1config DEFCONFIG_LIST 2 string 3 depends on !UML 4 option defconfig_list 5 default "/lib/modules/$UNAME_RELEASE/.config" 6 default "/etc/kernel-config" 7 default "/boot/config-$UNAME_RELEASE" 8 default "arch/$ARCH/defconfig" 9 10menu "General setup" 11 12config EXPERIMENTAL 13 bool "Prompt for development and/or incomplete code/drivers" 14 ---help--- 15 Some of the various things that Linux supports (such as network 16 drivers, file systems, network protocols, etc.) can be in a state 17 of development where the functionality, stability, or the level of 18 testing is not yet high enough for general use. This is usually 19 known as the "alpha-test" phase among developers. If a feature is 20 currently in alpha-test, then the developers usually discourage 21 uninformed widespread use of this feature by the general public to 22 avoid "Why doesn't this work?" type mail messages. However, active 23 testing and use of these systems is welcomed. Just be aware that it 24 may not meet the normal level of reliability or it may fail to work 25 in some special cases. Detailed bug reports from people familiar 26 with the kernel internals are usually welcomed by the developers 27 (before submitting bug reports, please read the documents 28 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 29 <file:Documentation/BUG-HUNTING>, and 30 <file:Documentation/oops-tracing.txt> in the kernel source). 31 32 This option will also make obsoleted drivers available. These are 33 drivers that have been replaced by something else, and/or are 34 scheduled to be removed in a future kernel release. 35 36 Unless you intend to help test and develop a feature or driver that 37 falls into this category, or you have a situation that requires 38 using these features, you should probably say N here, which will 39 cause the configurator to present you with fewer choices. If 40 you say Y here, you will be offered the choice of using features or 41 drivers that are currently considered to be in the alpha-test phase. 42 43config BROKEN 44 bool 45 46config BROKEN_ON_SMP 47 bool 48 depends on BROKEN || !SMP 49 default y 50 51config LOCK_KERNEL 52 bool 53 depends on SMP || PREEMPT 54 default y 55 56config INIT_ENV_ARG_LIMIT 57 int 58 default 32 if !UML 59 default 128 if UML 60 help 61 Maximum of each of the number of arguments and environment 62 variables passed to init from the kernel command line. 63 64 65config LOCALVERSION 66 string "Local version - append to kernel release" 67 help 68 Append an extra string to the end of your kernel version. 69 This will show up when you type uname, for example. 70 The string you set here will be appended after the contents of 71 any files with a filename matching localversion* in your 72 object and source tree, in that order. Your total string can 73 be a maximum of 64 characters. 74 75config LOCALVERSION_AUTO 76 bool "Automatically append version information to the version string" 77 default y 78 help 79 This will try to automatically determine if the current tree is a 80 release tree by looking for git tags that belong to the current 81 top of tree revision. 82 83 A string of the format -gxxxxxxxx will be added to the localversion 84 if a git-based tree is found. The string generated by this will be 85 appended after any matching localversion* files, and after the value 86 set in CONFIG_LOCALVERSION. 87 88 (The actual string used here is the first eight characters produced 89 by running the command: 90 91 $ git rev-parse --verify HEAD 92 93 which is done within the script "scripts/setlocalversion".) 94 95config SWAP 96 bool "Support for paging of anonymous memory (swap)" 97 depends on MMU && BLOCK 98 default y 99 help 100 This option allows you to choose whether you want to have support 101 for so called swap devices or swap files in your kernel that are 102 used to provide more virtual memory than the actual RAM present 103 in your computer. If unsure say Y. 104 105config SYSVIPC 106 bool "System V IPC" 107 ---help--- 108 Inter Process Communication is a suite of library functions and 109 system calls which let processes (running programs) synchronize and 110 exchange information. It is generally considered to be a good thing, 111 and some programs won't run unless you say Y here. In particular, if 112 you want to run the DOS emulator dosemu under Linux (read the 113 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 114 you'll need to say Y here. 115 116 You can find documentation about IPC with "info ipc" and also in 117 section 6.4 of the Linux Programmer's Guide, available from 118 <http://www.tldp.org/guides.html>. 119 120config SYSVIPC_SYSCTL 121 bool 122 depends on SYSVIPC 123 depends on SYSCTL 124 default y 125 126config POSIX_MQUEUE 127 bool "POSIX Message Queues" 128 depends on NET && EXPERIMENTAL 129 ---help--- 130 POSIX variant of message queues is a part of IPC. In POSIX message 131 queues every message has a priority which decides about succession 132 of receiving it by a process. If you want to compile and run 133 programs written e.g. for Solaris with use of its POSIX message 134 queues (functions mq_*) say Y here. 135 136 POSIX message queues are visible as a filesystem called 'mqueue' 137 and can be mounted somewhere if you want to do filesystem 138 operations on message queues. 139 140 If unsure, say Y. 141 142config BSD_PROCESS_ACCT 143 bool "BSD Process Accounting" 144 help 145 If you say Y here, a user level program will be able to instruct the 146 kernel (via a special system call) to write process accounting 147 information to a file: whenever a process exits, information about 148 that process will be appended to the file by the kernel. The 149 information includes things such as creation time, owning user, 150 command name, memory usage, controlling terminal etc. (the complete 151 list is in the struct acct in <file:include/linux/acct.h>). It is 152 up to the user level program to do useful things with this 153 information. This is generally a good idea, so say Y. 154 155config BSD_PROCESS_ACCT_V3 156 bool "BSD Process Accounting version 3 file format" 157 depends on BSD_PROCESS_ACCT 158 default n 159 help 160 If you say Y here, the process accounting information is written 161 in a new file format that also logs the process IDs of each 162 process and it's parent. Note that this file format is incompatible 163 with previous v0/v1/v2 file formats, so you will need updated tools 164 for processing it. A preliminary version of these tools is available 165 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>. 166 167config TASKSTATS 168 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 169 depends on NET 170 default n 171 help 172 Export selected statistics for tasks/processes through the 173 generic netlink interface. Unlike BSD process accounting, the 174 statistics are available during the lifetime of tasks/processes as 175 responses to commands. Like BSD accounting, they are sent to user 176 space on task exit. 177 178 Say N if unsure. 179 180config TASK_DELAY_ACCT 181 bool "Enable per-task delay accounting (EXPERIMENTAL)" 182 depends on TASKSTATS 183 help 184 Collect information on time spent by a task waiting for system 185 resources like cpu, synchronous block I/O completion and swapping 186 in pages. Such statistics can help in setting a task's priorities 187 relative to other tasks for cpu, io, rss limits etc. 188 189 Say N if unsure. 190 191config TASK_XACCT 192 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 193 depends on TASKSTATS 194 help 195 Collect extended task accounting data and send the data 196 to userland for processing over the taskstats interface. 197 198 Say N if unsure. 199 200config TASK_IO_ACCOUNTING 201 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 202 depends on TASK_XACCT 203 help 204 Collect information on the number of bytes of storage I/O which this 205 task has caused. 206 207 Say N if unsure. 208 209config USER_NS 210 bool "User Namespaces (EXPERIMENTAL)" 211 default n 212 depends on EXPERIMENTAL 213 help 214 Support user namespaces. This allows containers, i.e. 215 vservers, to use user namespaces to provide different 216 user info for different servers. If unsure, say N. 217 218config PID_NS 219 bool "PID Namespaces (EXPERIMENTAL)" 220 default n 221 depends on EXPERIMENTAL 222 help 223 Suport process id namespaces. This allows having multiple 224 process with the same pid as long as they are in different 225 pid namespaces. This is a building block of containers. 226 227 Unless you want to work with an experimental feature 228 say N here. 229 230config AUDIT 231 bool "Auditing support" 232 depends on NET 233 help 234 Enable auditing infrastructure that can be used with another 235 kernel subsystem, such as SELinux (which requires this for 236 logging of avc messages output). Does not do system-call 237 auditing without CONFIG_AUDITSYSCALL. 238 239config AUDITSYSCALL 240 bool "Enable system-call auditing support" 241 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH) 242 default y if SECURITY_SELINUX 243 help 244 Enable low-overhead system-call auditing infrastructure that 245 can be used independently or with another kernel subsystem, 246 such as SELinux. To use audit's filesystem watch feature, please 247 ensure that INOTIFY is configured. 248 249config AUDIT_TREE 250 def_bool y 251 depends on AUDITSYSCALL && INOTIFY 252 253config IKCONFIG 254 tristate "Kernel .config support" 255 ---help--- 256 This option enables the complete Linux kernel ".config" file 257 contents to be saved in the kernel. It provides documentation 258 of which kernel options are used in a running kernel or in an 259 on-disk kernel. This information can be extracted from the kernel 260 image file with the script scripts/extract-ikconfig and used as 261 input to rebuild the current kernel or to build another kernel. 262 It can also be extracted from a running kernel by reading 263 /proc/config.gz if enabled (below). 264 265config IKCONFIG_PROC 266 bool "Enable access to .config through /proc/config.gz" 267 depends on IKCONFIG && PROC_FS 268 ---help--- 269 This option enables access to the kernel configuration file 270 through /proc/config.gz. 271 272config LOG_BUF_SHIFT 273 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 274 range 12 21 275 default 17 if S390 || LOCKDEP 276 default 16 if X86_NUMAQ || IA64 277 default 15 if SMP 278 default 14 279 help 280 Select kernel log buffer size as a power of 2. 281 Defaults and Examples: 282 17 => 128 KB for S/390 283 16 => 64 KB for x86 NUMAQ or IA-64 284 15 => 32 KB for SMP 285 14 => 16 KB for uniprocessor 286 13 => 8 KB 287 12 => 4 KB 288 289config CGROUPS 290 bool "Control Group support" 291 help 292 This option will let you use process cgroup subsystems 293 such as Cpusets 294 295 Say N if unsure. 296 297config CGROUP_DEBUG 298 bool "Example debug cgroup subsystem" 299 depends on CGROUPS 300 help 301 This option enables a simple cgroup subsystem that 302 exports useful debugging information about the cgroups 303 framework 304 305 Say N if unsure 306 307config CGROUP_NS 308 bool "Namespace cgroup subsystem" 309 depends on CGROUPS 310 help 311 Provides a simple namespace cgroup subsystem to 312 provide hierarchical naming of sets of namespaces, 313 for instance virtual servers and checkpoint/restart 314 jobs. 315 316config CPUSETS 317 bool "Cpuset support" 318 depends on SMP && CGROUPS 319 help 320 This option will let you create and manage CPUSETs which 321 allow dynamically partitioning a system into sets of CPUs and 322 Memory Nodes and assigning tasks to run only within those sets. 323 This is primarily useful on large SMP or NUMA systems. 324 325 Say N if unsure. 326 327config FAIR_GROUP_SCHED 328 bool "Fair group CPU scheduler" 329 default y 330 help 331 This feature lets CPU scheduler recognize task groups and control CPU 332 bandwidth allocation to such task groups. 333 334choice 335 depends on FAIR_GROUP_SCHED 336 prompt "Basis for grouping tasks" 337 default FAIR_USER_SCHED 338 339config FAIR_USER_SCHED 340 bool "user id" 341 help 342 This option will choose userid as the basis for grouping 343 tasks, thus providing equal CPU bandwidth to each user. 344 345config FAIR_CGROUP_SCHED 346 bool "Control groups" 347 depends on CGROUPS 348 help 349 This option allows you to create arbitrary task groups 350 using the "cgroup" pseudo filesystem and control 351 the cpu bandwidth allocated to each such task group. 352 Refer to Documentation/cgroups.txt for more information 353 on "cgroup" pseudo filesystem. 354 355endchoice 356 357config CGROUP_CPUACCT 358 bool "Simple CPU accounting cgroup subsystem" 359 depends on CGROUPS 360 help 361 Provides a simple Resource Controller for monitoring the 362 total CPU consumed by the tasks in a cgroup 363 364config SYSFS_DEPRECATED 365 bool "Create deprecated sysfs files" 366 depends on SYSFS 367 default y 368 help 369 This option creates deprecated symlinks such as the 370 "device"-link, the <subsystem>:<name>-link, and the 371 "bus"-link. It may also add deprecated key in the 372 uevent environment. 373 None of these features or values should be used today, as 374 they export driver core implementation details to userspace 375 or export properties which can't be kept stable across kernel 376 releases. 377 378 If enabled, this option will also move any device structures 379 that belong to a class, back into the /sys/class hierarchy, in 380 order to support older versions of udev. 381 382 If you are using a distro that was released in 2006 or later, 383 it should be safe to say N here. 384 385config PROC_PID_CPUSET 386 bool "Include legacy /proc/<pid>/cpuset file" 387 depends on CPUSETS 388 default y 389 390config RELAY 391 bool "Kernel->user space relay support (formerly relayfs)" 392 help 393 This option enables support for relay interface support in 394 certain file systems (such as debugfs). 395 It is designed to provide an efficient mechanism for tools and 396 facilities to relay large amounts of data from kernel space to 397 user space. 398 399 If unsure, say N. 400 401config BLK_DEV_INITRD 402 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 403 depends on BROKEN || !FRV 404 help 405 The initial RAM filesystem is a ramfs which is loaded by the 406 boot loader (loadlin or lilo) and that is mounted as root 407 before the normal boot procedure. It is typically used to 408 load modules needed to mount the "real" root file system, 409 etc. See <file:Documentation/initrd.txt> for details. 410 411 If RAM disk support (BLK_DEV_RAM) is also included, this 412 also enables initial RAM disk (initrd) support and adds 413 15 Kbytes (more on some other architectures) to the kernel size. 414 415 If unsure say Y. 416 417if BLK_DEV_INITRD 418 419source "usr/Kconfig" 420 421endif 422 423config CC_OPTIMIZE_FOR_SIZE 424 bool "Optimize for size (Look out for broken compilers!)" 425 default y 426 depends on ARM || H8300 || SUPERH || EXPERIMENTAL 427 help 428 Enabling this option will pass "-Os" instead of "-O2" to gcc 429 resulting in a smaller kernel. 430 431 WARNING: some versions of gcc may generate incorrect code with this 432 option. If problems are observed, a gcc upgrade may be needed. 433 434 If unsure, say N. 435 436config SYSCTL 437 bool 438 439menuconfig EMBEDDED 440 bool "Configure standard kernel features (for small systems)" 441 help 442 This option allows certain base kernel options and settings 443 to be disabled or tweaked. This is for specialized 444 environments which can tolerate a "non-standard" kernel. 445 Only use this if you really know what you are doing. 446 447config UID16 448 bool "Enable 16-bit UID system calls" if EMBEDDED 449 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION) 450 default y 451 help 452 This enables the legacy 16-bit UID syscall wrappers. 453 454config SYSCTL_SYSCALL 455 bool "Sysctl syscall support" if EMBEDDED 456 default y 457 select SYSCTL 458 ---help--- 459 sys_sysctl uses binary paths that have been found challenging 460 to properly maintain and use. The interface in /proc/sys 461 using paths with ascii names is now the primary path to this 462 information. 463 464 Almost nothing using the binary sysctl interface so if you are 465 trying to save some space it is probably safe to disable this, 466 making your kernel marginally smaller. 467 468 If unsure say Y here. 469 470config KALLSYMS 471 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 472 default y 473 help 474 Say Y here to let the kernel print out symbolic crash information and 475 symbolic stack backtraces. This increases the size of the kernel 476 somewhat, as all symbols have to be loaded into the kernel image. 477 478config KALLSYMS_ALL 479 bool "Include all symbols in kallsyms" 480 depends on DEBUG_KERNEL && KALLSYMS 481 help 482 Normally kallsyms only contains the symbols of functions, for nicer 483 OOPS messages. Some debuggers can use kallsyms for other 484 symbols too: say Y here to include all symbols, if you need them 485 and you don't care about adding 300k to the size of your kernel. 486 487 Say N. 488 489config KALLSYMS_EXTRA_PASS 490 bool "Do an extra kallsyms pass" 491 depends on KALLSYMS 492 help 493 If kallsyms is not working correctly, the build will fail with 494 inconsistent kallsyms data. If that occurs, log a bug report and 495 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 496 Always say N here unless you find a bug in kallsyms, which must be 497 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 498 you wait for kallsyms to be fixed. 499 500 501config HOTPLUG 502 bool "Support for hot-pluggable devices" if EMBEDDED 503 default y 504 help 505 This option is provided for the case where no hotplug or uevent 506 capabilities is wanted by the kernel. You should only consider 507 disabling this option for embedded systems that do not use modules, a 508 dynamic /dev tree, or dynamic device discovery. Just say Y. 509 510config PRINTK 511 default y 512 bool "Enable support for printk" if EMBEDDED 513 help 514 This option enables normal printk support. Removing it 515 eliminates most of the message strings from the kernel image 516 and makes the kernel more or less silent. As this makes it 517 very difficult to diagnose system problems, saying N here is 518 strongly discouraged. 519 520config BUG 521 bool "BUG() support" if EMBEDDED 522 default y 523 help 524 Disabling this option eliminates support for BUG and WARN, reducing 525 the size of your kernel image and potentially quietly ignoring 526 numerous fatal conditions. You should only consider disabling this 527 option for embedded systems with no facilities for reporting errors. 528 Just say Y. 529 530config ELF_CORE 531 default y 532 bool "Enable ELF core dumps" if EMBEDDED 533 help 534 Enable support for generating core dumps. Disabling saves about 4k. 535 536config BASE_FULL 537 default y 538 bool "Enable full-sized data structures for core" if EMBEDDED 539 help 540 Disabling this option reduces the size of miscellaneous core 541 kernel data structures. This saves memory on small machines, 542 but may reduce performance. 543 544config FUTEX 545 bool "Enable futex support" if EMBEDDED 546 default y 547 select RT_MUTEXES 548 help 549 Disabling this option will cause the kernel to be built without 550 support for "fast userspace mutexes". The resulting kernel may not 551 run glibc-based applications correctly. 552 553config ANON_INODES 554 bool 555 556config EPOLL 557 bool "Enable eventpoll support" if EMBEDDED 558 default y 559 select ANON_INODES 560 help 561 Disabling this option will cause the kernel to be built without 562 support for epoll family of system calls. 563 564config SIGNALFD 565 bool "Enable signalfd() system call" if EMBEDDED 566 select ANON_INODES 567 default y 568 help 569 Enable the signalfd() system call that allows to receive signals 570 on a file descriptor. 571 572 If unsure, say Y. 573 574config TIMERFD 575 bool "Enable timerfd() system call" if EMBEDDED 576 select ANON_INODES 577 depends on BROKEN 578 default y 579 help 580 Enable the timerfd() system call that allows to receive timer 581 events on a file descriptor. 582 583 If unsure, say Y. 584 585config EVENTFD 586 bool "Enable eventfd() system call" if EMBEDDED 587 select ANON_INODES 588 default y 589 help 590 Enable the eventfd() system call that allows to receive both 591 kernel notification (ie. KAIO) or userspace notifications. 592 593 If unsure, say Y. 594 595config SHMEM 596 bool "Use full shmem filesystem" if EMBEDDED 597 default y 598 depends on MMU 599 help 600 The shmem is an internal filesystem used to manage shared memory. 601 It is backed by swap and manages resource limits. It is also exported 602 to userspace as tmpfs if TMPFS is enabled. Disabling this 603 option replaces shmem and tmpfs with the much simpler ramfs code, 604 which may be appropriate on small systems without swap. 605 606config VM_EVENT_COUNTERS 607 default y 608 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 609 help 610 VM event counters are needed for event counts to be shown. 611 This option allows the disabling of the VM event counters 612 on EMBEDDED systems. /proc/vmstat will only show page counts 613 if VM event counters are disabled. 614 615config SLUB_DEBUG 616 default y 617 bool "Enable SLUB debugging support" if EMBEDDED 618 depends on SLUB 619 help 620 SLUB has extensive debug support features. Disabling these can 621 result in significant savings in code size. This also disables 622 SLUB sysfs support. /sys/slab will not exist and there will be 623 no support for cache validation etc. 624 625choice 626 prompt "Choose SLAB allocator" 627 default SLUB 628 help 629 This option allows to select a slab allocator. 630 631config SLAB 632 bool "SLAB" 633 help 634 The regular slab allocator that is established and known to work 635 well in all environments. It organizes cache hot objects in 636 per cpu and per node queues. SLAB is the default choice for 637 a slab allocator. 638 639config SLUB 640 bool "SLUB (Unqueued Allocator)" 641 help 642 SLUB is a slab allocator that minimizes cache line usage 643 instead of managing queues of cached objects (SLAB approach). 644 Per cpu caching is realized using slabs of objects instead 645 of queues of objects. SLUB can use memory efficiently 646 and has enhanced diagnostics. 647 648config SLOB 649 depends on EMBEDDED 650 bool "SLOB (Simple Allocator)" 651 help 652 SLOB replaces the SLAB allocator with a drastically simpler 653 allocator. SLOB is more space efficient than SLAB but does not 654 scale well (single lock for all operations) and is also highly 655 susceptible to fragmentation. SLUB can accomplish a higher object 656 density. It is usually better to use SLUB instead of SLOB. 657 658endchoice 659 660endmenu # General setup 661 662config SLABINFO 663 bool 664 depends on PROC_FS 665 depends on SLAB || SLUB 666 default y 667 668config RT_MUTEXES 669 boolean 670 select PLIST 671 672config TINY_SHMEM 673 default !SHMEM 674 bool 675 676config BASE_SMALL 677 int 678 default 0 if BASE_FULL 679 default 1 if !BASE_FULL 680 681menuconfig MODULES 682 bool "Enable loadable module support" 683 help 684 Kernel modules are small pieces of compiled code which can 685 be inserted in the running kernel, rather than being 686 permanently built into the kernel. You use the "modprobe" 687 tool to add (and sometimes remove) them. If you say Y here, 688 many parts of the kernel can be built as modules (by 689 answering M instead of Y where indicated): this is most 690 useful for infrequently used options which are not required 691 for booting. For more information, see the man pages for 692 modprobe, lsmod, modinfo, insmod and rmmod. 693 694 If you say Y here, you will need to run "make 695 modules_install" to put the modules under /lib/modules/ 696 where modprobe can find them (you may need to be root to do 697 this). 698 699 If unsure, say Y. 700 701config MODULE_UNLOAD 702 bool "Module unloading" 703 depends on MODULES 704 help 705 Without this option you will not be able to unload any 706 modules (note that some modules may not be unloadable 707 anyway), which makes your kernel slightly smaller and 708 simpler. If unsure, say Y. 709 710config MODULE_FORCE_UNLOAD 711 bool "Forced module unloading" 712 depends on MODULE_UNLOAD && EXPERIMENTAL 713 help 714 This option allows you to force a module to unload, even if the 715 kernel believes it is unsafe: the kernel will remove the module 716 without waiting for anyone to stop using it (using the -f option to 717 rmmod). This is mainly for kernel developers and desperate users. 718 If unsure, say N. 719 720config MODVERSIONS 721 bool "Module versioning support" 722 depends on MODULES 723 help 724 Usually, you have to use modules compiled with your kernel. 725 Saying Y here makes it sometimes possible to use modules 726 compiled for different kernels, by adding enough information 727 to the modules to (hopefully) spot any changes which would 728 make them incompatible with the kernel you are running. If 729 unsure, say N. 730 731config MODULE_SRCVERSION_ALL 732 bool "Source checksum for all modules" 733 depends on MODULES 734 help 735 Modules which contain a MODULE_VERSION get an extra "srcversion" 736 field inserted into their modinfo section, which contains a 737 sum of the source files which made it. This helps maintainers 738 see exactly which source was used to build a module (since 739 others sometimes change the module source without updating 740 the version). With this option, such a "srcversion" field 741 will be created for all modules. If unsure, say N. 742 743config KMOD 744 bool "Automatic kernel module loading" 745 depends on MODULES 746 help 747 Normally when you have selected some parts of the kernel to 748 be created as kernel modules, you must load them (using the 749 "modprobe" command) before you can use them. If you say Y 750 here, some parts of the kernel will be able to load modules 751 automatically: when a part of the kernel needs a module, it 752 runs modprobe with the appropriate arguments, thereby 753 loading the module if it is available. If unsure, say Y. 754 755config STOP_MACHINE 756 bool 757 default y 758 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 759 help 760 Need stop_machine() primitive. 761 762source "block/Kconfig" 763 764config PREEMPT_NOTIFIERS 765 bool 766 767choice 768 prompt "RCU implementation type:" 769 default CLASSIC_RCU 770 771config CLASSIC_RCU 772 bool "Classic RCU" 773 help 774 This option selects the classic RCU implementation that is 775 designed for best read-side performance on non-realtime 776 systems. 777 778 Say Y if you are unsure. 779 780config PREEMPT_RCU 781 bool "Preemptible RCU" 782 depends on PREEMPT 783 help 784 This option reduces the latency of the kernel by making certain 785 RCU sections preemptible. Normally RCU code is non-preemptible, if 786 this option is selected then read-only RCU sections become 787 preemptible. This helps latency, but may expose bugs due to 788 now-naive assumptions about each RCU read-side critical section 789 remaining on a given CPU through its execution. 790 791 Say N if you are unsure. 792 793endchoice 794