1config ARCH 2 string 3 option env="ARCH" 4 5config KERNELVERSION 6 string 7 option env="KERNELVERSION" 8 9config DEFCONFIG_LIST 10 string 11 depends on !UML 12 option defconfig_list 13 default "/lib/modules/$UNAME_RELEASE/.config" 14 default "/etc/kernel-config" 15 default "/boot/config-$UNAME_RELEASE" 16 default "arch/$ARCH/defconfig" 17 18menu "General setup" 19 20config EXPERIMENTAL 21 bool "Prompt for development and/or incomplete code/drivers" 22 ---help--- 23 Some of the various things that Linux supports (such as network 24 drivers, file systems, network protocols, etc.) can be in a state 25 of development where the functionality, stability, or the level of 26 testing is not yet high enough for general use. This is usually 27 known as the "alpha-test" phase among developers. If a feature is 28 currently in alpha-test, then the developers usually discourage 29 uninformed widespread use of this feature by the general public to 30 avoid "Why doesn't this work?" type mail messages. However, active 31 testing and use of these systems is welcomed. Just be aware that it 32 may not meet the normal level of reliability or it may fail to work 33 in some special cases. Detailed bug reports from people familiar 34 with the kernel internals are usually welcomed by the developers 35 (before submitting bug reports, please read the documents 36 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 37 <file:Documentation/BUG-HUNTING>, and 38 <file:Documentation/oops-tracing.txt> in the kernel source). 39 40 This option will also make obsoleted drivers available. These are 41 drivers that have been replaced by something else, and/or are 42 scheduled to be removed in a future kernel release. 43 44 Unless you intend to help test and develop a feature or driver that 45 falls into this category, or you have a situation that requires 46 using these features, you should probably say N here, which will 47 cause the configurator to present you with fewer choices. If 48 you say Y here, you will be offered the choice of using features or 49 drivers that are currently considered to be in the alpha-test phase. 50 51config BROKEN 52 bool 53 54config BROKEN_ON_SMP 55 bool 56 depends on BROKEN || !SMP 57 default y 58 59config LOCK_KERNEL 60 bool 61 depends on SMP || PREEMPT 62 default y 63 64config INIT_ENV_ARG_LIMIT 65 int 66 default 32 if !UML 67 default 128 if UML 68 help 69 Maximum of each of the number of arguments and environment 70 variables passed to init from the kernel command line. 71 72 73config LOCALVERSION 74 string "Local version - append to kernel release" 75 help 76 Append an extra string to the end of your kernel version. 77 This will show up when you type uname, for example. 78 The string you set here will be appended after the contents of 79 any files with a filename matching localversion* in your 80 object and source tree, in that order. Your total string can 81 be a maximum of 64 characters. 82 83config LOCALVERSION_AUTO 84 bool "Automatically append version information to the version string" 85 default y 86 help 87 This will try to automatically determine if the current tree is a 88 release tree by looking for git tags that belong to the current 89 top of tree revision. 90 91 A string of the format -gxxxxxxxx will be added to the localversion 92 if a git-based tree is found. The string generated by this will be 93 appended after any matching localversion* files, and after the value 94 set in CONFIG_LOCALVERSION. 95 96 (The actual string used here is the first eight characters produced 97 by running the command: 98 99 $ git rev-parse --verify HEAD 100 101 which is done within the script "scripts/setlocalversion".) 102 103config SWAP 104 bool "Support for paging of anonymous memory (swap)" 105 depends on MMU && BLOCK 106 default y 107 help 108 This option allows you to choose whether you want to have support 109 for so called swap devices or swap files in your kernel that are 110 used to provide more virtual memory than the actual RAM present 111 in your computer. If unsure say Y. 112 113config SYSVIPC 114 bool "System V IPC" 115 ---help--- 116 Inter Process Communication is a suite of library functions and 117 system calls which let processes (running programs) synchronize and 118 exchange information. It is generally considered to be a good thing, 119 and some programs won't run unless you say Y here. In particular, if 120 you want to run the DOS emulator dosemu under Linux (read the 121 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 122 you'll need to say Y here. 123 124 You can find documentation about IPC with "info ipc" and also in 125 section 6.4 of the Linux Programmer's Guide, available from 126 <http://www.tldp.org/guides.html>. 127 128config SYSVIPC_SYSCTL 129 bool 130 depends on SYSVIPC 131 depends on SYSCTL 132 default y 133 134config POSIX_MQUEUE 135 bool "POSIX Message Queues" 136 depends on NET && EXPERIMENTAL 137 ---help--- 138 POSIX variant of message queues is a part of IPC. In POSIX message 139 queues every message has a priority which decides about succession 140 of receiving it by a process. If you want to compile and run 141 programs written e.g. for Solaris with use of its POSIX message 142 queues (functions mq_*) say Y here. 143 144 POSIX message queues are visible as a filesystem called 'mqueue' 145 and can be mounted somewhere if you want to do filesystem 146 operations on message queues. 147 148 If unsure, say Y. 149 150config BSD_PROCESS_ACCT 151 bool "BSD Process Accounting" 152 help 153 If you say Y here, a user level program will be able to instruct the 154 kernel (via a special system call) to write process accounting 155 information to a file: whenever a process exits, information about 156 that process will be appended to the file by the kernel. The 157 information includes things such as creation time, owning user, 158 command name, memory usage, controlling terminal etc. (the complete 159 list is in the struct acct in <file:include/linux/acct.h>). It is 160 up to the user level program to do useful things with this 161 information. This is generally a good idea, so say Y. 162 163config BSD_PROCESS_ACCT_V3 164 bool "BSD Process Accounting version 3 file format" 165 depends on BSD_PROCESS_ACCT 166 default n 167 help 168 If you say Y here, the process accounting information is written 169 in a new file format that also logs the process IDs of each 170 process and it's parent. Note that this file format is incompatible 171 with previous v0/v1/v2 file formats, so you will need updated tools 172 for processing it. A preliminary version of these tools is available 173 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>. 174 175config TASKSTATS 176 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 177 depends on NET 178 default n 179 help 180 Export selected statistics for tasks/processes through the 181 generic netlink interface. Unlike BSD process accounting, the 182 statistics are available during the lifetime of tasks/processes as 183 responses to commands. Like BSD accounting, they are sent to user 184 space on task exit. 185 186 Say N if unsure. 187 188config TASK_DELAY_ACCT 189 bool "Enable per-task delay accounting (EXPERIMENTAL)" 190 depends on TASKSTATS 191 help 192 Collect information on time spent by a task waiting for system 193 resources like cpu, synchronous block I/O completion and swapping 194 in pages. Such statistics can help in setting a task's priorities 195 relative to other tasks for cpu, io, rss limits etc. 196 197 Say N if unsure. 198 199config TASK_XACCT 200 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 201 depends on TASKSTATS 202 help 203 Collect extended task accounting data and send the data 204 to userland for processing over the taskstats interface. 205 206 Say N if unsure. 207 208config TASK_IO_ACCOUNTING 209 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 210 depends on TASK_XACCT 211 help 212 Collect information on the number of bytes of storage I/O which this 213 task has caused. 214 215 Say N if unsure. 216 217config USER_NS 218 bool "User Namespaces (EXPERIMENTAL)" 219 default n 220 depends on EXPERIMENTAL 221 help 222 Support user namespaces. This allows containers, i.e. 223 vservers, to use user namespaces to provide different 224 user info for different servers. If unsure, say N. 225 226config PID_NS 227 bool "PID Namespaces (EXPERIMENTAL)" 228 default n 229 depends on EXPERIMENTAL 230 help 231 Suport process id namespaces. This allows having multiple 232 process with the same pid as long as they are in different 233 pid namespaces. This is a building block of containers. 234 235 Unless you want to work with an experimental feature 236 say N here. 237 238config AUDIT 239 bool "Auditing support" 240 depends on NET 241 help 242 Enable auditing infrastructure that can be used with another 243 kernel subsystem, such as SELinux (which requires this for 244 logging of avc messages output). Does not do system-call 245 auditing without CONFIG_AUDITSYSCALL. 246 247config AUDITSYSCALL 248 bool "Enable system-call auditing support" 249 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH) 250 default y if SECURITY_SELINUX 251 help 252 Enable low-overhead system-call auditing infrastructure that 253 can be used independently or with another kernel subsystem, 254 such as SELinux. To use audit's filesystem watch feature, please 255 ensure that INOTIFY is configured. 256 257config AUDIT_TREE 258 def_bool y 259 depends on AUDITSYSCALL && INOTIFY 260 261config IKCONFIG 262 tristate "Kernel .config support" 263 ---help--- 264 This option enables the complete Linux kernel ".config" file 265 contents to be saved in the kernel. It provides documentation 266 of which kernel options are used in a running kernel or in an 267 on-disk kernel. This information can be extracted from the kernel 268 image file with the script scripts/extract-ikconfig and used as 269 input to rebuild the current kernel or to build another kernel. 270 It can also be extracted from a running kernel by reading 271 /proc/config.gz if enabled (below). 272 273config IKCONFIG_PROC 274 bool "Enable access to .config through /proc/config.gz" 275 depends on IKCONFIG && PROC_FS 276 ---help--- 277 This option enables access to the kernel configuration file 278 through /proc/config.gz. 279 280config LOG_BUF_SHIFT 281 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 282 range 12 21 283 default 17 if S390 || LOCKDEP 284 default 16 if X86_NUMAQ || IA64 285 default 15 if SMP 286 default 14 287 help 288 Select kernel log buffer size as a power of 2. 289 Defaults and Examples: 290 17 => 128 KB for S/390 291 16 => 64 KB for x86 NUMAQ or IA-64 292 15 => 32 KB for SMP 293 14 => 16 KB for uniprocessor 294 13 => 8 KB 295 12 => 4 KB 296 297config CGROUPS 298 bool "Control Group support" 299 help 300 This option will let you use process cgroup subsystems 301 such as Cpusets 302 303 Say N if unsure. 304 305config CGROUP_DEBUG 306 bool "Example debug cgroup subsystem" 307 depends on CGROUPS 308 help 309 This option enables a simple cgroup subsystem that 310 exports useful debugging information about the cgroups 311 framework 312 313 Say N if unsure 314 315config CGROUP_NS 316 bool "Namespace cgroup subsystem" 317 depends on CGROUPS 318 help 319 Provides a simple namespace cgroup subsystem to 320 provide hierarchical naming of sets of namespaces, 321 for instance virtual servers and checkpoint/restart 322 jobs. 323 324config CPUSETS 325 bool "Cpuset support" 326 depends on SMP && CGROUPS 327 help 328 This option will let you create and manage CPUSETs which 329 allow dynamically partitioning a system into sets of CPUs and 330 Memory Nodes and assigning tasks to run only within those sets. 331 This is primarily useful on large SMP or NUMA systems. 332 333 Say N if unsure. 334 335config FAIR_GROUP_SCHED 336 bool "Fair group CPU scheduler" 337 default y 338 help 339 This feature lets CPU scheduler recognize task groups and control CPU 340 bandwidth allocation to such task groups. 341 342choice 343 depends on FAIR_GROUP_SCHED 344 prompt "Basis for grouping tasks" 345 default FAIR_USER_SCHED 346 347config FAIR_USER_SCHED 348 bool "user id" 349 help 350 This option will choose userid as the basis for grouping 351 tasks, thus providing equal CPU bandwidth to each user. 352 353config FAIR_CGROUP_SCHED 354 bool "Control groups" 355 depends on CGROUPS 356 help 357 This option allows you to create arbitrary task groups 358 using the "cgroup" pseudo filesystem and control 359 the cpu bandwidth allocated to each such task group. 360 Refer to Documentation/cgroups.txt for more information 361 on "cgroup" pseudo filesystem. 362 363endchoice 364 365config CGROUP_CPUACCT 366 bool "Simple CPU accounting cgroup subsystem" 367 depends on CGROUPS 368 help 369 Provides a simple Resource Controller for monitoring the 370 total CPU consumed by the tasks in a cgroup 371 372config SYSFS_DEPRECATED 373 bool "Create deprecated sysfs files" 374 depends on SYSFS 375 default y 376 help 377 This option creates deprecated symlinks such as the 378 "device"-link, the <subsystem>:<name>-link, and the 379 "bus"-link. It may also add deprecated key in the 380 uevent environment. 381 None of these features or values should be used today, as 382 they export driver core implementation details to userspace 383 or export properties which can't be kept stable across kernel 384 releases. 385 386 If enabled, this option will also move any device structures 387 that belong to a class, back into the /sys/class hierarchy, in 388 order to support older versions of udev. 389 390 If you are using a distro that was released in 2006 or later, 391 it should be safe to say N here. 392 393config PROC_PID_CPUSET 394 bool "Include legacy /proc/<pid>/cpuset file" 395 depends on CPUSETS 396 default y 397 398config RELAY 399 bool "Kernel->user space relay support (formerly relayfs)" 400 help 401 This option enables support for relay interface support in 402 certain file systems (such as debugfs). 403 It is designed to provide an efficient mechanism for tools and 404 facilities to relay large amounts of data from kernel space to 405 user space. 406 407 If unsure, say N. 408 409config BLK_DEV_INITRD 410 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 411 depends on BROKEN || !FRV 412 help 413 The initial RAM filesystem is a ramfs which is loaded by the 414 boot loader (loadlin or lilo) and that is mounted as root 415 before the normal boot procedure. It is typically used to 416 load modules needed to mount the "real" root file system, 417 etc. See <file:Documentation/initrd.txt> for details. 418 419 If RAM disk support (BLK_DEV_RAM) is also included, this 420 also enables initial RAM disk (initrd) support and adds 421 15 Kbytes (more on some other architectures) to the kernel size. 422 423 If unsure say Y. 424 425if BLK_DEV_INITRD 426 427source "usr/Kconfig" 428 429endif 430 431config CC_OPTIMIZE_FOR_SIZE 432 bool "Optimize for size (Look out for broken compilers!)" 433 default y 434 depends on ARM || H8300 || SUPERH || EXPERIMENTAL 435 help 436 Enabling this option will pass "-Os" instead of "-O2" to gcc 437 resulting in a smaller kernel. 438 439 WARNING: some versions of gcc may generate incorrect code with this 440 option. If problems are observed, a gcc upgrade may be needed. 441 442 If unsure, say N. 443 444config SYSCTL 445 bool 446 447menuconfig EMBEDDED 448 bool "Configure standard kernel features (for small systems)" 449 help 450 This option allows certain base kernel options and settings 451 to be disabled or tweaked. This is for specialized 452 environments which can tolerate a "non-standard" kernel. 453 Only use this if you really know what you are doing. 454 455config UID16 456 bool "Enable 16-bit UID system calls" if EMBEDDED 457 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION) 458 default y 459 help 460 This enables the legacy 16-bit UID syscall wrappers. 461 462config SYSCTL_SYSCALL 463 bool "Sysctl syscall support" if EMBEDDED 464 default y 465 select SYSCTL 466 ---help--- 467 sys_sysctl uses binary paths that have been found challenging 468 to properly maintain and use. The interface in /proc/sys 469 using paths with ascii names is now the primary path to this 470 information. 471 472 Almost nothing using the binary sysctl interface so if you are 473 trying to save some space it is probably safe to disable this, 474 making your kernel marginally smaller. 475 476 If unsure say Y here. 477 478config KALLSYMS 479 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 480 default y 481 help 482 Say Y here to let the kernel print out symbolic crash information and 483 symbolic stack backtraces. This increases the size of the kernel 484 somewhat, as all symbols have to be loaded into the kernel image. 485 486config KALLSYMS_ALL 487 bool "Include all symbols in kallsyms" 488 depends on DEBUG_KERNEL && KALLSYMS 489 help 490 Normally kallsyms only contains the symbols of functions, for nicer 491 OOPS messages. Some debuggers can use kallsyms for other 492 symbols too: say Y here to include all symbols, if you need them 493 and you don't care about adding 300k to the size of your kernel. 494 495 Say N. 496 497config KALLSYMS_EXTRA_PASS 498 bool "Do an extra kallsyms pass" 499 depends on KALLSYMS 500 help 501 If kallsyms is not working correctly, the build will fail with 502 inconsistent kallsyms data. If that occurs, log a bug report and 503 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 504 Always say N here unless you find a bug in kallsyms, which must be 505 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 506 you wait for kallsyms to be fixed. 507 508 509config HOTPLUG 510 bool "Support for hot-pluggable devices" if EMBEDDED 511 default y 512 help 513 This option is provided for the case where no hotplug or uevent 514 capabilities is wanted by the kernel. You should only consider 515 disabling this option for embedded systems that do not use modules, a 516 dynamic /dev tree, or dynamic device discovery. Just say Y. 517 518config PRINTK 519 default y 520 bool "Enable support for printk" if EMBEDDED 521 help 522 This option enables normal printk support. Removing it 523 eliminates most of the message strings from the kernel image 524 and makes the kernel more or less silent. As this makes it 525 very difficult to diagnose system problems, saying N here is 526 strongly discouraged. 527 528config BUG 529 bool "BUG() support" if EMBEDDED 530 default y 531 help 532 Disabling this option eliminates support for BUG and WARN, reducing 533 the size of your kernel image and potentially quietly ignoring 534 numerous fatal conditions. You should only consider disabling this 535 option for embedded systems with no facilities for reporting errors. 536 Just say Y. 537 538config ELF_CORE 539 default y 540 bool "Enable ELF core dumps" if EMBEDDED 541 help 542 Enable support for generating core dumps. Disabling saves about 4k. 543 544config BASE_FULL 545 default y 546 bool "Enable full-sized data structures for core" if EMBEDDED 547 help 548 Disabling this option reduces the size of miscellaneous core 549 kernel data structures. This saves memory on small machines, 550 but may reduce performance. 551 552config FUTEX 553 bool "Enable futex support" if EMBEDDED 554 default y 555 select RT_MUTEXES 556 help 557 Disabling this option will cause the kernel to be built without 558 support for "fast userspace mutexes". The resulting kernel may not 559 run glibc-based applications correctly. 560 561config ANON_INODES 562 bool 563 564config EPOLL 565 bool "Enable eventpoll support" if EMBEDDED 566 default y 567 select ANON_INODES 568 help 569 Disabling this option will cause the kernel to be built without 570 support for epoll family of system calls. 571 572config SIGNALFD 573 bool "Enable signalfd() system call" if EMBEDDED 574 select ANON_INODES 575 default y 576 help 577 Enable the signalfd() system call that allows to receive signals 578 on a file descriptor. 579 580 If unsure, say Y. 581 582config TIMERFD 583 bool "Enable timerfd() system call" if EMBEDDED 584 select ANON_INODES 585 depends on BROKEN 586 default y 587 help 588 Enable the timerfd() system call that allows to receive timer 589 events on a file descriptor. 590 591 If unsure, say Y. 592 593config EVENTFD 594 bool "Enable eventfd() system call" if EMBEDDED 595 select ANON_INODES 596 default y 597 help 598 Enable the eventfd() system call that allows to receive both 599 kernel notification (ie. KAIO) or userspace notifications. 600 601 If unsure, say Y. 602 603config SHMEM 604 bool "Use full shmem filesystem" if EMBEDDED 605 default y 606 depends on MMU 607 help 608 The shmem is an internal filesystem used to manage shared memory. 609 It is backed by swap and manages resource limits. It is also exported 610 to userspace as tmpfs if TMPFS is enabled. Disabling this 611 option replaces shmem and tmpfs with the much simpler ramfs code, 612 which may be appropriate on small systems without swap. 613 614config VM_EVENT_COUNTERS 615 default y 616 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 617 help 618 VM event counters are needed for event counts to be shown. 619 This option allows the disabling of the VM event counters 620 on EMBEDDED systems. /proc/vmstat will only show page counts 621 if VM event counters are disabled. 622 623config SLUB_DEBUG 624 default y 625 bool "Enable SLUB debugging support" if EMBEDDED 626 depends on SLUB 627 help 628 SLUB has extensive debug support features. Disabling these can 629 result in significant savings in code size. This also disables 630 SLUB sysfs support. /sys/slab will not exist and there will be 631 no support for cache validation etc. 632 633choice 634 prompt "Choose SLAB allocator" 635 default SLUB 636 help 637 This option allows to select a slab allocator. 638 639config SLAB 640 bool "SLAB" 641 help 642 The regular slab allocator that is established and known to work 643 well in all environments. It organizes cache hot objects in 644 per cpu and per node queues. SLAB is the default choice for 645 a slab allocator. 646 647config SLUB 648 bool "SLUB (Unqueued Allocator)" 649 help 650 SLUB is a slab allocator that minimizes cache line usage 651 instead of managing queues of cached objects (SLAB approach). 652 Per cpu caching is realized using slabs of objects instead 653 of queues of objects. SLUB can use memory efficiently 654 and has enhanced diagnostics. 655 656config SLOB 657 depends on EMBEDDED 658 bool "SLOB (Simple Allocator)" 659 help 660 SLOB replaces the SLAB allocator with a drastically simpler 661 allocator. SLOB is more space efficient than SLAB but does not 662 scale well (single lock for all operations) and is also highly 663 susceptible to fragmentation. SLUB can accomplish a higher object 664 density. It is usually better to use SLUB instead of SLOB. 665 666endchoice 667 668endmenu # General setup 669 670config SLABINFO 671 bool 672 depends on PROC_FS 673 depends on SLAB || SLUB 674 default y 675 676config RT_MUTEXES 677 boolean 678 select PLIST 679 680config TINY_SHMEM 681 default !SHMEM 682 bool 683 684config BASE_SMALL 685 int 686 default 0 if BASE_FULL 687 default 1 if !BASE_FULL 688 689menuconfig MODULES 690 bool "Enable loadable module support" 691 help 692 Kernel modules are small pieces of compiled code which can 693 be inserted in the running kernel, rather than being 694 permanently built into the kernel. You use the "modprobe" 695 tool to add (and sometimes remove) them. If you say Y here, 696 many parts of the kernel can be built as modules (by 697 answering M instead of Y where indicated): this is most 698 useful for infrequently used options which are not required 699 for booting. For more information, see the man pages for 700 modprobe, lsmod, modinfo, insmod and rmmod. 701 702 If you say Y here, you will need to run "make 703 modules_install" to put the modules under /lib/modules/ 704 where modprobe can find them (you may need to be root to do 705 this). 706 707 If unsure, say Y. 708 709config MODULE_UNLOAD 710 bool "Module unloading" 711 depends on MODULES 712 help 713 Without this option you will not be able to unload any 714 modules (note that some modules may not be unloadable 715 anyway), which makes your kernel slightly smaller and 716 simpler. If unsure, say Y. 717 718config MODULE_FORCE_UNLOAD 719 bool "Forced module unloading" 720 depends on MODULE_UNLOAD && EXPERIMENTAL 721 help 722 This option allows you to force a module to unload, even if the 723 kernel believes it is unsafe: the kernel will remove the module 724 without waiting for anyone to stop using it (using the -f option to 725 rmmod). This is mainly for kernel developers and desperate users. 726 If unsure, say N. 727 728config MODVERSIONS 729 bool "Module versioning support" 730 depends on MODULES 731 help 732 Usually, you have to use modules compiled with your kernel. 733 Saying Y here makes it sometimes possible to use modules 734 compiled for different kernels, by adding enough information 735 to the modules to (hopefully) spot any changes which would 736 make them incompatible with the kernel you are running. If 737 unsure, say N. 738 739config MODULE_SRCVERSION_ALL 740 bool "Source checksum for all modules" 741 depends on MODULES 742 help 743 Modules which contain a MODULE_VERSION get an extra "srcversion" 744 field inserted into their modinfo section, which contains a 745 sum of the source files which made it. This helps maintainers 746 see exactly which source was used to build a module (since 747 others sometimes change the module source without updating 748 the version). With this option, such a "srcversion" field 749 will be created for all modules. If unsure, say N. 750 751config KMOD 752 bool "Automatic kernel module loading" 753 depends on MODULES 754 help 755 Normally when you have selected some parts of the kernel to 756 be created as kernel modules, you must load them (using the 757 "modprobe" command) before you can use them. If you say Y 758 here, some parts of the kernel will be able to load modules 759 automatically: when a part of the kernel needs a module, it 760 runs modprobe with the appropriate arguments, thereby 761 loading the module if it is available. If unsure, say Y. 762 763config STOP_MACHINE 764 bool 765 default y 766 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 767 help 768 Need stop_machine() primitive. 769 770source "block/Kconfig" 771 772config PREEMPT_NOTIFIERS 773 bool 774 775choice 776 prompt "RCU implementation type:" 777 default CLASSIC_RCU 778 help 779 This allows you to choose either the classic RCU implementation 780 that is designed for best read-side performance on non-realtime 781 systems, or the preemptible RCU implementation for best latency 782 on realtime systems. Note that some kernel preemption modes 783 will restrict your choice. 784 785 Select the default if you are unsure. 786 787config CLASSIC_RCU 788 bool "Classic RCU" 789 help 790 This option selects the classic RCU implementation that is 791 designed for best read-side performance on non-realtime 792 systems. 793 794 Say Y if you are unsure. 795 796config PREEMPT_RCU 797 bool "Preemptible RCU" 798 depends on PREEMPT 799 help 800 This option reduces the latency of the kernel by making certain 801 RCU sections preemptible. Normally RCU code is non-preemptible, if 802 this option is selected then read-only RCU sections become 803 preemptible. This helps latency, but may expose bugs due to 804 now-naive assumptions about each RCU read-side critical section 805 remaining on a given CPU through its execution. 806 807 Say N if you are unsure. 808 809endchoice 810