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 "$ARCH_DEFCONFIG" 17 default "arch/$ARCH/defconfig" 18 19menu "General setup" 20 21config EXPERIMENTAL 22 bool "Prompt for development and/or incomplete code/drivers" 23 ---help--- 24 Some of the various things that Linux supports (such as network 25 drivers, file systems, network protocols, etc.) can be in a state 26 of development where the functionality, stability, or the level of 27 testing is not yet high enough for general use. This is usually 28 known as the "alpha-test" phase among developers. If a feature is 29 currently in alpha-test, then the developers usually discourage 30 uninformed widespread use of this feature by the general public to 31 avoid "Why doesn't this work?" type mail messages. However, active 32 testing and use of these systems is welcomed. Just be aware that it 33 may not meet the normal level of reliability or it may fail to work 34 in some special cases. Detailed bug reports from people familiar 35 with the kernel internals are usually welcomed by the developers 36 (before submitting bug reports, please read the documents 37 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 38 <file:Documentation/BUG-HUNTING>, and 39 <file:Documentation/oops-tracing.txt> in the kernel source). 40 41 This option will also make obsoleted drivers available. These are 42 drivers that have been replaced by something else, and/or are 43 scheduled to be removed in a future kernel release. 44 45 Unless you intend to help test and develop a feature or driver that 46 falls into this category, or you have a situation that requires 47 using these features, you should probably say N here, which will 48 cause the configurator to present you with fewer choices. If 49 you say Y here, you will be offered the choice of using features or 50 drivers that are currently considered to be in the alpha-test phase. 51 52config BROKEN 53 bool 54 55config BROKEN_ON_SMP 56 bool 57 depends on BROKEN || !SMP 58 default y 59 60config LOCK_KERNEL 61 bool 62 depends on SMP || PREEMPT 63 default y 64 65config INIT_ENV_ARG_LIMIT 66 int 67 default 32 if !UML 68 default 128 if UML 69 help 70 Maximum of each of the number of arguments and environment 71 variables passed to init from the kernel command line. 72 73 74config LOCALVERSION 75 string "Local version - append to kernel release" 76 help 77 Append an extra string to the end of your kernel version. 78 This will show up when you type uname, for example. 79 The string you set here will be appended after the contents of 80 any files with a filename matching localversion* in your 81 object and source tree, in that order. Your total string can 82 be a maximum of 64 characters. 83 84config LOCALVERSION_AUTO 85 bool "Automatically append version information to the version string" 86 default y 87 help 88 This will try to automatically determine if the current tree is a 89 release tree by looking for git tags that belong to the current 90 top of tree revision. 91 92 A string of the format -gxxxxxxxx will be added to the localversion 93 if a git-based tree is found. The string generated by this will be 94 appended after any matching localversion* files, and after the value 95 set in CONFIG_LOCALVERSION. 96 97 (The actual string used here is the first eight characters produced 98 by running the command: 99 100 $ git rev-parse --verify HEAD 101 102 which is done within the script "scripts/setlocalversion".) 103 104config SWAP 105 bool "Support for paging of anonymous memory (swap)" 106 depends on MMU && BLOCK 107 default y 108 help 109 This option allows you to choose whether you want to have support 110 for so called swap devices or swap files in your kernel that are 111 used to provide more virtual memory than the actual RAM present 112 in your computer. If unsure say Y. 113 114config SYSVIPC 115 bool "System V IPC" 116 ---help--- 117 Inter Process Communication is a suite of library functions and 118 system calls which let processes (running programs) synchronize and 119 exchange information. It is generally considered to be a good thing, 120 and some programs won't run unless you say Y here. In particular, if 121 you want to run the DOS emulator dosemu under Linux (read the 122 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 123 you'll need to say Y here. 124 125 You can find documentation about IPC with "info ipc" and also in 126 section 6.4 of the Linux Programmer's Guide, available from 127 <http://www.tldp.org/guides.html>. 128 129config SYSVIPC_SYSCTL 130 bool 131 depends on SYSVIPC 132 depends on SYSCTL 133 default y 134 135config POSIX_MQUEUE 136 bool "POSIX Message Queues" 137 depends on NET && EXPERIMENTAL 138 ---help--- 139 POSIX variant of message queues is a part of IPC. In POSIX message 140 queues every message has a priority which decides about succession 141 of receiving it by a process. If you want to compile and run 142 programs written e.g. for Solaris with use of its POSIX message 143 queues (functions mq_*) say Y here. 144 145 POSIX message queues are visible as a filesystem called 'mqueue' 146 and can be mounted somewhere if you want to do filesystem 147 operations on message queues. 148 149 If unsure, say Y. 150 151config BSD_PROCESS_ACCT 152 bool "BSD Process Accounting" 153 help 154 If you say Y here, a user level program will be able to instruct the 155 kernel (via a special system call) to write process accounting 156 information to a file: whenever a process exits, information about 157 that process will be appended to the file by the kernel. The 158 information includes things such as creation time, owning user, 159 command name, memory usage, controlling terminal etc. (the complete 160 list is in the struct acct in <file:include/linux/acct.h>). It is 161 up to the user level program to do useful things with this 162 information. This is generally a good idea, so say Y. 163 164config BSD_PROCESS_ACCT_V3 165 bool "BSD Process Accounting version 3 file format" 166 depends on BSD_PROCESS_ACCT 167 default n 168 help 169 If you say Y here, the process accounting information is written 170 in a new file format that also logs the process IDs of each 171 process and it's parent. Note that this file format is incompatible 172 with previous v0/v1/v2 file formats, so you will need updated tools 173 for processing it. A preliminary version of these tools is available 174 at <http://www.gnu.org/software/acct/>. 175 176config TASKSTATS 177 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 178 depends on NET 179 default n 180 help 181 Export selected statistics for tasks/processes through the 182 generic netlink interface. Unlike BSD process accounting, the 183 statistics are available during the lifetime of tasks/processes as 184 responses to commands. Like BSD accounting, they are sent to user 185 space on task exit. 186 187 Say N if unsure. 188 189config TASK_DELAY_ACCT 190 bool "Enable per-task delay accounting (EXPERIMENTAL)" 191 depends on TASKSTATS 192 help 193 Collect information on time spent by a task waiting for system 194 resources like cpu, synchronous block I/O completion and swapping 195 in pages. Such statistics can help in setting a task's priorities 196 relative to other tasks for cpu, io, rss limits etc. 197 198 Say N if unsure. 199 200config TASK_XACCT 201 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 202 depends on TASKSTATS 203 help 204 Collect extended task accounting data and send the data 205 to userland for processing over the taskstats interface. 206 207 Say N if unsure. 208 209config TASK_IO_ACCOUNTING 210 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 211 depends on TASK_XACCT 212 help 213 Collect information on the number of bytes of storage I/O which this 214 task has caused. 215 216 Say N if unsure. 217 218config AUDIT 219 bool "Auditing support" 220 depends on NET 221 help 222 Enable auditing infrastructure that can be used with another 223 kernel subsystem, such as SELinux (which requires this for 224 logging of avc messages output). Does not do system-call 225 auditing without CONFIG_AUDITSYSCALL. 226 227config AUDITSYSCALL 228 bool "Enable system-call auditing support" 229 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH) 230 default y if SECURITY_SELINUX 231 help 232 Enable low-overhead system-call auditing infrastructure that 233 can be used independently or with another kernel subsystem, 234 such as SELinux. To use audit's filesystem watch feature, please 235 ensure that INOTIFY is configured. 236 237config AUDIT_TREE 238 def_bool y 239 depends on AUDITSYSCALL && INOTIFY 240 241config IKCONFIG 242 tristate "Kernel .config support" 243 ---help--- 244 This option enables the complete Linux kernel ".config" file 245 contents to be saved in the kernel. It provides documentation 246 of which kernel options are used in a running kernel or in an 247 on-disk kernel. This information can be extracted from the kernel 248 image file with the script scripts/extract-ikconfig and used as 249 input to rebuild the current kernel or to build another kernel. 250 It can also be extracted from a running kernel by reading 251 /proc/config.gz if enabled (below). 252 253config IKCONFIG_PROC 254 bool "Enable access to .config through /proc/config.gz" 255 depends on IKCONFIG && PROC_FS 256 ---help--- 257 This option enables access to the kernel configuration file 258 through /proc/config.gz. 259 260config LOG_BUF_SHIFT 261 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 262 range 12 21 263 default 17 264 help 265 Select kernel log buffer size as a power of 2. 266 Examples: 267 17 => 128 KB 268 16 => 64 KB 269 15 => 32 KB 270 14 => 16 KB 271 13 => 8 KB 272 12 => 4 KB 273 274# 275# Architectures with an unreliable sched_clock() should select this: 276# 277config HAVE_UNSTABLE_SCHED_CLOCK 278 bool 279 280config GROUP_SCHED 281 bool "Group CPU scheduler" 282 depends on EXPERIMENTAL 283 default n 284 help 285 This feature lets CPU scheduler recognize task groups and control CPU 286 bandwidth allocation to such task groups. 287 In order to create a group from arbitrary set of processes, use 288 CONFIG_CGROUPS. (See Control Group support.) 289 290config FAIR_GROUP_SCHED 291 bool "Group scheduling for SCHED_OTHER" 292 depends on GROUP_SCHED 293 default GROUP_SCHED 294 295config RT_GROUP_SCHED 296 bool "Group scheduling for SCHED_RR/FIFO" 297 depends on EXPERIMENTAL 298 depends on GROUP_SCHED 299 default n 300 help 301 This feature lets you explicitly allocate real CPU bandwidth 302 to users or control groups (depending on the "Basis for grouping tasks" 303 setting below. If enabled, it will also make it impossible to 304 schedule realtime tasks for non-root users until you allocate 305 realtime bandwidth for them. 306 See Documentation/scheduler/sched-rt-group.txt for more information. 307 308choice 309 depends on GROUP_SCHED 310 prompt "Basis for grouping tasks" 311 default USER_SCHED 312 313config USER_SCHED 314 bool "user id" 315 help 316 This option will choose userid as the basis for grouping 317 tasks, thus providing equal CPU bandwidth to each user. 318 319config CGROUP_SCHED 320 bool "Control groups" 321 depends on CGROUPS 322 help 323 This option allows you to create arbitrary task groups 324 using the "cgroup" pseudo filesystem and control 325 the cpu bandwidth allocated to each such task group. 326 Refer to Documentation/cgroups.txt for more information 327 on "cgroup" pseudo filesystem. 328 329endchoice 330 331menu "Control Group support" 332config CGROUPS 333 bool "Control Group support" 334 help 335 This option add support for grouping sets of processes together, for 336 use with process control subsystems such as Cpusets, CFS, memory 337 controls or device isolation. 338 See 339 - Documentation/cpusets.txt (Cpusets) 340 - Documentation/scheduler/sched-design-CFS.txt (CFS) 341 - Documentation/cgroups/ (features for grouping, isolation) 342 - Documentation/controllers/ (features for resource control) 343 344 Say N if unsure. 345 346config CGROUP_DEBUG 347 bool "Example debug cgroup subsystem" 348 depends on CGROUPS 349 default n 350 help 351 This option enables a simple cgroup subsystem that 352 exports useful debugging information about the cgroups 353 framework 354 355 Say N if unsure 356 357config CGROUP_NS 358 bool "Namespace cgroup subsystem" 359 depends on CGROUPS 360 help 361 Provides a simple namespace cgroup subsystem to 362 provide hierarchical naming of sets of namespaces, 363 for instance virtual servers and checkpoint/restart 364 jobs. 365 366config CGROUP_FREEZER 367 bool "control group freezer subsystem" 368 depends on CGROUPS 369 help 370 Provides a way to freeze and unfreeze all tasks in a 371 cgroup. 372 373config CGROUP_DEVICE 374 bool "Device controller for cgroups" 375 depends on CGROUPS && EXPERIMENTAL 376 help 377 Provides a cgroup implementing whitelists for devices which 378 a process in the cgroup can mknod or open. 379 380config CPUSETS 381 bool "Cpuset support" 382 depends on SMP && CGROUPS 383 help 384 This option will let you create and manage CPUSETs which 385 allow dynamically partitioning a system into sets of CPUs and 386 Memory Nodes and assigning tasks to run only within those sets. 387 This is primarily useful on large SMP or NUMA systems. 388 389 Say N if unsure. 390 391config CGROUP_CPUACCT 392 bool "Simple CPU accounting cgroup subsystem" 393 depends on CGROUPS 394 help 395 Provides a simple Resource Controller for monitoring the 396 total CPU consumed by the tasks in a cgroup 397 398config RESOURCE_COUNTERS 399 bool "Resource counters" 400 help 401 This option enables controller independent resource accounting 402 infrastructure that works with cgroups 403 depends on CGROUPS 404 405config CGROUP_MEM_RES_CTLR 406 bool "Memory Resource Controller for Control Groups" 407 depends on CGROUPS && RESOURCE_COUNTERS 408 select MM_OWNER 409 help 410 Provides a memory resource controller that manages both anonymous 411 memory and page cache. (See Documentation/controllers/memory.txt) 412 413 Note that setting this option increases fixed memory overhead 414 associated with each page of memory in the system. By this, 415 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 416 usage tracking struct at boot. Total amount of this is printed out 417 at boot. 418 419 Only enable when you're ok with these trade offs and really 420 sure you need the memory resource controller. Even when you enable 421 this, you can set "cgroup_disable=memory" at your boot option to 422 disable memory resource controller and you can avoid overheads. 423 (and lose benefits of memory resource controller) 424 425 This config option also selects MM_OWNER config option, which 426 could in turn add some fork/exit overhead. 427 428config MM_OWNER 429 bool 430 431config CGROUP_MEM_RES_CTLR_SWAP 432 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)" 433 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL 434 help 435 Add swap management feature to memory resource controller. When you 436 enable this, you can limit mem+swap usage per cgroup. In other words, 437 when you disable this, memory resource controller has no cares to 438 usage of swap...a process can exhaust all of the swap. This extension 439 is useful when you want to avoid exhaustion swap but this itself 440 adds more overheads and consumes memory for remembering information. 441 Especially if you use 32bit system or small memory system, please 442 be careful about enabling this. When memory resource controller 443 is disabled by boot option, this will be automatically disabled and 444 there will be no overhead from this. Even when you set this config=y, 445 if boot option "noswapaccount" is set, swap will not be accounted. 446 447 448endmenu 449 450config SYSFS_DEPRECATED 451 bool 452 453config SYSFS_DEPRECATED_V2 454 bool "Create deprecated sysfs layout for older userspace tools" 455 depends on SYSFS 456 default y 457 select SYSFS_DEPRECATED 458 help 459 This option switches the layout of sysfs to the deprecated 460 version. 461 462 The current sysfs layout features a unified device tree at 463 /sys/devices/, which is able to express a hierarchy between 464 class devices. If the deprecated option is set to Y, the 465 unified device tree is split into a bus device tree at 466 /sys/devices/ and several individual class device trees at 467 /sys/class/. The class and bus devices will be connected by 468 "<subsystem>:<name>" and the "device" links. The "block" 469 class devices, will not show up in /sys/class/block/. Some 470 subsystems will suppress the creation of some devices which 471 depend on the unified device tree. 472 473 This option is not a pure compatibility option that can 474 be safely enabled on newer distributions. It will change the 475 layout of sysfs to the non-extensible deprecated version, 476 and disable some features, which can not be exported without 477 confusing older userspace tools. Since 2007/2008 all major 478 distributions do not enable this option, and ship no tools which 479 depend on the deprecated layout or this option. 480 481 If you are using a new kernel on an older distribution, or use 482 older userspace tools, you might need to say Y here. Do not say Y, 483 if the original kernel, that came with your distribution, has 484 this option set to N. 485 486config PROC_PID_CPUSET 487 bool "Include legacy /proc/<pid>/cpuset file" 488 depends on CPUSETS 489 default y 490 491config RELAY 492 bool "Kernel->user space relay support (formerly relayfs)" 493 help 494 This option enables support for relay interface support in 495 certain file systems (such as debugfs). 496 It is designed to provide an efficient mechanism for tools and 497 facilities to relay large amounts of data from kernel space to 498 user space. 499 500 If unsure, say N. 501 502config NAMESPACES 503 bool "Namespaces support" if EMBEDDED 504 default !EMBEDDED 505 help 506 Provides the way to make tasks work with different objects using 507 the same id. For example same IPC id may refer to different objects 508 or same user id or pid may refer to different tasks when used in 509 different namespaces. 510 511config UTS_NS 512 bool "UTS namespace" 513 depends on NAMESPACES 514 help 515 In this namespace tasks see different info provided with the 516 uname() system call 517 518config IPC_NS 519 bool "IPC namespace" 520 depends on NAMESPACES && SYSVIPC 521 help 522 In this namespace tasks work with IPC ids which correspond to 523 different IPC objects in different namespaces 524 525config USER_NS 526 bool "User namespace (EXPERIMENTAL)" 527 depends on NAMESPACES && EXPERIMENTAL 528 help 529 This allows containers, i.e. vservers, to use user namespaces 530 to provide different user info for different servers. 531 If unsure, say N. 532 533config PID_NS 534 bool "PID Namespaces (EXPERIMENTAL)" 535 default n 536 depends on NAMESPACES && EXPERIMENTAL 537 help 538 Support process id namespaces. This allows having multiple 539 process with the same pid as long as they are in different 540 pid namespaces. This is a building block of containers. 541 542 Unless you want to work with an experimental feature 543 say N here. 544 545config BLK_DEV_INITRD 546 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 547 depends on BROKEN || !FRV 548 help 549 The initial RAM filesystem is a ramfs which is loaded by the 550 boot loader (loadlin or lilo) and that is mounted as root 551 before the normal boot procedure. It is typically used to 552 load modules needed to mount the "real" root file system, 553 etc. See <file:Documentation/initrd.txt> for details. 554 555 If RAM disk support (BLK_DEV_RAM) is also included, this 556 also enables initial RAM disk (initrd) support and adds 557 15 Kbytes (more on some other architectures) to the kernel size. 558 559 If unsure say Y. 560 561if BLK_DEV_INITRD 562 563source "usr/Kconfig" 564 565endif 566 567config CC_OPTIMIZE_FOR_SIZE 568 bool "Optimize for size" 569 default y 570 help 571 Enabling this option will pass "-Os" instead of "-O2" to gcc 572 resulting in a smaller kernel. 573 574 If unsure, say Y. 575 576config SYSCTL 577 bool 578 579menuconfig EMBEDDED 580 bool "Configure standard kernel features (for small systems)" 581 help 582 This option allows certain base kernel options and settings 583 to be disabled or tweaked. This is for specialized 584 environments which can tolerate a "non-standard" kernel. 585 Only use this if you really know what you are doing. 586 587config UID16 588 bool "Enable 16-bit UID system calls" if EMBEDDED 589 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 590 default y 591 help 592 This enables the legacy 16-bit UID syscall wrappers. 593 594config SYSCTL_SYSCALL 595 bool "Sysctl syscall support" if EMBEDDED 596 default y 597 select SYSCTL 598 ---help--- 599 sys_sysctl uses binary paths that have been found challenging 600 to properly maintain and use. The interface in /proc/sys 601 using paths with ascii names is now the primary path to this 602 information. 603 604 Almost nothing using the binary sysctl interface so if you are 605 trying to save some space it is probably safe to disable this, 606 making your kernel marginally smaller. 607 608 If unsure say Y here. 609 610config KALLSYMS 611 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 612 default y 613 help 614 Say Y here to let the kernel print out symbolic crash information and 615 symbolic stack backtraces. This increases the size of the kernel 616 somewhat, as all symbols have to be loaded into the kernel image. 617 618config KALLSYMS_ALL 619 bool "Include all symbols in kallsyms" 620 depends on DEBUG_KERNEL && KALLSYMS 621 help 622 Normally kallsyms only contains the symbols of functions, for nicer 623 OOPS messages. Some debuggers can use kallsyms for other 624 symbols too: say Y here to include all symbols, if you need them 625 and you don't care about adding 300k to the size of your kernel. 626 627 Say N. 628 629config KALLSYMS_STRIP_GENERATED 630 bool "Strip machine generated symbols from kallsyms" 631 depends on KALLSYMS_ALL 632 default y 633 help 634 Say N if you want kallsyms to retain even machine generated symbols. 635 636config KALLSYMS_EXTRA_PASS 637 bool "Do an extra kallsyms pass" 638 depends on KALLSYMS 639 help 640 If kallsyms is not working correctly, the build will fail with 641 inconsistent kallsyms data. If that occurs, log a bug report and 642 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 643 Always say N here unless you find a bug in kallsyms, which must be 644 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 645 you wait for kallsyms to be fixed. 646 647 648config HOTPLUG 649 bool "Support for hot-pluggable devices" if EMBEDDED 650 default y 651 help 652 This option is provided for the case where no hotplug or uevent 653 capabilities is wanted by the kernel. You should only consider 654 disabling this option for embedded systems that do not use modules, a 655 dynamic /dev tree, or dynamic device discovery. Just say Y. 656 657config PRINTK 658 default y 659 bool "Enable support for printk" if EMBEDDED 660 help 661 This option enables normal printk support. Removing it 662 eliminates most of the message strings from the kernel image 663 and makes the kernel more or less silent. As this makes it 664 very difficult to diagnose system problems, saying N here is 665 strongly discouraged. 666 667config BUG 668 bool "BUG() support" if EMBEDDED 669 default y 670 help 671 Disabling this option eliminates support for BUG and WARN, reducing 672 the size of your kernel image and potentially quietly ignoring 673 numerous fatal conditions. You should only consider disabling this 674 option for embedded systems with no facilities for reporting errors. 675 Just say Y. 676 677config ELF_CORE 678 default y 679 bool "Enable ELF core dumps" if EMBEDDED 680 help 681 Enable support for generating core dumps. Disabling saves about 4k. 682 683config PCSPKR_PLATFORM 684 bool "Enable PC-Speaker support" if EMBEDDED 685 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 686 default y 687 help 688 This option allows to disable the internal PC-Speaker 689 support, saving some memory. 690 691config COMPAT_BRK 692 bool "Disable heap randomization" 693 default y 694 help 695 Randomizing heap placement makes heap exploits harder, but it 696 also breaks ancient binaries (including anything libc5 based). 697 This option changes the bootup default to heap randomization 698 disabled, and can be overriden runtime by setting 699 /proc/sys/kernel/randomize_va_space to 2. 700 701 On non-ancient distros (post-2000 ones) N is usually a safe choice. 702 703config BASE_FULL 704 default y 705 bool "Enable full-sized data structures for core" if EMBEDDED 706 help 707 Disabling this option reduces the size of miscellaneous core 708 kernel data structures. This saves memory on small machines, 709 but may reduce performance. 710 711config FUTEX 712 bool "Enable futex support" if EMBEDDED 713 default y 714 select RT_MUTEXES 715 help 716 Disabling this option will cause the kernel to be built without 717 support for "fast userspace mutexes". The resulting kernel may not 718 run glibc-based applications correctly. 719 720config ANON_INODES 721 bool 722 723config EPOLL 724 bool "Enable eventpoll support" if EMBEDDED 725 default y 726 select ANON_INODES 727 help 728 Disabling this option will cause the kernel to be built without 729 support for epoll family of system calls. 730 731config SIGNALFD 732 bool "Enable signalfd() system call" if EMBEDDED 733 select ANON_INODES 734 default y 735 help 736 Enable the signalfd() system call that allows to receive signals 737 on a file descriptor. 738 739 If unsure, say Y. 740 741config TIMERFD 742 bool "Enable timerfd() system call" if EMBEDDED 743 select ANON_INODES 744 default y 745 help 746 Enable the timerfd() system call that allows to receive timer 747 events on a file descriptor. 748 749 If unsure, say Y. 750 751config EVENTFD 752 bool "Enable eventfd() system call" if EMBEDDED 753 select ANON_INODES 754 default y 755 help 756 Enable the eventfd() system call that allows to receive both 757 kernel notification (ie. KAIO) or userspace notifications. 758 759 If unsure, say Y. 760 761config SHMEM 762 bool "Use full shmem filesystem" if EMBEDDED 763 default y 764 depends on MMU 765 help 766 The shmem is an internal filesystem used to manage shared memory. 767 It is backed by swap and manages resource limits. It is also exported 768 to userspace as tmpfs if TMPFS is enabled. Disabling this 769 option replaces shmem and tmpfs with the much simpler ramfs code, 770 which may be appropriate on small systems without swap. 771 772config AIO 773 bool "Enable AIO support" if EMBEDDED 774 default y 775 help 776 This option enables POSIX asynchronous I/O which may by used 777 by some high performance threaded applications. Disabling 778 this option saves about 7k. 779 780config VM_EVENT_COUNTERS 781 default y 782 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 783 help 784 VM event counters are needed for event counts to be shown. 785 This option allows the disabling of the VM event counters 786 on EMBEDDED systems. /proc/vmstat will only show page counts 787 if VM event counters are disabled. 788 789config PCI_QUIRKS 790 default y 791 bool "Enable PCI quirk workarounds" if EMBEDDED 792 depends on PCI 793 help 794 This enables workarounds for various PCI chipset 795 bugs/quirks. Disable this only if your target machine is 796 unaffected by PCI quirks. 797 798config SLUB_DEBUG 799 default y 800 bool "Enable SLUB debugging support" if EMBEDDED 801 depends on SLUB && SYSFS 802 help 803 SLUB has extensive debug support features. Disabling these can 804 result in significant savings in code size. This also disables 805 SLUB sysfs support. /sys/slab will not exist and there will be 806 no support for cache validation etc. 807 808choice 809 prompt "Choose SLAB allocator" 810 default SLUB 811 help 812 This option allows to select a slab allocator. 813 814config SLAB 815 bool "SLAB" 816 help 817 The regular slab allocator that is established and known to work 818 well in all environments. It organizes cache hot objects in 819 per cpu and per node queues. 820 821config SLUB 822 bool "SLUB (Unqueued Allocator)" 823 help 824 SLUB is a slab allocator that minimizes cache line usage 825 instead of managing queues of cached objects (SLAB approach). 826 Per cpu caching is realized using slabs of objects instead 827 of queues of objects. SLUB can use memory efficiently 828 and has enhanced diagnostics. SLUB is the default choice for 829 a slab allocator. 830 831config SLOB 832 depends on EMBEDDED 833 bool "SLOB (Simple Allocator)" 834 help 835 SLOB replaces the stock allocator with a drastically simpler 836 allocator. SLOB is generally more space efficient but 837 does not perform as well on large systems. 838 839endchoice 840 841config PROFILING 842 bool "Profiling support (EXPERIMENTAL)" 843 help 844 Say Y here to enable the extended profiling support mechanisms used 845 by profilers such as OProfile. 846 847# 848# Place an empty function call at each tracepoint site. Can be 849# dynamically changed for a probe function. 850# 851config TRACEPOINTS 852 bool 853 854config MARKERS 855 bool "Activate markers" 856 depends on TRACEPOINTS 857 help 858 Place an empty function call at each marker site. Can be 859 dynamically changed for a probe function. 860 861source "arch/Kconfig" 862 863endmenu # General setup 864 865config HAVE_GENERIC_DMA_COHERENT 866 bool 867 default n 868 869config SLABINFO 870 bool 871 depends on PROC_FS 872 depends on SLAB || SLUB_DEBUG 873 default y 874 875config RT_MUTEXES 876 boolean 877 select PLIST 878 879config BASE_SMALL 880 int 881 default 0 if BASE_FULL 882 default 1 if !BASE_FULL 883 884menuconfig MODULES 885 bool "Enable loadable module support" 886 help 887 Kernel modules are small pieces of compiled code which can 888 be inserted in the running kernel, rather than being 889 permanently built into the kernel. You use the "modprobe" 890 tool to add (and sometimes remove) them. If you say Y here, 891 many parts of the kernel can be built as modules (by 892 answering M instead of Y where indicated): this is most 893 useful for infrequently used options which are not required 894 for booting. For more information, see the man pages for 895 modprobe, lsmod, modinfo, insmod and rmmod. 896 897 If you say Y here, you will need to run "make 898 modules_install" to put the modules under /lib/modules/ 899 where modprobe can find them (you may need to be root to do 900 this). 901 902 If unsure, say Y. 903 904if MODULES 905 906config MODULE_FORCE_LOAD 907 bool "Forced module loading" 908 default n 909 help 910 Allow loading of modules without version information (ie. modprobe 911 --force). Forced module loading sets the 'F' (forced) taint flag and 912 is usually a really bad idea. 913 914config MODULE_UNLOAD 915 bool "Module unloading" 916 help 917 Without this option you will not be able to unload any 918 modules (note that some modules may not be unloadable 919 anyway), which makes your kernel smaller, faster 920 and simpler. If unsure, say Y. 921 922config MODULE_FORCE_UNLOAD 923 bool "Forced module unloading" 924 depends on MODULE_UNLOAD && EXPERIMENTAL 925 help 926 This option allows you to force a module to unload, even if the 927 kernel believes it is unsafe: the kernel will remove the module 928 without waiting for anyone to stop using it (using the -f option to 929 rmmod). This is mainly for kernel developers and desperate users. 930 If unsure, say N. 931 932config MODVERSIONS 933 bool "Module versioning support" 934 help 935 Usually, you have to use modules compiled with your kernel. 936 Saying Y here makes it sometimes possible to use modules 937 compiled for different kernels, by adding enough information 938 to the modules to (hopefully) spot any changes which would 939 make them incompatible with the kernel you are running. If 940 unsure, say N. 941 942config MODULE_SRCVERSION_ALL 943 bool "Source checksum for all modules" 944 help 945 Modules which contain a MODULE_VERSION get an extra "srcversion" 946 field inserted into their modinfo section, which contains a 947 sum of the source files which made it. This helps maintainers 948 see exactly which source was used to build a module (since 949 others sometimes change the module source without updating 950 the version). With this option, such a "srcversion" field 951 will be created for all modules. If unsure, say N. 952 953endif # MODULES 954 955config INIT_ALL_POSSIBLE 956 bool 957 help 958 Back when each arch used to define their own cpu_online_map and 959 cpu_possible_map, some of them chose to initialize cpu_possible_map 960 with all 1s, and others with all 0s. When they were centralised, 961 it was better to provide this option than to break all the archs 962 and have several arch maintainers persuing me down dark alleys. 963 964config STOP_MACHINE 965 bool 966 default y 967 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 968 help 969 Need stop_machine() primitive. 970 971source "block/Kconfig" 972 973config PREEMPT_NOTIFIERS 974 bool 975 976choice 977 prompt "RCU Implementation" 978 default CLASSIC_RCU 979 980config CLASSIC_RCU 981 bool "Classic RCU" 982 help 983 This option selects the classic RCU implementation that is 984 designed for best read-side performance on non-realtime 985 systems. 986 987 Select this option if you are unsure. 988 989config TREE_RCU 990 bool "Tree-based hierarchical RCU" 991 help 992 This option selects the RCU implementation that is 993 designed for very large SMP system with hundreds or 994 thousands of CPUs. 995 996config PREEMPT_RCU 997 bool "Preemptible RCU" 998 depends on PREEMPT 999 help 1000 This option reduces the latency of the kernel by making certain 1001 RCU sections preemptible. Normally RCU code is non-preemptible, if 1002 this option is selected then read-only RCU sections become 1003 preemptible. This helps latency, but may expose bugs due to 1004 now-naive assumptions about each RCU read-side critical section 1005 remaining on a given CPU through its execution. 1006 1007endchoice 1008 1009config RCU_TRACE 1010 bool "Enable tracing for RCU" 1011 depends on TREE_RCU || PREEMPT_RCU 1012 help 1013 This option provides tracing in RCU which presents stats 1014 in debugfs for debugging RCU implementation. 1015 1016 Say Y here if you want to enable RCU tracing 1017 Say N if you are unsure. 1018 1019config RCU_FANOUT 1020 int "Tree-based hierarchical RCU fanout value" 1021 range 2 64 if 64BIT 1022 range 2 32 if !64BIT 1023 depends on TREE_RCU 1024 default 64 if 64BIT 1025 default 32 if !64BIT 1026 help 1027 This option controls the fanout of hierarchical implementations 1028 of RCU, allowing RCU to work efficiently on machines with 1029 large numbers of CPUs. This value must be at least the cube 1030 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit 1031 systems and up to 262,144 for 64-bit systems. 1032 1033 Select a specific number if testing RCU itself. 1034 Take the default if unsure. 1035 1036config RCU_FANOUT_EXACT 1037 bool "Disable tree-based hierarchical RCU auto-balancing" 1038 depends on TREE_RCU 1039 default n 1040 help 1041 This option forces use of the exact RCU_FANOUT value specified, 1042 regardless of imbalances in the hierarchy. This is useful for 1043 testing RCU itself, and might one day be useful on systems with 1044 strong NUMA behavior. 1045 1046 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 1047 1048 Say N if unsure. 1049 1050config TREE_RCU_TRACE 1051 def_bool RCU_TRACE && TREE_RCU 1052 select DEBUG_FS 1053 help 1054 This option provides tracing for the TREE_RCU implementation, 1055 permitting Makefile to trivially select kernel/rcutree_trace.c. 1056 1057config PREEMPT_RCU_TRACE 1058 def_bool RCU_TRACE && PREEMPT_RCU 1059 select DEBUG_FS 1060 help 1061 This option provides tracing for the PREEMPT_RCU implementation, 1062 permitting Makefile to trivially select kernel/rcupreempt_trace.c. 1063