arch/Kconfig

   1 #
   2 # General architecture dependent options
   3 #
   4
   5 config KEXEC_CORE
   6         bool
   7
   8 config OPROFILE
   9         tristate "OProfile system profiling"
  10         depends on PROFILING
  11         depends on HAVE_OPROFILE
  12         select RING_BUFFER
  13         select RING_BUFFER_ALLOW_SWAP
  14         help
  15           OProfile is a profiling system capable of profiling the
  16           whole system, include the kernel, kernel modules, libraries,
  17           and applications.
  18
  19           If unsure, say N.
  20
  21 config OPROFILE_EVENT_MULTIPLEX
  22         bool "OProfile multiplexing support (EXPERIMENTAL)"
  23         default n
  24         depends on OPROFILE && X86
  25         help
  26           The number of hardware counters is limited. The multiplexing
  27           feature enables OProfile to gather more events than counters
  28           are provided by the hardware. This is realized by switching
  29           between events at an user specified time interval.
  30
  31           If unsure, say N.
  32
  33 config HAVE_OPROFILE
  34         bool
  35
  36 config OPROFILE_NMI_TIMER
  37         def_bool y
  38         depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
  39
  40 config KPROBES
  41         bool "Kprobes"
  42         depends on MODULES
  43         depends on HAVE_KPROBES
  44         select KALLSYMS
  45         help
  46           Kprobes allows you to trap at almost any kernel address and
  47           execute a callback function.  register_kprobe() establishes
  48           a probepoint and specifies the callback.  Kprobes is useful
  49           for kernel debugging, non-intrusive instrumentation and testing.
  50           If in doubt, say "N".
  51
  52 config JUMP_LABEL
  53        bool "Optimize very unlikely/likely branches"
  54        depends on HAVE_ARCH_JUMP_LABEL
  55        help
  56          This option enables a transparent branch optimization that
  57          makes certain almost-always-true or almost-always-false branch
  58          conditions even cheaper to execute within the kernel.
  59
  60          Certain performance-sensitive kernel code, such as trace points,
  61          scheduler functionality, networking code and KVM have such
  62          branches and include support for this optimization technique.
  63
  64          If it is detected that the compiler has support for "asm goto",
  65          the kernel will compile such branches with just a nop
  66          instruction. When the condition flag is toggled to true, the
  67          nop will be converted to a jump instruction to execute the
  68          conditional block of instructions.
  69
  70          This technique lowers overhead and stress on the branch prediction
  71          of the processor and generally makes the kernel faster. The update
  72          of the condition is slower, but those are always very rare.
  73
  74          ( On 32-bit x86, the necessary options added to the compiler
  75            flags may increase the size of the kernel slightly. )
  76
  77 config STATIC_KEYS_SELFTEST
  78         bool "Static key selftest"
  79         depends on JUMP_LABEL
  80         help
  81           Boot time self-test of the branch patching code.
  82
  83 config OPTPROBES
  84         def_bool y
  85         depends on KPROBES && HAVE_OPTPROBES
  86         depends on !PREEMPT
  87
  88 config KPROBES_ON_FTRACE
  89         def_bool y
  90         depends on KPROBES && HAVE_KPROBES_ON_FTRACE
  91         depends on DYNAMIC_FTRACE_WITH_REGS
  92         help
  93          If function tracer is enabled and the arch supports full
  94          passing of pt_regs to function tracing, then kprobes can
  95          optimize on top of function tracing.
  96
  97 config UPROBES
  98         def_bool n
  99         help
 100           Uprobes is the user-space counterpart to kprobes: they
 101           enable instrumentation applications (such as 'perf probe')
 102           to establish unintrusive probes in user-space binaries and
 103           libraries, by executing handler functions when the probes
 104           are hit by user-space applications.
 105
 106           ( These probes come in the form of single-byte breakpoints,
 107             managed by the kernel and kept transparent to the probed
 108             application. )
 109
 110 config HAVE_64BIT_ALIGNED_ACCESS
 111         def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
 112         help
 113           Some architectures require 64 bit accesses to be 64 bit
 114           aligned, which also requires structs containing 64 bit values
 115           to be 64 bit aligned too. This includes some 32 bit
 116           architectures which can do 64 bit accesses, as well as 64 bit
 117           architectures without unaligned access.
 118
 119           This symbol should be selected by an architecture if 64 bit
 120           accesses are required to be 64 bit aligned in this way even
 121           though it is not a 64 bit architecture.
 122
 123           See Documentation/unaligned-memory-access.txt for more
 124           information on the topic of unaligned memory accesses.
 125
 126 config HAVE_EFFICIENT_UNALIGNED_ACCESS
 127         bool
 128         help
 129           Some architectures are unable to perform unaligned accesses
 130           without the use of get_unaligned/put_unaligned. Others are
 131           unable to perform such accesses efficiently (e.g. trap on
 132           unaligned access and require fixing it up in the exception
 133           handler.)
 134
 135           This symbol should be selected by an architecture if it can
 136           perform unaligned accesses efficiently to allow different
 137           code paths to be selected for these cases. Some network
 138           drivers, for example, could opt to not fix up alignment
 139           problems with received packets if doing so would not help
 140           much.
 141
 142           See Documentation/unaligned-memory-access.txt for more
 143           information on the topic of unaligned memory accesses.
 144
 145 config ARCH_USE_BUILTIN_BSWAP
 146        bool
 147        help
 148          Modern versions of GCC (since 4.4) have builtin functions
 149          for handling byte-swapping. Using these, instead of the old
 150          inline assembler that the architecture code provides in the
 151          __arch_bswapXX() macros, allows the compiler to see what's
 152          happening and offers more opportunity for optimisation. In
 153          particular, the compiler will be able to combine the byteswap
 154          with a nearby load or store and use load-and-swap or
 155          store-and-swap instructions if the architecture has them. It
 156          should almost *never* result in code which is worse than the
 157          hand-coded assembler in <asm/swab.h>.  But just in case it
 158          does, the use of the builtins is optional.
 159
 160          Any architecture with load-and-swap or store-and-swap
 161          instructions should set this. And it shouldn't hurt to set it
 162          on architectures that don't have such instructions.
 163
 164 config KRETPROBES
 165         def_bool y
 166         depends on KPROBES && HAVE_KRETPROBES
 167
 168 config USER_RETURN_NOTIFIER
 169         bool
 170         depends on HAVE_USER_RETURN_NOTIFIER
 171         help
 172           Provide a kernel-internal notification when a cpu is about to
 173           switch to user mode.
 174
 175 config HAVE_IOREMAP_PROT
 176         bool
 177
 178 config HAVE_KPROBES
 179         bool
 180
 181 config HAVE_KRETPROBES
 182         bool
 183
 184 config HAVE_OPTPROBES
 185         bool
 186
 187 config HAVE_KPROBES_ON_FTRACE
 188         bool
 189
 190 config HAVE_NMI
 191         bool
 192
 193 config HAVE_NMI_WATCHDOG
 194         depends on HAVE_NMI
 195         bool
 196 #
 197 # An arch should select this if it provides all these things:
 198 #
 199 #       task_pt_regs()          in asm/processor.h or asm/ptrace.h
 200 #       arch_has_single_step()  if there is hardware single-step support
 201 #       arch_has_block_step()   if there is hardware block-step support
 202 #       asm/syscall.h           supplying asm-generic/syscall.h interface
 203 #       linux/regset.h          user_regset interfaces
 204 #       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
 205 #       TIF_SYSCALL_TRACE       calls tracehook_report_syscall_{entry,exit}
 206 #       TIF_NOTIFY_RESUME       calls tracehook_notify_resume()
 207 #       signal delivery         calls tracehook_signal_handler()
 208 #
 209 config HAVE_ARCH_TRACEHOOK
 210         bool
 211
 212 config HAVE_DMA_CONTIGUOUS
 213         bool
 214
 215 config GENERIC_SMP_IDLE_THREAD
 216        bool
 217
 218 config GENERIC_IDLE_POLL_SETUP
 219        bool
 220
 221 # Select if arch init_task initializer is different to init/init_task.c
 222 config ARCH_INIT_TASK
 223        bool
 224
 225 # Select if arch has its private alloc_task_struct() function
 226 config ARCH_TASK_STRUCT_ALLOCATOR
 227         bool
 228
 229 # Select if arch has its private alloc_thread_stack() function
 230 config ARCH_THREAD_STACK_ALLOCATOR
 231         bool
 232
 233 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
 234 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
 235         bool
 236
 237 config HAVE_REGS_AND_STACK_ACCESS_API
 238         bool
 239         help
 240           This symbol should be selected by an architecure if it supports
 241           the API needed to access registers and stack entries from pt_regs,
 242           declared in asm/ptrace.h
 243           For example the kprobes-based event tracer needs this API.
 244
 245 config HAVE_CLK
 246         bool
 247         help
 248           The <linux/clk.h> calls support software clock gating and
 249           thus are a key power management tool on many systems.
 250
 251 config HAVE_DMA_API_DEBUG
 252         bool
 253
 254 config HAVE_HW_BREAKPOINT
 255         bool
 256         depends on PERF_EVENTS
 257
 258 config HAVE_MIXED_BREAKPOINTS_REGS
 259         bool
 260         depends on HAVE_HW_BREAKPOINT
 261         help
 262           Depending on the arch implementation of hardware breakpoints,
 263           some of them have separate registers for data and instruction
 264           breakpoints addresses, others have mixed registers to store
 265           them but define the access type in a control register.
 266           Select this option if your arch implements breakpoints under the
 267           latter fashion.
 268
 269 config HAVE_USER_RETURN_NOTIFIER
 270         bool
 271
 272 config HAVE_PERF_EVENTS_NMI
 273         bool
 274         help
 275           System hardware can generate an NMI using the perf event
 276           subsystem.  Also has support for calculating CPU cycle events
 277           to determine how many clock cycles in a given period.
 278
 279 config HAVE_PERF_REGS
 280         bool
 281         help
 282           Support selective register dumps for perf events. This includes
 283           bit-mapping of each registers and a unique architecture id.
 284
 285 config HAVE_PERF_USER_STACK_DUMP
 286         bool
 287         help
 288           Support user stack dumps for perf event samples. This needs
 289           access to the user stack pointer which is not unified across
 290           architectures.
 291
 292 config HAVE_ARCH_JUMP_LABEL
 293         bool
 294
 295 config HAVE_RCU_TABLE_FREE
 296         bool
 297
 298 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 299         bool
 300
 301 config HAVE_ALIGNED_STRUCT_PAGE
 302         bool
 303         help
 304           This makes sure that struct pages are double word aligned and that
 305           e.g. the SLUB allocator can perform double word atomic operations
 306           on a struct page for better performance. However selecting this
 307           might increase the size of a struct page by a word.
 308
 309 config HAVE_CMPXCHG_LOCAL
 310         bool
 311
 312 config HAVE_CMPXCHG_DOUBLE
 313         bool
 314
 315 config ARCH_WANT_IPC_PARSE_VERSION
 316         bool
 317
 318 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 319         bool
 320
 321 config ARCH_WANT_OLD_COMPAT_IPC
 322         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 323         bool
 324
 325 config HAVE_ARCH_SECCOMP_FILTER
 326         bool
 327         help
 328           An arch should select this symbol if it provides all of these things:
 329           - syscall_get_arch()
 330           - syscall_get_arguments()
 331           - syscall_rollback()
 332           - syscall_set_return_value()
 333           - SIGSYS siginfo_t support
 334           - secure_computing is called from a ptrace_event()-safe context
 335           - secure_computing return value is checked and a return value of -1
 336             results in the system call being skipped immediately.
 337           - seccomp syscall wired up
 338
 339           For best performance, an arch should use seccomp_phase1 and
 340           seccomp_phase2 directly.  It should call seccomp_phase1 for all
 341           syscalls if TIF_SECCOMP is set, but seccomp_phase1 does not
 342           need to be called from a ptrace-safe context.  It must then
 343           call seccomp_phase2 if seccomp_phase1 returns anything other
 344           than SECCOMP_PHASE1_OK or SECCOMP_PHASE1_SKIP.
 345
 346           As an additional optimization, an arch may provide seccomp_data
 347           directly to seccomp_phase1; this avoids multiple calls
 348           to the syscall_xyz helpers for every syscall.
 349
 350 config SECCOMP_FILTER
 351         def_bool y
 352         depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
 353         help
 354           Enable tasks to build secure computing environments defined
 355           in terms of Berkeley Packet Filter programs which implement
 356           task-defined system call filtering polices.
 357
 358           See Documentation/prctl/seccomp_filter.txt for details.
 359
 360 config HAVE_GCC_PLUGINS
 361         bool
 362         help
 363           An arch should select this symbol if it supports building with
 364           GCC plugins.
 365
 366 menuconfig GCC_PLUGINS
 367         bool "GCC plugins"
 368         depends on HAVE_GCC_PLUGINS
 369         depends on !COMPILE_TEST
 370         help
 371           GCC plugins are loadable modules that provide extra features to the
 372           compiler. They are useful for runtime instrumentation and static analysis.
 373
 374           See Documentation/gcc-plugins.txt for details.
 375
 376 config GCC_PLUGIN_CYC_COMPLEXITY
 377         bool "Compute the cyclomatic complexity of a function"
 378         depends on GCC_PLUGINS
 379         help
 380           The complexity M of a function's control flow graph is defined as:
 381            M = E - N + 2P
 382           where
 383
 384           E = the number of edges
 385           N = the number of nodes
 386           P = the number of connected components (exit nodes).
 387
 388 config GCC_PLUGIN_SANCOV
 389         bool
 390         depends on GCC_PLUGINS
 391         help
 392           This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
 393           basic blocks. It supports all gcc versions with plugin support (from
 394           gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
 395           by Dmitry Vyukov <dvyukov@google.com>.
 396
 397 config HAVE_CC_STACKPROTECTOR
 398         bool
 399         help
 400           An arch should select this symbol if:
 401           - its compiler supports the -fstack-protector option
 402           - it has implemented a stack canary (e.g. __stack_chk_guard)
 403
 404 config CC_STACKPROTECTOR
 405         def_bool n
 406         help
 407           Set when a stack-protector mode is enabled, so that the build
 408           can enable kernel-side support for the GCC feature.
 409
 410 choice
 411         prompt "Stack Protector buffer overflow detection"
 412         depends on HAVE_CC_STACKPROTECTOR
 413         default CC_STACKPROTECTOR_NONE
 414         help
 415           This option turns on the "stack-protector" GCC feature. This
 416           feature puts, at the beginning of functions, a canary value on
 417           the stack just before the return address, and validates
 418           the value just before actually returning.  Stack based buffer
 419           overflows (that need to overwrite this return address) now also
 420           overwrite the canary, which gets detected and the attack is then
 421           neutralized via a kernel panic.
 422
 423 config CC_STACKPROTECTOR_NONE
 424         bool "None"
 425         help
 426           Disable "stack-protector" GCC feature.
 427
 428 config CC_STACKPROTECTOR_REGULAR
 429         bool "Regular"
 430         select CC_STACKPROTECTOR
 431         help
 432           Functions will have the stack-protector canary logic added if they
 433           have an 8-byte or larger character array on the stack.
 434
 435           This feature requires gcc version 4.2 or above, or a distribution
 436           gcc with the feature backported ("-fstack-protector").
 437
 438           On an x86 "defconfig" build, this feature adds canary checks to
 439           about 3% of all kernel functions, which increases kernel code size
 440           by about 0.3%.
 441
 442 config CC_STACKPROTECTOR_STRONG
 443         bool "Strong"
 444         select CC_STACKPROTECTOR
 445         help
 446           Functions will have the stack-protector canary logic added in any
 447           of the following conditions:
 448
 449           - local variable's address used as part of the right hand side of an
 450             assignment or function argument
 451           - local variable is an array (or union containing an array),
 452             regardless of array type or length
 453           - uses register local variables
 454
 455           This feature requires gcc version 4.9 or above, or a distribution
 456           gcc with the feature backported ("-fstack-protector-strong").
 457
 458           On an x86 "defconfig" build, this feature adds canary checks to
 459           about 20% of all kernel functions, which increases the kernel code
 460           size by about 2%.
 461
 462 endchoice
 463
 464 config HAVE_ARCH_WITHIN_STACK_FRAMES
 465         bool
 466         help
 467           An architecture should select this if it can walk the kernel stack
 468           frames to determine if an object is part of either the arguments
 469           or local variables (i.e. that it excludes saved return addresses,
 470           and similar) by implementing an inline arch_within_stack_frames(),
 471           which is used by CONFIG_HARDENED_USERCOPY.
 472
 473 config HAVE_CONTEXT_TRACKING
 474         bool
 475         help
 476           Provide kernel/user boundaries probes necessary for subsystems
 477           that need it, such as userspace RCU extended quiescent state.
 478           Syscalls need to be wrapped inside user_exit()-user_enter() through
 479           the slow path using TIF_NOHZ flag. Exceptions handlers must be
 480           wrapped as well. Irqs are already protected inside
 481           rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
 482           irq exit still need to be protected.
 483
 484 config HAVE_VIRT_CPU_ACCOUNTING
 485         bool
 486
 487 config HAVE_VIRT_CPU_ACCOUNTING_GEN
 488         bool
 489         default y if 64BIT
 490         help
 491           With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
 492           Before enabling this option, arch code must be audited
 493           to ensure there are no races in concurrent read/write of
 494           cputime_t. For example, reading/writing 64-bit cputime_t on
 495           some 32-bit arches may require multiple accesses, so proper
 496           locking is needed to protect against concurrent accesses.
 497
 498
 499 config HAVE_IRQ_TIME_ACCOUNTING
 500         bool
 501         help
 502           Archs need to ensure they use a high enough resolution clock to
 503           support irq time accounting and then call enable_sched_clock_irqtime().
 504
 505 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
 506         bool
 507
 508 config HAVE_ARCH_HUGE_VMAP
 509         bool
 510
 511 config HAVE_ARCH_SOFT_DIRTY
 512         bool
 513
 514 config HAVE_MOD_ARCH_SPECIFIC
 515         bool
 516         help
 517           The arch uses struct mod_arch_specific to store data.  Many arches
 518           just need a simple module loader without arch specific data - those
 519           should not enable this.
 520
 521 config MODULES_USE_ELF_RELA
 522         bool
 523         help
 524           Modules only use ELF RELA relocations.  Modules with ELF REL
 525           relocations will give an error.
 526
 527 config MODULES_USE_ELF_REL
 528         bool
 529         help
 530           Modules only use ELF REL relocations.  Modules with ELF RELA
 531           relocations will give an error.
 532
 533 config HAVE_UNDERSCORE_SYMBOL_PREFIX
 534         bool
 535         help
 536           Some architectures generate an _ in front of C symbols; things like
 537           module loading and assembly files need to know about this.
 538
 539 config HAVE_IRQ_EXIT_ON_IRQ_STACK
 540         bool
 541         help
 542           Architecture doesn't only execute the irq handler on the irq stack
 543           but also irq_exit(). This way we can process softirqs on this irq
 544           stack instead of switching to a new one when we call __do_softirq()
 545           in the end of an hardirq.
 546           This spares a stack switch and improves cache usage on softirq
 547           processing.
 548
 549 config PGTABLE_LEVELS
 550         int
 551         default 2
 552
 553 config ARCH_HAS_ELF_RANDOMIZE
 554         bool
 555         help
 556           An architecture supports choosing randomized locations for
 557           stack, mmap, brk, and ET_DYN. Defined functions:
 558           - arch_mmap_rnd()
 559           - arch_randomize_brk()
 560
 561 config HAVE_ARCH_MMAP_RND_BITS
 562         bool
 563         help
 564           An arch should select this symbol if it supports setting a variable
 565           number of bits for use in establishing the base address for mmap
 566           allocations, has MMU enabled and provides values for both:
 567           - ARCH_MMAP_RND_BITS_MIN
 568           - ARCH_MMAP_RND_BITS_MAX
 569
 570 config HAVE_EXIT_THREAD
 571         bool
 572         help
 573           An architecture implements exit_thread.
 574
 575 config ARCH_MMAP_RND_BITS_MIN
 576         int
 577
 578 config ARCH_MMAP_RND_BITS_MAX
 579         int
 580
 581 config ARCH_MMAP_RND_BITS_DEFAULT
 582         int
 583
 584 config ARCH_MMAP_RND_BITS
 585         int "Number of bits to use for ASLR of mmap base address" if EXPERT
 586         range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
 587         default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
 588         default ARCH_MMAP_RND_BITS_MIN
 589         depends on HAVE_ARCH_MMAP_RND_BITS
 590         help
 591           This value can be used to select the number of bits to use to
 592           determine the random offset to the base address of vma regions
 593           resulting from mmap allocations. This value will be bounded
 594           by the architecture's minimum and maximum supported values.
 595
 596           This value can be changed after boot using the
 597           /proc/sys/vm/mmap_rnd_bits tunable
 598
 599 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
 600         bool
 601         help
 602           An arch should select this symbol if it supports running applications
 603           in compatibility mode, supports setting a variable number of bits for
 604           use in establishing the base address for mmap allocations, has MMU
 605           enabled and provides values for both:
 606           - ARCH_MMAP_RND_COMPAT_BITS_MIN
 607           - ARCH_MMAP_RND_COMPAT_BITS_MAX
 608
 609 config ARCH_MMAP_RND_COMPAT_BITS_MIN
 610         int
 611
 612 config ARCH_MMAP_RND_COMPAT_BITS_MAX
 613         int
 614
 615 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
 616         int
 617
 618 config ARCH_MMAP_RND_COMPAT_BITS
 619         int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
 620         range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
 621         default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
 622         default ARCH_MMAP_RND_COMPAT_BITS_MIN
 623         depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
 624         help
 625           This value can be used to select the number of bits to use to
 626           determine the random offset to the base address of vma regions
 627           resulting from mmap allocations for compatible applications This
 628           value will be bounded by the architecture's minimum and maximum
 629           supported values.
 630
 631           This value can be changed after boot using the
 632           /proc/sys/vm/mmap_rnd_compat_bits tunable
 633
 634 config HAVE_COPY_THREAD_TLS
 635         bool
 636         help
 637           Architecture provides copy_thread_tls to accept tls argument via
 638           normal C parameter passing, rather than extracting the syscall
 639           argument from pt_regs.
 640
 641 config HAVE_STACK_VALIDATION
 642         bool
 643         help
 644           Architecture supports the 'objtool check' host tool command, which
 645           performs compile-time stack metadata validation.
 646
 647 config HAVE_ARCH_HASH
 648         bool
 649         default n
 650         help
 651           If this is set, the architecture provides an <asm/hash.h>
 652           file which provides platform-specific implementations of some
 653           functions in <linux/hash.h> or fs/namei.c.
 654
 655 config ISA_BUS_API
 656         def_bool ISA
 657
 658 #
 659 # ABI hall of shame
 660 #
 661 config CLONE_BACKWARDS
 662         bool
 663         help
 664           Architecture has tls passed as the 4th argument of clone(2),
 665           not the 5th one.
 666
 667 config CLONE_BACKWARDS2
 668         bool
 669         help
 670           Architecture has the first two arguments of clone(2) swapped.
 671
 672 config CLONE_BACKWARDS3
 673         bool
 674         help
 675           Architecture has tls passed as the 3rd argument of clone(2),
 676           not the 5th one.
 677
 678 config ODD_RT_SIGACTION
 679         bool
 680         help
 681           Architecture has unusual rt_sigaction(2) arguments
 682
 683 config OLD_SIGSUSPEND
 684         bool
 685         help
 686           Architecture has old sigsuspend(2) syscall, of one-argument variety
 687
 688 config OLD_SIGSUSPEND3
 689         bool
 690         help
 691           Even weirder antique ABI - three-argument sigsuspend(2)
 692
 693 config OLD_SIGACTION
 694         bool
 695         help
 696           Architecture has old sigaction(2) syscall.  Nope, not the same
 697           as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
 698           but fairly different variant of sigaction(2), thanks to OSF/1
 699           compatibility...
 700
 701 config COMPAT_OLD_SIGACTION
 702         bool
 703
 704 config ARCH_NO_COHERENT_DMA_MMAP
 705         bool
 706
 707 config CPU_NO_EFFICIENT_FFS
 708         def_bool n
 709
 710 source "kernel/gcov/Kconfig"