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_EFFICIENT_UNALIGNED_ACCESS
  98         bool
  99         help
 100           Some architectures are unable to perform unaligned accesses
 101           without the use of get_unaligned/put_unaligned. Others are
 102           unable to perform such accesses efficiently (e.g. trap on
 103           unaligned access and require fixing it up in the exception
 104           handler.)
 105
 106           This symbol should be selected by an architecture if it can
 107           perform unaligned accesses efficiently to allow different
 108           code paths to be selected for these cases. Some network
 109           drivers, for example, could opt to not fix up alignment
 110           problems with received packets if doing so would not help
 111           much.
 112
 113           See Documentation/unaligned-memory-access.txt for more
 114           information on the topic of unaligned memory accesses.
 115
 116 config HAVE_SYSCALL_WRAPPERS
 117         bool
 118
 119 config KRETPROBES
 120         def_bool y
 121         depends on KPROBES && HAVE_KRETPROBES
 122
 123 config USER_RETURN_NOTIFIER
 124         bool
 125         depends on HAVE_USER_RETURN_NOTIFIER
 126         help
 127           Provide a kernel-internal notification when a cpu is about to
 128           switch to user mode.
 129
 130 config HAVE_IOREMAP_PROT
 131         bool
 132
 133 config HAVE_KPROBES
 134         bool
 135
 136 config HAVE_KRETPROBES
 137         bool
 138
 139 config HAVE_OPTPROBES
 140         bool
 141
 142 config HAVE_NMI_WATCHDOG
 143         bool
 144 #
 145 # An arch should select this if it provides all these things:
 146 #
 147 #       task_pt_regs()          in asm/processor.h or asm/ptrace.h
 148 #       arch_has_single_step()  if there is hardware single-step support
 149 #       arch_has_block_step()   if there is hardware block-step support
 150 #       asm/syscall.h           supplying asm-generic/syscall.h interface
 151 #       linux/regset.h          user_regset interfaces
 152 #       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
 153 #       TIF_SYSCALL_TRACE       calls tracehook_report_syscall_{entry,exit}
 154 #       TIF_NOTIFY_RESUME       calls tracehook_notify_resume()
 155 #       signal delivery         calls tracehook_signal_handler()
 156 #
 157 config HAVE_ARCH_TRACEHOOK
 158         bool
 159
 160 config HAVE_DMA_ATTRS
 161         bool
 162
 163 config HAVE_DMA_CONTIGUOUS
 164         bool
 165
 166 config USE_GENERIC_SMP_HELPERS
 167         bool
 168
 169 config GENERIC_SMP_IDLE_THREAD
 170        bool
 171
 172 # Select if arch init_task initializer is different to init/init_task.c
 173 config ARCH_INIT_TASK
 174        bool
 175
 176 # Select if arch has its private alloc_task_struct() function
 177 config ARCH_TASK_STRUCT_ALLOCATOR
 178         bool
 179
 180 # Select if arch has its private alloc_thread_info() function
 181 config ARCH_THREAD_INFO_ALLOCATOR
 182         bool
 183
 184 config HAVE_REGS_AND_STACK_ACCESS_API
 185         bool
 186         help
 187           This symbol should be selected by an architecure if it supports
 188           the API needed to access registers and stack entries from pt_regs,
 189           declared in asm/ptrace.h
 190           For example the kprobes-based event tracer needs this API.
 191
 192 config HAVE_CLK
 193         bool
 194         help
 195           The <linux/clk.h> calls support software clock gating and
 196           thus are a key power management tool on many systems.
 197
 198 config HAVE_DMA_API_DEBUG
 199         bool
 200
 201 config HAVE_HW_BREAKPOINT
 202         bool
 203         depends on PERF_EVENTS
 204
 205 config HAVE_MIXED_BREAKPOINTS_REGS
 206         bool
 207         depends on HAVE_HW_BREAKPOINT
 208         help
 209           Depending on the arch implementation of hardware breakpoints,
 210           some of them have separate registers for data and instruction
 211           breakpoints addresses, others have mixed registers to store
 212           them but define the access type in a control register.
 213           Select this option if your arch implements breakpoints under the
 214           latter fashion.
 215
 216 config HAVE_USER_RETURN_NOTIFIER
 217         bool
 218
 219 config HAVE_PERF_EVENTS_NMI
 220         bool
 221         help
 222           System hardware can generate an NMI using the perf event
 223           subsystem.  Also has support for calculating CPU cycle events
 224           to determine how many clock cycles in a given period.
 225
 226 config HAVE_PERF_REGS
 227         bool
 228         help
 229           Support selective register dumps for perf events. This includes
 230           bit-mapping of each registers and a unique architecture id.
 231
 232 config HAVE_PERF_USER_STACK_DUMP
 233         bool
 234         help
 235           Support user stack dumps for perf event samples. This needs
 236           access to the user stack pointer which is not unified across
 237           architectures.
 238
 239 config HAVE_ARCH_JUMP_LABEL
 240         bool
 241
 242 config HAVE_ARCH_MUTEX_CPU_RELAX
 243         bool
 244
 245 config HAVE_RCU_TABLE_FREE
 246         bool
 247
 248 config ARCH_HAVE_NMI_SAFE_CMPXCHG
 249         bool
 250
 251 config HAVE_ALIGNED_STRUCT_PAGE
 252         bool
 253         help
 254           This makes sure that struct pages are double word aligned and that
 255           e.g. the SLUB allocator can perform double word atomic operations
 256           on a struct page for better performance. However selecting this
 257           might increase the size of a struct page by a word.
 258
 259 config HAVE_CMPXCHG_LOCAL
 260         bool
 261
 262 config HAVE_CMPXCHG_DOUBLE
 263         bool
 264
 265 config ARCH_WANT_IPC_PARSE_VERSION
 266         bool
 267
 268 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 269         bool
 270
 271 config ARCH_WANT_OLD_COMPAT_IPC
 272         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 273         bool
 274
 275 config GENERIC_KERNEL_THREAD
 276         bool
 277
 278 config GENERIC_KERNEL_EXECVE
 279         bool
 280
 281 config HAVE_ARCH_SECCOMP_FILTER
 282         bool
 283         help
 284           An arch should select this symbol if it provides all of these things:
 285           - syscall_get_arch()
 286           - syscall_get_arguments()
 287           - syscall_rollback()
 288           - syscall_set_return_value()
 289           - SIGSYS siginfo_t support
 290           - secure_computing is called from a ptrace_event()-safe context
 291           - secure_computing return value is checked and a return value of -1
 292             results in the system call being skipped immediately.
 293
 294 config SECCOMP_FILTER
 295         def_bool y
 296         depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
 297         help
 298           Enable tasks to build secure computing environments defined
 299           in terms of Berkeley Packet Filter programs which implement
 300           task-defined system call filtering polices.
 301
 302           See Documentation/prctl/seccomp_filter.txt for details.
 303
 304 config HAVE_CONTEXT_TRACKING
 305         bool
 306         help
 307           Provide kernel/user boundaries probes necessary for subsystems
 308           that need it, such as userspace RCU extended quiescent state.
 309           Syscalls need to be wrapped inside user_exit()-user_enter() through
 310           the slow path using TIF_NOHZ flag. Exceptions handlers must be
 311           wrapped as well. Irqs are already protected inside
 312           rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
 313           irq exit still need to be protected.
 314
 315 config HAVE_VIRT_CPU_ACCOUNTING
 316         bool
 317
 318 config HAVE_IRQ_TIME_ACCOUNTING
 319         bool
 320         help
 321           Archs need to ensure they use a high enough resolution clock to
 322           support irq time accounting and then call enable_sched_clock_irqtime().
 323
 324 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
 325         bool
 326
 327 config HAVE_MOD_ARCH_SPECIFIC
 328         bool
 329         help
 330           The arch uses struct mod_arch_specific to store data.  Many arches
 331           just need a simple module loader without arch specific data - those
 332           should not enable this.
 333
 334 config MODULES_USE_ELF_RELA
 335         bool
 336         help
 337           Modules only use ELF RELA relocations.  Modules with ELF REL
 338           relocations will give an error.
 339
 340 config MODULES_USE_ELF_REL
 341         bool
 342         help
 343           Modules only use ELF REL relocations.  Modules with ELF RELA
 344           relocations will give an error.
 345
 346 #
 347 # ABI hall of shame
 348 #
 349 config CLONE_BACKWARDS
 350         bool
 351         help
 352           Architecture has tls passed as the 4th argument of clone(2),
 353           not the 5th one.
 354
 355 config CLONE_BACKWARDS2
 356         bool
 357         help
 358           Architecture has the first two arguments of clone(2) swapped.
 359
 360 source "kernel/gcov/Kconfig"