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_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
  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 HAVE_DMA_CONTIGUOUS
 163         bool
 164
 165 config USE_GENERIC_SMP_HELPERS
 166         bool
 167
 168 config GENERIC_SMP_IDLE_THREAD
 169        bool
 170
 171 # Select if arch init_task initializer is different to init/init_task.c
 172 config ARCH_INIT_TASK
 173        bool
 174
 175 # Select if arch has its private alloc_task_struct() function
 176 config ARCH_TASK_STRUCT_ALLOCATOR
 177         bool
 178
 179 # Select if arch has its private alloc_thread_info() function
 180 config ARCH_THREAD_INFO_ALLOCATOR
 181         bool
 182
 183 config 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
 191 config 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
 197 config HAVE_DMA_API_DEBUG
 198         bool
 199
 200 config HAVE_HW_BREAKPOINT
 201         bool
 202         depends on PERF_EVENTS
 203
 204 config 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
 215 config HAVE_USER_RETURN_NOTIFIER
 216         bool
 217
 218 config 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
 225 config HAVE_ARCH_JUMP_LABEL
 226         bool
 227
 228 config HAVE_ARCH_MUTEX_CPU_RELAX
 229         bool
 230
 231 config HAVE_RCU_TABLE_FREE
 232         bool
 233
 234 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 235         bool
 236
 237 config 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
 245 config HAVE_CMPXCHG_LOCAL
 246         bool
 247
 248 config HAVE_CMPXCHG_DOUBLE
 249         bool
 250
 251 config ARCH_WANT_IPC_PARSE_VERSION
 252         bool
 253
 254 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 255         bool
 256
 257 config ARCH_WANT_OLD_COMPAT_IPC
 258         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 259         bool
 260
 261 config 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
 274 config 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
 284 source "kernel/gcov/Kconfig"