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 These are 41 drivers that have been replaced by something else, and/or are 42 scheduled to be removed in a future kernel release. 43 44 Unless you intend to help test and develop a feature or driver that 45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 GROUP_SCHED 315 bool "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 321config FAIR_GROUP_SCHED 322 bool "Group scheduling for SCHED_OTHER" 323 depends on GROUP_SCHED 324 default y 325 326config RT_GROUP_SCHED 327 bool "Group scheduling for SCHED_RR/FIFO" 328 depends on EXPERIMENTAL 329 depends on GROUP_SCHED 330 default n 331 332choice 333 depends on GROUP_SCHED 334 prompt "Basis for grouping tasks" 335 default USER_SCHED 336 337config USER_SCHED 338 bool "user id" 339 help 340 This option will choose userid as the basis for grouping 341 tasks, thus providing equal CPU bandwidth to each user. 342 343config CGROUP_SCHED 344 bool "Control groups" 345 depends on CGROUPS 346 help 347 This option allows you to create arbitrary task groups 348 using the "cgroup" pseudo filesystem and control 349 the cpu bandwidth allocated to each such task group. 350 Refer to Documentation/cgroups.txt for more information 351 on "cgroup" pseudo filesystem. 352 353endchoice 354 355config CGROUP_CPUACCT 356 bool "Simple CPU accounting cgroup subsystem" 357 depends on CGROUPS 358 help 359 Provides a simple Resource Controller for monitoring the 360 total CPU consumed by the tasks in a cgroup 361 362config RESOURCE_COUNTERS 363 bool "Resource counters" 364 help 365 This option enables controller independent resource accounting 366 infrastructure that works with cgroups 367 depends on CGROUPS 368 369config SYSFS_DEPRECATED 370 bool "Create deprecated sysfs files" 371 depends on SYSFS 372 default y 373 help 374 This option creates deprecated symlinks such as the 375 "device"-link, the <subsystem>:<name>-link, and the 376 "bus"-link. It may also add deprecated key in the 377 uevent environment. 378 None of these features or values should be used today, as 379 they export driver core implementation details to userspace 380 or export properties which can't be kept stable across kernel 381 releases. 382 383 If enabled, this option will also move any device structures 384 that belong to a class, back into the /sys/class hierarchy, in 385 order to support older versions of udev. 386 387 If you are using a distro that was released in 2006 or later, 388 it should be safe to say N here. 389 390config CGROUP_MEM_CONT 391 bool "Memory controller for cgroups" 392 depends on CGROUPS && RESOURCE_COUNTERS 393 help 394 Provides a memory controller that manages both page cache and 395 RSS memory. 396 397 Note that setting this option increases fixed memory overhead 398 associated with each page of memory in the system by 4/8 bytes 399 and also increases cache misses because struct page on many 64bit 400 systems will not fit into a single cache line anymore. 401 402 Only enable when you're ok with these trade offs and really 403 sure you need the memory controller. 404 405config PROC_PID_CPUSET 406 bool "Include legacy /proc/<pid>/cpuset file" 407 depends on CPUSETS 408 default y 409 410config RELAY 411 bool "Kernel->user space relay support (formerly relayfs)" 412 help 413 This option enables support for relay interface support in 414 certain file systems (such as debugfs). 415 It is designed to provide an efficient mechanism for tools and 416 facilities to relay large amounts of data from kernel space to 417 user space. 418 419 If unsure, say N. 420 421config NAMESPACES 422 bool "Namespaces support" if EMBEDDED 423 default !EMBEDDED 424 help 425 Provides the way to make tasks work with different objects using 426 the same id. For example same IPC id may refer to different objects 427 or same user id or pid may refer to different tasks when used in 428 different namespaces. 429 430config UTS_NS 431 bool "UTS namespace" 432 depends on NAMESPACES 433 help 434 In this namespace tasks see different info provided with the 435 uname() system call 436 437config IPC_NS 438 bool "IPC namespace" 439 depends on NAMESPACES && SYSVIPC 440 help 441 In this namespace tasks work with IPC ids which correspond to 442 different IPC objects in different namespaces 443 444config USER_NS 445 bool "User namespace (EXPERIMENTAL)" 446 depends on NAMESPACES && EXPERIMENTAL 447 help 448 This allows containers, i.e. vservers, to use user namespaces 449 to provide different user info for different servers. 450 If unsure, say N. 451 452config PID_NS 453 bool "PID Namespaces (EXPERIMENTAL)" 454 default n 455 depends on NAMESPACES && EXPERIMENTAL 456 help 457 Suport process id namespaces. This allows having multiple 458 process with the same pid as long as they are in different 459 pid namespaces. This is a building block of containers. 460 461 Unless you want to work with an experimental feature 462 say N here. 463 464config BLK_DEV_INITRD 465 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 466 depends on BROKEN || !FRV 467 help 468 The initial RAM filesystem is a ramfs which is loaded by the 469 boot loader (loadlin or lilo) and that is mounted as root 470 before the normal boot procedure. It is typically used to 471 load modules needed to mount the "real" root file system, 472 etc. See <file:Documentation/initrd.txt> for details. 473 474 If RAM disk support (BLK_DEV_RAM) is also included, this 475 also enables initial RAM disk (initrd) support and adds 476 15 Kbytes (more on some other architectures) to the kernel size. 477 478 If unsure say Y. 479 480if BLK_DEV_INITRD 481 482source "usr/Kconfig" 483 484endif 485 486config CC_OPTIMIZE_FOR_SIZE 487 bool "Optimize for size (Look out for broken compilers!)" 488 default y 489 depends on ARM || H8300 || SUPERH || EXPERIMENTAL 490 help 491 Enabling this option will pass "-Os" instead of "-O2" to gcc 492 resulting in a smaller kernel. 493 494 WARNING: some versions of gcc may generate incorrect code with this 495 option. If problems are observed, a gcc upgrade may be needed. 496 497 If unsure, say N. 498 499config SYSCTL 500 bool 501 502menuconfig EMBEDDED 503 bool "Configure standard kernel features (for small systems)" 504 help 505 This option allows certain base kernel options and settings 506 to be disabled or tweaked. This is for specialized 507 environments which can tolerate a "non-standard" kernel. 508 Only use this if you really know what you are doing. 509 510config UID16 511 bool "Enable 16-bit UID system calls" if EMBEDDED 512 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION) 513 default y 514 help 515 This enables the legacy 16-bit UID syscall wrappers. 516 517config SYSCTL_SYSCALL 518 bool "Sysctl syscall support" if EMBEDDED 519 default y 520 select SYSCTL 521 ---help--- 522 sys_sysctl uses binary paths that have been found challenging 523 to properly maintain and use. The interface in /proc/sys 524 using paths with ascii names is now the primary path to this 525 information. 526 527 Almost nothing using the binary sysctl interface so if you are 528 trying to save some space it is probably safe to disable this, 529 making your kernel marginally smaller. 530 531 If unsure say Y here. 532 533config KALLSYMS 534 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 535 default y 536 help 537 Say Y here to let the kernel print out symbolic crash information and 538 symbolic stack backtraces. This increases the size of the kernel 539 somewhat, as all symbols have to be loaded into the kernel image. 540 541config KALLSYMS_ALL 542 bool "Include all symbols in kallsyms" 543 depends on DEBUG_KERNEL && KALLSYMS 544 help 545 Normally kallsyms only contains the symbols of functions, for nicer 546 OOPS messages. Some debuggers can use kallsyms for other 547 symbols too: say Y here to include all symbols, if you need them 548 and you don't care about adding 300k to the size of your kernel. 549 550 Say N. 551 552config KALLSYMS_EXTRA_PASS 553 bool "Do an extra kallsyms pass" 554 depends on KALLSYMS 555 help 556 If kallsyms is not working correctly, the build will fail with 557 inconsistent kallsyms data. If that occurs, log a bug report and 558 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 559 Always say N here unless you find a bug in kallsyms, which must be 560 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 561 you wait for kallsyms to be fixed. 562 563 564config HOTPLUG 565 bool "Support for hot-pluggable devices" if EMBEDDED 566 default y 567 help 568 This option is provided for the case where no hotplug or uevent 569 capabilities is wanted by the kernel. You should only consider 570 disabling this option for embedded systems that do not use modules, a 571 dynamic /dev tree, or dynamic device discovery. Just say Y. 572 573config PRINTK 574 default y 575 bool "Enable support for printk" if EMBEDDED 576 help 577 This option enables normal printk support. Removing it 578 eliminates most of the message strings from the kernel image 579 and makes the kernel more or less silent. As this makes it 580 very difficult to diagnose system problems, saying N here is 581 strongly discouraged. 582 583config BUG 584 bool "BUG() support" if EMBEDDED 585 default y 586 help 587 Disabling this option eliminates support for BUG and WARN, reducing 588 the size of your kernel image and potentially quietly ignoring 589 numerous fatal conditions. You should only consider disabling this 590 option for embedded systems with no facilities for reporting errors. 591 Just say Y. 592 593config ELF_CORE 594 default y 595 bool "Enable ELF core dumps" if EMBEDDED 596 help 597 Enable support for generating core dumps. Disabling saves about 4k. 598 599config COMPAT_BRK 600 bool "Disable heap randomization" 601 default y 602 help 603 Randomizing heap placement makes heap exploits harder, but it 604 also breaks ancient binaries (including anything libc5 based). 605 This option changes the bootup default to heap randomization 606 disabled, and can be overriden runtime by setting 607 /proc/sys/kernel/randomize_va_space to 2. 608 609 On non-ancient distros (post-2000 ones) N is usually a safe choice. 610 611config BASE_FULL 612 default y 613 bool "Enable full-sized data structures for core" if EMBEDDED 614 help 615 Disabling this option reduces the size of miscellaneous core 616 kernel data structures. This saves memory on small machines, 617 but may reduce performance. 618 619config FUTEX 620 bool "Enable futex support" if EMBEDDED 621 default y 622 select RT_MUTEXES 623 help 624 Disabling this option will cause the kernel to be built without 625 support for "fast userspace mutexes". The resulting kernel may not 626 run glibc-based applications correctly. 627 628config ANON_INODES 629 bool 630 631config EPOLL 632 bool "Enable eventpoll support" if EMBEDDED 633 default y 634 select ANON_INODES 635 help 636 Disabling this option will cause the kernel to be built without 637 support for epoll family of system calls. 638 639config SIGNALFD 640 bool "Enable signalfd() system call" if EMBEDDED 641 select ANON_INODES 642 default y 643 help 644 Enable the signalfd() system call that allows to receive signals 645 on a file descriptor. 646 647 If unsure, say Y. 648 649config TIMERFD 650 bool "Enable timerfd() system call" if EMBEDDED 651 select ANON_INODES 652 default y 653 help 654 Enable the timerfd() system call that allows to receive timer 655 events on a file descriptor. 656 657 If unsure, say Y. 658 659config EVENTFD 660 bool "Enable eventfd() system call" if EMBEDDED 661 select ANON_INODES 662 default y 663 help 664 Enable the eventfd() system call that allows to receive both 665 kernel notification (ie. KAIO) or userspace notifications. 666 667 If unsure, say Y. 668 669config SHMEM 670 bool "Use full shmem filesystem" if EMBEDDED 671 default y 672 depends on MMU 673 help 674 The shmem is an internal filesystem used to manage shared memory. 675 It is backed by swap and manages resource limits. It is also exported 676 to userspace as tmpfs if TMPFS is enabled. Disabling this 677 option replaces shmem and tmpfs with the much simpler ramfs code, 678 which may be appropriate on small systems without swap. 679 680config VM_EVENT_COUNTERS 681 default y 682 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 683 help 684 VM event counters are needed for event counts to be shown. 685 This option allows the disabling of the VM event counters 686 on EMBEDDED systems. /proc/vmstat will only show page counts 687 if VM event counters are disabled. 688 689config SLUB_DEBUG 690 default y 691 bool "Enable SLUB debugging support" if EMBEDDED 692 depends on SLUB 693 help 694 SLUB has extensive debug support features. Disabling these can 695 result in significant savings in code size. This also disables 696 SLUB sysfs support. /sys/slab will not exist and there will be 697 no support for cache validation etc. 698 699choice 700 prompt "Choose SLAB allocator" 701 default SLUB 702 help 703 This option allows to select a slab allocator. 704 705config SLAB 706 bool "SLAB" 707 help 708 The regular slab allocator that is established and known to work 709 well in all environments. It organizes cache hot objects in 710 per cpu and per node queues. SLAB is the default choice for 711 a slab allocator. 712 713config SLUB 714 bool "SLUB (Unqueued Allocator)" 715 help 716 SLUB is a slab allocator that minimizes cache line usage 717 instead of managing queues of cached objects (SLAB approach). 718 Per cpu caching is realized using slabs of objects instead 719 of queues of objects. SLUB can use memory efficiently 720 and has enhanced diagnostics. 721 722config SLOB 723 depends on EMBEDDED 724 bool "SLOB (Simple Allocator)" 725 help 726 SLOB replaces the stock allocator with a drastically simpler 727 allocator. SLOB is generally more space efficient but 728 does not perform as well on large systems. 729 730endchoice 731 732config PROFILING 733 bool "Profiling support (EXPERIMENTAL)" 734 help 735 Say Y here to enable the extended profiling support mechanisms used 736 by profilers such as OProfile. 737 738config MARKERS 739 bool "Activate markers" 740 help 741 Place an empty function call at each marker site. Can be 742 dynamically changed for a probe function. 743 744source "arch/Kconfig" 745 746config PROC_PAGE_MONITOR 747 default y 748 depends on PROC_FS && MMU 749 bool "Enable /proc page monitoring" if EMBEDDED 750 help 751 Various /proc files exist to monitor process memory utilization: 752 /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap, 753 /proc/kpagecount, and /proc/kpageflags. Disabling these 754 interfaces will reduce the size of the kernel by approximately 4kb. 755 756endmenu # General setup 757 758config SLABINFO 759 bool 760 depends on PROC_FS 761 depends on SLAB || SLUB 762 default y 763 764config RT_MUTEXES 765 boolean 766 select PLIST 767 768config TINY_SHMEM 769 default !SHMEM 770 bool 771 772config BASE_SMALL 773 int 774 default 0 if BASE_FULL 775 default 1 if !BASE_FULL 776 777menuconfig MODULES 778 bool "Enable loadable module support" 779 help 780 Kernel modules are small pieces of compiled code which can 781 be inserted in the running kernel, rather than being 782 permanently built into the kernel. You use the "modprobe" 783 tool to add (and sometimes remove) them. If you say Y here, 784 many parts of the kernel can be built as modules (by 785 answering M instead of Y where indicated): this is most 786 useful for infrequently used options which are not required 787 for booting. For more information, see the man pages for 788 modprobe, lsmod, modinfo, insmod and rmmod. 789 790 If you say Y here, you will need to run "make 791 modules_install" to put the modules under /lib/modules/ 792 where modprobe can find them (you may need to be root to do 793 this). 794 795 If unsure, say Y. 796 797config MODULE_UNLOAD 798 bool "Module unloading" 799 depends on MODULES 800 help 801 Without this option you will not be able to unload any 802 modules (note that some modules may not be unloadable 803 anyway), which makes your kernel slightly smaller and 804 simpler. If unsure, say Y. 805 806config MODULE_FORCE_UNLOAD 807 bool "Forced module unloading" 808 depends on MODULE_UNLOAD && EXPERIMENTAL 809 help 810 This option allows you to force a module to unload, even if the 811 kernel believes it is unsafe: the kernel will remove the module 812 without waiting for anyone to stop using it (using the -f option to 813 rmmod). This is mainly for kernel developers and desperate users. 814 If unsure, say N. 815 816config MODVERSIONS 817 bool "Module versioning support" 818 depends on MODULES 819 help 820 Usually, you have to use modules compiled with your kernel. 821 Saying Y here makes it sometimes possible to use modules 822 compiled for different kernels, by adding enough information 823 to the modules to (hopefully) spot any changes which would 824 make them incompatible with the kernel you are running. If 825 unsure, say N. 826 827config MODULE_SRCVERSION_ALL 828 bool "Source checksum for all modules" 829 depends on MODULES 830 help 831 Modules which contain a MODULE_VERSION get an extra "srcversion" 832 field inserted into their modinfo section, which contains a 833 sum of the source files which made it. This helps maintainers 834 see exactly which source was used to build a module (since 835 others sometimes change the module source without updating 836 the version). With this option, such a "srcversion" field 837 will be created for all modules. If unsure, say N. 838 839config KMOD 840 bool "Automatic kernel module loading" 841 depends on MODULES 842 help 843 Normally when you have selected some parts of the kernel to 844 be created as kernel modules, you must load them (using the 845 "modprobe" command) before you can use them. If you say Y 846 here, some parts of the kernel will be able to load modules 847 automatically: when a part of the kernel needs a module, it 848 runs modprobe with the appropriate arguments, thereby 849 loading the module if it is available. If unsure, say Y. 850 851config STOP_MACHINE 852 bool 853 default y 854 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 855 help 856 Need stop_machine() primitive. 857 858source "block/Kconfig" 859 860config PREEMPT_NOTIFIERS 861 bool 862 863choice 864 prompt "RCU implementation type:" 865 default CLASSIC_RCU 866 help 867 This allows you to choose either the classic RCU implementation 868 that is designed for best read-side performance on non-realtime 869 systems, or the preemptible RCU implementation for best latency 870 on realtime systems. Note that some kernel preemption modes 871 will restrict your choice. 872 873 Select the default if you are unsure. 874 875config CLASSIC_RCU 876 bool "Classic RCU" 877 help 878 This option selects the classic RCU implementation that is 879 designed for best read-side performance on non-realtime 880 systems. 881 882 Say Y if you are unsure. 883 884config PREEMPT_RCU 885 bool "Preemptible RCU" 886 depends on PREEMPT 887 help 888 This option reduces the latency of the kernel by making certain 889 RCU sections preemptible. Normally RCU code is non-preemptible, if 890 this option is selected then read-only RCU sections become 891 preemptible. This helps latency, but may expose bugs due to 892 now-naive assumptions about each RCU read-side critical section 893 remaining on a given CPU through its execution. 894 895 Say N if you are unsure. 896 897endchoice 898