Merge tag 'nfs-for-3.10-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / Kconfig
1 #
2 # General architecture dependent options
3 #
4
5 config 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
18 config 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
30 config HAVE_OPROFILE
31 bool
32
33 config OPROFILE_NMI_TIMER
34 def_bool y
35 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
36
37 config 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
49 config 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
74 config OPTPROBES
75 def_bool y
76 depends on KPROBES && HAVE_OPTPROBES
77 depends on !PREEMPT
78
79 config 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
88 config 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
106 config 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
122 config 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
141 config 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
160 config KRETPROBES
161 def_bool y
162 depends on KPROBES && HAVE_KRETPROBES
163
164 config 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
171 config HAVE_IOREMAP_PROT
172 bool
173
174 config HAVE_KPROBES
175 bool
176
177 config HAVE_KRETPROBES
178 bool
179
180 config HAVE_OPTPROBES
181 bool
182
183 config HAVE_KPROBES_ON_FTRACE
184 bool
185
186 config 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 #
201 config HAVE_ARCH_TRACEHOOK
202 bool
203
204 config HAVE_DMA_ATTRS
205 bool
206
207 config HAVE_DMA_CONTIGUOUS
208 bool
209
210 config USE_GENERIC_SMP_HELPERS
211 bool
212
213 config GENERIC_SMP_IDLE_THREAD
214 bool
215
216 # Select if arch init_task initializer is different to init/init_task.c
217 config ARCH_INIT_TASK
218 bool
219
220 # Select if arch has its private alloc_task_struct() function
221 config ARCH_TASK_STRUCT_ALLOCATOR
222 bool
223
224 # Select if arch has its private alloc_thread_info() function
225 config ARCH_THREAD_INFO_ALLOCATOR
226 bool
227
228 config 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
236 config 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
242 config HAVE_DMA_API_DEBUG
243 bool
244
245 config HAVE_HW_BREAKPOINT
246 bool
247 depends on PERF_EVENTS
248
249 config 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
260 config HAVE_USER_RETURN_NOTIFIER
261 bool
262
263 config 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
270 config 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
276 config 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
283 config HAVE_ARCH_JUMP_LABEL
284 bool
285
286 config HAVE_ARCH_MUTEX_CPU_RELAX
287 bool
288
289 config HAVE_RCU_TABLE_FREE
290 bool
291
292 config ARCH_HAVE_NMI_SAFE_CMPXCHG
293 bool
294
295 config 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
303 config HAVE_CMPXCHG_LOCAL
304 bool
305
306 config HAVE_CMPXCHG_DOUBLE
307 bool
308
309 config ARCH_WANT_IPC_PARSE_VERSION
310 bool
311
312 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
313 bool
314
315 config ARCH_WANT_OLD_COMPAT_IPC
316 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
317 bool
318
319 config 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
332 config 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
342 config 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
353 config HAVE_VIRT_CPU_ACCOUNTING
354 bool
355
356 config 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
362 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
363 bool
364
365 config 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
372 config 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
378 config 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
384 config 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 #
393 config CLONE_BACKWARDS
394 bool
395 help
396 Architecture has tls passed as the 4th argument of clone(2),
397 not the 5th one.
398
399 config CLONE_BACKWARDS2
400 bool
401 help
402 Architecture has the first two arguments of clone(2) swapped.
403
404 config ODD_RT_SIGACTION
405 bool
406 help
407 Architecture has unusual rt_sigaction(2) arguments
408
409 config OLD_SIGSUSPEND
410 bool
411 help
412 Architecture has old sigsuspend(2) syscall, of one-argument variety
413
414 config OLD_SIGSUSPEND3
415 bool
416 help
417 Even weirder antique ABI - three-argument sigsuspend(2)
418
419 config 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
427 config COMPAT_OLD_SIGACTION
428 bool
429
430 source "kernel/gcov/Kconfig"