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 KPROBES_ON_FTRACE
  80         def_bool y
  81         depends on KPROBES && HAVE_KPROBES_ON_FTRACE
  82         depends on DYNAMIC_FTRACE_WITH_REGS
  83         help
  84          If function tracer is enabled and the arch supports full
  85          passing of pt_regs to function tracing, then kprobes can
  86          optimize on top of function tracing.
  87
  88 config UPROBES
  89         bool "Transparent user-space probes (EXPERIMENTAL)"
  90         depends on UPROBE_EVENT && PERF_EVENTS
  91         default n
  92         select PERCPU_RWSEM
  93         help
  94           Uprobes is the user-space counterpart to kprobes: they
  95           enable instrumentation applications (such as 'perf probe')
  96           to establish unintrusive probes in user-space binaries and
  97           libraries, by executing handler functions when the probes
  98           are hit by user-space applications.
  99
 100           ( These probes come in the form of single-byte breakpoints,
 101             managed by the kernel and kept transparent to the probed
 102             application. )
 103
 104           If in doubt, say "N".
 105
 106 config HAVE_EFFICIENT_UNALIGNED_ACCESS
 107         bool
 108         help
 109           Some architectures are unable to perform unaligned accesses
 110           without the use of get_unaligned/put_unaligned. Others are
 111           unable to perform such accesses efficiently (e.g. trap on
 112           unaligned access and require fixing it up in the exception
 113           handler.)
 114
 115           This symbol should be selected by an architecture if it can
 116           perform unaligned accesses efficiently to allow different
 117           code paths to be selected for these cases. Some network
 118           drivers, for example, could opt to not fix up alignment
 119           problems with received packets if doing so would not help
 120           much.
 121
 122           See Documentation/unaligned-memory-access.txt for more
 123           information on the topic of unaligned memory accesses.
 124
 125 config ARCH_USE_BUILTIN_BSWAP
 126        bool
 127        help
 128          Modern versions of GCC (since 4.4) have builtin functions
 129          for handling byte-swapping. Using these, instead of the old
 130          inline assembler that the architecture code provides in the
 131          __arch_bswapXX() macros, allows the compiler to see what's
 132          happening and offers more opportunity for optimisation. In
 133          particular, the compiler will be able to combine the byteswap
 134          with a nearby load or store and use load-and-swap or
 135          store-and-swap instructions if the architecture has them. It
 136          should almost *never* result in code which is worse than the
 137          hand-coded assembler in <asm/swab.h>.  But just in case it
 138          does, the use of the builtins is optional.
 139
 140          Any architecture with load-and-swap or store-and-swap
 141          instructions should set this. And it shouldn't hurt to set it
 142          on architectures that don't have such instructions.
 143
 144 config HAVE_SYSCALL_WRAPPERS
 145         bool
 146
 147 config KRETPROBES
 148         def_bool y
 149         depends on KPROBES && HAVE_KRETPROBES
 150
 151 config USER_RETURN_NOTIFIER
 152         bool
 153         depends on HAVE_USER_RETURN_NOTIFIER
 154         help
 155           Provide a kernel-internal notification when a cpu is about to
 156           switch to user mode.
 157
 158 config HAVE_IOREMAP_PROT
 159         bool
 160
 161 config HAVE_KPROBES
 162         bool
 163
 164 config HAVE_KRETPROBES
 165         bool
 166
 167 config HAVE_OPTPROBES
 168         bool
 169
 170 config HAVE_KPROBES_ON_FTRACE
 171         bool
 172
 173 config HAVE_NMI_WATCHDOG
 174         bool
 175 #
 176 # An arch should select this if it provides all these things:
 177 #
 178 #       task_pt_regs()          in asm/processor.h or asm/ptrace.h
 179 #       arch_has_single_step()  if there is hardware single-step support
 180 #       arch_has_block_step()   if there is hardware block-step support
 181 #       asm/syscall.h           supplying asm-generic/syscall.h interface
 182 #       linux/regset.h          user_regset interfaces
 183 #       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
 184 #       TIF_SYSCALL_TRACE       calls tracehook_report_syscall_{entry,exit}
 185 #       TIF_NOTIFY_RESUME       calls tracehook_notify_resume()
 186 #       signal delivery         calls tracehook_signal_handler()
 187 #
 188 config HAVE_ARCH_TRACEHOOK
 189         bool
 190
 191 config HAVE_DMA_ATTRS
 192         bool
 193
 194 config HAVE_DMA_CONTIGUOUS
 195         bool
 196
 197 config USE_GENERIC_SMP_HELPERS
 198         bool
 199
 200 config GENERIC_SMP_IDLE_THREAD
 201        bool
 202
 203 # Select if arch init_task initializer is different to init/init_task.c
 204 config ARCH_INIT_TASK
 205        bool
 206
 207 # Select if arch has its private alloc_task_struct() function
 208 config ARCH_TASK_STRUCT_ALLOCATOR
 209         bool
 210
 211 # Select if arch has its private alloc_thread_info() function
 212 config ARCH_THREAD_INFO_ALLOCATOR
 213         bool
 214
 215 config HAVE_REGS_AND_STACK_ACCESS_API
 216         bool
 217         help
 218           This symbol should be selected by an architecure if it supports
 219           the API needed to access registers and stack entries from pt_regs,
 220           declared in asm/ptrace.h
 221           For example the kprobes-based event tracer needs this API.
 222
 223 config HAVE_CLK
 224         bool
 225         help
 226           The <linux/clk.h> calls support software clock gating and
 227           thus are a key power management tool on many systems.
 228
 229 config HAVE_DMA_API_DEBUG
 230         bool
 231
 232 config HAVE_HW_BREAKPOINT
 233         bool
 234         depends on PERF_EVENTS
 235
 236 config HAVE_MIXED_BREAKPOINTS_REGS
 237         bool
 238         depends on HAVE_HW_BREAKPOINT
 239         help
 240           Depending on the arch implementation of hardware breakpoints,
 241           some of them have separate registers for data and instruction
 242           breakpoints addresses, others have mixed registers to store
 243           them but define the access type in a control register.
 244           Select this option if your arch implements breakpoints under the
 245           latter fashion.
 246
 247 config HAVE_USER_RETURN_NOTIFIER
 248         bool
 249
 250 config HAVE_PERF_EVENTS_NMI
 251         bool
 252         help
 253           System hardware can generate an NMI using the perf event
 254           subsystem.  Also has support for calculating CPU cycle events
 255           to determine how many clock cycles in a given period.
 256
 257 config HAVE_PERF_REGS
 258         bool
 259         help
 260           Support selective register dumps for perf events. This includes
 261           bit-mapping of each registers and a unique architecture id.
 262
 263 config HAVE_PERF_USER_STACK_DUMP
 264         bool
 265         help
 266           Support user stack dumps for perf event samples. This needs
 267           access to the user stack pointer which is not unified across
 268           architectures.
 269
 270 config HAVE_ARCH_JUMP_LABEL
 271         bool
 272
 273 config HAVE_ARCH_MUTEX_CPU_RELAX
 274         bool
 275
 276 config HAVE_RCU_TABLE_FREE
 277         bool
 278
 279 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 280         bool
 281
 282 config HAVE_ALIGNED_STRUCT_PAGE
 283         bool
 284         help
 285           This makes sure that struct pages are double word aligned and that
 286           e.g. the SLUB allocator can perform double word atomic operations
 287           on a struct page for better performance. However selecting this
 288           might increase the size of a struct page by a word.
 289
 290 config HAVE_CMPXCHG_LOCAL
 291         bool
 292
 293 config HAVE_CMPXCHG_DOUBLE
 294         bool
 295
 296 config ARCH_WANT_IPC_PARSE_VERSION
 297         bool
 298
 299 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 300         bool
 301
 302 config ARCH_WANT_OLD_COMPAT_IPC
 303         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 304         bool
 305
 306 config HAVE_VIRT_TO_BUS
 307         bool
 308         help
 309           An architecture should select this if it implements the
 310           deprecated interface virt_to_bus().  All new architectures
 311           should probably not select this.
 312
 313 config HAVE_ARCH_SECCOMP_FILTER
 314         bool
 315         help
 316           An arch should select this symbol if it provides all of these things:
 317           - syscall_get_arch()
 318           - syscall_get_arguments()
 319           - syscall_rollback()
 320           - syscall_set_return_value()
 321           - SIGSYS siginfo_t support
 322           - secure_computing is called from a ptrace_event()-safe context
 323           - secure_computing return value is checked and a return value of -1
 324             results in the system call being skipped immediately.
 325
 326 config SECCOMP_FILTER
 327         def_bool y
 328         depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
 329         help
 330           Enable tasks to build secure computing environments defined
 331           in terms of Berkeley Packet Filter programs which implement
 332           task-defined system call filtering polices.
 333
 334           See Documentation/prctl/seccomp_filter.txt for details.
 335
 336 config HAVE_CONTEXT_TRACKING
 337         bool
 338         help
 339           Provide kernel/user boundaries probes necessary for subsystems
 340           that need it, such as userspace RCU extended quiescent state.
 341           Syscalls need to be wrapped inside user_exit()-user_enter() through
 342           the slow path using TIF_NOHZ flag. Exceptions handlers must be
 343           wrapped as well. Irqs are already protected inside
 344           rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
 345           irq exit still need to be protected.
 346
 347 config HAVE_VIRT_CPU_ACCOUNTING
 348         bool
 349
 350 config HAVE_IRQ_TIME_ACCOUNTING
 351         bool
 352         help
 353           Archs need to ensure they use a high enough resolution clock to
 354           support irq time accounting and then call enable_sched_clock_irqtime().
 355
 356 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
 357         bool
 358
 359 config HAVE_MOD_ARCH_SPECIFIC
 360         bool
 361         help
 362           The arch uses struct mod_arch_specific to store data.  Many arches
 363           just need a simple module loader without arch specific data - those
 364           should not enable this.
 365
 366 config MODULES_USE_ELF_RELA
 367         bool
 368         help
 369           Modules only use ELF RELA relocations.  Modules with ELF REL
 370           relocations will give an error.
 371
 372 config MODULES_USE_ELF_REL
 373         bool
 374         help
 375           Modules only use ELF REL relocations.  Modules with ELF RELA
 376           relocations will give an error.
 377
 378 #
 379 # ABI hall of shame
 380 #
 381 config CLONE_BACKWARDS
 382         bool
 383         help
 384           Architecture has tls passed as the 4th argument of clone(2),
 385           not the 5th one.
 386
 387 config CLONE_BACKWARDS2
 388         bool
 389         help
 390           Architecture has the first two arguments of clone(2) swapped.
 391
 392 config ODD_RT_SIGACTION
 393         bool
 394         help
 395           Architecture has unusual rt_sigaction(2) arguments
 396
 397 config OLD_SIGSUSPEND
 398         bool
 399         help
 400           Architecture has old sigsuspend(2) syscall, of one-argument variety
 401
 402 config OLD_SIGSUSPEND3
 403         bool
 404         help
 405           Even weirder antique ABI - three-argument sigsuspend(2)
 406
 407 config OLD_SIGACTION
 408         bool
 409         help
 410           Architecture has old sigaction(2) syscall.  Nope, not the same
 411           as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
 412           but fairly different variant of sigaction(2), thanks to OSF/1
 413           compatibility...
 414
 415 config COMPAT_OLD_SIGACTION
 416         bool
 417
 418 source "kernel/gcov/Kconfig"