arch/Kconfig

   1 #
   2 # General architecture dependent options
   3 #
   4
   5 config 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
  18 config 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
  30 config HAVE_OPROFILE
  31         bool
  32
  33 config OPROFILE_NMI_TIMER
  34         def_bool y
  35         depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
  36
  37 config 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
  49 config 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
  74 config OPTPROBES
  75         def_bool y
  76         depends on KPROBES && HAVE_OPTPROBES
  77         depends on !PREEMPT
  78
  79 config UPROBES
  80         bool "Transparent user-space probes (EXPERIMENTAL)"
  81         depends on UPROBE_EVENTS && 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
  96 config 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
 115 config HAVE_SYSCALL_WRAPPERS
 116         bool
 117
 118 config KRETPROBES
 119         def_bool y
 120         depends on KPROBES && HAVE_KRETPROBES
 121
 122 config 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
 129 config HAVE_IOREMAP_PROT
 130         bool
 131
 132 config HAVE_KPROBES
 133         bool
 134
 135 config HAVE_KRETPROBES
 136         bool
 137
 138 config HAVE_OPTPROBES
 139         bool
 140
 141 config 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 #
 156 config HAVE_ARCH_TRACEHOOK
 157         bool
 158
 159 config HAVE_DMA_ATTRS
 160         bool
 161
 162 config USE_GENERIC_SMP_HELPERS
 163         bool
 164
 165 config HAVE_REGS_AND_STACK_ACCESS_API
 166         bool
 167         help
 168           This symbol should be selected by an architecure if it supports
 169           the API needed to access registers and stack entries from pt_regs,
 170           declared in asm/ptrace.h
 171           For example the kprobes-based event tracer needs this API.
 172
 173 config HAVE_CLK
 174         bool
 175         help
 176           The <linux/clk.h> calls support software clock gating and
 177           thus are a key power management tool on many systems.
 178
 179 config HAVE_DMA_API_DEBUG
 180         bool
 181
 182 config HAVE_HW_BREAKPOINT
 183         bool
 184         depends on PERF_EVENTS
 185
 186 config HAVE_MIXED_BREAKPOINTS_REGS
 187         bool
 188         depends on HAVE_HW_BREAKPOINT
 189         help
 190           Depending on the arch implementation of hardware breakpoints,
 191           some of them have separate registers for data and instruction
 192           breakpoints addresses, others have mixed registers to store
 193           them but define the access type in a control register.
 194           Select this option if your arch implements breakpoints under the
 195           latter fashion.
 196
 197 config HAVE_USER_RETURN_NOTIFIER
 198         bool
 199
 200 config HAVE_PERF_EVENTS_NMI
 201         bool
 202         help
 203           System hardware can generate an NMI using the perf event
 204           subsystem.  Also has support for calculating CPU cycle events
 205           to determine how many clock cycles in a given period.
 206
 207 config HAVE_ARCH_JUMP_LABEL
 208         bool
 209
 210 config HAVE_ARCH_MUTEX_CPU_RELAX
 211         bool
 212
 213 config HAVE_RCU_TABLE_FREE
 214         bool
 215
 216 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 217         bool
 218
 219 config HAVE_ALIGNED_STRUCT_PAGE
 220         bool
 221         help
 222           This makes sure that struct pages are double word aligned and that
 223           e.g. the SLUB allocator can perform double word atomic operations
 224           on a struct page for better performance. However selecting this
 225           might increase the size of a struct page by a word.
 226
 227 config HAVE_CMPXCHG_LOCAL
 228         bool
 229
 230 config HAVE_CMPXCHG_DOUBLE
 231         bool
 232
 233 config ARCH_WANT_OLD_COMPAT_IPC
 234         bool
 235
 236 source "kernel/gcov/Kconfig"