# # 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 config HAVE_ARCH_SECCOMP_FILTER bool help An arch should select this symbol if it provides all of these things: - syscall_get_arch() - syscall_get_arguments() - syscall_rollback() - syscall_set_return_value() - SIGSYS siginfo_t support - secure_computing is called from a ptrace_event()-safe context - secure_computing return value is checked and a return value of -1 results in the system call being skipped immediately. - seccomp syscall wired up config SECCOMP_FILTER def_bool y depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET help Enable tasks to build secure computing environments defined in terms of Berkeley Packet Filter programs which implement task-defined system call filtering polices. See Documentation/prctl/seccomp_filter.txt for details. config HAVE_ARCH_MMAP_RND_BITS bool help An arch should select this symbol if it supports setting a variable number of bits for use in establishing the base address for mmap allocations, has MMU enabled and provides values for both: - ARCH_MMAP_RND_BITS_MIN - ARCH_MMAP_RND_BITS_MAX config ARCH_MMAP_RND_BITS_MIN int config ARCH_MMAP_RND_BITS_MAX int config ARCH_MMAP_RND_BITS_DEFAULT int config ARCH_MMAP_RND_BITS int "Number of bits to use for ASLR of mmap base address" if EXPERT range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT default ARCH_MMAP_RND_BITS_MIN depends on HAVE_ARCH_MMAP_RND_BITS help This value can be used to select the number of bits to use to determine the random offset to the base address of vma regions resulting from mmap allocations. This value will be bounded by the architecture's minimum and maximum supported values. This value can be changed after boot using the /proc/sys/vm/mmap_rnd_bits tunable config HAVE_ARCH_MMAP_RND_COMPAT_BITS bool help An arch should select this symbol if it supports running applications in compatibility mode, supports setting a variable number of bits for use in establishing the base address for mmap allocations, has MMU enabled and provides values for both: - ARCH_MMAP_RND_COMPAT_BITS_MIN - ARCH_MMAP_RND_COMPAT_BITS_MAX config ARCH_MMAP_RND_COMPAT_BITS_MIN int config ARCH_MMAP_RND_COMPAT_BITS_MAX int config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT int config ARCH_MMAP_RND_COMPAT_BITS int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT default ARCH_MMAP_RND_COMPAT_BITS_MIN depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS help This value can be used to select the number of bits to use to determine the random offset to the base address of vma regions resulting from mmap allocations for compatible applications This value will be bounded by the architecture's minimum and maximum supported values. This value can be changed after boot using the /proc/sys/vm/mmap_rnd_compat_bits tunable source "kernel/gcov/Kconfig"