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
79 config HAVE_EFFICIENT_UNALIGNED_ACCESS
82 Some architectures are unable to perform unaligned accesses
83 without the use of get_unaligned/put_unaligned. Others are
84 unable to perform such accesses efficiently (e.g. trap on
85 unaligned access and require fixing it up in the exception
88 This symbol should be selected by an architecture if it can
89 perform unaligned accesses efficiently to allow different
90 code paths to be selected for these cases. Some network
91 drivers, for example, could opt to not fix up alignment
92 problems with received packets if doing so would not help
95 See Documentation/unaligned-memory-access.txt for more
96 information on the topic of unaligned memory accesses.
98 config HAVE_SYSCALL_WRAPPERS
103 depends on KPROBES && HAVE_KRETPROBES
105 config USER_RETURN_NOTIFIER
107 depends on HAVE_USER_RETURN_NOTIFIER
109 Provide a kernel-internal notification when a cpu is about to
112 config HAVE_IOREMAP_PROT
118 config HAVE_KRETPROBES
121 config HAVE_OPTPROBES
124 config HAVE_NMI_WATCHDOG
127 # An arch should select this if it provides all these things:
129 # task_pt_regs() in asm/processor.h or asm/ptrace.h
130 # arch_has_single_step() if there is hardware single-step support
131 # arch_has_block_step() if there is hardware block-step support
132 # asm/syscall.h supplying asm-generic/syscall.h interface
133 # linux/regset.h user_regset interfaces
134 # CORE_DUMP_USE_REGSET #define'd in linux/elf.h
135 # TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
136 # TIF_NOTIFY_RESUME calls tracehook_notify_resume()
137 # signal delivery calls tracehook_signal_handler()
139 config HAVE_ARCH_TRACEHOOK
142 config HAVE_DMA_ATTRS
145 config USE_GENERIC_SMP_HELPERS
148 config GENERIC_SMP_IDLE_THREAD
151 # Select if arch init_task initializer is different to init/init_task.c
152 config ARCH_INIT_TASK
155 # Select if arch has its private alloc_task_struct() function
156 config ARCH_TASK_STRUCT_ALLOCATOR
159 # Select if arch has its private alloc_thread_info() function
160 config ARCH_THREAD_INFO_ALLOCATOR
163 config HAVE_REGS_AND_STACK_ACCESS_API
166 This symbol should be selected by an architecure if it supports
167 the API needed to access registers and stack entries from pt_regs,
168 declared in asm/ptrace.h
169 For example the kprobes-based event tracer needs this API.
174 The <linux/clk.h> calls support software clock gating and
175 thus are a key power management tool on many systems.
177 config HAVE_DMA_API_DEBUG
180 config HAVE_HW_BREAKPOINT
182 depends on PERF_EVENTS
184 config HAVE_MIXED_BREAKPOINTS_REGS
186 depends on HAVE_HW_BREAKPOINT
188 Depending on the arch implementation of hardware breakpoints,
189 some of them have separate registers for data and instruction
190 breakpoints addresses, others have mixed registers to store
191 them but define the access type in a control register.
192 Select this option if your arch implements breakpoints under the
195 config HAVE_USER_RETURN_NOTIFIER
198 config HAVE_PERF_EVENTS_NMI
201 System hardware can generate an NMI using the perf event
202 subsystem. Also has support for calculating CPU cycle events
203 to determine how many clock cycles in a given period.
205 config HAVE_ARCH_JUMP_LABEL
208 config HAVE_ARCH_MUTEX_CPU_RELAX
211 config HAVE_RCU_TABLE_FREE
214 config ARCH_HAVE_NMI_SAFE_CMPXCHG
217 config HAVE_ALIGNED_STRUCT_PAGE
220 This makes sure that struct pages are double word aligned and that
221 e.g. the SLUB allocator can perform double word atomic operations
222 on a struct page for better performance. However selecting this
223 might increase the size of a struct page by a word.
225 config HAVE_CMPXCHG_LOCAL
228 config HAVE_CMPXCHG_DOUBLE
231 config ARCH_WANT_OLD_COMPAT_IPC
234 config HAVE_ARCH_SECCOMP_FILTER
237 An arch should select this symbol if it provides all of these things:
239 - syscall_get_arguments()
241 - syscall_set_return_value()
242 - SIGSYS siginfo_t support
243 - secure_computing is called from a ptrace_event()-safe context
244 - secure_computing return value is checked and a return value of -1
245 results in the system call being skipped immediately.
247 config SECCOMP_FILTER
249 depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
251 Enable tasks to build secure computing environments defined
252 in terms of Berkeley Packet Filter programs which implement
253 task-defined system call filtering polices.
255 See Documentation/prctl/seccomp_filter.txt for details.
257 source "kernel/gcov/Kconfig"