[linux.git] / arch / Kconfig

#
# General architecture dependent options
#

config OPROFILE
	tristate "OProfile system profiling"
	depends on PROFILING
	depends on HAVE_OPROFILE
	select RING_BUFFER
	select RING_BUFFER_ALLOW_SWAP
	help
	  OProfile is a profiling system capable of profiling the
	  whole system, include the kernel, kernel modules, libraries,
	  and applications.

	  If unsure, say N.

config OPROFILE_EVENT_MULTIPLEX
	bool "OProfile multiplexing support (EXPERIMENTAL)"
	default n
	depends on OPROFILE && X86
	help
	  The number of hardware counters is limited. The multiplexing
	  feature enables OProfile to gather more events than counters
	  are provided by the hardware. This is realized by switching
	  between events at an user specified time interval.

	  If unsure, say N.

config HAVE_OPROFILE
	bool

config OPROFILE_NMI_TIMER
	def_bool y
	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI

config KPROBES
	bool "Kprobes"
	depends on MODULES
	depends on HAVE_KPROBES
	select KALLSYMS
	help
	  Kprobes allows you to trap at almost any kernel address and
	  execute a callback function.  register_kprobe() establishes
	  a probepoint and specifies the callback.  Kprobes is useful
	  for kernel debugging, non-intrusive instrumentation and testing.
	  If in doubt, say "N".

config JUMP_LABEL
       bool "Optimize very unlikely/likely branches"
       depends on HAVE_ARCH_JUMP_LABEL
       help
         This option enables a transparent branch optimization that
	 makes certain almost-always-true or almost-always-false branch
	 conditions even cheaper to execute within the kernel.

	 Certain performance-sensitive kernel code, such as trace points,
	 scheduler functionality, networking code and KVM have such
	 branches and include support for this optimization technique.

         If it is detected that the compiler has support for "asm goto",
	 the kernel will compile such branches with just a nop
	 instruction. When the condition flag is toggled to true, the
	 nop will be converted to a jump instruction to execute the
	 conditional block of instructions.

	 This technique lowers overhead and stress on the branch prediction
	 of the processor and generally makes the kernel faster. The update
	 of the condition is slower, but those are always very rare.

	 ( On 32-bit x86, the necessary options added to the compiler
	   flags may increase the size of the kernel slightly. )

config OPTPROBES
	def_bool y
	depends on KPROBES && HAVE_OPTPROBES
	depends on !PREEMPT

config KPROBES_ON_FTRACE
	def_bool y
	depends on KPROBES && HAVE_KPROBES_ON_FTRACE
	depends on DYNAMIC_FTRACE_WITH_REGS
	help
	 If function tracer is enabled and the arch supports full
	 passing of pt_regs to function tracing, then kprobes can
	 optimize on top of function tracing.

config UPROBES
	def_bool n
	select PERCPU_RWSEM
	help
	  Uprobes is the user-space counterpart to kprobes: they
	  enable instrumentation applications (such as 'perf probe')
	  to establish unintrusive probes in user-space binaries and
	  libraries, by executing handler functions when the probes
	  are hit by user-space applications.

	  ( These probes come in the form of single-byte breakpoints,
	    managed by the kernel and kept transparent to the probed
	    application. )

config HAVE_64BIT_ALIGNED_ACCESS
	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
	help
	  Some architectures require 64 bit accesses to be 64 bit
	  aligned, which also requires structs containing 64 bit values
	  to be 64 bit aligned too. This includes some 32 bit
	  architectures which can do 64 bit accesses, as well as 64 bit
	  architectures without unaligned access.

	  This symbol should be selected by an architecture if 64 bit
	  accesses are required to be 64 bit aligned in this way even
	  though it is not a 64 bit architecture.

	  See Documentation/unaligned-memory-access.txt for more
	  information on the topic of unaligned memory accesses.

config HAVE_EFFICIENT_UNALIGNED_ACCESS
	bool
	help
	  Some architectures are unable to perform unaligned accesses
	  without the use of get_unaligned/put_unaligned. Others are
	  unable to perform such accesses efficiently (e.g. trap on
	  unaligned access and require fixing it up in the exception
	  handler.)

	  This symbol should be selected by an architecture if it can
	  perform unaligned accesses efficiently to allow different
	  code paths to be selected for these cases. Some network
	  drivers, for example, could opt to not fix up alignment
	  problems with received packets if doing so would not help
	  much.

	  See Documentation/unaligned-memory-access.txt for more
	  information on the topic of unaligned memory accesses.

config ARCH_USE_BUILTIN_BSWAP
       bool
       help
	 Modern versions of GCC (since 4.4) have builtin functions
	 for handling byte-swapping. Using these, instead of the old
	 inline assembler that the architecture code provides in the
	 __arch_bswapXX() macros, allows the compiler to see what's
	 happening and offers more opportunity for optimisation. In
	 particular, the compiler will be able to combine the byteswap
	 with a nearby load or store and use load-and-swap or
	 store-and-swap instructions if the architecture has them. It
	 should almost *never* result in code which is worse than the
	 hand-coded assembler in <asm/swab.h>.  But just in case it
	 does, the use of the builtins is optional.

	 Any architecture with load-and-swap or store-and-swap
	 instructions should set this. And it shouldn't hurt to set it
	 on architectures that don't have such instructions.

config KRETPROBES
	def_bool y
	depends on KPROBES && HAVE_KRETPROBES

config USER_RETURN_NOTIFIER
	bool
	depends on HAVE_USER_RETURN_NOTIFIER
	help
	  Provide a kernel-internal notification when a cpu is about to
	  switch to user mode.

config HAVE_IOREMAP_PROT
	bool

config HAVE_KPROBES
	bool

config HAVE_KRETPROBES
	bool

config HAVE_OPTPROBES
	bool

config HAVE_KPROBES_ON_FTRACE
	bool

config HAVE_NMI_WATCHDOG
	bool
#
# An arch should select this if it provides all these things:
#
#	task_pt_regs()		in asm/processor.h or asm/ptrace.h
#	arch_has_single_step()	if there is hardware single-step support
#	arch_has_block_step()	if there is hardware block-step support
#	asm/syscall.h		supplying asm-generic/syscall.h interface
#	linux/regset.h		user_regset interfaces
#	CORE_DUMP_USE_REGSET	#define'd in linux/elf.h
#	TIF_SYSCALL_TRACE	calls tracehook_report_syscall_{entry,exit}
#	TIF_NOTIFY_RESUME	calls tracehook_notify_resume()
#	signal delivery		calls tracehook_signal_handler()
#
config HAVE_ARCH_TRACEHOOK
	bool

config HAVE_DMA_ATTRS
	bool

config HAVE_DMA_CONTIGUOUS
	bool

config GENERIC_SMP_IDLE_THREAD
       bool

config GENERIC_IDLE_POLL_SETUP
       bool

# Select if arch init_task initializer is different to init/init_task.c
config ARCH_INIT_TASK
       bool

# Select if arch has its private alloc_task_struct() function
config ARCH_TASK_STRUCT_ALLOCATOR
	bool

# Select if arch has its private alloc_thread_info() function
config ARCH_THREAD_INFO_ALLOCATOR
	bool

config HAVE_REGS_AND_STACK_ACCESS_API
	bool
	help
	  This symbol should be selected by an architecure if it supports
	  the API needed to access registers and stack entries from pt_regs,
	  declared in asm/ptrace.h
	  For example the kprobes-based event tracer needs this API.

config HAVE_CLK
	bool
	help
	  The <linux/clk.h> calls support software clock gating and
	  thus are a key power management tool on many systems.

config HAVE_DMA_API_DEBUG
	bool

config HAVE_HW_BREAKPOINT
	bool
	depends on PERF_EVENTS

config HAVE_MIXED_BREAKPOINTS_REGS
	bool
	depends on HAVE_HW_BREAKPOINT
	help
	  Depending on the arch implementation of hardware breakpoints,
	  some of them have separate registers for data and instruction
	  breakpoints addresses, others have mixed registers to store
	  them but define the access type in a control register.
	  Select this option if your arch implements breakpoints under the
	  latter fashion.

config HAVE_USER_RETURN_NOTIFIER
	bool

config HAVE_PERF_EVENTS_NMI
	bool
	help
	  System hardware can generate an NMI using the perf event
	  subsystem.  Also has support for calculating CPU cycle events
	  to determine how many clock cycles in a given period.

config HAVE_PERF_REGS
	bool
	help
	  Support selective register dumps for perf events. This includes
	  bit-mapping of each registers and a unique architecture id.

config HAVE_PERF_USER_STACK_DUMP
	bool
	help
	  Support user stack dumps for perf event samples. This needs
	  access to the user stack pointer which is not unified across
	  architectures.

config HAVE_ARCH_JUMP_LABEL
	bool

config HAVE_RCU_TABLE_FREE
	bool

config ARCH_HAVE_NMI_SAFE_CMPXCHG
	bool

config HAVE_ALIGNED_STRUCT_PAGE
	bool
	help
	  This makes sure that struct pages are double word aligned and that
	  e.g. the SLUB allocator can perform double word atomic operations
	  on a struct page for better performance. However selecting this
	  might increase the size of a struct page by a word.

config HAVE_CMPXCHG_LOCAL
	bool

config HAVE_CMPXCHG_DOUBLE
	bool

config ARCH_WANT_IPC_PARSE_VERSION
	bool

config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
	bool

config ARCH_WANT_OLD_COMPAT_IPC
	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
	bool

config HAVE_ARCH_SECCOMP_FILTER
	bool
	help
	  An arch should select this symbol if it provides all of these things:
	  - syscall_get_arch()
	  - syscall_get_arguments()
	  - syscall_rollback()
	  - syscall_set_return_value()
	  - SIGSYS siginfo_t support
	  - secure_computing is called from a ptrace_event()-safe context
	  - secure_computing return value is checked and a return value of -1
	    results in the system call being skipped immediately.
	  - seccomp syscall wired up

	  For best performance, an arch should use seccomp_phase1 and
	  seccomp_phase2 directly.  It should call seccomp_phase1 for all
	  syscalls if TIF_SECCOMP is set, but seccomp_phase1 does not
	  need to be called from a ptrace-safe context.  It must then
	  call seccomp_phase2 if seccomp_phase1 returns anything other
	  than SECCOMP_PHASE1_OK or SECCOMP_PHASE1_SKIP.

	  As an additional optimization, an arch may provide seccomp_data
	  directly to seccomp_phase1; this avoids multiple calls
	  to the syscall_xyz helpers for every syscall.

config SECCOMP_FILTER
	def_bool y
	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
	help
	  Enable tasks to build secure computing environments defined
	  in terms of Berkeley Packet Filter programs which implement
	  task-defined system call filtering polices.

	  See Documentation/prctl/seccomp_filter.txt for details.

config HAVE_CC_STACKPROTECTOR
	bool
	help
	  An arch should select this symbol if:
	  - its compiler supports the -fstack-protector option
	  - it has implemented a stack canary (e.g. __stack_chk_guard)

config CC_STACKPROTECTOR
	def_bool n
	help
	  Set when a stack-protector mode is enabled, so that the build
	  can enable kernel-side support for the GCC feature.

choice
	prompt "Stack Protector buffer overflow detection"
	depends on HAVE_CC_STACKPROTECTOR
	default CC_STACKPROTECTOR_NONE
	help
	  This option turns on the "stack-protector" GCC feature. This
	  feature puts, at the beginning of functions, a canary value on
	  the stack just before the return address, and validates
	  the value just before actually returning.  Stack based buffer
	  overflows (that need to overwrite this return address) now also
	  overwrite the canary, which gets detected and the attack is then
	  neutralized via a kernel panic.

config CC_STACKPROTECTOR_NONE
	bool "None"
	help
	  Disable "stack-protector" GCC feature.

config CC_STACKPROTECTOR_REGULAR
	bool "Regular"
	select CC_STACKPROTECTOR
	help
	  Functions will have the stack-protector canary logic added if they
	  have an 8-byte or larger character array on the stack.

	  This feature requires gcc version 4.2 or above, or a distribution
	  gcc with the feature backported ("-fstack-protector").

	  On an x86 "defconfig" build, this feature adds canary checks to
	  about 3% of all kernel functions, which increases kernel code size
	  by about 0.3%.

config CC_STACKPROTECTOR_STRONG
	bool "Strong"
	select CC_STACKPROTECTOR
	help
	  Functions will have the stack-protector canary logic added in any
	  of the following conditions:

	  - local variable's address used as part of the right hand side of an
	    assignment or function argument
	  - local variable is an array (or union containing an array),
	    regardless of array type or length
	  - uses register local variables

	  This feature requires gcc version 4.9 or above, or a distribution
	  gcc with the feature backported ("-fstack-protector-strong").

	  On an x86 "defconfig" build, this feature adds canary checks to
	  about 20% of all kernel functions, which increases the kernel code
	  size by about 2%.

endchoice

config HAVE_CONTEXT_TRACKING
	bool
	help
	  Provide kernel/user boundaries probes necessary for subsystems
	  that need it, such as userspace RCU extended quiescent state.
	  Syscalls need to be wrapped inside user_exit()-user_enter() through
	  the slow path using TIF_NOHZ flag. Exceptions handlers must be
	  wrapped as well. Irqs are already protected inside
	  rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
	  irq exit still need to be protected.

config HAVE_VIRT_CPU_ACCOUNTING
	bool

config HAVE_VIRT_CPU_ACCOUNTING_GEN
	bool
	default y if 64BIT
	help
	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
	  Before enabling this option, arch code must be audited
	  to ensure there are no races in concurrent read/write of
	  cputime_t. For example, reading/writing 64-bit cputime_t on
	  some 32-bit arches may require multiple accesses, so proper
	  locking is needed to protect against concurrent accesses.


config HAVE_IRQ_TIME_ACCOUNTING
	bool
	help
	  Archs need to ensure they use a high enough resolution clock to
	  support irq time accounting and then call enable_sched_clock_irqtime().

config HAVE_ARCH_TRANSPARENT_HUGEPAGE
	bool

config HAVE_ARCH_SOFT_DIRTY
	bool

config HAVE_MOD_ARCH_SPECIFIC
	bool
	help
	  The arch uses struct mod_arch_specific to store data.  Many arches
	  just need a simple module loader without arch specific data - those
	  should not enable this.

config MODULES_USE_ELF_RELA
	bool
	help
	  Modules only use ELF RELA relocations.  Modules with ELF REL
	  relocations will give an error.

config MODULES_USE_ELF_REL
	bool
	help
	  Modules only use ELF REL relocations.  Modules with ELF RELA
	  relocations will give an error.

config HAVE_UNDERSCORE_SYMBOL_PREFIX
	bool
	help
	  Some architectures generate an _ in front of C symbols; things like
	  module loading and assembly files need to know about this.

config HAVE_IRQ_EXIT_ON_IRQ_STACK
	bool
	help
	  Architecture doesn't only execute the irq handler on the irq stack
	  but also irq_exit(). This way we can process softirqs on this irq
	  stack instead of switching to a new one when we call __do_softirq()
	  in the end of an hardirq.
	  This spares a stack switch and improves cache usage on softirq
	  processing.

#
# ABI hall of shame
#
config CLONE_BACKWARDS
	bool
	help
	  Architecture has tls passed as the 4th argument of clone(2),
	  not the 5th one.

config CLONE_BACKWARDS2
	bool
	help
	  Architecture has the first two arguments of clone(2) swapped.

config CLONE_BACKWARDS3
	bool
	help
	  Architecture has tls passed as the 3rd argument of clone(2),
	  not the 5th one.

config ODD_RT_SIGACTION
	bool
	help
	  Architecture has unusual rt_sigaction(2) arguments

config OLD_SIGSUSPEND
	bool
	help
	  Architecture has old sigsuspend(2) syscall, of one-argument variety

config OLD_SIGSUSPEND3
	bool
	help
	  Even weirder antique ABI - three-argument sigsuspend(2)

config OLD_SIGACTION
	bool
	help
	  Architecture has old sigaction(2) syscall.  Nope, not the same
	  as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
	  but fairly different variant of sigaction(2), thanks to OSF/1
	  compatibility...

config COMPAT_OLD_SIGACTION
	bool

source "kernel/gcov/Kconfig"
Commit	Line	Data
fb32e03f MD	1	#
	2	# General architecture dependent options
	3	#
125e5645 MD	4
125e5645 MD	5	config OPROFILE
b309a294	6	tristate "OProfile system profiling"
125e5645 MD	7	depends on PROFILING
125e5645 MD	8	depends on HAVE_OPROFILE
d69d59f4	9	select RING_BUFFER
9a5963eb	10	select RING_BUFFER_ALLOW_SWAP
125e5645 MD	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
4d4036e0 JY	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
125e5645	30	config HAVE_OPROFILE
9ba16087	31	bool
125e5645	32
dcfce4a0 RR	33	config OPROFILE_NMI_TIMER
	34	def_bool y
	35	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
	36
125e5645 MD	37	config KPROBES
125e5645 MD	38	bool "Kprobes"
05ed160e	39	depends on MODULES
125e5645	40	depends on HAVE_KPROBES
05ed160e	41	select KALLSYMS
125e5645 MD	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
45f81b1c	49	config JUMP_LABEL
c5905afb	50	bool "Optimize very unlikely/likely branches"
45f81b1c SR	51	depends on HAVE_ARCH_JUMP_LABEL
45f81b1c SR	52	help
c5905afb IM	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
45f81b1c	61	If it is detected that the compiler has support for "asm goto",
c5905afb IM	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.
45f81b1c	70
c5905afb IM	71	( On 32-bit x86, the necessary options added to the compiler
c5905afb IM	72	flags may increase the size of the kernel slightly. )
45f81b1c	73
afd66255	74	config OPTPROBES
5cc718b9 MH	75	def_bool y
5cc718b9 MH	76	depends on KPROBES && HAVE_OPTPROBES
afd66255	77	depends on !PREEMPT
afd66255	78
e7dbfe34 MH	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
2b144498	88	config UPROBES
09294e31	89	def_bool n
22b361d1	90	select PERCPU_RWSEM
2b144498	91	help
7b2d81d4 IM	92	Uprobes is the user-space counterpart to kprobes: they
	93	enable instrumentation applications (such as 'perf probe')
	94	to establish unintrusive probes in user-space binaries and
	95	libraries, by executing handler functions when the probes
	96	are hit by user-space applications.
	97
	98	( These probes come in the form of single-byte breakpoints,
	99	managed by the kernel and kept transparent to the probed
	100	application. )
2b144498	101
c19fa94a JH	102	config HAVE_64BIT_ALIGNED_ACCESS
	103	def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
	104	help
	105	Some architectures require 64 bit accesses to be 64 bit
	106	aligned, which also requires structs containing 64 bit values
	107	to be 64 bit aligned too. This includes some 32 bit
	108	architectures which can do 64 bit accesses, as well as 64 bit
	109	architectures without unaligned access.
	110
	111	This symbol should be selected by an architecture if 64 bit
	112	accesses are required to be 64 bit aligned in this way even
	113	though it is not a 64 bit architecture.
	114
	115	See Documentation/unaligned-memory-access.txt for more
	116	information on the topic of unaligned memory accesses.
	117
58340a07	118	config HAVE_EFFICIENT_UNALIGNED_ACCESS
9ba16087	119	bool
58340a07 JB	120	help
	121	Some architectures are unable to perform unaligned accesses
	122	without the use of get_unaligned/put_unaligned. Others are
	123	unable to perform such accesses efficiently (e.g. trap on
	124	unaligned access and require fixing it up in the exception
	125	handler.)
	126
	127	This symbol should be selected by an architecture if it can
	128	perform unaligned accesses efficiently to allow different
	129	code paths to be selected for these cases. Some network
	130	drivers, for example, could opt to not fix up alignment
	131	problems with received packets if doing so would not help
	132	much.
	133
	134	See Documentation/unaligned-memory-access.txt for more
	135	information on the topic of unaligned memory accesses.
	136
cf66bb93 DW	137	config ARCH_USE_BUILTIN_BSWAP
	138	bool
	139	help
	140	Modern versions of GCC (since 4.4) have builtin functions
	141	for handling byte-swapping. Using these, instead of the old
	142	inline assembler that the architecture code provides in the
	143	__arch_bswapXX() macros, allows the compiler to see what's
	144	happening and offers more opportunity for optimisation. In
	145	particular, the compiler will be able to combine the byteswap
	146	with a nearby load or store and use load-and-swap or
	147	store-and-swap instructions if the architecture has them. It
	148	should almost never result in code which is worse than the
	149	hand-coded assembler in <asm/swab.h>. But just in case it
	150	does, the use of the builtins is optional.
	151
	152	Any architecture with load-and-swap or store-and-swap
	153	instructions should set this. And it shouldn't hurt to set it
	154	on architectures that don't have such instructions.
	155
9edddaa2 AM	156	config KRETPROBES
	157	def_bool y
	158	depends on KPROBES && HAVE_KRETPROBES
	159
7c68af6e AK	160	config USER_RETURN_NOTIFIER
	161	bool
	162	depends on HAVE_USER_RETURN_NOTIFIER
	163	help
	164	Provide a kernel-internal notification when a cpu is about to
	165	switch to user mode.
	166
28b2ee20	167	config HAVE_IOREMAP_PROT
9ba16087	168	bool
28b2ee20	169
125e5645	170	config HAVE_KPROBES
9ba16087	171	bool
9edddaa2 AM	172
9edddaa2 AM	173	config HAVE_KRETPROBES
9ba16087	174	bool
74bc7cee	175
afd66255 MH	176	config HAVE_OPTPROBES
afd66255 MH	177	bool
d314d74c	178
e7dbfe34 MH	179	config HAVE_KPROBES_ON_FTRACE
	180	bool
	181
d314d74c CW	182	config HAVE_NMI_WATCHDOG
d314d74c CW	183	bool
1f5a4ad9 RM	184	#
	185	# An arch should select this if it provides all these things:
	186	#
	187	# task_pt_regs() in asm/processor.h or asm/ptrace.h
	188	# arch_has_single_step() if there is hardware single-step support
	189	# arch_has_block_step() if there is hardware block-step support
1f5a4ad9 RM	190	# asm/syscall.h supplying asm-generic/syscall.h interface
	191	# linux/regset.h user_regset interfaces
	192	# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
	193	# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
	194	# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
	195	# signal delivery calls tracehook_signal_handler()
	196	#
	197	config HAVE_ARCH_TRACEHOOK
9ba16087	198	bool
1f5a4ad9	199
74bc7cee	200	config HAVE_DMA_ATTRS
9ba16087	201	bool
3d442233	202
c64be2bb MS	203	config HAVE_DMA_CONTIGUOUS
	204	bool
	205
29d5e047 TG	206	config GENERIC_SMP_IDLE_THREAD
	207	bool
	208
485cf5da KH	209	config GENERIC_IDLE_POLL_SETUP
	210	bool
	211
a6359d1e TG	212	# Select if arch init_task initializer is different to init/init_task.c
a6359d1e TG	213	config ARCH_INIT_TASK
a4a2eb49 TG	214	bool
a4a2eb49 TG	215
f5e10287 TG	216	# Select if arch has its private alloc_task_struct() function
	217	config ARCH_TASK_STRUCT_ALLOCATOR
	218	bool
	219
	220	# Select if arch has its private alloc_thread_info() function
	221	config ARCH_THREAD_INFO_ALLOCATOR
	222	bool
	223
f850c30c HC	224	config HAVE_REGS_AND_STACK_ACCESS_API
f850c30c HC	225	bool
e01292b1 HC	226	help
	227	This symbol should be selected by an architecure if it supports
	228	the API needed to access registers and stack entries from pt_regs,
	229	declared in asm/ptrace.h
	230	For example the kprobes-based event tracer needs this API.
f850c30c	231
9483a578	232	config HAVE_CLK
9ba16087	233	bool
9483a578 DB	234	help
	235	The <linux/clk.h> calls support software clock gating and
	236	thus are a key power management tool on many systems.
	237
5ee00bd4 JR	238	config HAVE_DMA_API_DEBUG
5ee00bd4 JR	239	bool
36cd3c9f	240
62a038d3 P	241	config HAVE_HW_BREAKPOINT
62a038d3 P	242	bool
99e8c5a3	243	depends on PERF_EVENTS
62a038d3	244
0102752e FW	245	config HAVE_MIXED_BREAKPOINTS_REGS
	246	bool
	247	depends on HAVE_HW_BREAKPOINT
	248	help
	249	Depending on the arch implementation of hardware breakpoints,
	250	some of them have separate registers for data and instruction
	251	breakpoints addresses, others have mixed registers to store
	252	them but define the access type in a control register.
	253	Select this option if your arch implements breakpoints under the
	254	latter fashion.
	255
7c68af6e AK	256	config HAVE_USER_RETURN_NOTIFIER
7c68af6e AK	257	bool
a1922ed6	258
c01d4323 FW	259	config HAVE_PERF_EVENTS_NMI
c01d4323 FW	260	bool
23637d47 FW	261	help
	262	System hardware can generate an NMI using the perf event
	263	subsystem. Also has support for calculating CPU cycle events
	264	to determine how many clock cycles in a given period.
c01d4323	265
c5e63197 JO	266	config HAVE_PERF_REGS
	267	bool
	268	help
	269	Support selective register dumps for perf events. This includes
	270	bit-mapping of each registers and a unique architecture id.
	271
c5ebcedb JO	272	config HAVE_PERF_USER_STACK_DUMP
	273	bool
	274	help
	275	Support user stack dumps for perf event samples. This needs
	276	access to the user stack pointer which is not unified across
	277	architectures.
	278
bf5438fc JB	279	config HAVE_ARCH_JUMP_LABEL
	280	bool
	281
26723911 PZ	282	config HAVE_RCU_TABLE_FREE
	283	bool
	284
df013ffb YH	285	config ARCH_HAVE_NMI_SAFE_CMPXCHG
	286	bool
	287
43570fd2 HC	288	config HAVE_ALIGNED_STRUCT_PAGE
	289	bool
	290	help
	291	This makes sure that struct pages are double word aligned and that
	292	e.g. the SLUB allocator can perform double word atomic operations
	293	on a struct page for better performance. However selecting this
	294	might increase the size of a struct page by a word.
	295
4156153c HC	296	config HAVE_CMPXCHG_LOCAL
	297	bool
	298
2565409f HC	299	config HAVE_CMPXCHG_DOUBLE
	300	bool
	301
c1d7e01d WD	302	config ARCH_WANT_IPC_PARSE_VERSION
	303	bool
	304
	305	config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
	306	bool
	307
48b25c43	308	config ARCH_WANT_OLD_COMPAT_IPC
c1d7e01d	309	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
48b25c43 CM	310	bool
48b25c43 CM	311
e2cfabdf WD	312	config HAVE_ARCH_SECCOMP_FILTER
	313	bool
	314	help
fb0fadf9	315	An arch should select this symbol if it provides all of these things:
bb6ea430 WD	316	- syscall_get_arch()
	317	- syscall_get_arguments()
	318	- syscall_rollback()
	319	- syscall_set_return_value()
fb0fadf9 WD	320	- SIGSYS siginfo_t support
	321	- secure_computing is called from a ptrace_event()-safe context
	322	- secure_computing return value is checked and a return value of -1
	323	results in the system call being skipped immediately.
48dc92b9	324	- seccomp syscall wired up
e2cfabdf	325
ff27f38e AL	326	For best performance, an arch should use seccomp_phase1 and
	327	seccomp_phase2 directly. It should call seccomp_phase1 for all
	328	syscalls if TIF_SECCOMP is set, but seccomp_phase1 does not
	329	need to be called from a ptrace-safe context. It must then
	330	call seccomp_phase2 if seccomp_phase1 returns anything other
	331	than SECCOMP_PHASE1_OK or SECCOMP_PHASE1_SKIP.
	332
	333	As an additional optimization, an arch may provide seccomp_data
	334	directly to seccomp_phase1; this avoids multiple calls
	335	to the syscall_xyz helpers for every syscall.
	336
e2cfabdf WD	337	config SECCOMP_FILTER
	338	def_bool y
	339	depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
	340	help
	341	Enable tasks to build secure computing environments defined
	342	in terms of Berkeley Packet Filter programs which implement
	343	task-defined system call filtering polices.
	344
	345	See Documentation/prctl/seccomp_filter.txt for details.
	346
19952a92 KC	347	config HAVE_CC_STACKPROTECTOR
	348	bool
	349	help
	350	An arch should select this symbol if:
	351	- its compiler supports the -fstack-protector option
	352	- it has implemented a stack canary (e.g. __stack_chk_guard)
	353
	354	config CC_STACKPROTECTOR
8779657d KC	355	def_bool n
	356	help
	357	Set when a stack-protector mode is enabled, so that the build
	358	can enable kernel-side support for the GCC feature.
	359
	360	choice
	361	prompt "Stack Protector buffer overflow detection"
19952a92	362	depends on HAVE_CC_STACKPROTECTOR
8779657d	363	default CC_STACKPROTECTOR_NONE
19952a92	364	help
8779657d	365	This option turns on the "stack-protector" GCC feature. This
19952a92 KC	366	feature puts, at the beginning of functions, a canary value on
	367	the stack just before the return address, and validates
	368	the value just before actually returning. Stack based buffer
	369	overflows (that need to overwrite this return address) now also
	370	overwrite the canary, which gets detected and the attack is then
	371	neutralized via a kernel panic.
	372
8779657d KC	373	config CC_STACKPROTECTOR_NONE
	374	bool "None"
	375	help
	376	Disable "stack-protector" GCC feature.
	377
	378	config CC_STACKPROTECTOR_REGULAR
	379	bool "Regular"
	380	select CC_STACKPROTECTOR
	381	help
	382	Functions will have the stack-protector canary logic added if they
	383	have an 8-byte or larger character array on the stack.
	384
19952a92	385	This feature requires gcc version 4.2 or above, or a distribution
8779657d KC	386	gcc with the feature backported ("-fstack-protector").
	387
	388	On an x86 "defconfig" build, this feature adds canary checks to
	389	about 3% of all kernel functions, which increases kernel code size
	390	by about 0.3%.
	391
	392	config CC_STACKPROTECTOR_STRONG
	393	bool "Strong"
	394	select CC_STACKPROTECTOR
	395	help
	396	Functions will have the stack-protector canary logic added in any
	397	of the following conditions:
	398
	399	- local variable's address used as part of the right hand side of an
	400	assignment or function argument
	401	- local variable is an array (or union containing an array),
	402	regardless of array type or length
	403	- uses register local variables
	404
	405	This feature requires gcc version 4.9 or above, or a distribution
	406	gcc with the feature backported ("-fstack-protector-strong").
	407
	408	On an x86 "defconfig" build, this feature adds canary checks to
	409	about 20% of all kernel functions, which increases the kernel code
	410	size by about 2%.
	411
	412	endchoice
19952a92	413
91d1aa43	414	config HAVE_CONTEXT_TRACKING
2b1d5024 FW	415	bool
2b1d5024 FW	416	help
91d1aa43 FW	417	Provide kernel/user boundaries probes necessary for subsystems
	418	that need it, such as userspace RCU extended quiescent state.
	419	Syscalls need to be wrapped inside user_exit()-user_enter() through
	420	the slow path using TIF_NOHZ flag. Exceptions handlers must be
	421	wrapped as well. Irqs are already protected inside
	422	rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
	423	irq exit still need to be protected.
2b1d5024	424
b952741c FW	425	config HAVE_VIRT_CPU_ACCOUNTING
	426	bool
	427
554b0004 KH	428	config HAVE_VIRT_CPU_ACCOUNTING_GEN
	429	bool
	430	default y if 64BIT
	431	help
	432	With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
	433	Before enabling this option, arch code must be audited
	434	to ensure there are no races in concurrent read/write of
	435	cputime_t. For example, reading/writing 64-bit cputime_t on
	436	some 32-bit arches may require multiple accesses, so proper
	437	locking is needed to protect against concurrent accesses.
	438
	439
fdf9c356 FW	440	config HAVE_IRQ_TIME_ACCOUNTING
	441	bool
	442	help
	443	Archs need to ensure they use a high enough resolution clock to
	444	support irq time accounting and then call enable_sched_clock_irqtime().
	445
15626062 GS	446	config HAVE_ARCH_TRANSPARENT_HUGEPAGE
	447	bool
	448
0f8975ec PE	449	config HAVE_ARCH_SOFT_DIRTY
	450	bool
	451
786d35d4 DH	452	config HAVE_MOD_ARCH_SPECIFIC
	453	bool
	454	help
	455	The arch uses struct mod_arch_specific to store data. Many arches
	456	just need a simple module loader without arch specific data - those
	457	should not enable this.
	458
	459	config MODULES_USE_ELF_RELA
	460	bool
	461	help
	462	Modules only use ELF RELA relocations. Modules with ELF REL
	463	relocations will give an error.
	464
	465	config MODULES_USE_ELF_REL
	466	bool
	467	help
	468	Modules only use ELF REL relocations. Modules with ELF RELA
	469	relocations will give an error.
	470
b92021b0 RR	471	config HAVE_UNDERSCORE_SYMBOL_PREFIX
	472	bool
	473	help
	474	Some architectures generate an _ in front of C symbols; things like
	475	module loading and assembly files need to know about this.
	476
cc1f0274 FW	477	config HAVE_IRQ_EXIT_ON_IRQ_STACK
	478	bool
	479	help
	480	Architecture doesn't only execute the irq handler on the irq stack
	481	but also irq_exit(). This way we can process softirqs on this irq
	482	stack instead of switching to a new one when we call __do_softirq()
	483	in the end of an hardirq.
	484	This spares a stack switch and improves cache usage on softirq
	485	processing.
	486
d2125043 AV	487	#
	488	# ABI hall of shame
	489	#
	490	config CLONE_BACKWARDS
	491	bool
	492	help
	493	Architecture has tls passed as the 4th argument of clone(2),
	494	not the 5th one.
	495
	496	config CLONE_BACKWARDS2
	497	bool
	498	help
	499	Architecture has the first two arguments of clone(2) swapped.
	500
dfa9771a MS	501	config CLONE_BACKWARDS3
	502	bool
	503	help
	504	Architecture has tls passed as the 3rd argument of clone(2),
	505	not the 5th one.
	506
eaca6eae AV	507	config ODD_RT_SIGACTION
	508	bool
	509	help
	510	Architecture has unusual rt_sigaction(2) arguments
	511
0a0e8cdf AV	512	config OLD_SIGSUSPEND
	513	bool
	514	help
	515	Architecture has old sigsuspend(2) syscall, of one-argument variety
	516
	517	config OLD_SIGSUSPEND3
	518	bool
	519	help
	520	Even weirder antique ABI - three-argument sigsuspend(2)
	521
495dfbf7 AV	522	config OLD_SIGACTION
	523	bool
	524	help
	525	Architecture has old sigaction(2) syscall. Nope, not the same
	526	as OLD_SIGSUSPEND \| OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
	527	but fairly different variant of sigaction(2), thanks to OSF/1
	528	compatibility...
	529
	530	config COMPAT_OLD_SIGACTION
	531	bool
	532
2521f2c2	533	source "kernel/gcov/Kconfig"