1fb32e03fSMathieu Desnoyers# 2fb32e03fSMathieu Desnoyers# General architecture dependent options 3fb32e03fSMathieu Desnoyers# 4125e5645SMathieu Desnoyers 5125e5645SMathieu Desnoyersconfig OPROFILE 6b309a294SRobert Richter tristate "OProfile system profiling" 7125e5645SMathieu Desnoyers depends on PROFILING 8125e5645SMathieu Desnoyers depends on HAVE_OPROFILE 9d69d59f4SIngo Molnar select RING_BUFFER 109a5963ebSChristian Borntraeger select RING_BUFFER_ALLOW_SWAP 11125e5645SMathieu Desnoyers help 12125e5645SMathieu Desnoyers OProfile is a profiling system capable of profiling the 13125e5645SMathieu Desnoyers whole system, include the kernel, kernel modules, libraries, 14125e5645SMathieu Desnoyers and applications. 15125e5645SMathieu Desnoyers 16125e5645SMathieu Desnoyers If unsure, say N. 17125e5645SMathieu Desnoyers 184d4036e0SJason Yehconfig OPROFILE_EVENT_MULTIPLEX 194d4036e0SJason Yeh bool "OProfile multiplexing support (EXPERIMENTAL)" 204d4036e0SJason Yeh default n 214d4036e0SJason Yeh depends on OPROFILE && X86 224d4036e0SJason Yeh help 234d4036e0SJason Yeh The number of hardware counters is limited. The multiplexing 244d4036e0SJason Yeh feature enables OProfile to gather more events than counters 254d4036e0SJason Yeh are provided by the hardware. This is realized by switching 264d4036e0SJason Yeh between events at an user specified time interval. 274d4036e0SJason Yeh 284d4036e0SJason Yeh If unsure, say N. 294d4036e0SJason Yeh 30125e5645SMathieu Desnoyersconfig HAVE_OPROFILE 319ba16087SJan Beulich bool 32125e5645SMathieu Desnoyers 33dcfce4a0SRobert Richterconfig OPROFILE_NMI_TIMER 34dcfce4a0SRobert Richter def_bool y 35dcfce4a0SRobert Richter depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI 36dcfce4a0SRobert Richter 37125e5645SMathieu Desnoyersconfig KPROBES 38125e5645SMathieu Desnoyers bool "Kprobes" 3905ed160eSMasami Hiramatsu depends on MODULES 40125e5645SMathieu Desnoyers depends on HAVE_KPROBES 4105ed160eSMasami Hiramatsu select KALLSYMS 42125e5645SMathieu Desnoyers help 43125e5645SMathieu Desnoyers Kprobes allows you to trap at almost any kernel address and 44125e5645SMathieu Desnoyers execute a callback function. register_kprobe() establishes 45125e5645SMathieu Desnoyers a probepoint and specifies the callback. Kprobes is useful 46125e5645SMathieu Desnoyers for kernel debugging, non-intrusive instrumentation and testing. 47125e5645SMathieu Desnoyers If in doubt, say "N". 48125e5645SMathieu Desnoyers 4945f81b1cSSteven Rostedtconfig JUMP_LABEL 50c5905afbSIngo Molnar bool "Optimize very unlikely/likely branches" 5145f81b1cSSteven Rostedt depends on HAVE_ARCH_JUMP_LABEL 5245f81b1cSSteven Rostedt help 53c5905afbSIngo Molnar This option enables a transparent branch optimization that 54c5905afbSIngo Molnar makes certain almost-always-true or almost-always-false branch 55c5905afbSIngo Molnar conditions even cheaper to execute within the kernel. 5645f81b1cSSteven Rostedt 57c5905afbSIngo Molnar Certain performance-sensitive kernel code, such as trace points, 58c5905afbSIngo Molnar scheduler functionality, networking code and KVM have such 59c5905afbSIngo Molnar branches and include support for this optimization technique. 60c5905afbSIngo Molnar 61c5905afbSIngo Molnar If it is detected that the compiler has support for "asm goto", 62c5905afbSIngo Molnar the kernel will compile such branches with just a nop 63c5905afbSIngo Molnar instruction. When the condition flag is toggled to true, the 64c5905afbSIngo Molnar nop will be converted to a jump instruction to execute the 65c5905afbSIngo Molnar conditional block of instructions. 66c5905afbSIngo Molnar 67c5905afbSIngo Molnar This technique lowers overhead and stress on the branch prediction 68c5905afbSIngo Molnar of the processor and generally makes the kernel faster. The update 69c5905afbSIngo Molnar of the condition is slower, but those are always very rare. 70c5905afbSIngo Molnar 71c5905afbSIngo Molnar ( On 32-bit x86, the necessary options added to the compiler 72c5905afbSIngo Molnar flags may increase the size of the kernel slightly. ) 7345f81b1cSSteven Rostedt 74afd66255SMasami Hiramatsuconfig OPTPROBES 755cc718b9SMasami Hiramatsu def_bool y 765cc718b9SMasami Hiramatsu depends on KPROBES && HAVE_OPTPROBES 77afd66255SMasami Hiramatsu depends on !PREEMPT 78afd66255SMasami Hiramatsu 792b144498SSrikar Dronamrajuconfig UPROBES 807b2d81d4SIngo Molnar bool "Transparent user-space probes (EXPERIMENTAL)" 81ec83db0fSSrikar Dronamraju depends on UPROBE_EVENT && PERF_EVENTS 822b144498SSrikar Dronamraju default n 832b144498SSrikar Dronamraju help 847b2d81d4SIngo Molnar Uprobes is the user-space counterpart to kprobes: they 857b2d81d4SIngo Molnar enable instrumentation applications (such as 'perf probe') 867b2d81d4SIngo Molnar to establish unintrusive probes in user-space binaries and 877b2d81d4SIngo Molnar libraries, by executing handler functions when the probes 887b2d81d4SIngo Molnar are hit by user-space applications. 897b2d81d4SIngo Molnar 907b2d81d4SIngo Molnar ( These probes come in the form of single-byte breakpoints, 917b2d81d4SIngo Molnar managed by the kernel and kept transparent to the probed 927b2d81d4SIngo Molnar application. ) 932b144498SSrikar Dronamraju 942b144498SSrikar Dronamraju If in doubt, say "N". 952b144498SSrikar Dronamraju 9658340a07SJohannes Bergconfig HAVE_EFFICIENT_UNALIGNED_ACCESS 979ba16087SJan Beulich bool 9858340a07SJohannes Berg help 9958340a07SJohannes Berg Some architectures are unable to perform unaligned accesses 10058340a07SJohannes Berg without the use of get_unaligned/put_unaligned. Others are 10158340a07SJohannes Berg unable to perform such accesses efficiently (e.g. trap on 10258340a07SJohannes Berg unaligned access and require fixing it up in the exception 10358340a07SJohannes Berg handler.) 10458340a07SJohannes Berg 10558340a07SJohannes Berg This symbol should be selected by an architecture if it can 10658340a07SJohannes Berg perform unaligned accesses efficiently to allow different 10758340a07SJohannes Berg code paths to be selected for these cases. Some network 10858340a07SJohannes Berg drivers, for example, could opt to not fix up alignment 10958340a07SJohannes Berg problems with received packets if doing so would not help 11058340a07SJohannes Berg much. 11158340a07SJohannes Berg 11258340a07SJohannes Berg See Documentation/unaligned-memory-access.txt for more 11358340a07SJohannes Berg information on the topic of unaligned memory accesses. 11458340a07SJohannes Berg 115cf66bb93SDavid Woodhouseconfig ARCH_USE_BUILTIN_BSWAP 116cf66bb93SDavid Woodhouse bool 117cf66bb93SDavid Woodhouse help 118cf66bb93SDavid Woodhouse Modern versions of GCC (since 4.4) have builtin functions 119cf66bb93SDavid Woodhouse for handling byte-swapping. Using these, instead of the old 120cf66bb93SDavid Woodhouse inline assembler that the architecture code provides in the 121cf66bb93SDavid Woodhouse __arch_bswapXX() macros, allows the compiler to see what's 122cf66bb93SDavid Woodhouse happening and offers more opportunity for optimisation. In 123cf66bb93SDavid Woodhouse particular, the compiler will be able to combine the byteswap 124cf66bb93SDavid Woodhouse with a nearby load or store and use load-and-swap or 125cf66bb93SDavid Woodhouse store-and-swap instructions if the architecture has them. It 126cf66bb93SDavid Woodhouse should almost *never* result in code which is worse than the 127cf66bb93SDavid Woodhouse hand-coded assembler in <asm/swab.h>. But just in case it 128cf66bb93SDavid Woodhouse does, the use of the builtins is optional. 129cf66bb93SDavid Woodhouse 130cf66bb93SDavid Woodhouse Any architecture with load-and-swap or store-and-swap 131cf66bb93SDavid Woodhouse instructions should set this. And it shouldn't hurt to set it 132cf66bb93SDavid Woodhouse on architectures that don't have such instructions. 133cf66bb93SDavid Woodhouse 1341a94bc34SHeiko Carstensconfig HAVE_SYSCALL_WRAPPERS 1351a94bc34SHeiko Carstens bool 1361a94bc34SHeiko Carstens 1379edddaa2SAnanth N Mavinakayanahalliconfig KRETPROBES 1389edddaa2SAnanth N Mavinakayanahalli def_bool y 1399edddaa2SAnanth N Mavinakayanahalli depends on KPROBES && HAVE_KRETPROBES 1409edddaa2SAnanth N Mavinakayanahalli 1417c68af6eSAvi Kivityconfig USER_RETURN_NOTIFIER 1427c68af6eSAvi Kivity bool 1437c68af6eSAvi Kivity depends on HAVE_USER_RETURN_NOTIFIER 1447c68af6eSAvi Kivity help 1457c68af6eSAvi Kivity Provide a kernel-internal notification when a cpu is about to 1467c68af6eSAvi Kivity switch to user mode. 1477c68af6eSAvi Kivity 14828b2ee20SRik van Rielconfig HAVE_IOREMAP_PROT 1499ba16087SJan Beulich bool 15028b2ee20SRik van Riel 151125e5645SMathieu Desnoyersconfig HAVE_KPROBES 1529ba16087SJan Beulich bool 1539edddaa2SAnanth N Mavinakayanahalli 1549edddaa2SAnanth N Mavinakayanahalliconfig HAVE_KRETPROBES 1559ba16087SJan Beulich bool 15674bc7ceeSArthur Kepner 157afd66255SMasami Hiramatsuconfig HAVE_OPTPROBES 158afd66255SMasami Hiramatsu bool 159d314d74cSCong Wang 160d314d74cSCong Wangconfig HAVE_NMI_WATCHDOG 161d314d74cSCong Wang bool 1621f5a4ad9SRoland McGrath# 1631f5a4ad9SRoland McGrath# An arch should select this if it provides all these things: 1641f5a4ad9SRoland McGrath# 1651f5a4ad9SRoland McGrath# task_pt_regs() in asm/processor.h or asm/ptrace.h 1661f5a4ad9SRoland McGrath# arch_has_single_step() if there is hardware single-step support 1671f5a4ad9SRoland McGrath# arch_has_block_step() if there is hardware block-step support 1681f5a4ad9SRoland McGrath# asm/syscall.h supplying asm-generic/syscall.h interface 1691f5a4ad9SRoland McGrath# linux/regset.h user_regset interfaces 1701f5a4ad9SRoland McGrath# CORE_DUMP_USE_REGSET #define'd in linux/elf.h 1711f5a4ad9SRoland McGrath# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit} 1721f5a4ad9SRoland McGrath# TIF_NOTIFY_RESUME calls tracehook_notify_resume() 1731f5a4ad9SRoland McGrath# signal delivery calls tracehook_signal_handler() 1741f5a4ad9SRoland McGrath# 1751f5a4ad9SRoland McGrathconfig HAVE_ARCH_TRACEHOOK 1769ba16087SJan Beulich bool 1771f5a4ad9SRoland McGrath 17874bc7ceeSArthur Kepnerconfig HAVE_DMA_ATTRS 1799ba16087SJan Beulich bool 1803d442233SJens Axboe 181c64be2bbSMarek Szyprowskiconfig HAVE_DMA_CONTIGUOUS 182c64be2bbSMarek Szyprowski bool 183c64be2bbSMarek Szyprowski 1843d442233SJens Axboeconfig USE_GENERIC_SMP_HELPERS 1859ba16087SJan Beulich bool 1869483a578SDavid Brownell 18729d5e047SThomas Gleixnerconfig GENERIC_SMP_IDLE_THREAD 18829d5e047SThomas Gleixner bool 18929d5e047SThomas Gleixner 190a6359d1eSThomas Gleixner# Select if arch init_task initializer is different to init/init_task.c 191a6359d1eSThomas Gleixnerconfig ARCH_INIT_TASK 192a4a2eb49SThomas Gleixner bool 193a4a2eb49SThomas Gleixner 194f5e10287SThomas Gleixner# Select if arch has its private alloc_task_struct() function 195f5e10287SThomas Gleixnerconfig ARCH_TASK_STRUCT_ALLOCATOR 196f5e10287SThomas Gleixner bool 197f5e10287SThomas Gleixner 198f5e10287SThomas Gleixner# Select if arch has its private alloc_thread_info() function 199f5e10287SThomas Gleixnerconfig ARCH_THREAD_INFO_ALLOCATOR 200f5e10287SThomas Gleixner bool 201f5e10287SThomas Gleixner 202f850c30cSHeiko Carstensconfig HAVE_REGS_AND_STACK_ACCESS_API 203f850c30cSHeiko Carstens bool 204e01292b1SHeiko Carstens help 205e01292b1SHeiko Carstens This symbol should be selected by an architecure if it supports 206e01292b1SHeiko Carstens the API needed to access registers and stack entries from pt_regs, 207e01292b1SHeiko Carstens declared in asm/ptrace.h 208e01292b1SHeiko Carstens For example the kprobes-based event tracer needs this API. 209f850c30cSHeiko Carstens 2109483a578SDavid Brownellconfig HAVE_CLK 2119ba16087SJan Beulich bool 2129483a578SDavid Brownell help 2139483a578SDavid Brownell The <linux/clk.h> calls support software clock gating and 2149483a578SDavid Brownell thus are a key power management tool on many systems. 2159483a578SDavid Brownell 2165ee00bd4SJoerg Roedelconfig HAVE_DMA_API_DEBUG 2175ee00bd4SJoerg Roedel bool 21836cd3c9fSHeiko Carstens 21962a038d3SK.Prasadconfig HAVE_HW_BREAKPOINT 22062a038d3SK.Prasad bool 22199e8c5a3SFrederic Weisbecker depends on PERF_EVENTS 22262a038d3SK.Prasad 2230102752eSFrederic Weisbeckerconfig HAVE_MIXED_BREAKPOINTS_REGS 2240102752eSFrederic Weisbecker bool 2250102752eSFrederic Weisbecker depends on HAVE_HW_BREAKPOINT 2260102752eSFrederic Weisbecker help 2270102752eSFrederic Weisbecker Depending on the arch implementation of hardware breakpoints, 2280102752eSFrederic Weisbecker some of them have separate registers for data and instruction 2290102752eSFrederic Weisbecker breakpoints addresses, others have mixed registers to store 2300102752eSFrederic Weisbecker them but define the access type in a control register. 2310102752eSFrederic Weisbecker Select this option if your arch implements breakpoints under the 2320102752eSFrederic Weisbecker latter fashion. 2330102752eSFrederic Weisbecker 2347c68af6eSAvi Kivityconfig HAVE_USER_RETURN_NOTIFIER 2357c68af6eSAvi Kivity bool 236a1922ed6SIngo Molnar 237c01d4323SFrederic Weisbeckerconfig HAVE_PERF_EVENTS_NMI 238c01d4323SFrederic Weisbecker bool 23923637d47SFrederic Weisbecker help 24023637d47SFrederic Weisbecker System hardware can generate an NMI using the perf event 24123637d47SFrederic Weisbecker subsystem. Also has support for calculating CPU cycle events 24223637d47SFrederic Weisbecker to determine how many clock cycles in a given period. 243c01d4323SFrederic Weisbecker 244c5e63197SJiri Olsaconfig HAVE_PERF_REGS 245c5e63197SJiri Olsa bool 246c5e63197SJiri Olsa help 247c5e63197SJiri Olsa Support selective register dumps for perf events. This includes 248c5e63197SJiri Olsa bit-mapping of each registers and a unique architecture id. 249c5e63197SJiri Olsa 250c5ebcedbSJiri Olsaconfig HAVE_PERF_USER_STACK_DUMP 251c5ebcedbSJiri Olsa bool 252c5ebcedbSJiri Olsa help 253c5ebcedbSJiri Olsa Support user stack dumps for perf event samples. This needs 254c5ebcedbSJiri Olsa access to the user stack pointer which is not unified across 255c5ebcedbSJiri Olsa architectures. 256c5ebcedbSJiri Olsa 257bf5438fcSJason Baronconfig HAVE_ARCH_JUMP_LABEL 258bf5438fcSJason Baron bool 259bf5438fcSJason Baron 260335d7afbSGerald Schaeferconfig HAVE_ARCH_MUTEX_CPU_RELAX 261335d7afbSGerald Schaefer bool 262335d7afbSGerald Schaefer 26326723911SPeter Zijlstraconfig HAVE_RCU_TABLE_FREE 26426723911SPeter Zijlstra bool 26526723911SPeter Zijlstra 266df013ffbSHuang Yingconfig ARCH_HAVE_NMI_SAFE_CMPXCHG 267df013ffbSHuang Ying bool 268df013ffbSHuang Ying 26943570fd2SHeiko Carstensconfig HAVE_ALIGNED_STRUCT_PAGE 27043570fd2SHeiko Carstens bool 27143570fd2SHeiko Carstens help 27243570fd2SHeiko Carstens This makes sure that struct pages are double word aligned and that 27343570fd2SHeiko Carstens e.g. the SLUB allocator can perform double word atomic operations 27443570fd2SHeiko Carstens on a struct page for better performance. However selecting this 27543570fd2SHeiko Carstens might increase the size of a struct page by a word. 27643570fd2SHeiko Carstens 2774156153cSHeiko Carstensconfig HAVE_CMPXCHG_LOCAL 2784156153cSHeiko Carstens bool 2794156153cSHeiko Carstens 2802565409fSHeiko Carstensconfig HAVE_CMPXCHG_DOUBLE 2812565409fSHeiko Carstens bool 2822565409fSHeiko Carstens 283c1d7e01dSWill Deaconconfig ARCH_WANT_IPC_PARSE_VERSION 284c1d7e01dSWill Deacon bool 285c1d7e01dSWill Deacon 286c1d7e01dSWill Deaconconfig ARCH_WANT_COMPAT_IPC_PARSE_VERSION 287c1d7e01dSWill Deacon bool 288c1d7e01dSWill Deacon 28948b25c43SChris Metcalfconfig ARCH_WANT_OLD_COMPAT_IPC 290c1d7e01dSWill Deacon select ARCH_WANT_COMPAT_IPC_PARSE_VERSION 29148b25c43SChris Metcalf bool 29248b25c43SChris Metcalf 2932aa3a7f8SAl Viroconfig GENERIC_KERNEL_THREAD 2942aa3a7f8SAl Viro bool 2952aa3a7f8SAl Viro 296a74fb73cSAl Viroconfig GENERIC_KERNEL_EXECVE 297a74fb73cSAl Viro bool 298a74fb73cSAl Viro 299e2cfabdfSWill Drewryconfig HAVE_ARCH_SECCOMP_FILTER 300e2cfabdfSWill Drewry bool 301e2cfabdfSWill Drewry help 302fb0fadf9SWill Drewry An arch should select this symbol if it provides all of these things: 303bb6ea430SWill Drewry - syscall_get_arch() 304bb6ea430SWill Drewry - syscall_get_arguments() 305bb6ea430SWill Drewry - syscall_rollback() 306bb6ea430SWill Drewry - syscall_set_return_value() 307fb0fadf9SWill Drewry - SIGSYS siginfo_t support 308fb0fadf9SWill Drewry - secure_computing is called from a ptrace_event()-safe context 309fb0fadf9SWill Drewry - secure_computing return value is checked and a return value of -1 310fb0fadf9SWill Drewry results in the system call being skipped immediately. 311e2cfabdfSWill Drewry 312e2cfabdfSWill Drewryconfig SECCOMP_FILTER 313e2cfabdfSWill Drewry def_bool y 314e2cfabdfSWill Drewry depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET 315e2cfabdfSWill Drewry help 316e2cfabdfSWill Drewry Enable tasks to build secure computing environments defined 317e2cfabdfSWill Drewry in terms of Berkeley Packet Filter programs which implement 318e2cfabdfSWill Drewry task-defined system call filtering polices. 319e2cfabdfSWill Drewry 320e2cfabdfSWill Drewry See Documentation/prctl/seccomp_filter.txt for details. 321e2cfabdfSWill Drewry 3222b1d5024SFrederic Weisbeckerconfig HAVE_RCU_USER_QS 3232b1d5024SFrederic Weisbecker bool 3242b1d5024SFrederic Weisbecker help 3252b1d5024SFrederic Weisbecker Provide kernel entry/exit hooks necessary for userspace 3262b1d5024SFrederic Weisbecker RCU extended quiescent state. Syscalls need to be wrapped inside 3272b1d5024SFrederic Weisbecker rcu_user_exit()-rcu_user_enter() through the slow path using 3282b1d5024SFrederic Weisbecker TIF_NOHZ flag. Exceptions handlers must be wrapped as well. Irqs 3292b1d5024SFrederic Weisbecker are already protected inside rcu_irq_enter/rcu_irq_exit() but 3302b1d5024SFrederic Weisbecker preemption or signal handling on irq exit still need to be protected. 3312b1d5024SFrederic Weisbecker 332b952741cSFrederic Weisbeckerconfig HAVE_VIRT_CPU_ACCOUNTING 333b952741cSFrederic Weisbecker bool 334b952741cSFrederic Weisbecker 335fdf9c356SFrederic Weisbeckerconfig HAVE_IRQ_TIME_ACCOUNTING 336fdf9c356SFrederic Weisbecker bool 337fdf9c356SFrederic Weisbecker help 338fdf9c356SFrederic Weisbecker Archs need to ensure they use a high enough resolution clock to 339fdf9c356SFrederic Weisbecker support irq time accounting and then call enable_sched_clock_irqtime(). 340fdf9c356SFrederic Weisbecker 34115626062SGerald Schaeferconfig HAVE_ARCH_TRANSPARENT_HUGEPAGE 34215626062SGerald Schaefer bool 34315626062SGerald Schaefer 344786d35d4SDavid Howellsconfig HAVE_MOD_ARCH_SPECIFIC 345786d35d4SDavid Howells bool 346786d35d4SDavid Howells help 347786d35d4SDavid Howells The arch uses struct mod_arch_specific to store data. Many arches 348786d35d4SDavid Howells just need a simple module loader without arch specific data - those 349786d35d4SDavid Howells should not enable this. 350786d35d4SDavid Howells 351786d35d4SDavid Howellsconfig MODULES_USE_ELF_RELA 352786d35d4SDavid Howells bool 353786d35d4SDavid Howells help 354786d35d4SDavid Howells Modules only use ELF RELA relocations. Modules with ELF REL 355786d35d4SDavid Howells relocations will give an error. 356786d35d4SDavid Howells 357786d35d4SDavid Howellsconfig MODULES_USE_ELF_REL 358786d35d4SDavid Howells bool 359786d35d4SDavid Howells help 360786d35d4SDavid Howells Modules only use ELF REL relocations. Modules with ELF RELA 361786d35d4SDavid Howells relocations will give an error. 362786d35d4SDavid Howells 3632521f2c2SPeter Oberparleitersource "kernel/gcov/Kconfig" 364