2 # General architecture dependent options
6 tristate "OProfile system profiling"
8 depends on HAVE_OPROFILE
10 select RING_BUFFER_ALLOW_SWAP
12 OProfile is a profiling system capable of profiling the
13 whole system, include the kernel, kernel modules, libraries,
18 config OPROFILE_EVENT_MULTIPLEX
19 bool "OProfile multiplexing support (EXPERIMENTAL)"
21 depends on OPROFILE && X86
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.
33 config OPROFILE_NMI_TIMER
35 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
40 depends on HAVE_KPROBES
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.
50 bool "Optimize very unlikely/likely branches"
51 depends on HAVE_ARCH_JUMP_LABEL
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.
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.
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.
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.
71 ( On 32-bit x86, the necessary options added to the compiler
72 flags may increase the size of the kernel slightly. )
76 depends on KPROBES && HAVE_OPTPROBES
80 bool "Transparent user-space probes (EXPERIMENTAL)"
81 depends on UPROBE_EVENT && PERF_EVENTS
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.
91 ( These probes come in the form of single-byte breakpoints,
92 managed by the kernel and kept transparent to the probed
97 config HAVE_EFFICIENT_UNALIGNED_ACCESS
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
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
113 See Documentation/unaligned-memory-access.txt for more
114 information on the topic of unaligned memory accesses.
116 config ARCH_USE_BUILTIN_BSWAP
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.
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.
135 config HAVE_SYSCALL_WRAPPERS
140 depends on KPROBES && HAVE_KRETPROBES
142 config USER_RETURN_NOTIFIER
144 depends on HAVE_USER_RETURN_NOTIFIER
146 Provide a kernel-internal notification when a cpu is about to
149 config HAVE_IOREMAP_PROT
155 config HAVE_KRETPROBES
158 config HAVE_OPTPROBES
161 config HAVE_NMI_WATCHDOG
164 # An arch should select this if it provides all these things:
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()
176 config HAVE_ARCH_TRACEHOOK
179 config HAVE_DMA_ATTRS
182 config HAVE_DMA_CONTIGUOUS
185 config USE_GENERIC_SMP_HELPERS
188 config GENERIC_SMP_IDLE_THREAD
191 # Select if arch init_task initializer is different to init/init_task.c
192 config ARCH_INIT_TASK
195 # Select if arch has its private alloc_task_struct() function
196 config ARCH_TASK_STRUCT_ALLOCATOR
199 # Select if arch has its private alloc_thread_info() function
200 config ARCH_THREAD_INFO_ALLOCATOR
203 config HAVE_REGS_AND_STACK_ACCESS_API
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.
214 The <linux/clk.h> calls support software clock gating and
215 thus are a key power management tool on many systems.
217 config HAVE_DMA_API_DEBUG
220 config HAVE_HW_BREAKPOINT
222 depends on PERF_EVENTS
224 config HAVE_MIXED_BREAKPOINTS_REGS
226 depends on HAVE_HW_BREAKPOINT
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
235 config HAVE_USER_RETURN_NOTIFIER
238 config HAVE_PERF_EVENTS_NMI
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.
245 config HAVE_PERF_REGS
248 Support selective register dumps for perf events. This includes
249 bit-mapping of each registers and a unique architecture id.
251 config HAVE_PERF_USER_STACK_DUMP
254 Support user stack dumps for perf event samples. This needs
255 access to the user stack pointer which is not unified across
258 config HAVE_ARCH_JUMP_LABEL
261 config HAVE_ARCH_MUTEX_CPU_RELAX
264 config HAVE_RCU_TABLE_FREE
267 config ARCH_HAVE_NMI_SAFE_CMPXCHG
270 config HAVE_ALIGNED_STRUCT_PAGE
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.
278 config HAVE_CMPXCHG_LOCAL
281 config HAVE_CMPXCHG_DOUBLE
284 config ARCH_WANT_IPC_PARSE_VERSION
287 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
290 config ARCH_WANT_OLD_COMPAT_IPC
291 select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
294 config HAVE_ARCH_SECCOMP_FILTER
297 An arch should select this symbol if it provides all of these things:
299 - syscall_get_arguments()
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.
307 config SECCOMP_FILTER
309 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
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.
315 See Documentation/prctl/seccomp_filter.txt for details.
317 config HAVE_CONTEXT_TRACKING
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.
328 config HAVE_VIRT_CPU_ACCOUNTING
331 config HAVE_IRQ_TIME_ACCOUNTING
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().
337 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
340 config HAVE_MOD_ARCH_SPECIFIC
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.
347 config MODULES_USE_ELF_RELA
350 Modules only use ELF RELA relocations. Modules with ELF REL
351 relocations will give an error.
353 config MODULES_USE_ELF_REL
356 Modules only use ELF REL relocations. Modules with ELF RELA
357 relocations will give an error.
359 config GENERIC_SIGALTSTACK
365 config CLONE_BACKWARDS
368 Architecture has tls passed as the 4th argument of clone(2),
371 config CLONE_BACKWARDS2
374 Architecture has the first two arguments of clone(2) swapped.
376 source "kernel/gcov/Kconfig"