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 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
88config 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
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
122config 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
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
160config HAVE_SYSCALL_WRAPPERS
161    bool
162
163config KRETPROBES
164    def_bool y
165    depends on KPROBES && HAVE_KRETPROBES
166
167config USER_RETURN_NOTIFIER
168    bool
169    depends on HAVE_USER_RETURN_NOTIFIER
170    help
171      Provide a kernel-internal notification when a cpu is about to
172      switch to user mode.
173
174config HAVE_IOREMAP_PROT
175    bool
176
177config HAVE_KPROBES
178    bool
179
180config HAVE_KRETPROBES
181    bool
182
183config HAVE_OPTPROBES
184    bool
185
186config HAVE_KPROBES_ON_FTRACE
187    bool
188
189config HAVE_NMI_WATCHDOG
190    bool
191#
192# An arch should select this if it provides all these things:
193#
194# task_pt_regs() in asm/processor.h or asm/ptrace.h
195# arch_has_single_step() if there is hardware single-step support
196# arch_has_block_step() if there is hardware block-step support
197# asm/syscall.h supplying asm-generic/syscall.h interface
198# linux/regset.h user_regset interfaces
199# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
200# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
201# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
202# signal delivery calls tracehook_signal_handler()
203#
204config HAVE_ARCH_TRACEHOOK
205    bool
206
207config HAVE_DMA_ATTRS
208    bool
209
210config HAVE_DMA_CONTIGUOUS
211    bool
212
213config USE_GENERIC_SMP_HELPERS
214    bool
215
216config GENERIC_SMP_IDLE_THREAD
217       bool
218
219# Select if arch init_task initializer is different to init/init_task.c
220config ARCH_INIT_TASK
221       bool
222
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
231config HAVE_REGS_AND_STACK_ACCESS_API
232    bool
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.
238
239config HAVE_CLK
240    bool
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
245config HAVE_DMA_API_DEBUG
246    bool
247
248config HAVE_HW_BREAKPOINT
249    bool
250    depends on PERF_EVENTS
251
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
263config HAVE_USER_RETURN_NOTIFIER
264    bool
265
266config HAVE_PERF_EVENTS_NMI
267    bool
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.
272
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
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
286config HAVE_ARCH_JUMP_LABEL
287    bool
288
289config HAVE_ARCH_MUTEX_CPU_RELAX
290    bool
291
292config HAVE_RCU_TABLE_FREE
293    bool
294
295config ARCH_HAVE_NMI_SAFE_CMPXCHG
296    bool
297
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
306config HAVE_CMPXCHG_LOCAL
307    bool
308
309config HAVE_CMPXCHG_DOUBLE
310    bool
311
312config ARCH_WANT_IPC_PARSE_VERSION
313    bool
314
315config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
316    bool
317
318config ARCH_WANT_OLD_COMPAT_IPC
319    select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
320    bool
321
322config HAVE_ARCH_SECCOMP_FILTER
323    bool
324    help
325      An arch should select this symbol if it provides all of these things:
326      - syscall_get_arch()
327      - syscall_get_arguments()
328      - syscall_rollback()
329      - syscall_set_return_value()
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.
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
345config HAVE_CONTEXT_TRACKING
346    bool
347    help
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.
355
356config HAVE_VIRT_CPU_ACCOUNTING
357    bool
358
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
365config HAVE_ARCH_TRANSPARENT_HUGEPAGE
366    bool
367
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
387#
388# ABI hall of shame
389#
390config CLONE_BACKWARDS
391    bool
392    help
393      Architecture has tls passed as the 4th argument of clone(2),
394      not the 5th one.
395
396config CLONE_BACKWARDS2
397    bool
398    help
399      Architecture has the first two arguments of clone(2) swapped.
400
401config ODD_RT_SIGACTION
402    bool
403    help
404      Architecture has unusual rt_sigaction(2) arguments
405
406config OLD_SIGSUSPEND
407    bool
408    help
409      Architecture has old sigsuspend(2) syscall, of one-argument variety
410
411config OLD_SIGSUSPEND3
412    bool
413    help
414      Even weirder antique ABI - three-argument sigsuspend(2)
415
416config OLD_SIGACTION
417    bool
418    help
419      Architecture has old sigaction(2) syscall. Nope, not the same
420      as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
421      but fairly different variant of sigaction(2), thanks to OSF/1
422      compatibility...
423
424config COMPAT_OLD_SIGACTION
425    bool
426
427source "kernel/gcov/Kconfig"
428

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