init/Kconfig

   1 config ARCH
   2         string
   3         option env="ARCH"
   4
   5 config KERNELVERSION
   6         string
   7         option env="KERNELVERSION"
   8
   9 config 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
  19 config CONSTRUCTORS
  20         bool
  21         depends on !UML
  22
  23 config HAVE_IRQ_WORK
  24         bool
  25
  26 config IRQ_WORK
  27         bool
  28         depends on HAVE_IRQ_WORK
  29
  30 menu "General setup"
  31
  32 config EXPERIMENTAL
  33         bool "Prompt for development and/or incomplete code/drivers"
  34         ---help---
  35           Some of the various things that Linux supports (such as network
  36           drivers, file systems, network protocols, etc.) can be in a state
  37           of development where the functionality, stability, or the level of
  38           testing is not yet high enough for general use. This is usually
  39           known as the "alpha-test" phase among developers. If a feature is
  40           currently in alpha-test, then the developers usually discourage
  41           uninformed widespread use of this feature by the general public to
  42           avoid "Why doesn't this work?" type mail messages. However, active
  43           testing and use of these systems is welcomed. Just be aware that it
  44           may not meet the normal level of reliability or it may fail to work
  45           in some special cases. Detailed bug reports from people familiar
  46           with the kernel internals are usually welcomed by the developers
  47           (before submitting bug reports, please read the documents
  48           <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  49           <file:Documentation/BUG-HUNTING>, and
  50           <file:Documentation/oops-tracing.txt> in the kernel source).
  51
  52           This option will also make obsoleted drivers available. These are
  53           drivers that have been replaced by something else, and/or are
  54           scheduled to be removed in a future kernel release.
  55
  56           Unless you intend to help test and develop a feature or driver that
  57           falls into this category, or you have a situation that requires
  58           using these features, you should probably say N here, which will
  59           cause the configurator to present you with fewer choices. If
  60           you say Y here, you will be offered the choice of using features or
  61           drivers that are currently considered to be in the alpha-test phase.
  62
  63 config BROKEN
  64         bool
  65
  66 config BROKEN_ON_SMP
  67         bool
  68         depends on BROKEN || !SMP
  69         default y
  70
  71 config INIT_ENV_ARG_LIMIT
  72         int
  73         default 32 if !UML
  74         default 128 if UML
  75         help
  76           Maximum of each of the number of arguments and environment
  77           variables passed to init from the kernel command line.
  78
  79
  80 config CROSS_COMPILE
  81         string "Cross-compiler tool prefix"
  82         help
  83           Same as running 'make CROSS_COMPILE=prefix-' but stored for
  84           default make runs in this kernel build directory.  You don't
  85           need to set this unless you want the configured kernel build
  86           directory to select the cross-compiler automatically.
  87
  88 config LOCALVERSION
  89         string "Local version - append to kernel release"
  90         help
  91           Append an extra string to the end of your kernel version.
  92           This will show up when you type uname, for example.
  93           The string you set here will be appended after the contents of
  94           any files with a filename matching localversion* in your
  95           object and source tree, in that order.  Your total string can
  96           be a maximum of 64 characters.
  97
  98 config LOCALVERSION_AUTO
  99         bool "Automatically append version information to the version string"
 100         default y
 101         help
 102           This will try to automatically determine if the current tree is a
 103           release tree by looking for git tags that belong to the current
 104           top of tree revision.
 105
 106           A string of the format -gxxxxxxxx will be added to the localversion
 107           if a git-based tree is found.  The string generated by this will be
 108           appended after any matching localversion* files, and after the value
 109           set in CONFIG_LOCALVERSION.
 110
 111           (The actual string used here is the first eight characters produced
 112           by running the command:
 113
 114             $ git rev-parse --verify HEAD
 115
 116           which is done within the script "scripts/setlocalversion".)
 117
 118 config HAVE_KERNEL_GZIP
 119         bool
 120
 121 config HAVE_KERNEL_BZIP2
 122         bool
 123
 124 config HAVE_KERNEL_LZMA
 125         bool
 126
 127 config HAVE_KERNEL_XZ
 128         bool
 129
 130 config HAVE_KERNEL_LZO
 131         bool
 132
 133 choice
 134         prompt "Kernel compression mode"
 135         default KERNEL_GZIP
 136         depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
 137         help
 138           The linux kernel is a kind of self-extracting executable.
 139           Several compression algorithms are available, which differ
 140           in efficiency, compression and decompression speed.
 141           Compression speed is only relevant when building a kernel.
 142           Decompression speed is relevant at each boot.
 143
 144           If you have any problems with bzip2 or lzma compressed
 145           kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 146           version of this functionality (bzip2 only), for 2.4, was
 147           supplied by Christian Ludwig)
 148
 149           High compression options are mostly useful for users, who
 150           are low on disk space (embedded systems), but for whom ram
 151           size matters less.
 152
 153           If in doubt, select 'gzip'
 154
 155 config KERNEL_GZIP
 156         bool "Gzip"
 157         depends on HAVE_KERNEL_GZIP
 158         help
 159           The old and tried gzip compression. It provides a good balance
 160           between compression ratio and decompression speed.
 161
 162 config KERNEL_BZIP2
 163         bool "Bzip2"
 164         depends on HAVE_KERNEL_BZIP2
 165         help
 166           Its compression ratio and speed is intermediate.
 167           Decompression speed is slowest among the three.  The kernel
 168           size is about 10% smaller with bzip2, in comparison to gzip.
 169           Bzip2 uses a large amount of memory. For modern kernels you
 170           will need at least 8MB RAM or more for booting.
 171
 172 config KERNEL_LZMA
 173         bool "LZMA"
 174         depends on HAVE_KERNEL_LZMA
 175         help
 176           The most recent compression algorithm.
 177           Its ratio is best, decompression speed is between the other
 178           two. Compression is slowest.  The kernel size is about 33%
 179           smaller with LZMA in comparison to gzip.
 180
 181 config KERNEL_XZ
 182         bool "XZ"
 183         depends on HAVE_KERNEL_XZ
 184         help
 185           XZ uses the LZMA2 algorithm and instruction set specific
 186           BCJ filters which can improve compression ratio of executable
 187           code. The size of the kernel is about 30% smaller with XZ in
 188           comparison to gzip. On architectures for which there is a BCJ
 189           filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
 190           will create a few percent smaller kernel than plain LZMA.
 191
 192           The speed is about the same as with LZMA: The decompression
 193           speed of XZ is better than that of bzip2 but worse than gzip
 194           and LZO. Compression is slow.
 195
 196 config KERNEL_LZO
 197         bool "LZO"
 198         depends on HAVE_KERNEL_LZO
 199         help
 200           Its compression ratio is the poorest among the 4. The kernel
 201           size is about 10% bigger than gzip; however its speed
 202           (both compression and decompression) is the fastest.
 203
 204 endchoice
 205
 206 config DEFAULT_HOSTNAME
 207         string "Default hostname"
 208         default "(none)"
 209         help
 210           This option determines the default system hostname before userspace
 211           calls sethostname(2). The kernel traditionally uses "(none)" here,
 212           but you may wish to use a different default here to make a minimal
 213           system more usable with less configuration.
 214
 215 config SWAP
 216         bool "Support for paging of anonymous memory (swap)"
 217         depends on MMU && BLOCK
 218         default y
 219         help
 220           This option allows you to choose whether you want to have support
 221           for so called swap devices or swap files in your kernel that are
 222           used to provide more virtual memory than the actual RAM present
 223           in your computer.  If unsure say Y.
 224
 225 config SYSVIPC
 226         bool "System V IPC"
 227         ---help---
 228           Inter Process Communication is a suite of library functions and
 229           system calls which let processes (running programs) synchronize and
 230           exchange information. It is generally considered to be a good thing,
 231           and some programs won't run unless you say Y here. In particular, if
 232           you want to run the DOS emulator dosemu under Linux (read the
 233           DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 234           you'll need to say Y here.
 235
 236           You can find documentation about IPC with "info ipc" and also in
 237           section 6.4 of the Linux Programmer's Guide, available from
 238           <http://www.tldp.org/guides.html>.
 239
 240 config SYSVIPC_SYSCTL
 241         bool
 242         depends on SYSVIPC
 243         depends on SYSCTL
 244         default y
 245
 246 config POSIX_MQUEUE
 247         bool "POSIX Message Queues"
 248         depends on NET && EXPERIMENTAL
 249         ---help---
 250           POSIX variant of message queues is a part of IPC. In POSIX message
 251           queues every message has a priority which decides about succession
 252           of receiving it by a process. If you want to compile and run
 253           programs written e.g. for Solaris with use of its POSIX message
 254           queues (functions mq_*) say Y here.
 255
 256           POSIX message queues are visible as a filesystem called 'mqueue'
 257           and can be mounted somewhere if you want to do filesystem
 258           operations on message queues.
 259
 260           If unsure, say Y.
 261
 262 config POSIX_MQUEUE_SYSCTL
 263         bool
 264         depends on POSIX_MQUEUE
 265         depends on SYSCTL
 266         default y
 267
 268 config BSD_PROCESS_ACCT
 269         bool "BSD Process Accounting"
 270         help
 271           If you say Y here, a user level program will be able to instruct the
 272           kernel (via a special system call) to write process accounting
 273           information to a file: whenever a process exits, information about
 274           that process will be appended to the file by the kernel.  The
 275           information includes things such as creation time, owning user,
 276           command name, memory usage, controlling terminal etc. (the complete
 277           list is in the struct acct in <file:include/linux/acct.h>).  It is
 278           up to the user level program to do useful things with this
 279           information.  This is generally a good idea, so say Y.
 280
 281 config BSD_PROCESS_ACCT_V3
 282         bool "BSD Process Accounting version 3 file format"
 283         depends on BSD_PROCESS_ACCT
 284         default n
 285         help
 286           If you say Y here, the process accounting information is written
 287           in a new file format that also logs the process IDs of each
 288           process and it's parent. Note that this file format is incompatible
 289           with previous v0/v1/v2 file formats, so you will need updated tools
 290           for processing it. A preliminary version of these tools is available
 291           at <http://www.gnu.org/software/acct/>.
 292
 293 config FHANDLE
 294         bool "open by fhandle syscalls"
 295         select EXPORTFS
 296         help
 297           If you say Y here, a user level program will be able to map
 298           file names to handle and then later use the handle for
 299           different file system operations. This is useful in implementing
 300           userspace file servers, which now track files using handles instead
 301           of names. The handle would remain the same even if file names
 302           get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
 303           syscalls.
 304
 305 config TASKSTATS
 306         bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 307         depends on NET
 308         default n
 309         help
 310           Export selected statistics for tasks/processes through the
 311           generic netlink interface. Unlike BSD process accounting, the
 312           statistics are available during the lifetime of tasks/processes as
 313           responses to commands. Like BSD accounting, they are sent to user
 314           space on task exit.
 315
 316           Say N if unsure.
 317
 318 config TASK_DELAY_ACCT
 319         bool "Enable per-task delay accounting (EXPERIMENTAL)"
 320         depends on TASKSTATS
 321         help
 322           Collect information on time spent by a task waiting for system
 323           resources like cpu, synchronous block I/O completion and swapping
 324           in pages. Such statistics can help in setting a task's priorities
 325           relative to other tasks for cpu, io, rss limits etc.
 326
 327           Say N if unsure.
 328
 329 config TASK_XACCT
 330         bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 331         depends on TASKSTATS
 332         help
 333           Collect extended task accounting data and send the data
 334           to userland for processing over the taskstats interface.
 335
 336           Say N if unsure.
 337
 338 config TASK_IO_ACCOUNTING
 339         bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 340         depends on TASK_XACCT
 341         help
 342           Collect information on the number of bytes of storage I/O which this
 343           task has caused.
 344
 345           Say N if unsure.
 346
 347 config AUDIT
 348         bool "Auditing support"
 349         depends on NET
 350         help
 351           Enable auditing infrastructure that can be used with another
 352           kernel subsystem, such as SELinux (which requires this for
 353           logging of avc messages output).  Does not do system-call
 354           auditing without CONFIG_AUDITSYSCALL.
 355
 356 config AUDITSYSCALL
 357         bool "Enable system-call auditing support"
 358         depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM)
 359         default y if SECURITY_SELINUX
 360         help
 361           Enable low-overhead system-call auditing infrastructure that
 362           can be used independently or with another kernel subsystem,
 363           such as SELinux.
 364
 365 config AUDIT_WATCH
 366         def_bool y
 367         depends on AUDITSYSCALL
 368         select FSNOTIFY
 369
 370 config AUDIT_TREE
 371         def_bool y
 372         depends on AUDITSYSCALL
 373         select FSNOTIFY
 374
 375 config AUDIT_LOGINUID_IMMUTABLE
 376         bool "Make audit loginuid immutable"
 377         depends on AUDIT
 378         help
 379           The config option toggles if a task setting its loginuid requires
 380           CAP_SYS_AUDITCONTROL or if that task should require no special permissions
 381           but should instead only allow setting its loginuid if it was never
 382           previously set.  On systems which use systemd or a similar central
 383           process to restart login services this should be set to true.  On older
 384           systems in which an admin would typically have to directly stop and
 385           start processes this should be set to false.  Setting this to true allows
 386           one to drop potentially dangerous capabilites from the login tasks,
 387           but may not be backwards compatible with older init systems.
 388
 389 source "kernel/irq/Kconfig"
 390
 391 menu "RCU Subsystem"
 392
 393 choice
 394         prompt "RCU Implementation"
 395         default TREE_RCU
 396
 397 config TREE_RCU
 398         bool "Tree-based hierarchical RCU"
 399         depends on !PREEMPT && SMP
 400         help
 401           This option selects the RCU implementation that is
 402           designed for very large SMP system with hundreds or
 403           thousands of CPUs.  It also scales down nicely to
 404           smaller systems.
 405
 406 config TREE_PREEMPT_RCU
 407         bool "Preemptible tree-based hierarchical RCU"
 408         depends on PREEMPT && SMP
 409         help
 410           This option selects the RCU implementation that is
 411           designed for very large SMP systems with hundreds or
 412           thousands of CPUs, but for which real-time response
 413           is also required.  It also scales down nicely to
 414           smaller systems.
 415
 416 config TINY_RCU
 417         bool "UP-only small-memory-footprint RCU"
 418         depends on !PREEMPT && !SMP
 419         help
 420           This option selects the RCU implementation that is
 421           designed for UP systems from which real-time response
 422           is not required.  This option greatly reduces the
 423           memory footprint of RCU.
 424
 425 config TINY_PREEMPT_RCU
 426         bool "Preemptible UP-only small-memory-footprint RCU"
 427         depends on PREEMPT && !SMP
 428         help
 429           This option selects the RCU implementation that is designed
 430           for real-time UP systems.  This option greatly reduces the
 431           memory footprint of RCU.
 432
 433 endchoice
 434
 435 config PREEMPT_RCU
 436         def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
 437         help
 438           This option enables preemptible-RCU code that is common between
 439           the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
 440
 441 config RCU_FANOUT
 442         int "Tree-based hierarchical RCU fanout value"
 443         range 2 64 if 64BIT
 444         range 2 32 if !64BIT
 445         depends on TREE_RCU || TREE_PREEMPT_RCU
 446         default 64 if 64BIT
 447         default 32 if !64BIT
 448         help
 449           This option controls the fanout of hierarchical implementations
 450           of RCU, allowing RCU to work efficiently on machines with
 451           large numbers of CPUs.  This value must be at least the fourth
 452           root of NR_CPUS, which allows NR_CPUS to be insanely large.
 453           The default value of RCU_FANOUT should be used for production
 454           systems, but if you are stress-testing the RCU implementation
 455           itself, small RCU_FANOUT values allow you to test large-system
 456           code paths on small(er) systems.
 457
 458           Select a specific number if testing RCU itself.
 459           Take the default if unsure.
 460
 461 config RCU_FANOUT_EXACT
 462         bool "Disable tree-based hierarchical RCU auto-balancing"
 463         depends on TREE_RCU || TREE_PREEMPT_RCU
 464         default n
 465         help
 466           This option forces use of the exact RCU_FANOUT value specified,
 467           regardless of imbalances in the hierarchy.  This is useful for
 468           testing RCU itself, and might one day be useful on systems with
 469           strong NUMA behavior.
 470
 471           Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 472
 473           Say N if unsure.
 474
 475 config RCU_FAST_NO_HZ
 476         bool "Accelerate last non-dyntick-idle CPU's grace periods"
 477         depends on NO_HZ && SMP
 478         default n
 479         help
 480           This option causes RCU to attempt to accelerate grace periods
 481           in order to allow CPUs to enter dynticks-idle state more
 482           quickly.  On the other hand, this option increases the overhead
 483           of the dynticks-idle checking, particularly on systems with
 484           large numbers of CPUs.
 485
 486           Say Y if energy efficiency is critically important, particularly
 487                 if you have relatively few CPUs.
 488
 489           Say N if you are unsure.
 490
 491 config TREE_RCU_TRACE
 492         def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 493         select DEBUG_FS
 494         help
 495           This option provides tracing for the TREE_RCU and
 496           TREE_PREEMPT_RCU implementations, permitting Makefile to
 497           trivially select kernel/rcutree_trace.c.
 498
 499 config RCU_BOOST
 500         bool "Enable RCU priority boosting"
 501         depends on RT_MUTEXES && PREEMPT_RCU
 502         default n
 503         help
 504           This option boosts the priority of preempted RCU readers that
 505           block the current preemptible RCU grace period for too long.
 506           This option also prevents heavy loads from blocking RCU
 507           callback invocation for all flavors of RCU.
 508
 509           Say Y here if you are working with real-time apps or heavy loads
 510           Say N here if you are unsure.
 511
 512 config RCU_BOOST_PRIO
 513         int "Real-time priority to boost RCU readers to"
 514         range 1 99
 515         depends on RCU_BOOST
 516         default 1
 517         help
 518           This option specifies the real-time priority to which preempted
 519           RCU readers are to be boosted.  If you are working with CPU-bound
 520           real-time applications, you should specify a priority higher then
 521           the highest-priority CPU-bound application.
 522
 523           Specify the real-time priority, or take the default if unsure.
 524
 525 config RCU_BOOST_DELAY
 526         int "Milliseconds to delay boosting after RCU grace-period start"
 527         range 0 3000
 528         depends on RCU_BOOST
 529         default 500
 530         help
 531           This option specifies the time to wait after the beginning of
 532           a given grace period before priority-boosting preempted RCU
 533           readers blocking that grace period.  Note that any RCU reader
 534           blocking an expedited RCU grace period is boosted immediately.
 535
 536           Accept the default if unsure.
 537
 538 endmenu # "RCU Subsystem"
 539
 540 config IKCONFIG
 541         tristate "Kernel .config support"
 542         ---help---
 543           This option enables the complete Linux kernel ".config" file
 544           contents to be saved in the kernel. It provides documentation
 545           of which kernel options are used in a running kernel or in an
 546           on-disk kernel.  This information can be extracted from the kernel
 547           image file with the script scripts/extract-ikconfig and used as
 548           input to rebuild the current kernel or to build another kernel.
 549           It can also be extracted from a running kernel by reading
 550           /proc/config.gz if enabled (below).
 551
 552 config IKCONFIG_PROC
 553         bool "Enable access to .config through /proc/config.gz"
 554         depends on IKCONFIG && PROC_FS
 555         ---help---
 556           This option enables access to the kernel configuration file
 557           through /proc/config.gz.
 558
 559 config LOG_BUF_SHIFT
 560         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 561         range 12 21
 562         default 17
 563         help
 564           Select kernel log buffer size as a power of 2.
 565           Examples:
 566                      17 => 128 KB
 567                      16 => 64 KB
 568                      15 => 32 KB
 569                      14 => 16 KB
 570                      13 =>  8 KB
 571                      12 =>  4 KB
 572
 573 #
 574 # Architectures with an unreliable sched_clock() should select this:
 575 #
 576 config HAVE_UNSTABLE_SCHED_CLOCK
 577         bool
 578
 579 menuconfig CGROUPS
 580         boolean "Control Group support"
 581         depends on EVENTFD
 582         help
 583           This option adds support for grouping sets of processes together, for
 584           use with process control subsystems such as Cpusets, CFS, memory
 585           controls or device isolation.
 586           See
 587                 - Documentation/scheduler/sched-design-CFS.txt  (CFS)
 588                 - Documentation/cgroups/ (features for grouping, isolation
 589                                           and resource control)
 590
 591           Say N if unsure.
 592
 593 if CGROUPS
 594
 595 config CGROUP_DEBUG
 596         bool "Example debug cgroup subsystem"
 597         default n
 598         help
 599           This option enables a simple cgroup subsystem that
 600           exports useful debugging information about the cgroups
 601           framework.
 602
 603           Say N if unsure.
 604
 605 config CGROUP_FREEZER
 606         bool "Freezer cgroup subsystem"
 607         help
 608           Provides a way to freeze and unfreeze all tasks in a
 609           cgroup.
 610
 611 config CGROUP_DEVICE
 612         bool "Device controller for cgroups"
 613         help
 614           Provides a cgroup implementing whitelists for devices which
 615           a process in the cgroup can mknod or open.
 616
 617 config CPUSETS
 618         bool "Cpuset support"
 619         help
 620           This option will let you create and manage CPUSETs which
 621           allow dynamically partitioning a system into sets of CPUs and
 622           Memory Nodes and assigning tasks to run only within those sets.
 623           This is primarily useful on large SMP or NUMA systems.
 624
 625           Say N if unsure.
 626
 627 config PROC_PID_CPUSET
 628         bool "Include legacy /proc/<pid>/cpuset file"
 629         depends on CPUSETS
 630         default y
 631
 632 config CGROUP_CPUACCT
 633         bool "Simple CPU accounting cgroup subsystem"
 634         help
 635           Provides a simple Resource Controller for monitoring the
 636           total CPU consumed by the tasks in a cgroup.
 637
 638 config RESOURCE_COUNTERS
 639         bool "Resource counters"
 640         help
 641           This option enables controller independent resource accounting
 642           infrastructure that works with cgroups.
 643
 644 config CGROUP_MEM_RES_CTLR
 645         bool "Memory Resource Controller for Control Groups"
 646         depends on RESOURCE_COUNTERS
 647         select MM_OWNER
 648         help
 649           Provides a memory resource controller that manages both anonymous
 650           memory and page cache. (See Documentation/cgroups/memory.txt)
 651
 652           Note that setting this option increases fixed memory overhead
 653           associated with each page of memory in the system. By this,
 654           20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 655           usage tracking struct at boot. Total amount of this is printed out
 656           at boot.
 657
 658           Only enable when you're ok with these trade offs and really
 659           sure you need the memory resource controller. Even when you enable
 660           this, you can set "cgroup_disable=memory" at your boot option to
 661           disable memory resource controller and you can avoid overheads.
 662           (and lose benefits of memory resource controller)
 663
 664           This config option also selects MM_OWNER config option, which
 665           could in turn add some fork/exit overhead.
 666
 667 config CGROUP_MEM_RES_CTLR_SWAP
 668         bool "Memory Resource Controller Swap Extension"
 669         depends on CGROUP_MEM_RES_CTLR && SWAP
 670         help
 671           Add swap management feature to memory resource controller. When you
 672           enable this, you can limit mem+swap usage per cgroup. In other words,
 673           when you disable this, memory resource controller has no cares to
 674           usage of swap...a process can exhaust all of the swap. This extension
 675           is useful when you want to avoid exhaustion swap but this itself
 676           adds more overheads and consumes memory for remembering information.
 677           Especially if you use 32bit system or small memory system, please
 678           be careful about enabling this. When memory resource controller
 679           is disabled by boot option, this will be automatically disabled and
 680           there will be no overhead from this. Even when you set this config=y,
 681           if boot option "swapaccount=0" is set, swap will not be accounted.
 682           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 683           size is 4096bytes, 512k per 1Gbytes of swap.
 684 config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
 685         bool "Memory Resource Controller Swap Extension enabled by default"
 686         depends on CGROUP_MEM_RES_CTLR_SWAP
 687         default y
 688         help
 689           Memory Resource Controller Swap Extension comes with its price in
 690           a bigger memory consumption. General purpose distribution kernels
 691           which want to enable the feature but keep it disabled by default
 692           and let the user enable it by swapaccount boot command line
 693           parameter should have this option unselected.
 694           For those who want to have the feature enabled by default should
 695           select this option (if, for some reason, they need to disable it
 696           then swapaccount=0 does the trick).
 697 config CGROUP_MEM_RES_CTLR_KMEM
 698         bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
 699         depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL
 700         default n
 701         help
 702           The Kernel Memory extension for Memory Resource Controller can limit
 703           the amount of memory used by kernel objects in the system. Those are
 704           fundamentally different from the entities handled by the standard
 705           Memory Controller, which are page-based, and can be swapped. Users of
 706           the kmem extension can use it to guarantee that no group of processes
 707           will ever exhaust kernel resources alone.
 708
 709 config CGROUP_PERF
 710         bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
 711         depends on PERF_EVENTS && CGROUPS
 712         help
 713           This option extends the per-cpu mode to restrict monitoring to
 714           threads which belong to the cgroup specified and run on the
 715           designated cpu.
 716
 717           Say N if unsure.
 718
 719 menuconfig CGROUP_SCHED
 720         bool "Group CPU scheduler"
 721         default n
 722         help
 723           This feature lets CPU scheduler recognize task groups and control CPU
 724           bandwidth allocation to such task groups. It uses cgroups to group
 725           tasks.
 726
 727 if CGROUP_SCHED
 728 config FAIR_GROUP_SCHED
 729         bool "Group scheduling for SCHED_OTHER"
 730         depends on CGROUP_SCHED
 731         default CGROUP_SCHED
 732
 733 config CFS_BANDWIDTH
 734         bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
 735         depends on EXPERIMENTAL
 736         depends on FAIR_GROUP_SCHED
 737         default n
 738         help
 739           This option allows users to define CPU bandwidth rates (limits) for
 740           tasks running within the fair group scheduler.  Groups with no limit
 741           set are considered to be unconstrained and will run with no
 742           restriction.
 743           See tip/Documentation/scheduler/sched-bwc.txt for more information.
 744
 745 config RT_GROUP_SCHED
 746         bool "Group scheduling for SCHED_RR/FIFO"
 747         depends on EXPERIMENTAL
 748         depends on CGROUP_SCHED
 749         default n
 750         help
 751           This feature lets you explicitly allocate real CPU bandwidth
 752           to task groups. If enabled, it will also make it impossible to
 753           schedule realtime tasks for non-root users until you allocate
 754           realtime bandwidth for them.
 755           See Documentation/scheduler/sched-rt-group.txt for more information.
 756
 757 endif #CGROUP_SCHED
 758
 759 config BLK_CGROUP
 760         tristate "Block IO controller"
 761         depends on BLOCK
 762         default n
 763         ---help---
 764         Generic block IO controller cgroup interface. This is the common
 765         cgroup interface which should be used by various IO controlling
 766         policies.
 767
 768         Currently, CFQ IO scheduler uses it to recognize task groups and
 769         control disk bandwidth allocation (proportional time slice allocation)
 770         to such task groups. It is also used by bio throttling logic in
 771         block layer to implement upper limit in IO rates on a device.
 772
 773         This option only enables generic Block IO controller infrastructure.
 774         One needs to also enable actual IO controlling logic/policy. For
 775         enabling proportional weight division of disk bandwidth in CFQ, set
 776         CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 777         CONFIG_BLK_DEV_THROTTLING=y.
 778
 779         See Documentation/cgroups/blkio-controller.txt for more information.
 780
 781 config DEBUG_BLK_CGROUP
 782         bool "Enable Block IO controller debugging"
 783         depends on BLK_CGROUP
 784         default n
 785         ---help---
 786         Enable some debugging help. Currently it exports additional stat
 787         files in a cgroup which can be useful for debugging.
 788
 789 endif # CGROUPS
 790
 791 config CHECKPOINT_RESTORE
 792         bool "Checkpoint/restore support" if EXPERT
 793         default n
 794         help
 795           Enables additional kernel features in a sake of checkpoint/restore.
 796           In particular it adds auxiliary prctl codes to setup process text,
 797           data and heap segment sizes, and a few additional /proc filesystem
 798           entries.
 799
 800           If unsure, say N here.
 801
 802 menuconfig NAMESPACES
 803         bool "Namespaces support" if EXPERT
 804         default !EXPERT
 805         help
 806           Provides the way to make tasks work with different objects using
 807           the same id. For example same IPC id may refer to different objects
 808           or same user id or pid may refer to different tasks when used in
 809           different namespaces.
 810
 811 if NAMESPACES
 812
 813 config UTS_NS
 814         bool "UTS namespace"
 815         default y
 816         help
 817           In this namespace tasks see different info provided with the
 818           uname() system call
 819
 820 config IPC_NS
 821         bool "IPC namespace"
 822         depends on (SYSVIPC || POSIX_MQUEUE)
 823         default y
 824         help
 825           In this namespace tasks work with IPC ids which correspond to
 826           different IPC objects in different namespaces.
 827
 828 config USER_NS
 829         bool "User namespace (EXPERIMENTAL)"
 830         depends on EXPERIMENTAL
 831         default y
 832         help
 833           This allows containers, i.e. vservers, to use user namespaces
 834           to provide different user info for different servers.
 835           If unsure, say N.
 836
 837 config PID_NS
 838         bool "PID Namespaces"
 839         default y
 840         help
 841           Support process id namespaces.  This allows having multiple
 842           processes with the same pid as long as they are in different
 843           pid namespaces.  This is a building block of containers.
 844
 845 config NET_NS
 846         bool "Network namespace"
 847         depends on NET
 848         default y
 849         help
 850           Allow user space to create what appear to be multiple instances
 851           of the network stack.
 852
 853 endif # NAMESPACES
 854
 855 config SCHED_AUTOGROUP
 856         bool "Automatic process group scheduling"
 857         select EVENTFD
 858         select CGROUPS
 859         select CGROUP_SCHED
 860         select FAIR_GROUP_SCHED
 861         help
 862           This option optimizes the scheduler for common desktop workloads by
 863           automatically creating and populating task groups.  This separation
 864           of workloads isolates aggressive CPU burners (like build jobs) from
 865           desktop applications.  Task group autogeneration is currently based
 866           upon task session.
 867
 868 config MM_OWNER
 869         bool
 870
 871 config SYSFS_DEPRECATED
 872         bool "Enable deprecated sysfs features to support old userspace tools"
 873         depends on SYSFS
 874         default n
 875         help
 876           This option adds code that switches the layout of the "block" class
 877           devices, to not show up in /sys/class/block/, but only in
 878           /sys/block/.
 879
 880           This switch is only active when the sysfs.deprecated=1 boot option is
 881           passed or the SYSFS_DEPRECATED_V2 option is set.
 882
 883           This option allows new kernels to run on old distributions and tools,
 884           which might get confused by /sys/class/block/. Since 2007/2008 all
 885           major distributions and tools handle this just fine.
 886
 887           Recent distributions and userspace tools after 2009/2010 depend on
 888           the existence of /sys/class/block/, and will not work with this
 889           option enabled.
 890
 891           Only if you are using a new kernel on an old distribution, you might
 892           need to say Y here.
 893
 894 config SYSFS_DEPRECATED_V2
 895         bool "Enable deprecated sysfs features by default"
 896         default n
 897         depends on SYSFS
 898         depends on SYSFS_DEPRECATED
 899         help
 900           Enable deprecated sysfs by default.
 901
 902           See the CONFIG_SYSFS_DEPRECATED option for more details about this
 903           option.
 904
 905           Only if you are using a new kernel on an old distribution, you might
 906           need to say Y here. Even then, odds are you would not need it
 907           enabled, you can always pass the boot option if absolutely necessary.
 908
 909 config RELAY
 910         bool "Kernel->user space relay support (formerly relayfs)"
 911         help
 912           This option enables support for relay interface support in
 913           certain file systems (such as debugfs).
 914           It is designed to provide an efficient mechanism for tools and
 915           facilities to relay large amounts of data from kernel space to
 916           user space.
 917
 918           If unsure, say N.
 919
 920 config BLK_DEV_INITRD
 921         bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 922         depends on BROKEN || !FRV
 923         help
 924           The initial RAM filesystem is a ramfs which is loaded by the
 925           boot loader (loadlin or lilo) and that is mounted as root
 926           before the normal boot procedure. It is typically used to
 927           load modules needed to mount the "real" root file system,
 928           etc. See <file:Documentation/initrd.txt> for details.
 929
 930           If RAM disk support (BLK_DEV_RAM) is also included, this
 931           also enables initial RAM disk (initrd) support and adds
 932           15 Kbytes (more on some other architectures) to the kernel size.
 933
 934           If unsure say Y.
 935
 936 if BLK_DEV_INITRD
 937
 938 source "usr/Kconfig"
 939
 940 endif
 941
 942 config CC_OPTIMIZE_FOR_SIZE
 943         bool "Optimize for size"
 944         help
 945           Enabling this option will pass "-Os" instead of "-O2" to gcc
 946           resulting in a smaller kernel.
 947
 948           If unsure, say Y.
 949
 950 config SYSCTL
 951         bool
 952
 953 config ANON_INODES
 954         bool
 955
 956 menuconfig EXPERT
 957         bool "Configure standard kernel features (expert users)"
 958         # Unhide debug options, to make the on-by-default options visible
 959         select DEBUG_KERNEL
 960         help
 961           This option allows certain base kernel options and settings
 962           to be disabled or tweaked. This is for specialized
 963           environments which can tolerate a "non-standard" kernel.
 964           Only use this if you really know what you are doing.
 965
 966 config UID16
 967         bool "Enable 16-bit UID system calls" if EXPERT
 968         depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 969         default y
 970         help
 971           This enables the legacy 16-bit UID syscall wrappers.
 972
 973 config SYSCTL_SYSCALL
 974         bool "Sysctl syscall support" if EXPERT
 975         depends on PROC_SYSCTL
 976         default n
 977         select SYSCTL
 978         ---help---
 979           sys_sysctl uses binary paths that have been found challenging
 980           to properly maintain and use.  The interface in /proc/sys
 981           using paths with ascii names is now the primary path to this
 982           information.
 983
 984           Almost nothing using the binary sysctl interface so if you are
 985           trying to save some space it is probably safe to disable this,
 986           making your kernel marginally smaller.
 987
 988           If unsure say N here.
 989
 990 config KALLSYMS
 991          bool "Load all symbols for debugging/ksymoops" if EXPERT
 992          default y
 993          help
 994            Say Y here to let the kernel print out symbolic crash information and
 995            symbolic stack backtraces. This increases the size of the kernel
 996            somewhat, as all symbols have to be loaded into the kernel image.
 997
 998 config KALLSYMS_ALL
 999         bool "Include all symbols in kallsyms"
1000         depends on DEBUG_KERNEL && KALLSYMS
1001         help
1002            Normally kallsyms only contains the symbols of functions for nicer
1003            OOPS messages and backtraces (i.e., symbols from the text and inittext
1004            sections). This is sufficient for most cases. And only in very rare
1005            cases (e.g., when a debugger is used) all symbols are required (e.g.,
1006            names of variables from the data sections, etc).
1007
1008            This option makes sure that all symbols are loaded into the kernel
1009            image (i.e., symbols from all sections) in cost of increased kernel
1010            size (depending on the kernel configuration, it may be 300KiB or
1011            something like this).
1012
1013            Say N unless you really need all symbols.
1014
1015 config HOTPLUG
1016         bool "Support for hot-pluggable devices" if EXPERT
1017         default y
1018         help
1019           This option is provided for the case where no hotplug or uevent
1020           capabilities is wanted by the kernel.  You should only consider
1021           disabling this option for embedded systems that do not use modules, a
1022           dynamic /dev tree, or dynamic device discovery.  Just say Y.
1023
1024 config PRINTK
1025         default y
1026         bool "Enable support for printk" if EXPERT
1027         help
1028           This option enables normal printk support. Removing it
1029           eliminates most of the message strings from the kernel image
1030           and makes the kernel more or less silent. As this makes it
1031           very difficult to diagnose system problems, saying N here is
1032           strongly discouraged.
1033
1034 config BUG
1035         bool "BUG() support" if EXPERT
1036         default y
1037         help
1038           Disabling this option eliminates support for BUG and WARN, reducing
1039           the size of your kernel image and potentially quietly ignoring
1040           numerous fatal conditions. You should only consider disabling this
1041           option for embedded systems with no facilities for reporting errors.
1042           Just say Y.
1043
1044 config ELF_CORE
1045         default y
1046         bool "Enable ELF core dumps" if EXPERT
1047         help
1048           Enable support for generating core dumps. Disabling saves about 4k.
1049
1050
1051 config PCSPKR_PLATFORM
1052         bool "Enable PC-Speaker support" if EXPERT
1053         depends on HAVE_PCSPKR_PLATFORM
1054         select I8253_LOCK
1055         default y
1056         help
1057           This option allows to disable the internal PC-Speaker
1058           support, saving some memory.
1059
1060 config HAVE_PCSPKR_PLATFORM
1061         bool
1062
1063 config BASE_FULL
1064         default y
1065         bool "Enable full-sized data structures for core" if EXPERT
1066         help
1067           Disabling this option reduces the size of miscellaneous core
1068           kernel data structures. This saves memory on small machines,
1069           but may reduce performance.
1070
1071 config FUTEX
1072         bool "Enable futex support" if EXPERT
1073         default y
1074         select RT_MUTEXES
1075         help
1076           Disabling this option will cause the kernel to be built without
1077           support for "fast userspace mutexes".  The resulting kernel may not
1078           run glibc-based applications correctly.
1079
1080 config EPOLL
1081         bool "Enable eventpoll support" if EXPERT
1082         default y
1083         select ANON_INODES
1084         help
1085           Disabling this option will cause the kernel to be built without
1086           support for epoll family of system calls.
1087
1088 config SIGNALFD
1089         bool "Enable signalfd() system call" if EXPERT
1090         select ANON_INODES
1091         default y
1092         help
1093           Enable the signalfd() system call that allows to receive signals
1094           on a file descriptor.
1095
1096           If unsure, say Y.
1097
1098 config TIMERFD
1099         bool "Enable timerfd() system call" if EXPERT
1100         select ANON_INODES
1101         default y
1102         help
1103           Enable the timerfd() system call that allows to receive timer
1104           events on a file descriptor.
1105
1106           If unsure, say Y.
1107
1108 config EVENTFD
1109         bool "Enable eventfd() system call" if EXPERT
1110         select ANON_INODES
1111         default y
1112         help
1113           Enable the eventfd() system call that allows to receive both
1114           kernel notification (ie. KAIO) or userspace notifications.
1115
1116           If unsure, say Y.
1117
1118 config SHMEM
1119         bool "Use full shmem filesystem" if EXPERT
1120         default y
1121         depends on MMU
1122         help
1123           The shmem is an internal filesystem used to manage shared memory.
1124           It is backed by swap and manages resource limits. It is also exported
1125           to userspace as tmpfs if TMPFS is enabled. Disabling this
1126           option replaces shmem and tmpfs with the much simpler ramfs code,
1127           which may be appropriate on small systems without swap.
1128
1129 config AIO
1130         bool "Enable AIO support" if EXPERT
1131         default y
1132         help
1133           This option enables POSIX asynchronous I/O which may by used
1134           by some high performance threaded applications. Disabling
1135           this option saves about 7k.
1136
1137 config EMBEDDED
1138         bool "Embedded system"
1139         select EXPERT
1140         help
1141           This option should be enabled if compiling the kernel for
1142           an embedded system so certain expert options are available
1143           for configuration.
1144
1145 config HAVE_PERF_EVENTS
1146         bool
1147         help
1148           See tools/perf/design.txt for details.
1149
1150 config PERF_USE_VMALLOC
1151         bool
1152         help
1153           See tools/perf/design.txt for details
1154
1155 menu "Kernel Performance Events And Counters"
1156
1157 config PERF_EVENTS
1158         bool "Kernel performance events and counters"
1159         default y if (PROFILING || PERF_COUNTERS)
1160         depends on HAVE_PERF_EVENTS
1161         select ANON_INODES
1162         select IRQ_WORK
1163         help
1164           Enable kernel support for various performance events provided
1165           by software and hardware.
1166
1167           Software events are supported either built-in or via the
1168           use of generic tracepoints.
1169
1170           Most modern CPUs support performance events via performance
1171           counter registers. These registers count the number of certain
1172           types of hw events: such as instructions executed, cachemisses
1173           suffered, or branches mis-predicted - without slowing down the
1174           kernel or applications. These registers can also trigger interrupts
1175           when a threshold number of events have passed - and can thus be
1176           used to profile the code that runs on that CPU.
1177
1178           The Linux Performance Event subsystem provides an abstraction of
1179           these software and hardware event capabilities, available via a
1180           system call and used by the "perf" utility in tools/perf/. It
1181           provides per task and per CPU counters, and it provides event
1182           capabilities on top of those.
1183
1184           Say Y if unsure.
1185
1186 config PERF_COUNTERS
1187         bool "Kernel performance counters (old config option)"
1188         depends on HAVE_PERF_EVENTS
1189         help
1190           This config has been obsoleted by the PERF_EVENTS
1191           config option - please see that one for details.
1192
1193           It has no effect on the kernel whether you enable
1194           it or not, it is a compatibility placeholder.
1195
1196           Say N if unsure.
1197
1198 config DEBUG_PERF_USE_VMALLOC
1199         default n
1200         bool "Debug: use vmalloc to back perf mmap() buffers"
1201         depends on PERF_EVENTS && DEBUG_KERNEL
1202         select PERF_USE_VMALLOC
1203         help
1204          Use vmalloc memory to back perf mmap() buffers.
1205
1206          Mostly useful for debugging the vmalloc code on platforms
1207          that don't require it.
1208
1209          Say N if unsure.
1210
1211 endmenu
1212
1213 config VM_EVENT_COUNTERS
1214         default y
1215         bool "Enable VM event counters for /proc/vmstat" if EXPERT
1216         help
1217           VM event counters are needed for event counts to be shown.
1218           This option allows the disabling of the VM event counters
1219           on EXPERT systems.  /proc/vmstat will only show page counts
1220           if VM event counters are disabled.
1221
1222 config PCI_QUIRKS
1223         default y
1224         bool "Enable PCI quirk workarounds" if EXPERT
1225         depends on PCI
1226         help
1227           This enables workarounds for various PCI chipset
1228           bugs/quirks. Disable this only if your target machine is
1229           unaffected by PCI quirks.
1230
1231 config SLUB_DEBUG
1232         default y
1233         bool "Enable SLUB debugging support" if EXPERT
1234         depends on SLUB && SYSFS
1235         help
1236           SLUB has extensive debug support features. Disabling these can
1237           result in significant savings in code size. This also disables
1238           SLUB sysfs support. /sys/slab will not exist and there will be
1239           no support for cache validation etc.
1240
1241 config COMPAT_BRK
1242         bool "Disable heap randomization"
1243         default y
1244         help
1245           Randomizing heap placement makes heap exploits harder, but it
1246           also breaks ancient binaries (including anything libc5 based).
1247           This option changes the bootup default to heap randomization
1248           disabled, and can be overridden at runtime by setting
1249           /proc/sys/kernel/randomize_va_space to 2.
1250
1251           On non-ancient distros (post-2000 ones) N is usually a safe choice.
1252
1253 choice
1254         prompt "Choose SLAB allocator"
1255         default SLUB
1256         help
1257            This option allows to select a slab allocator.
1258
1259 config SLAB
1260         bool "SLAB"
1261         help
1262           The regular slab allocator that is established and known to work
1263           well in all environments. It organizes cache hot objects in
1264           per cpu and per node queues.
1265
1266 config SLUB
1267         bool "SLUB (Unqueued Allocator)"
1268         help
1269            SLUB is a slab allocator that minimizes cache line usage
1270            instead of managing queues of cached objects (SLAB approach).
1271            Per cpu caching is realized using slabs of objects instead
1272            of queues of objects. SLUB can use memory efficiently
1273            and has enhanced diagnostics. SLUB is the default choice for
1274            a slab allocator.
1275
1276 config SLOB
1277         depends on EXPERT
1278         bool "SLOB (Simple Allocator)"
1279         help
1280            SLOB replaces the stock allocator with a drastically simpler
1281            allocator. SLOB is generally more space efficient but
1282            does not perform as well on large systems.
1283
1284 endchoice
1285
1286 config MMAP_ALLOW_UNINITIALIZED
1287         bool "Allow mmapped anonymous memory to be uninitialized"
1288         depends on EXPERT && !MMU
1289         default n
1290         help
1291           Normally, and according to the Linux spec, anonymous memory obtained
1292           from mmap() has it's contents cleared before it is passed to
1293           userspace.  Enabling this config option allows you to request that
1294           mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1295           providing a huge performance boost.  If this option is not enabled,
1296           then the flag will be ignored.
1297
1298           This is taken advantage of by uClibc's malloc(), and also by
1299           ELF-FDPIC binfmt's brk and stack allocator.
1300
1301           Because of the obvious security issues, this option should only be
1302           enabled on embedded devices where you control what is run in
1303           userspace.  Since that isn't generally a problem on no-MMU systems,
1304           it is normally safe to say Y here.
1305
1306           See Documentation/nommu-mmap.txt for more information.
1307
1308 config PROFILING
1309         bool "Profiling support"
1310         help
1311           Say Y here to enable the extended profiling support mechanisms used
1312           by profilers such as OProfile.
1313
1314 #
1315 # Place an empty function call at each tracepoint site. Can be
1316 # dynamically changed for a probe function.
1317 #
1318 config TRACEPOINTS
1319         bool
1320
1321 source "arch/Kconfig"
1322
1323 endmenu         # General setup
1324
1325 config HAVE_GENERIC_DMA_COHERENT
1326         bool
1327         default n
1328
1329 config SLABINFO
1330         bool
1331         depends on PROC_FS
1332         depends on SLAB || SLUB_DEBUG
1333         default y
1334
1335 config RT_MUTEXES
1336         boolean
1337
1338 config BASE_SMALL
1339         int
1340         default 0 if BASE_FULL
1341         default 1 if !BASE_FULL
1342
1343 menuconfig MODULES
1344         bool "Enable loadable module support"
1345         help
1346           Kernel modules are small pieces of compiled code which can
1347           be inserted in the running kernel, rather than being
1348           permanently built into the kernel.  You use the "modprobe"
1349           tool to add (and sometimes remove) them.  If you say Y here,
1350           many parts of the kernel can be built as modules (by
1351           answering M instead of Y where indicated): this is most
1352           useful for infrequently used options which are not required
1353           for booting.  For more information, see the man pages for
1354           modprobe, lsmod, modinfo, insmod and rmmod.
1355
1356           If you say Y here, you will need to run "make
1357           modules_install" to put the modules under /lib/modules/
1358           where modprobe can find them (you may need to be root to do
1359           this).
1360
1361           If unsure, say Y.
1362
1363 if MODULES
1364
1365 config MODULE_FORCE_LOAD
1366         bool "Forced module loading"
1367         default n
1368         help
1369           Allow loading of modules without version information (ie. modprobe
1370           --force).  Forced module loading sets the 'F' (forced) taint flag and
1371           is usually a really bad idea.
1372
1373 config MODULE_UNLOAD
1374         bool "Module unloading"
1375         help
1376           Without this option you will not be able to unload any
1377           modules (note that some modules may not be unloadable
1378           anyway), which makes your kernel smaller, faster
1379           and simpler.  If unsure, say Y.
1380
1381 config MODULE_FORCE_UNLOAD
1382         bool "Forced module unloading"
1383         depends on MODULE_UNLOAD && EXPERIMENTAL
1384         help
1385           This option allows you to force a module to unload, even if the
1386           kernel believes it is unsafe: the kernel will remove the module
1387           without waiting for anyone to stop using it (using the -f option to
1388           rmmod).  This is mainly for kernel developers and desperate users.
1389           If unsure, say N.
1390
1391 config MODVERSIONS
1392         bool "Module versioning support"
1393         help
1394           Usually, you have to use modules compiled with your kernel.
1395           Saying Y here makes it sometimes possible to use modules
1396           compiled for different kernels, by adding enough information
1397           to the modules to (hopefully) spot any changes which would
1398           make them incompatible with the kernel you are running.  If
1399           unsure, say N.
1400
1401 config MODULE_SRCVERSION_ALL
1402         bool "Source checksum for all modules"
1403         help
1404           Modules which contain a MODULE_VERSION get an extra "srcversion"
1405           field inserted into their modinfo section, which contains a
1406           sum of the source files which made it.  This helps maintainers
1407           see exactly which source was used to build a module (since
1408           others sometimes change the module source without updating
1409           the version).  With this option, such a "srcversion" field
1410           will be created for all modules.  If unsure, say N.
1411
1412 endif # MODULES
1413
1414 config INIT_ALL_POSSIBLE
1415         bool
1416         help
1417           Back when each arch used to define their own cpu_online_map and
1418           cpu_possible_map, some of them chose to initialize cpu_possible_map
1419           with all 1s, and others with all 0s.  When they were centralised,
1420           it was better to provide this option than to break all the archs
1421           and have several arch maintainers pursuing me down dark alleys.
1422
1423 config STOP_MACHINE
1424         bool
1425         default y
1426         depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1427         help
1428           Need stop_machine() primitive.
1429
1430 source "block/Kconfig"
1431
1432 config PREEMPT_NOTIFIERS
1433         bool
1434
1435 config PADATA
1436         depends on SMP
1437         bool
1438
1439 source "kernel/Kconfig.locks"