
459 bool
460
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461config HAVE_ARCH_HUGE_VMAP
462 bool
463
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PE
464config HAVE_ARCH_SOFT_DIRTY
465 bool
466
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467config HAVE_MOD_ARCH_SPECIFIC
468 bool
469 help
470 The arch uses struct mod_arch_specific to store data. Many arches
471 just need a simple module loader without arch specific data - those
472 should not enable this.
473
474config MODULES_USE_ELF_RELA
475 bool
476 help
477 Modules only use ELF RELA relocations. Modules with ELF REL
478 relocations will give an error.
479
480config MODULES_USE_ELF_REL
481 bool
482 help
483 Modules only use ELF REL relocations. Modules with ELF RELA
484 relocations will give an error.
485
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RR
486config HAVE_UNDERSCORE_SYMBOL_PREFIX
487 bool
488 help
489 Some architectures generate an _ in front of C symbols; things like
490 module loading and assembly files need to know about this.
491
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FW
492config HAVE_IRQ_EXIT_ON_IRQ_STACK
493 bool
494 help
495 Architecture doesn't only execute the irq handler on the irq stack
496 but also irq_exit(). This way we can process softirqs on this irq
497 stack instead of switching to a new one when we call __do_softirq()
498 in the end of an hardirq.
499 This spares a stack switch and improves cache usage on softirq
500 processing.
501
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502config PGTABLE_LEVELS
503 int
504 default 2
505
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506config ARCH_HAS_ELF_RANDOMIZE
507 bool
508 help
509 An architecture supports choosing randomized locations for
510 stack, mmap, brk, and ET_DYN. Defined functions:
511 - arch_mmap_rnd()
204db6ed 512 - arch_randomize_brk()
2b68f6ca 513
3033f14a
JT
514config HAVE_COPY_THREAD_TLS
515 bool
516 help
517 Architecture provides copy_thread_tls to accept tls argument via
518 normal C parameter passing, rather than extracting the syscall
519 argument from pt_regs.
520
d2125043
AV
521#
522# ABI hall of shame
523#
524config CLONE_BACKWARDS
525 bool
526 help
527 Architecture has tls passed as the 4th argument of clone(2),
528 not the 5th one.
529
530config CLONE_BACKWARDS2
531 bool
532 help
533 Architecture has the first two arguments of clone(2) swapped.
534
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MS
535config CLONE_BACKWARDS3
536 bool
537 help
538 Architecture has tls passed as the 3rd argument of clone(2),
539 not the 5th one.
540
eaca6eae
AV
541config ODD_RT_SIGACTION
542 bool
543 help
544 Architecture has unusual rt_sigaction(2) arguments
545
0a0e8cdf
AV
546config OLD_SIGSUSPEND
547 bool
548 help
549 Architecture has old sigsuspend(2) syscall, of one-argument variety
550
551config OLD_SIGSUSPEND3
552 bool
553 help
554 Even weirder antique ABI - three-argument sigsuspend(2)
555
495dfbf7
AV
556config OLD_SIGACTION
557 bool
558 help
559 Architecture has old sigaction(2) syscall. Nope, not the same
560 as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
561 but fairly different variant of sigaction(2), thanks to OSF/1
562 compatibility...
563
564config COMPAT_OLD_SIGACTION
565 bool
566
2521f2c2 567source "kernel/gcov/Kconfig"