## 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	bool "Transparent user-space probes (EXPERIMENTAL)"	depends on UPROBE_EVENT && PERF_EVENTS	default 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. ) 	  If in doubt, say "N". 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.cconfig ARCH_INIT_TASK       bool # Select if arch has its private alloc_task_struct() functionconfig ARCH_TASK_STRUCT_ALLOCATOR	bool # Select if arch has its private alloc_thread_info() functionconfig 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. 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_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"