linux/arch/Kconfig
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   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 UPROBES
  80        bool "Transparent user-space probes (EXPERIMENTAL)"
  81        depends on UPROBE_EVENT && PERF_EVENTS
  82        default n
  83        help
  84          Uprobes is the user-space counterpart to kprobes: they
  85          enable instrumentation applications (such as 'perf probe')
  86          to establish unintrusive probes in user-space binaries and
  87          libraries, by executing handler functions when the probes
  88          are hit by user-space applications.
  89
  90          ( These probes come in the form of single-byte breakpoints,
  91            managed by the kernel and kept transparent to the probed
  92            application. )
  93
  94          If in doubt, say "N".
  95
  96config HAVE_EFFICIENT_UNALIGNED_ACCESS
  97        bool
  98        help
  99          Some architectures are unable to perform unaligned accesses
 100          without the use of get_unaligned/put_unaligned. Others are
 101          unable to perform such accesses efficiently (e.g. trap on
 102          unaligned access and require fixing it up in the exception
 103          handler.)
 104
 105          This symbol should be selected by an architecture if it can
 106          perform unaligned accesses efficiently to allow different
 107          code paths to be selected for these cases. Some network
 108          drivers, for example, could opt to not fix up alignment
 109          problems with received packets if doing so would not help
 110          much.
 111
 112          See Documentation/unaligned-memory-access.txt for more
 113          information on the topic of unaligned memory accesses.
 114
 115config HAVE_SYSCALL_WRAPPERS
 116        bool
 117
 118config KRETPROBES
 119        def_bool y
 120        depends on KPROBES && HAVE_KRETPROBES
 121
 122config USER_RETURN_NOTIFIER
 123        bool
 124        depends on HAVE_USER_RETURN_NOTIFIER
 125        help
 126          Provide a kernel-internal notification when a cpu is about to
 127          switch to user mode.
 128
 129config HAVE_IOREMAP_PROT
 130        bool
 131
 132config HAVE_KPROBES
 133        bool
 134
 135config HAVE_KRETPROBES
 136        bool
 137
 138config HAVE_OPTPROBES
 139        bool
 140
 141config HAVE_NMI_WATCHDOG
 142        bool
 143#
 144# An arch should select this if it provides all these things:
 145#
 146#       task_pt_regs()          in asm/processor.h or asm/ptrace.h
 147#       arch_has_single_step()  if there is hardware single-step support
 148#       arch_has_block_step()   if there is hardware block-step support
 149#       asm/syscall.h           supplying asm-generic/syscall.h interface
 150#       linux/regset.h          user_regset interfaces
 151#       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
 152#       TIF_SYSCALL_TRACE       calls tracehook_report_syscall_{entry,exit}
 153#       TIF_NOTIFY_RESUME       calls tracehook_notify_resume()
 154#       signal delivery         calls tracehook_signal_handler()
 155#
 156config HAVE_ARCH_TRACEHOOK
 157        bool
 158
 159config HAVE_DMA_ATTRS
 160        bool
 161
 162config HAVE_DMA_CONTIGUOUS
 163        bool
 164
 165config USE_GENERIC_SMP_HELPERS
 166        bool
 167
 168config GENERIC_SMP_IDLE_THREAD
 169       bool
 170
 171# Select if arch init_task initializer is different to init/init_task.c
 172config ARCH_INIT_TASK
 173       bool
 174
 175# Select if arch has its private alloc_task_struct() function
 176config ARCH_TASK_STRUCT_ALLOCATOR
 177        bool
 178
 179# Select if arch has its private alloc_thread_info() function
 180config ARCH_THREAD_INFO_ALLOCATOR
 181        bool
 182
 183config HAVE_REGS_AND_STACK_ACCESS_API
 184        bool
 185        help
 186          This symbol should be selected by an architecure if it supports
 187          the API needed to access registers and stack entries from pt_regs,
 188          declared in asm/ptrace.h
 189          For example the kprobes-based event tracer needs this API.
 190
 191config HAVE_CLK
 192        bool
 193        help
 194          The <linux/clk.h> calls support software clock gating and
 195          thus are a key power management tool on many systems.
 196
 197config HAVE_DMA_API_DEBUG
 198        bool
 199
 200config HAVE_HW_BREAKPOINT
 201        bool
 202        depends on PERF_EVENTS
 203
 204config HAVE_MIXED_BREAKPOINTS_REGS
 205        bool
 206        depends on HAVE_HW_BREAKPOINT
 207        help
 208          Depending on the arch implementation of hardware breakpoints,
 209          some of them have separate registers for data and instruction
 210          breakpoints addresses, others have mixed registers to store
 211          them but define the access type in a control register.
 212          Select this option if your arch implements breakpoints under the
 213          latter fashion.
 214
 215config HAVE_USER_RETURN_NOTIFIER
 216        bool
 217
 218config HAVE_PERF_EVENTS_NMI
 219        bool
 220        help
 221          System hardware can generate an NMI using the perf event
 222          subsystem.  Also has support for calculating CPU cycle events
 223          to determine how many clock cycles in a given period.
 224
 225config HAVE_ARCH_JUMP_LABEL
 226        bool
 227
 228config HAVE_ARCH_MUTEX_CPU_RELAX
 229        bool
 230
 231config HAVE_RCU_TABLE_FREE
 232        bool
 233
 234config ARCH_HAVE_NMI_SAFE_CMPXCHG
 235        bool
 236
 237config HAVE_ALIGNED_STRUCT_PAGE
 238        bool
 239        help
 240          This makes sure that struct pages are double word aligned and that
 241          e.g. the SLUB allocator can perform double word atomic operations
 242          on a struct page for better performance. However selecting this
 243          might increase the size of a struct page by a word.
 244
 245config HAVE_CMPXCHG_LOCAL
 246        bool
 247
 248config HAVE_CMPXCHG_DOUBLE
 249        bool
 250
 251config ARCH_WANT_IPC_PARSE_VERSION
 252        bool
 253
 254config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 255        bool
 256
 257config ARCH_WANT_OLD_COMPAT_IPC
 258        select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 259        bool
 260
 261config HAVE_ARCH_SECCOMP_FILTER
 262        bool
 263        help
 264          An arch should select this symbol if it provides all of these things:
 265          - syscall_get_arch()
 266          - syscall_get_arguments()
 267          - syscall_rollback()
 268          - syscall_set_return_value()
 269          - SIGSYS siginfo_t support
 270          - secure_computing is called from a ptrace_event()-safe context
 271          - secure_computing return value is checked and a return value of -1
 272            results in the system call being skipped immediately.
 273
 274config SECCOMP_FILTER
 275        def_bool y
 276        depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
 277        help
 278          Enable tasks to build secure computing environments defined
 279          in terms of Berkeley Packet Filter programs which implement
 280          task-defined system call filtering polices.
 281
 282          See Documentation/prctl/seccomp_filter.txt for details.
 283
 284source "kernel/gcov/Kconfig"
 285
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