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 These are 41 drivers that have been replaced by something else, and/or are 42 scheduled to be removed in a future kernel release. 43 44 Unless you intend to help test and develop a feature or driver that 45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 AUDIT 218 bool "Auditing support" 219 depends on NET 220 help 221 Enable auditing infrastructure that can be used with another 222 kernel subsystem, such as SELinux (which requires this for 223 logging of avc messages output). Does not do system-call 224 auditing without CONFIG_AUDITSYSCALL. 225 226config AUDITSYSCALL 227 bool "Enable system-call auditing support" 228 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH) 229 default y if SECURITY_SELINUX 230 help 231 Enable low-overhead system-call auditing infrastructure that 232 can be used independently or with another kernel subsystem, 233 such as SELinux. To use audit's filesystem watch feature, please 234 ensure that INOTIFY is configured. 235 236config AUDIT_TREE 237 def_bool y 238 depends on AUDITSYSCALL && INOTIFY 239 240config IKCONFIG 241 tristate "Kernel .config support" 242 ---help--- 243 This option enables the complete Linux kernel ".config" file 244 contents to be saved in the kernel. It provides documentation 245 of which kernel options are used in a running kernel or in an 246 on-disk kernel. This information can be extracted from the kernel 247 image file with the script scripts/extract-ikconfig and used as 248 input to rebuild the current kernel or to build another kernel. 249 It can also be extracted from a running kernel by reading 250 /proc/config.gz if enabled (below). 251 252config IKCONFIG_PROC 253 bool "Enable access to .config through /proc/config.gz" 254 depends on IKCONFIG && PROC_FS 255 ---help--- 256 This option enables access to the kernel configuration file 257 through /proc/config.gz. 258 259config LOG_BUF_SHIFT 260 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 261 range 12 21 262 default 17 if S390 || LOCKDEP 263 default 16 if X86_NUMAQ || IA64 264 default 15 if SMP 265 default 14 266 help 267 Select kernel log buffer size as a power of 2. 268 Defaults and Examples: 269 17 => 128 KB for S/390 270 16 => 64 KB for x86 NUMAQ or IA-64 271 15 => 32 KB for SMP 272 14 => 16 KB for uniprocessor 273 13 => 8 KB 274 12 => 4 KB 275 276config CGROUPS 277 bool "Control Group support" 278 help 279 This option will let you use process cgroup subsystems 280 such as Cpusets 281 282 Say N if unsure. 283 284config CGROUP_DEBUG 285 bool "Example debug cgroup subsystem" 286 depends on CGROUPS 287 help 288 This option enables a simple cgroup subsystem that 289 exports useful debugging information about the cgroups 290 framework 291 292 Say N if unsure 293 294config CGROUP_NS 295 bool "Namespace cgroup subsystem" 296 depends on CGROUPS 297 help 298 Provides a simple namespace cgroup subsystem to 299 provide hierarchical naming of sets of namespaces, 300 for instance virtual servers and checkpoint/restart 301 jobs. 302 303config CPUSETS 304 bool "Cpuset support" 305 depends on SMP && CGROUPS 306 help 307 This option will let you create and manage CPUSETs which 308 allow dynamically partitioning a system into sets of CPUs and 309 Memory Nodes and assigning tasks to run only within those sets. 310 This is primarily useful on large SMP or NUMA systems. 311 312 Say N if unsure. 313 314config FAIR_GROUP_SCHED 315 bool "Fair group CPU scheduler" 316 default y 317 help 318 This feature lets CPU scheduler recognize task groups and control CPU 319 bandwidth allocation to such task groups. 320 321choice 322 depends on FAIR_GROUP_SCHED 323 prompt "Basis for grouping tasks" 324 default FAIR_USER_SCHED 325 326config FAIR_USER_SCHED 327 bool "user id" 328 help 329 This option will choose userid as the basis for grouping 330 tasks, thus providing equal CPU bandwidth to each user. 331 332config FAIR_CGROUP_SCHED 333 bool "Control groups" 334 depends on CGROUPS 335 help 336 This option allows you to create arbitrary task groups 337 using the "cgroup" pseudo filesystem and control 338 the cpu bandwidth allocated to each such task group. 339 Refer to Documentation/cgroups.txt for more information 340 on "cgroup" pseudo filesystem. 341 342endchoice 343 344config CGROUP_CPUACCT 345 bool "Simple CPU accounting cgroup subsystem" 346 depends on CGROUPS 347 help 348 Provides a simple Resource Controller for monitoring the 349 total CPU consumed by the tasks in a cgroup 350 351config RESOURCE_COUNTERS 352 bool "Resource counters" 353 help 354 This option enables controller independent resource accounting 355 infrastructure that works with cgroups 356 depends on CGROUPS 357 358config SYSFS_DEPRECATED 359 bool "Create deprecated sysfs files" 360 depends on SYSFS 361 default y 362 help 363 This option creates deprecated symlinks such as the 364 "device"-link, the <subsystem>:<name>-link, and the 365 "bus"-link. It may also add deprecated key in the 366 uevent environment. 367 None of these features or values should be used today, as 368 they export driver core implementation details to userspace 369 or export properties which can't be kept stable across kernel 370 releases. 371 372 If enabled, this option will also move any device structures 373 that belong to a class, back into the /sys/class hierarchy, in 374 order to support older versions of udev. 375 376 If you are using a distro that was released in 2006 or later, 377 it should be safe to say N here. 378 379config CGROUP_MEM_CONT 380 bool "Memory controller for cgroups" 381 depends on CGROUPS && RESOURCE_COUNTERS 382 help 383 Provides a memory controller that manages both page cache and 384 RSS memory. 385 386config PROC_PID_CPUSET 387 bool "Include legacy /proc/<pid>/cpuset file" 388 depends on CPUSETS 389 default y 390 391config RELAY 392 bool "Kernel->user space relay support (formerly relayfs)" 393 help 394 This option enables support for relay interface support in 395 certain file systems (such as debugfs). 396 It is designed to provide an efficient mechanism for tools and 397 facilities to relay large amounts of data from kernel space to 398 user space. 399 400 If unsure, say N. 401 402config NAMESPACES 403 bool "Namespaces support" if EMBEDDED 404 default !EMBEDDED 405 help 406 Provides the way to make tasks work with different objects using 407 the same id. For example same IPC id may refer to different objects 408 or same user id or pid may refer to different tasks when used in 409 different namespaces. 410 411config UTS_NS 412 bool "UTS namespace" 413 depends on NAMESPACES 414 help 415 In this namespace tasks see different info provided with the 416 uname() system call 417 418config IPC_NS 419 bool "IPC namespace" 420 depends on NAMESPACES && SYSVIPC 421 help 422 In this namespace tasks work with IPC ids which correspond to 423 different IPC objects in different namespaces 424 425config USER_NS 426 bool "User namespace (EXPERIMENTAL)" 427 depends on NAMESPACES && EXPERIMENTAL 428 help 429 This allows containers, i.e. vservers, to use user namespaces 430 to provide different user info for different servers. 431 If unsure, say N. 432 433config PID_NS 434 bool "PID Namespaces (EXPERIMENTAL)" 435 default n 436 depends on NAMESPACES && EXPERIMENTAL 437 help 438 Suport process id namespaces. This allows having multiple 439 process with the same pid as long as they are in different 440 pid namespaces. This is a building block of containers. 441 442 Unless you want to work with an experimental feature 443 say N here. 444 445config BLK_DEV_INITRD 446 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 447 depends on BROKEN || !FRV 448 help 449 The initial RAM filesystem is a ramfs which is loaded by the 450 boot loader (loadlin or lilo) and that is mounted as root 451 before the normal boot procedure. It is typically used to 452 load modules needed to mount the "real" root file system, 453 etc. See <file:Documentation/initrd.txt> for details. 454 455 If RAM disk support (BLK_DEV_RAM) is also included, this 456 also enables initial RAM disk (initrd) support and adds 457 15 Kbytes (more on some other architectures) to the kernel size. 458 459 If unsure say Y. 460 461if BLK_DEV_INITRD 462 463source "usr/Kconfig" 464 465endif 466 467config CC_OPTIMIZE_FOR_SIZE 468 bool "Optimize for size (Look out for broken compilers!)" 469 default y 470 depends on ARM || H8300 || SUPERH || EXPERIMENTAL 471 help 472 Enabling this option will pass "-Os" instead of "-O2" to gcc 473 resulting in a smaller kernel. 474 475 WARNING: some versions of gcc may generate incorrect code with this 476 option. If problems are observed, a gcc upgrade may be needed. 477 478 If unsure, say N. 479 480config SYSCTL 481 bool 482 483menuconfig EMBEDDED 484 bool "Configure standard kernel features (for small systems)" 485 help 486 This option allows certain base kernel options and settings 487 to be disabled or tweaked. This is for specialized 488 environments which can tolerate a "non-standard" kernel. 489 Only use this if you really know what you are doing. 490 491config UID16 492 bool "Enable 16-bit UID system calls" if EMBEDDED 493 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION) 494 default y 495 help 496 This enables the legacy 16-bit UID syscall wrappers. 497 498config SYSCTL_SYSCALL 499 bool "Sysctl syscall support" if EMBEDDED 500 default y 501 select SYSCTL 502 ---help--- 503 sys_sysctl uses binary paths that have been found challenging 504 to properly maintain and use. The interface in /proc/sys 505 using paths with ascii names is now the primary path to this 506 information. 507 508 Almost nothing using the binary sysctl interface so if you are 509 trying to save some space it is probably safe to disable this, 510 making your kernel marginally smaller. 511 512 If unsure say Y here. 513 514config KALLSYMS 515 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 516 default y 517 help 518 Say Y here to let the kernel print out symbolic crash information and 519 symbolic stack backtraces. This increases the size of the kernel 520 somewhat, as all symbols have to be loaded into the kernel image. 521 522config KALLSYMS_ALL 523 bool "Include all symbols in kallsyms" 524 depends on DEBUG_KERNEL && KALLSYMS 525 help 526 Normally kallsyms only contains the symbols of functions, for nicer 527 OOPS messages. Some debuggers can use kallsyms for other 528 symbols too: say Y here to include all symbols, if you need them 529 and you don't care about adding 300k to the size of your kernel. 530 531 Say N. 532 533config KALLSYMS_EXTRA_PASS 534 bool "Do an extra kallsyms pass" 535 depends on KALLSYMS 536 help 537 If kallsyms is not working correctly, the build will fail with 538 inconsistent kallsyms data. If that occurs, log a bug report and 539 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 540 Always say N here unless you find a bug in kallsyms, which must be 541 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 542 you wait for kallsyms to be fixed. 543 544 545config HOTPLUG 546 bool "Support for hot-pluggable devices" if EMBEDDED 547 default y 548 help 549 This option is provided for the case where no hotplug or uevent 550 capabilities is wanted by the kernel. You should only consider 551 disabling this option for embedded systems that do not use modules, a 552 dynamic /dev tree, or dynamic device discovery. Just say Y. 553 554config PRINTK 555 default y 556 bool "Enable support for printk" if EMBEDDED 557 help 558 This option enables normal printk support. Removing it 559 eliminates most of the message strings from the kernel image 560 and makes the kernel more or less silent. As this makes it 561 very difficult to diagnose system problems, saying N here is 562 strongly discouraged. 563 564config BUG 565 bool "BUG() support" if EMBEDDED 566 default y 567 help 568 Disabling this option eliminates support for BUG and WARN, reducing 569 the size of your kernel image and potentially quietly ignoring 570 numerous fatal conditions. You should only consider disabling this 571 option for embedded systems with no facilities for reporting errors. 572 Just say Y. 573 574config ELF_CORE 575 default y 576 bool "Enable ELF core dumps" if EMBEDDED 577 help 578 Enable support for generating core dumps. Disabling saves about 4k. 579 580config COMPAT_BRK 581 bool "Disable heap randomization" 582 default y 583 help 584 Randomizing heap placement makes heap exploits harder, but it 585 also breaks ancient binaries (including anything libc5 based). 586 This option changes the bootup default to heap randomization 587 disabled, and can be overriden runtime by setting 588 /proc/sys/kernel/randomize_va_space to 2. 589 590 On non-ancient distros (post-2000 ones) N is usually a safe choice. 591 592config BASE_FULL 593 default y 594 bool "Enable full-sized data structures for core" if EMBEDDED 595 help 596 Disabling this option reduces the size of miscellaneous core 597 kernel data structures. This saves memory on small machines, 598 but may reduce performance. 599 600config FUTEX 601 bool "Enable futex support" if EMBEDDED 602 default y 603 select RT_MUTEXES 604 help 605 Disabling this option will cause the kernel to be built without 606 support for "fast userspace mutexes". The resulting kernel may not 607 run glibc-based applications correctly. 608 609config ANON_INODES 610 bool 611 612config EPOLL 613 bool "Enable eventpoll support" if EMBEDDED 614 default y 615 select ANON_INODES 616 help 617 Disabling this option will cause the kernel to be built without 618 support for epoll family of system calls. 619 620config SIGNALFD 621 bool "Enable signalfd() system call" if EMBEDDED 622 select ANON_INODES 623 default y 624 help 625 Enable the signalfd() system call that allows to receive signals 626 on a file descriptor. 627 628 If unsure, say Y. 629 630config TIMERFD 631 bool "Enable timerfd() system call" if EMBEDDED 632 select ANON_INODES 633 default y 634 help 635 Enable the timerfd() system call that allows to receive timer 636 events on a file descriptor. 637 638 If unsure, say Y. 639 640config EVENTFD 641 bool "Enable eventfd() system call" if EMBEDDED 642 select ANON_INODES 643 default y 644 help 645 Enable the eventfd() system call that allows to receive both 646 kernel notification (ie. KAIO) or userspace notifications. 647 648 If unsure, say Y. 649 650config SHMEM 651 bool "Use full shmem filesystem" if EMBEDDED 652 default y 653 depends on MMU 654 help 655 The shmem is an internal filesystem used to manage shared memory. 656 It is backed by swap and manages resource limits. It is also exported 657 to userspace as tmpfs if TMPFS is enabled. Disabling this 658 option replaces shmem and tmpfs with the much simpler ramfs code, 659 which may be appropriate on small systems without swap. 660 661config VM_EVENT_COUNTERS 662 default y 663 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 664 help 665 VM event counters are needed for event counts to be shown. 666 This option allows the disabling of the VM event counters 667 on EMBEDDED systems. /proc/vmstat will only show page counts 668 if VM event counters are disabled. 669 670config SLUB_DEBUG 671 default y 672 bool "Enable SLUB debugging support" if EMBEDDED 673 depends on SLUB 674 help 675 SLUB has extensive debug support features. Disabling these can 676 result in significant savings in code size. This also disables 677 SLUB sysfs support. /sys/slab will not exist and there will be 678 no support for cache validation etc. 679 680choice 681 prompt "Choose SLAB allocator" 682 default SLUB 683 help 684 This option allows to select a slab allocator. 685 686config SLAB 687 bool "SLAB" 688 help 689 The regular slab allocator that is established and known to work 690 well in all environments. It organizes cache hot objects in 691 per cpu and per node queues. SLAB is the default choice for 692 a slab allocator. 693 694config SLUB 695 bool "SLUB (Unqueued Allocator)" 696 help 697 SLUB is a slab allocator that minimizes cache line usage 698 instead of managing queues of cached objects (SLAB approach). 699 Per cpu caching is realized using slabs of objects instead 700 of queues of objects. SLUB can use memory efficiently 701 and has enhanced diagnostics. 702 703config SLOB 704 depends on EMBEDDED 705 bool "SLOB (Simple Allocator)" 706 help 707 SLOB replaces the stock allocator with a drastically simpler 708 allocator. SLOB is generally more space efficient but 709 does not perform as well on large systems. 710 711endchoice 712 713config PROFILING 714 bool "Profiling support (EXPERIMENTAL)" 715 help 716 Say Y here to enable the extended profiling support mechanisms used 717 by profilers such as OProfile. 718 719config MARKERS 720 bool "Activate markers" 721 help 722 Place an empty function call at each marker site. Can be 723 dynamically changed for a probe function. 724 725source "arch/Kconfig" 726 727config PROC_PAGE_MONITOR 728 default y 729 depends on PROC_FS && MMU 730 bool "Enable /proc page monitoring" if EMBEDDED 731 help 732 Various /proc files exist to monitor process memory utilization: 733 /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap, 734 /proc/kpagecount, and /proc/kpageflags. Disabling these 735 interfaces will reduce the size of the kernel by approximately 4kb. 736 737endmenu # General setup 738 739config SLABINFO 740 bool 741 depends on PROC_FS 742 depends on SLAB || SLUB 743 default y 744 745config RT_MUTEXES 746 boolean 747 select PLIST 748 749config TINY_SHMEM 750 default !SHMEM 751 bool 752 753config BASE_SMALL 754 int 755 default 0 if BASE_FULL 756 default 1 if !BASE_FULL 757 758menuconfig MODULES 759 bool "Enable loadable module support" 760 help 761 Kernel modules are small pieces of compiled code which can 762 be inserted in the running kernel, rather than being 763 permanently built into the kernel. You use the "modprobe" 764 tool to add (and sometimes remove) them. If you say Y here, 765 many parts of the kernel can be built as modules (by 766 answering M instead of Y where indicated): this is most 767 useful for infrequently used options which are not required 768 for booting. For more information, see the man pages for 769 modprobe, lsmod, modinfo, insmod and rmmod. 770 771 If you say Y here, you will need to run "make 772 modules_install" to put the modules under /lib/modules/ 773 where modprobe can find them (you may need to be root to do 774 this). 775 776 If unsure, say Y. 777 778config MODULE_UNLOAD 779 bool "Module unloading" 780 depends on MODULES 781 help 782 Without this option you will not be able to unload any 783 modules (note that some modules may not be unloadable 784 anyway), which makes your kernel slightly smaller and 785 simpler. If unsure, say Y. 786 787config MODULE_FORCE_UNLOAD 788 bool "Forced module unloading" 789 depends on MODULE_UNLOAD && EXPERIMENTAL 790 help 791 This option allows you to force a module to unload, even if the 792 kernel believes it is unsafe: the kernel will remove the module 793 without waiting for anyone to stop using it (using the -f option to 794 rmmod). This is mainly for kernel developers and desperate users. 795 If unsure, say N. 796 797config MODVERSIONS 798 bool "Module versioning support" 799 depends on MODULES 800 help 801 Usually, you have to use modules compiled with your kernel. 802 Saying Y here makes it sometimes possible to use modules 803 compiled for different kernels, by adding enough information 804 to the modules to (hopefully) spot any changes which would 805 make them incompatible with the kernel you are running. If 806 unsure, say N. 807 808config MODULE_SRCVERSION_ALL 809 bool "Source checksum for all modules" 810 depends on MODULES 811 help 812 Modules which contain a MODULE_VERSION get an extra "srcversion" 813 field inserted into their modinfo section, which contains a 814 sum of the source files which made it. This helps maintainers 815 see exactly which source was used to build a module (since 816 others sometimes change the module source without updating 817 the version). With this option, such a "srcversion" field 818 will be created for all modules. If unsure, say N. 819 820config KMOD 821 bool "Automatic kernel module loading" 822 depends on MODULES 823 help 824 Normally when you have selected some parts of the kernel to 825 be created as kernel modules, you must load them (using the 826 "modprobe" command) before you can use them. If you say Y 827 here, some parts of the kernel will be able to load modules 828 automatically: when a part of the kernel needs a module, it 829 runs modprobe with the appropriate arguments, thereby 830 loading the module if it is available. If unsure, say Y. 831 832config STOP_MACHINE 833 bool 834 default y 835 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 836 help 837 Need stop_machine() primitive. 838 839source "block/Kconfig" 840 841config PREEMPT_NOTIFIERS 842 bool 843 844choice 845 prompt "RCU implementation type:" 846 default CLASSIC_RCU 847 help 848 This allows you to choose either the classic RCU implementation 849 that is designed for best read-side performance on non-realtime 850 systems, or the preemptible RCU implementation for best latency 851 on realtime systems. Note that some kernel preemption modes 852 will restrict your choice. 853 854 Select the default if you are unsure. 855 856config CLASSIC_RCU 857 bool "Classic RCU" 858 help 859 This option selects the classic RCU implementation that is 860 designed for best read-side performance on non-realtime 861 systems. 862 863 Say Y if you are unsure. 864 865config PREEMPT_RCU 866 bool "Preemptible RCU" 867 depends on PREEMPT 868 help 869 This option reduces the latency of the kernel by making certain 870 RCU sections preemptible. Normally RCU code is non-preemptible, if 871 this option is selected then read-only RCU sections become 872 preemptible. This helps latency, but may expose bugs due to 873 now-naive assumptions about each RCU read-side critical section 874 remaining on a given CPU through its execution. 875 876 Say N if you are unsure. 877 878endchoice 879