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         select PERCPU_RWSEM
  84         help
  85           Uprobes is the user-space counterpart to kprobes: they
  86           enable instrumentation applications (such as 'perf probe')
  87           to establish unintrusive probes in user-space binaries and
  88           libraries, by executing handler functions when the probes
  89           are hit by user-space applications.
  90
  91           ( These probes come in the form of single-byte breakpoints,
  92             managed by the kernel and kept transparent to the probed
  93             application. )
  94
  95           If in doubt, say "N".
  96
  97 config HAVE_64BIT_ALIGNED_ACCESS
  98         def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
  99         help
 100           Some architectures require 64 bit accesses to be 64 bit
 101           aligned, which also requires structs containing 64 bit values
 102           to be 64 bit aligned too. This includes some 32 bit
 103           architectures which can do 64 bit accesses, as well as 64 bit
 104           architectures without unaligned access.
 105
 106           This symbol should be selected by an architecture if 64 bit
 107           accesses are required to be 64 bit aligned in this way even
 108           though it is not a 64 bit architecture.
 109
 110           See Documentation/unaligned-memory-access.txt for more
 111           information on the topic of unaligned memory accesses.
 112
 113 config HAVE_EFFICIENT_UNALIGNED_ACCESS
 114         bool
 115         help
 116           Some architectures are unable to perform unaligned accesses
 117           without the use of get_unaligned/put_unaligned. Others are
 118           unable to perform such accesses efficiently (e.g. trap on
 119           unaligned access and require fixing it up in the exception
 120           handler.)
 121
 122           This symbol should be selected by an architecture if it can
 123           perform unaligned accesses efficiently to allow different
 124           code paths to be selected for these cases. Some network
 125           drivers, for example, could opt to not fix up alignment
 126           problems with received packets if doing so would not help
 127           much.
 128
 129           See Documentation/unaligned-memory-access.txt for more
 130           information on the topic of unaligned memory accesses.
 131
 132 config ARCH_USE_BUILTIN_BSWAP
 133        bool
 134        help
 135          Modern versions of GCC (since 4.4) have builtin functions
 136          for handling byte-swapping. Using these, instead of the old
 137          inline assembler that the architecture code provides in the
 138          __arch_bswapXX() macros, allows the compiler to see what's
 139          happening and offers more opportunity for optimisation. In
 140          particular, the compiler will be able to combine the byteswap
 141          with a nearby load or store and use load-and-swap or
 142          store-and-swap instructions if the architecture has them. It
 143          should almost *never* result in code which is worse than the
 144          hand-coded assembler in <asm/swab.h>.  But just in case it
 145          does, the use of the builtins is optional.
 146
 147          Any architecture with load-and-swap or store-and-swap
 148          instructions should set this. And it shouldn't hurt to set it
 149          on architectures that don't have such instructions.
 150
 151 config HAVE_SYSCALL_WRAPPERS
 152         bool
 153
 154 config KRETPROBES
 155         def_bool y
 156         depends on KPROBES && HAVE_KRETPROBES
 157
 158 config USER_RETURN_NOTIFIER
 159         bool
 160         depends on HAVE_USER_RETURN_NOTIFIER
 161         help
 162           Provide a kernel-internal notification when a cpu is about to
 163           switch to user mode.
 164
 165 config HAVE_IOREMAP_PROT
 166         bool
 167
 168 config HAVE_KPROBES
 169         bool
 170
 171 config HAVE_KRETPROBES
 172         bool
 173
 174 config HAVE_OPTPROBES
 175         bool
 176
 177 config HAVE_NMI_WATCHDOG
 178         bool
 179 #
 180 # An arch should select this if it provides all these things:
 181 #
 182 #       task_pt_regs()          in asm/processor.h or asm/ptrace.h
 183 #       arch_has_single_step()  if there is hardware single-step support
 184 #       arch_has_block_step()   if there is hardware block-step support
 185 #       asm/syscall.h           supplying asm-generic/syscall.h interface
 186 #       linux/regset.h          user_regset interfaces
 187 #       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
 188 #       TIF_SYSCALL_TRACE       calls tracehook_report_syscall_{entry,exit}
 189 #       TIF_NOTIFY_RESUME       calls tracehook_notify_resume()
 190 #       signal delivery         calls tracehook_signal_handler()
 191 #
 192 config HAVE_ARCH_TRACEHOOK
 193         bool
 194
 195 config HAVE_DMA_ATTRS
 196         bool
 197
 198 config HAVE_DMA_CONTIGUOUS
 199         bool
 200
 201 config USE_GENERIC_SMP_HELPERS
 202         bool
 203
 204 config GENERIC_SMP_IDLE_THREAD
 205        bool
 206
 207 # Select if arch init_task initializer is different to init/init_task.c
 208 config ARCH_INIT_TASK
 209        bool
 210
 211 # Select if arch has its private alloc_task_struct() function
 212 config ARCH_TASK_STRUCT_ALLOCATOR
 213         bool
 214
 215 # Select if arch has its private alloc_thread_info() function
 216 config ARCH_THREAD_INFO_ALLOCATOR
 217         bool
 218
 219 config HAVE_REGS_AND_STACK_ACCESS_API
 220         bool
 221         help
 222           This symbol should be selected by an architecure if it supports
 223           the API needed to access registers and stack entries from pt_regs,
 224           declared in asm/ptrace.h
 225           For example the kprobes-based event tracer needs this API.
 226
 227 config HAVE_CLK
 228         bool
 229         help
 230           The <linux/clk.h> calls support software clock gating and
 231           thus are a key power management tool on many systems.
 232
 233 config HAVE_DMA_API_DEBUG
 234         bool
 235
 236 config HAVE_HW_BREAKPOINT
 237         bool
 238         depends on PERF_EVENTS
 239
 240 config HAVE_MIXED_BREAKPOINTS_REGS
 241         bool
 242         depends on HAVE_HW_BREAKPOINT
 243         help
 244           Depending on the arch implementation of hardware breakpoints,
 245           some of them have separate registers for data and instruction
 246           breakpoints addresses, others have mixed registers to store
 247           them but define the access type in a control register.
 248           Select this option if your arch implements breakpoints under the
 249           latter fashion.
 250
 251 config HAVE_USER_RETURN_NOTIFIER
 252         bool
 253
 254 config HAVE_PERF_EVENTS_NMI
 255         bool
 256         help
 257           System hardware can generate an NMI using the perf event
 258           subsystem.  Also has support for calculating CPU cycle events
 259           to determine how many clock cycles in a given period.
 260
 261 config HAVE_PERF_REGS
 262         bool
 263         help
 264           Support selective register dumps for perf events. This includes
 265           bit-mapping of each registers and a unique architecture id.
 266
 267 config HAVE_PERF_USER_STACK_DUMP
 268         bool
 269         help
 270           Support user stack dumps for perf event samples. This needs
 271           access to the user stack pointer which is not unified across
 272           architectures.
 273
 274 config HAVE_ARCH_JUMP_LABEL
 275         bool
 276
 277 config HAVE_ARCH_MUTEX_CPU_RELAX
 278         bool
 279
 280 config HAVE_RCU_TABLE_FREE
 281         bool
 282
 283 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 284         bool
 285
 286 config HAVE_ALIGNED_STRUCT_PAGE
 287         bool
 288         help
 289           This makes sure that struct pages are double word aligned and that
 290           e.g. the SLUB allocator can perform double word atomic operations
 291           on a struct page for better performance. However selecting this
 292           might increase the size of a struct page by a word.
 293
 294 config HAVE_CMPXCHG_LOCAL
 295         bool
 296
 297 config HAVE_CMPXCHG_DOUBLE
 298         bool
 299
 300 config ARCH_WANT_IPC_PARSE_VERSION
 301         bool
 302
 303 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 304         bool
 305
 306 config ARCH_WANT_OLD_COMPAT_IPC
 307         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 308         bool
 309
 310 config HAVE_ARCH_SECCOMP_FILTER
 311         bool
 312         help
 313           An arch should select this symbol if it provides all of these things:
 314           - syscall_get_arch()
 315           - syscall_get_arguments()
 316           - syscall_rollback()
 317           - syscall_set_return_value()
 318           - SIGSYS siginfo_t support
 319           - secure_computing is called from a ptrace_event()-safe context
 320           - secure_computing return value is checked and a return value of -1
 321             results in the system call being skipped immediately.
 322
 323 config SECCOMP_FILTER
 324         def_bool y
 325         depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
 326         help
 327           Enable tasks to build secure computing environments defined
 328           in terms of Berkeley Packet Filter programs which implement
 329           task-defined system call filtering polices.
 330
 331           See Documentation/prctl/seccomp_filter.txt for details.
 332
 333 config HAVE_CONTEXT_TRACKING
 334         bool
 335         help
 336           Provide kernel/user boundaries probes necessary for subsystems
 337           that need it, such as userspace RCU extended quiescent state.
 338           Syscalls need to be wrapped inside user_exit()-user_enter() through
 339           the slow path using TIF_NOHZ flag. Exceptions handlers must be
 340           wrapped as well. Irqs are already protected inside
 341           rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
 342           irq exit still need to be protected.
 343
 344 config HAVE_VIRT_CPU_ACCOUNTING
 345         bool
 346
 347 config HAVE_IRQ_TIME_ACCOUNTING
 348         bool
 349         help
 350           Archs need to ensure they use a high enough resolution clock to
 351           support irq time accounting and then call enable_sched_clock_irqtime().
 352
 353 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
 354         bool
 355
 356 config HAVE_MOD_ARCH_SPECIFIC
 357         bool
 358         help
 359           The arch uses struct mod_arch_specific to store data.  Many arches
 360           just need a simple module loader without arch specific data - those
 361           should not enable this.
 362
 363 config MODULES_USE_ELF_RELA
 364         bool
 365         help
 366           Modules only use ELF RELA relocations.  Modules with ELF REL
 367           relocations will give an error.
 368
 369 config MODULES_USE_ELF_REL
 370         bool
 371         help
 372           Modules only use ELF REL relocations.  Modules with ELF RELA
 373           relocations will give an error.
 374
 375 config GENERIC_SIGALTSTACK
 376         bool
 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 source "kernel/gcov/Kconfig"