Root/arch/Kconfig

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 UPROBES
80    bool "Transparent user-space probes (EXPERIMENTAL)"
81    depends on UPROBE_EVENT && PERF_EVENTS
82    default n
83    help
84      Uprobes is the user-space counterpart to kprobes: they
85      enable instrumentation applications (such as 'perf probe')
86      to establish unintrusive probes in user-space binaries and
87      libraries, by executing handler functions when the probes
88      are hit by user-space applications.
89
90      ( These probes come in the form of single-byte breakpoints,
91        managed by the kernel and kept transparent to the probed
92        application. )
93
94      If in doubt, say "N".
95
96config HAVE_EFFICIENT_UNALIGNED_ACCESS
97    bool
98    help
99      Some architectures are unable to perform unaligned accesses
100      without the use of get_unaligned/put_unaligned. Others are
101      unable to perform such accesses efficiently (e.g. trap on
102      unaligned access and require fixing it up in the exception
103      handler.)
104
105      This symbol should be selected by an architecture if it can
106      perform unaligned accesses efficiently to allow different
107      code paths to be selected for these cases. Some network
108      drivers, for example, could opt to not fix up alignment
109      problems with received packets if doing so would not help
110      much.
111
112      See Documentation/unaligned-memory-access.txt for more
113      information on the topic of unaligned memory accesses.
114
115config HAVE_SYSCALL_WRAPPERS
116    bool
117
118config KRETPROBES
119    def_bool y
120    depends on KPROBES && HAVE_KRETPROBES
121
122config USER_RETURN_NOTIFIER
123    bool
124    depends on HAVE_USER_RETURN_NOTIFIER
125    help
126      Provide a kernel-internal notification when a cpu is about to
127      switch to user mode.
128
129config HAVE_IOREMAP_PROT
130    bool
131
132config HAVE_KPROBES
133    bool
134
135config HAVE_KRETPROBES
136    bool
137
138config HAVE_OPTPROBES
139    bool
140
141config HAVE_NMI_WATCHDOG
142    bool
143#
144# An arch should select this if it provides all these things:
145#
146# task_pt_regs() in asm/processor.h or asm/ptrace.h
147# arch_has_single_step() if there is hardware single-step support
148# arch_has_block_step() if there is hardware block-step support
149# asm/syscall.h supplying asm-generic/syscall.h interface
150# linux/regset.h user_regset interfaces
151# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
152# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
153# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
154# signal delivery calls tracehook_signal_handler()
155#
156config HAVE_ARCH_TRACEHOOK
157    bool
158
159config HAVE_DMA_ATTRS
160    bool
161
162config HAVE_DMA_CONTIGUOUS
163    bool
164
165config USE_GENERIC_SMP_HELPERS
166    bool
167
168config GENERIC_SMP_IDLE_THREAD
169       bool
170
171# Select if arch init_task initializer is different to init/init_task.c
172config ARCH_INIT_TASK
173       bool
174
175# Select if arch has its private alloc_task_struct() function
176config ARCH_TASK_STRUCT_ALLOCATOR
177    bool
178
179# Select if arch has its private alloc_thread_info() function
180config ARCH_THREAD_INFO_ALLOCATOR
181    bool
182
183config HAVE_REGS_AND_STACK_ACCESS_API
184    bool
185    help
186      This symbol should be selected by an architecure if it supports
187      the API needed to access registers and stack entries from pt_regs,
188      declared in asm/ptrace.h
189      For example the kprobes-based event tracer needs this API.
190
191config HAVE_CLK
192    bool
193    help
194      The <linux/clk.h> calls support software clock gating and
195      thus are a key power management tool on many systems.
196
197config HAVE_DMA_API_DEBUG
198    bool
199
200config HAVE_HW_BREAKPOINT
201    bool
202    depends on PERF_EVENTS
203
204config HAVE_MIXED_BREAKPOINTS_REGS
205    bool
206    depends on HAVE_HW_BREAKPOINT
207    help
208      Depending on the arch implementation of hardware breakpoints,
209      some of them have separate registers for data and instruction
210      breakpoints addresses, others have mixed registers to store
211      them but define the access type in a control register.
212      Select this option if your arch implements breakpoints under the
213      latter fashion.
214
215config HAVE_USER_RETURN_NOTIFIER
216    bool
217
218config HAVE_PERF_EVENTS_NMI
219    bool
220    help
221      System hardware can generate an NMI using the perf event
222      subsystem. Also has support for calculating CPU cycle events
223      to determine how many clock cycles in a given period.
224
225config HAVE_ARCH_JUMP_LABEL
226    bool
227
228config HAVE_ARCH_MUTEX_CPU_RELAX
229    bool
230
231config HAVE_RCU_TABLE_FREE
232    bool
233
234config ARCH_HAVE_NMI_SAFE_CMPXCHG
235    bool
236
237config HAVE_ALIGNED_STRUCT_PAGE
238    bool
239    help
240      This makes sure that struct pages are double word aligned and that
241      e.g. the SLUB allocator can perform double word atomic operations
242      on a struct page for better performance. However selecting this
243      might increase the size of a struct page by a word.
244
245config HAVE_CMPXCHG_LOCAL
246    bool
247
248config HAVE_CMPXCHG_DOUBLE
249    bool
250
251config ARCH_WANT_IPC_PARSE_VERSION
252    bool
253
254config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
255    bool
256
257config ARCH_WANT_OLD_COMPAT_IPC
258    select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
259    bool
260
261config HAVE_ARCH_SECCOMP_FILTER
262    bool
263    help
264      An arch should select this symbol if it provides all of these things:
265      - syscall_get_arch()
266      - syscall_get_arguments()
267      - syscall_rollback()
268      - syscall_set_return_value()
269      - SIGSYS siginfo_t support
270      - secure_computing is called from a ptrace_event()-safe context
271      - secure_computing return value is checked and a return value of -1
272        results in the system call being skipped immediately.
273
274config SECCOMP_FILTER
275    def_bool y
276    depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
277    help
278      Enable tasks to build secure computing environments defined
279      in terms of Berkeley Packet Filter programs which implement
280      task-defined system call filtering polices.
281
282      See Documentation/prctl/seccomp_filter.txt for details.
283
284source "kernel/gcov/Kconfig"
285

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