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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 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 | ||
97 | config 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 | ||
116 | config ARCH_USE_BUILTIN_BSWAP | |
117 | bool | |
118 | help | |
119 | Modern versions of GCC (since 4.4) have builtin functions | |
120 | for handling byte-swapping. Using these, instead of the old | |
121 | inline assembler that the architecture code provides in the | |
122 | __arch_bswapXX() macros, allows the compiler to see what's | |
123 | happening and offers more opportunity for optimisation. In | |
124 | particular, the compiler will be able to combine the byteswap | |
125 | with a nearby load or store and use load-and-swap or | |
126 | store-and-swap instructions if the architecture has them. It | |
127 | should almost *never* result in code which is worse than the | |
128 | hand-coded assembler in <asm/swab.h>. But just in case it | |
129 | does, the use of the builtins is optional. | |
130 | ||
131 | Any architecture with load-and-swap or store-and-swap | |
132 | instructions should set this. And it shouldn't hurt to set it | |
133 | on architectures that don't have such instructions. | |
134 | ||
135 | config HAVE_SYSCALL_WRAPPERS | |
136 | bool | |
137 | ||
138 | config KRETPROBES | |
139 | def_bool y | |
140 | depends on KPROBES && HAVE_KRETPROBES | |
141 | ||
142 | config USER_RETURN_NOTIFIER | |
143 | bool | |
144 | depends on HAVE_USER_RETURN_NOTIFIER | |
145 | help | |
146 | Provide a kernel-internal notification when a cpu is about to | |
147 | switch to user mode. | |
148 | ||
149 | config HAVE_IOREMAP_PROT | |
150 | bool | |
151 | ||
152 | config HAVE_KPROBES | |
153 | bool | |
154 | ||
155 | config HAVE_KRETPROBES | |
156 | bool | |
157 | ||
158 | config HAVE_OPTPROBES | |
159 | bool | |
160 | ||
161 | config HAVE_NMI_WATCHDOG | |
162 | bool | |
163 | # | |
164 | # An arch should select this if it provides all these things: | |
165 | # | |
166 | # task_pt_regs() in asm/processor.h or asm/ptrace.h | |
167 | # arch_has_single_step() if there is hardware single-step support | |
168 | # arch_has_block_step() if there is hardware block-step support | |
169 | # asm/syscall.h supplying asm-generic/syscall.h interface | |
170 | # linux/regset.h user_regset interfaces | |
171 | # CORE_DUMP_USE_REGSET #define'd in linux/elf.h | |
172 | # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} | |
173 | # TIF_NOTIFY_RESUME calls tracehook_notify_resume() | |
174 | # signal delivery calls tracehook_signal_handler() | |
175 | # | |
176 | config HAVE_ARCH_TRACEHOOK | |
177 | bool | |
178 | ||
179 | config HAVE_DMA_ATTRS | |
180 | bool | |
181 | ||
182 | config HAVE_DMA_CONTIGUOUS | |
183 | bool | |
184 | ||
185 | config USE_GENERIC_SMP_HELPERS | |
186 | bool | |
187 | ||
188 | config GENERIC_SMP_IDLE_THREAD | |
189 | bool | |
190 | ||
191 | # Select if arch init_task initializer is different to init/init_task.c | |
192 | config ARCH_INIT_TASK | |
193 | bool | |
194 | ||
195 | # Select if arch has its private alloc_task_struct() function | |
196 | config ARCH_TASK_STRUCT_ALLOCATOR | |
197 | bool | |
198 | ||
199 | # Select if arch has its private alloc_thread_info() function | |
200 | config ARCH_THREAD_INFO_ALLOCATOR | |
201 | bool | |
202 | ||
203 | config HAVE_REGS_AND_STACK_ACCESS_API | |
204 | bool | |
205 | help | |
206 | This symbol should be selected by an architecure if it supports | |
207 | the API needed to access registers and stack entries from pt_regs, | |
208 | declared in asm/ptrace.h | |
209 | For example the kprobes-based event tracer needs this API. | |
210 | ||
211 | config HAVE_CLK | |
212 | bool | |
213 | help | |
214 | The <linux/clk.h> calls support software clock gating and | |
215 | thus are a key power management tool on many systems. | |
216 | ||
217 | config HAVE_DMA_API_DEBUG | |
218 | bool | |
219 | ||
220 | config HAVE_HW_BREAKPOINT | |
221 | bool | |
222 | depends on PERF_EVENTS | |
223 | ||
224 | config HAVE_MIXED_BREAKPOINTS_REGS | |
225 | bool | |
226 | depends on HAVE_HW_BREAKPOINT | |
227 | help | |
228 | Depending on the arch implementation of hardware breakpoints, | |
229 | some of them have separate registers for data and instruction | |
230 | breakpoints addresses, others have mixed registers to store | |
231 | them but define the access type in a control register. | |
232 | Select this option if your arch implements breakpoints under the | |
233 | latter fashion. | |
234 | ||
235 | config HAVE_USER_RETURN_NOTIFIER | |
236 | bool | |
237 | ||
238 | config HAVE_PERF_EVENTS_NMI | |
239 | bool | |
240 | help | |
241 | System hardware can generate an NMI using the perf event | |
242 | subsystem. Also has support for calculating CPU cycle events | |
243 | to determine how many clock cycles in a given period. | |
244 | ||
245 | config HAVE_PERF_REGS | |
246 | bool | |
247 | help | |
248 | Support selective register dumps for perf events. This includes | |
249 | bit-mapping of each registers and a unique architecture id. | |
250 | ||
251 | config HAVE_PERF_USER_STACK_DUMP | |
252 | bool | |
253 | help | |
254 | Support user stack dumps for perf event samples. This needs | |
255 | access to the user stack pointer which is not unified across | |
256 | architectures. | |
257 | ||
258 | config HAVE_ARCH_JUMP_LABEL | |
259 | bool | |
260 | ||
261 | config HAVE_ARCH_MUTEX_CPU_RELAX | |
262 | bool | |
263 | ||
264 | config HAVE_RCU_TABLE_FREE | |
265 | bool | |
266 | ||
267 | config ARCH_HAVE_NMI_SAFE_CMPXCHG | |
268 | bool | |
269 | ||
270 | config HAVE_ALIGNED_STRUCT_PAGE | |
271 | bool | |
272 | help | |
273 | This makes sure that struct pages are double word aligned and that | |
274 | e.g. the SLUB allocator can perform double word atomic operations | |
275 | on a struct page for better performance. However selecting this | |
276 | might increase the size of a struct page by a word. | |
277 | ||
278 | config HAVE_CMPXCHG_LOCAL | |
279 | bool | |
280 | ||
281 | config HAVE_CMPXCHG_DOUBLE | |
282 | bool | |
283 | ||
284 | config ARCH_WANT_IPC_PARSE_VERSION | |
285 | bool | |
286 | ||
287 | config ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
288 | bool | |
289 | ||
290 | config ARCH_WANT_OLD_COMPAT_IPC | |
291 | select ARCH_WANT_COMPAT_IPC_PARSE_VERSION | |
292 | bool | |
293 | ||
294 | config HAVE_ARCH_SECCOMP_FILTER | |
295 | bool | |
296 | help | |
297 | An arch should select this symbol if it provides all of these things: | |
298 | - syscall_get_arch() | |
299 | - syscall_get_arguments() | |
300 | - syscall_rollback() | |
301 | - syscall_set_return_value() | |
302 | - SIGSYS siginfo_t support | |
303 | - secure_computing is called from a ptrace_event()-safe context | |
304 | - secure_computing return value is checked and a return value of -1 | |
305 | results in the system call being skipped immediately. | |
306 | ||
307 | config SECCOMP_FILTER | |
308 | def_bool y | |
309 | depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET | |
310 | help | |
311 | Enable tasks to build secure computing environments defined | |
312 | in terms of Berkeley Packet Filter programs which implement | |
313 | task-defined system call filtering polices. | |
314 | ||
315 | See Documentation/prctl/seccomp_filter.txt for details. | |
316 | ||
317 | config HAVE_CONTEXT_TRACKING | |
318 | bool | |
319 | help | |
320 | Provide kernel/user boundaries probes necessary for subsystems | |
321 | that need it, such as userspace RCU extended quiescent state. | |
322 | Syscalls need to be wrapped inside user_exit()-user_enter() through | |
323 | the slow path using TIF_NOHZ flag. Exceptions handlers must be | |
324 | wrapped as well. Irqs are already protected inside | |
325 | rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on | |
326 | irq exit still need to be protected. | |
327 | ||
328 | config HAVE_VIRT_CPU_ACCOUNTING | |
329 | bool | |
330 | ||
331 | config HAVE_IRQ_TIME_ACCOUNTING | |
332 | bool | |
333 | help | |
334 | Archs need to ensure they use a high enough resolution clock to | |
335 | support irq time accounting and then call enable_sched_clock_irqtime(). | |
336 | ||
337 | config HAVE_ARCH_TRANSPARENT_HUGEPAGE | |
338 | bool | |
339 | ||
340 | config HAVE_MOD_ARCH_SPECIFIC | |
341 | bool | |
342 | help | |
343 | The arch uses struct mod_arch_specific to store data. Many arches | |
344 | just need a simple module loader without arch specific data - those | |
345 | should not enable this. | |
346 | ||
347 | config MODULES_USE_ELF_RELA | |
348 | bool | |
349 | help | |
350 | Modules only use ELF RELA relocations. Modules with ELF REL | |
351 | relocations will give an error. | |
352 | ||
353 | config MODULES_USE_ELF_REL | |
354 | bool | |
355 | help | |
356 | Modules only use ELF REL relocations. Modules with ELF RELA | |
357 | relocations will give an error. | |
358 | ||
359 | config GENERIC_SIGALTSTACK | |
360 | bool | |
361 | ||
362 | # | |
363 | # ABI hall of shame | |
364 | # | |
365 | config CLONE_BACKWARDS | |
366 | bool | |
367 | help | |
368 | Architecture has tls passed as the 4th argument of clone(2), | |
369 | not the 5th one. | |
370 | ||
371 | config CLONE_BACKWARDS2 | |
372 | bool | |
373 | help | |
374 | Architecture has the first two arguments of clone(2) swapped. | |
375 | ||
376 | source "kernel/gcov/Kconfig" |