|  | # | 
|  | # General architecture dependent options | 
|  | # | 
|  |  | 
|  | config OPROFILE | 
|  | tristate "OProfile system profiling" | 
|  | depends on PROFILING | 
|  | depends on HAVE_OPROFILE | 
|  | select RING_BUFFER | 
|  | select RING_BUFFER_ALLOW_SWAP | 
|  | help | 
|  | OProfile is a profiling system capable of profiling the | 
|  | whole system, include the kernel, kernel modules, libraries, | 
|  | and applications. | 
|  |  | 
|  | If unsure, say N. | 
|  |  | 
|  | config OPROFILE_EVENT_MULTIPLEX | 
|  | bool "OProfile multiplexing support (EXPERIMENTAL)" | 
|  | default n | 
|  | depends on OPROFILE && X86 | 
|  | help | 
|  | The number of hardware counters is limited. The multiplexing | 
|  | feature enables OProfile to gather more events than counters | 
|  | are provided by the hardware. This is realized by switching | 
|  | between events at an user specified time interval. | 
|  |  | 
|  | If unsure, say N. | 
|  |  | 
|  | config HAVE_OPROFILE | 
|  | bool | 
|  |  | 
|  | config OPROFILE_NMI_TIMER | 
|  | def_bool y | 
|  | depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI | 
|  |  | 
|  | config KPROBES | 
|  | bool "Kprobes" | 
|  | depends on MODULES | 
|  | depends on HAVE_KPROBES | 
|  | select KALLSYMS | 
|  | help | 
|  | Kprobes allows you to trap at almost any kernel address and | 
|  | execute a callback function.  register_kprobe() establishes | 
|  | a probepoint and specifies the callback.  Kprobes is useful | 
|  | for kernel debugging, non-intrusive instrumentation and testing. | 
|  | If in doubt, say "N". | 
|  |  | 
|  | config JUMP_LABEL | 
|  | bool "Optimize very unlikely/likely branches" | 
|  | depends on HAVE_ARCH_JUMP_LABEL | 
|  | help | 
|  | This option enables a transparent branch optimization that | 
|  | makes certain almost-always-true or almost-always-false branch | 
|  | conditions even cheaper to execute within the kernel. | 
|  |  | 
|  | Certain performance-sensitive kernel code, such as trace points, | 
|  | scheduler functionality, networking code and KVM have such | 
|  | branches and include support for this optimization technique. | 
|  |  | 
|  | If it is detected that the compiler has support for "asm goto", | 
|  | the kernel will compile such branches with just a nop | 
|  | instruction. When the condition flag is toggled to true, the | 
|  | nop will be converted to a jump instruction to execute the | 
|  | conditional block of instructions. | 
|  |  | 
|  | This technique lowers overhead and stress on the branch prediction | 
|  | of the processor and generally makes the kernel faster. The update | 
|  | of the condition is slower, but those are always very rare. | 
|  |  | 
|  | ( On 32-bit x86, the necessary options added to the compiler | 
|  | flags may increase the size of the kernel slightly. ) | 
|  |  | 
|  | config OPTPROBES | 
|  | def_bool y | 
|  | depends on KPROBES && HAVE_OPTPROBES | 
|  | depends on !PREEMPT | 
|  |  | 
|  | config HAVE_EFFICIENT_UNALIGNED_ACCESS | 
|  | bool | 
|  | help | 
|  | Some architectures are unable to perform unaligned accesses | 
|  | without the use of get_unaligned/put_unaligned. Others are | 
|  | unable to perform such accesses efficiently (e.g. trap on | 
|  | unaligned access and require fixing it up in the exception | 
|  | handler.) | 
|  |  | 
|  | This symbol should be selected by an architecture if it can | 
|  | perform unaligned accesses efficiently to allow different | 
|  | code paths to be selected for these cases. Some network | 
|  | drivers, for example, could opt to not fix up alignment | 
|  | problems with received packets if doing so would not help | 
|  | much. | 
|  |  | 
|  | See Documentation/unaligned-memory-access.txt for more | 
|  | information on the topic of unaligned memory accesses. | 
|  |  | 
|  | config HAVE_SYSCALL_WRAPPERS | 
|  | bool | 
|  |  | 
|  | config KRETPROBES | 
|  | def_bool y | 
|  | depends on KPROBES && HAVE_KRETPROBES | 
|  |  | 
|  | config USER_RETURN_NOTIFIER | 
|  | bool | 
|  | depends on HAVE_USER_RETURN_NOTIFIER | 
|  | help | 
|  | Provide a kernel-internal notification when a cpu is about to | 
|  | switch to user mode. | 
|  |  | 
|  | config HAVE_IOREMAP_PROT | 
|  | bool | 
|  |  | 
|  | config HAVE_KPROBES | 
|  | bool | 
|  |  | 
|  | config HAVE_KRETPROBES | 
|  | bool | 
|  |  | 
|  | config HAVE_OPTPROBES | 
|  | bool | 
|  |  | 
|  | config HAVE_NMI_WATCHDOG | 
|  | bool | 
|  | # | 
|  | # An arch should select this if it provides all these things: | 
|  | # | 
|  | #	task_pt_regs()		in asm/processor.h or asm/ptrace.h | 
|  | #	arch_has_single_step()	if there is hardware single-step support | 
|  | #	arch_has_block_step()	if there is hardware block-step support | 
|  | #	asm/syscall.h		supplying asm-generic/syscall.h interface | 
|  | #	linux/regset.h		user_regset interfaces | 
|  | #	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h | 
|  | #	TIF_SYSCALL_TRACE	calls tracehook_report_syscall_{entry,exit} | 
|  | #	TIF_NOTIFY_RESUME	calls tracehook_notify_resume() | 
|  | #	signal delivery		calls tracehook_signal_handler() | 
|  | # | 
|  | config HAVE_ARCH_TRACEHOOK | 
|  | bool | 
|  |  | 
|  | config HAVE_DMA_ATTRS | 
|  | bool | 
|  |  | 
|  | config USE_GENERIC_SMP_HELPERS | 
|  | bool | 
|  |  | 
|  | config HAVE_REGS_AND_STACK_ACCESS_API | 
|  | bool | 
|  | help | 
|  | This symbol should be selected by an architecure if it supports | 
|  | the API needed to access registers and stack entries from pt_regs, | 
|  | declared in asm/ptrace.h | 
|  | For example the kprobes-based event tracer needs this API. | 
|  |  | 
|  | config HAVE_CLK | 
|  | bool | 
|  | help | 
|  | The <linux/clk.h> calls support software clock gating and | 
|  | thus are a key power management tool on many systems. | 
|  |  | 
|  | config HAVE_DMA_API_DEBUG | 
|  | bool | 
|  |  | 
|  | config HAVE_HW_BREAKPOINT | 
|  | bool | 
|  | depends on PERF_EVENTS | 
|  |  | 
|  | config HAVE_MIXED_BREAKPOINTS_REGS | 
|  | bool | 
|  | depends on HAVE_HW_BREAKPOINT | 
|  | help | 
|  | Depending on the arch implementation of hardware breakpoints, | 
|  | some of them have separate registers for data and instruction | 
|  | breakpoints addresses, others have mixed registers to store | 
|  | them but define the access type in a control register. | 
|  | Select this option if your arch implements breakpoints under the | 
|  | latter fashion. | 
|  |  | 
|  | config HAVE_USER_RETURN_NOTIFIER | 
|  | bool | 
|  |  | 
|  | config HAVE_PERF_EVENTS_NMI | 
|  | bool | 
|  | help | 
|  | System hardware can generate an NMI using the perf event | 
|  | subsystem.  Also has support for calculating CPU cycle events | 
|  | to determine how many clock cycles in a given period. | 
|  |  | 
|  | config HAVE_ARCH_JUMP_LABEL | 
|  | bool | 
|  |  | 
|  | config HAVE_ARCH_MUTEX_CPU_RELAX | 
|  | bool | 
|  |  | 
|  | config HAVE_RCU_TABLE_FREE | 
|  | bool | 
|  |  | 
|  | config ARCH_HAVE_NMI_SAFE_CMPXCHG | 
|  | bool | 
|  |  | 
|  | config HAVE_ALIGNED_STRUCT_PAGE | 
|  | bool | 
|  | help | 
|  | This makes sure that struct pages are double word aligned and that | 
|  | e.g. the SLUB allocator can perform double word atomic operations | 
|  | on a struct page for better performance. However selecting this | 
|  | might increase the size of a struct page by a word. | 
|  |  | 
|  | config HAVE_CMPXCHG_LOCAL | 
|  | bool | 
|  |  | 
|  | config HAVE_CMPXCHG_DOUBLE | 
|  | bool | 
|  |  | 
|  | config ARCH_WANT_OLD_COMPAT_IPC | 
|  | bool | 
|  |  | 
|  | source "kernel/gcov/Kconfig" |