Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5

Linux/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_WATCHDOG
191         bool
192 #
193 # An arch should select this if it provides all these things:
194 #
195 #       task_pt_regs()          in asm/processor.h or asm/ptrace.h
196 #       arch_has_single_step()  if there is hardware single-step support
197 #       arch_has_block_step()   if there is hardware block-step support
198 #       asm/syscall.h           supplying asm-generic/syscall.h interface
199 #       linux/regset.h          user_regset interfaces
200 #       CORE_DUMP_USE_REGSET    #define'd in linux/elf.h
201 #       TIF_SYSCALL_TRACE       calls tracehook_report_syscall_{entry,exit}
202 #       TIF_NOTIFY_RESUME       calls tracehook_notify_resume()
203 #       signal delivery         calls tracehook_signal_handler()
204 #
205 config HAVE_ARCH_TRACEHOOK
206         bool
207 
208 config HAVE_DMA_CONTIGUOUS
209         bool
210 
211 config GENERIC_SMP_IDLE_THREAD
212        bool
213 
214 config GENERIC_IDLE_POLL_SETUP
215        bool
216 
217 # Select if arch init_task initializer is different to init/init_task.c
218 config ARCH_INIT_TASK
219        bool
220 
221 # Select if arch has its private alloc_task_struct() function
222 config ARCH_TASK_STRUCT_ALLOCATOR
223         bool
224 
225 # Select if arch has its private alloc_thread_info() function
226 config ARCH_THREAD_INFO_ALLOCATOR
227         bool
228 
229 # Select if arch wants to size task_struct dynamically via arch_task_struct_size:
230 config ARCH_WANTS_DYNAMIC_TASK_STRUCT
231         bool
232 
233 config HAVE_REGS_AND_STACK_ACCESS_API
234         bool
235         help
236           This symbol should be selected by an architecure if it supports
237           the API needed to access registers and stack entries from pt_regs,
238           declared in asm/ptrace.h
239           For example the kprobes-based event tracer needs this API.
240 
241 config HAVE_CLK
242         bool
243         help
244           The <linux/clk.h> calls support software clock gating and
245           thus are a key power management tool on many systems.
246 
247 config HAVE_DMA_API_DEBUG
248         bool
249 
250 config HAVE_HW_BREAKPOINT
251         bool
252         depends on PERF_EVENTS
253 
254 config HAVE_MIXED_BREAKPOINTS_REGS
255         bool
256         depends on HAVE_HW_BREAKPOINT
257         help
258           Depending on the arch implementation of hardware breakpoints,
259           some of them have separate registers for data and instruction
260           breakpoints addresses, others have mixed registers to store
261           them but define the access type in a control register.
262           Select this option if your arch implements breakpoints under the
263           latter fashion.
264 
265 config HAVE_USER_RETURN_NOTIFIER
266         bool
267 
268 config HAVE_PERF_EVENTS_NMI
269         bool
270         help
271           System hardware can generate an NMI using the perf event
272           subsystem.  Also has support for calculating CPU cycle events
273           to determine how many clock cycles in a given period.
274 
275 config HAVE_PERF_REGS
276         bool
277         help
278           Support selective register dumps for perf events. This includes
279           bit-mapping of each registers and a unique architecture id.
280 
281 config HAVE_PERF_USER_STACK_DUMP
282         bool
283         help
284           Support user stack dumps for perf event samples. This needs
285           access to the user stack pointer which is not unified across
286           architectures.
287 
288 config HAVE_ARCH_JUMP_LABEL
289         bool
290 
291 config HAVE_RCU_TABLE_FREE
292         bool
293 
294 config ARCH_HAVE_NMI_SAFE_CMPXCHG
295         bool
296 
297 config HAVE_ALIGNED_STRUCT_PAGE
298         bool
299         help
300           This makes sure that struct pages are double word aligned and that
301           e.g. the SLUB allocator can perform double word atomic operations
302           on a struct page for better performance. However selecting this
303           might increase the size of a struct page by a word.
304 
305 config HAVE_CMPXCHG_LOCAL
306         bool
307 
308 config HAVE_CMPXCHG_DOUBLE
309         bool
310 
311 config ARCH_WANT_IPC_PARSE_VERSION
312         bool
313 
314 config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
315         bool
316 
317 config ARCH_WANT_OLD_COMPAT_IPC
318         select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
319         bool
320 
321 config HAVE_ARCH_SECCOMP_FILTER
322         bool
323         help
324           An arch should select this symbol if it provides all of these things:
325           - syscall_get_arch()
326           - syscall_get_arguments()
327           - syscall_rollback()
328           - syscall_set_return_value()
329           - SIGSYS siginfo_t support
330           - secure_computing is called from a ptrace_event()-safe context
331           - secure_computing return value is checked and a return value of -1
332             results in the system call being skipped immediately.
333           - seccomp syscall wired up
334 
335           For best performance, an arch should use seccomp_phase1 and
336           seccomp_phase2 directly.  It should call seccomp_phase1 for all
337           syscalls if TIF_SECCOMP is set, but seccomp_phase1 does not
338           need to be called from a ptrace-safe context.  It must then
339           call seccomp_phase2 if seccomp_phase1 returns anything other
340           than SECCOMP_PHASE1_OK or SECCOMP_PHASE1_SKIP.
341 
342           As an additional optimization, an arch may provide seccomp_data
343           directly to seccomp_phase1; this avoids multiple calls
344           to the syscall_xyz helpers for every syscall.
345 
346 config SECCOMP_FILTER
347         def_bool y
348         depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
349         help
350           Enable tasks to build secure computing environments defined
351           in terms of Berkeley Packet Filter programs which implement
352           task-defined system call filtering polices.
353 
354           See Documentation/prctl/seccomp_filter.txt for details.
355 
356 config HAVE_CC_STACKPROTECTOR
357         bool
358         help
359           An arch should select this symbol if:
360           - its compiler supports the -fstack-protector option
361           - it has implemented a stack canary (e.g. __stack_chk_guard)
362 
363 config CC_STACKPROTECTOR
364         def_bool n
365         help
366           Set when a stack-protector mode is enabled, so that the build
367           can enable kernel-side support for the GCC feature.
368 
369 choice
370         prompt "Stack Protector buffer overflow detection"
371         depends on HAVE_CC_STACKPROTECTOR
372         default CC_STACKPROTECTOR_NONE
373         help
374           This option turns on the "stack-protector" GCC feature. This
375           feature puts, at the beginning of functions, a canary value on
376           the stack just before the return address, and validates
377           the value just before actually returning.  Stack based buffer
378           overflows (that need to overwrite this return address) now also
379           overwrite the canary, which gets detected and the attack is then
380           neutralized via a kernel panic.
381 
382 config CC_STACKPROTECTOR_NONE
383         bool "None"
384         help
385           Disable "stack-protector" GCC feature.
386 
387 config CC_STACKPROTECTOR_REGULAR
388         bool "Regular"
389         select CC_STACKPROTECTOR
390         help
391           Functions will have the stack-protector canary logic added if they
392           have an 8-byte or larger character array on the stack.
393 
394           This feature requires gcc version 4.2 or above, or a distribution
395           gcc with the feature backported ("-fstack-protector").
396 
397           On an x86 "defconfig" build, this feature adds canary checks to
398           about 3% of all kernel functions, which increases kernel code size
399           by about 0.3%.
400 
401 config CC_STACKPROTECTOR_STRONG
402         bool "Strong"
403         select CC_STACKPROTECTOR
404         help
405           Functions will have the stack-protector canary logic added in any
406           of the following conditions:
407 
408           - local variable's address used as part of the right hand side of an
409             assignment or function argument
410           - local variable is an array (or union containing an array),
411             regardless of array type or length
412           - uses register local variables
413 
414           This feature requires gcc version 4.9 or above, or a distribution
415           gcc with the feature backported ("-fstack-protector-strong").
416 
417           On an x86 "defconfig" build, this feature adds canary checks to
418           about 20% of all kernel functions, which increases the kernel code
419           size by about 2%.
420 
421 endchoice
422 
423 config HAVE_CONTEXT_TRACKING
424         bool
425         help
426           Provide kernel/user boundaries probes necessary for subsystems
427           that need it, such as userspace RCU extended quiescent state.
428           Syscalls need to be wrapped inside user_exit()-user_enter() through
429           the slow path using TIF_NOHZ flag. Exceptions handlers must be
430           wrapped as well. Irqs are already protected inside
431           rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
432           irq exit still need to be protected.
433 
434 config HAVE_VIRT_CPU_ACCOUNTING
435         bool
436 
437 config HAVE_VIRT_CPU_ACCOUNTING_GEN
438         bool
439         default y if 64BIT
440         help
441           With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
442           Before enabling this option, arch code must be audited
443           to ensure there are no races in concurrent read/write of
444           cputime_t. For example, reading/writing 64-bit cputime_t on
445           some 32-bit arches may require multiple accesses, so proper
446           locking is needed to protect against concurrent accesses.
447 
448 
449 config HAVE_IRQ_TIME_ACCOUNTING
450         bool
451         help
452           Archs need to ensure they use a high enough resolution clock to
453           support irq time accounting and then call enable_sched_clock_irqtime().
454 
455 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
456         bool
457 
458 config HAVE_ARCH_HUGE_VMAP
459         bool
460 
461 config HAVE_ARCH_SOFT_DIRTY
462         bool
463 
464 config HAVE_MOD_ARCH_SPECIFIC
465         bool
466         help
467           The arch uses struct mod_arch_specific to store data.  Many arches
468           just need a simple module loader without arch specific data - those
469           should not enable this.
470 
471 config MODULES_USE_ELF_RELA
472         bool
473         help
474           Modules only use ELF RELA relocations.  Modules with ELF REL
475           relocations will give an error.
476 
477 config MODULES_USE_ELF_REL
478         bool
479         help
480           Modules only use ELF REL relocations.  Modules with ELF RELA
481           relocations will give an error.
482 
483 config HAVE_UNDERSCORE_SYMBOL_PREFIX
484         bool
485         help
486           Some architectures generate an _ in front of C symbols; things like
487           module loading and assembly files need to know about this.
488 
489 config HAVE_IRQ_EXIT_ON_IRQ_STACK
490         bool
491         help
492           Architecture doesn't only execute the irq handler on the irq stack
493           but also irq_exit(). This way we can process softirqs on this irq
494           stack instead of switching to a new one when we call __do_softirq()
495           in the end of an hardirq.
496           This spares a stack switch and improves cache usage on softirq
497           processing.
498 
499 config PGTABLE_LEVELS
500         int
501         default 2
502 
503 config ARCH_HAS_ELF_RANDOMIZE
504         bool
505         help
506           An architecture supports choosing randomized locations for
507           stack, mmap, brk, and ET_DYN. Defined functions:
508           - arch_mmap_rnd()
509           - arch_randomize_brk()
510 
511 config HAVE_ARCH_MMAP_RND_BITS
512         bool
513         help
514           An arch should select this symbol if it supports setting a variable
515           number of bits for use in establishing the base address for mmap
516           allocations, has MMU enabled and provides values for both:
517           - ARCH_MMAP_RND_BITS_MIN
518           - ARCH_MMAP_RND_BITS_MAX
519 
520 config ARCH_MMAP_RND_BITS_MIN
521         int
522 
523 config ARCH_MMAP_RND_BITS_MAX
524         int
525 
526 config ARCH_MMAP_RND_BITS_DEFAULT
527         int
528 
529 config ARCH_MMAP_RND_BITS
530         int "Number of bits to use for ASLR of mmap base address" if EXPERT
531         range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
532         default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
533         default ARCH_MMAP_RND_BITS_MIN
534         depends on HAVE_ARCH_MMAP_RND_BITS
535         help
536           This value can be used to select the number of bits to use to
537           determine the random offset to the base address of vma regions
538           resulting from mmap allocations. This value will be bounded
539           by the architecture's minimum and maximum supported values.
540 
541           This value can be changed after boot using the
542           /proc/sys/vm/mmap_rnd_bits tunable
543 
544 config HAVE_ARCH_MMAP_RND_COMPAT_BITS
545         bool
546         help
547           An arch should select this symbol if it supports running applications
548           in compatibility mode, supports setting a variable number of bits for
549           use in establishing the base address for mmap allocations, has MMU
550           enabled and provides values for both:
551           - ARCH_MMAP_RND_COMPAT_BITS_MIN
552           - ARCH_MMAP_RND_COMPAT_BITS_MAX
553 
554 config ARCH_MMAP_RND_COMPAT_BITS_MIN
555         int
556 
557 config ARCH_MMAP_RND_COMPAT_BITS_MAX
558         int
559 
560 config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
561         int
562 
563 config ARCH_MMAP_RND_COMPAT_BITS
564         int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
565         range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
566         default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
567         default ARCH_MMAP_RND_COMPAT_BITS_MIN
568         depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
569         help
570           This value can be used to select the number of bits to use to
571           determine the random offset to the base address of vma regions
572           resulting from mmap allocations for compatible applications This
573           value will be bounded by the architecture's minimum and maximum
574           supported values.
575 
576           This value can be changed after boot using the
577           /proc/sys/vm/mmap_rnd_compat_bits tunable
578 
579 config HAVE_COPY_THREAD_TLS
580         bool
581         help
582           Architecture provides copy_thread_tls to accept tls argument via
583           normal C parameter passing, rather than extracting the syscall
584           argument from pt_regs.
585 
586 #
587 # ABI hall of shame
588 #
589 config CLONE_BACKWARDS
590         bool
591         help
592           Architecture has tls passed as the 4th argument of clone(2),
593           not the 5th one.
594 
595 config CLONE_BACKWARDS2
596         bool
597         help
598           Architecture has the first two arguments of clone(2) swapped.
599 
600 config CLONE_BACKWARDS3
601         bool
602         help
603           Architecture has tls passed as the 3rd argument of clone(2),
604           not the 5th one.
605 
606 config ODD_RT_SIGACTION
607         bool
608         help
609           Architecture has unusual rt_sigaction(2) arguments
610 
611 config OLD_SIGSUSPEND
612         bool
613         help
614           Architecture has old sigsuspend(2) syscall, of one-argument variety
615 
616 config OLD_SIGSUSPEND3
617         bool
618         help
619           Even weirder antique ABI - three-argument sigsuspend(2)
620 
621 config OLD_SIGACTION
622         bool
623         help
624           Architecture has old sigaction(2) syscall.  Nope, not the same
625           as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
626           but fairly different variant of sigaction(2), thanks to OSF/1
627           compatibility...
628 
629 config COMPAT_OLD_SIGACTION
630         bool
631 
632 config ARCH_NO_COHERENT_DMA_MMAP
633         bool
634 
635 source "kernel/gcov/Kconfig"

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us