Root/init/Kconfig

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
19config CONSTRUCTORS
20    bool
21    depends on !UML
22
23config HAVE_IRQ_WORK
24    bool
25
26config IRQ_WORK
27    bool
28    depends on HAVE_IRQ_WORK
29
30config BUILDTIME_EXTABLE_SORT
31    bool
32
33menu "General setup"
34
35config EXPERIMENTAL
36    bool "Prompt for development and/or incomplete code/drivers"
37    ---help---
38      Some of the various things that Linux supports (such as network
39      drivers, file systems, network protocols, etc.) can be in a state
40      of development where the functionality, stability, or the level of
41      testing is not yet high enough for general use. This is usually
42      known as the "alpha-test" phase among developers. If a feature is
43      currently in alpha-test, then the developers usually discourage
44      uninformed widespread use of this feature by the general public to
45      avoid "Why doesn't this work?" type mail messages. However, active
46      testing and use of these systems is welcomed. Just be aware that it
47      may not meet the normal level of reliability or it may fail to work
48      in some special cases. Detailed bug reports from people familiar
49      with the kernel internals are usually welcomed by the developers
50      (before submitting bug reports, please read the documents
51      <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
52      <file:Documentation/BUG-HUNTING>, and
53      <file:Documentation/oops-tracing.txt> in the kernel source).
54
55      This option will also make obsoleted drivers available. These are
56      drivers that have been replaced by something else, and/or are
57      scheduled to be removed in a future kernel release.
58
59      Unless you intend to help test and develop a feature or driver that
60      falls into this category, or you have a situation that requires
61      using these features, you should probably say N here, which will
62      cause the configurator to present you with fewer choices. If
63      you say Y here, you will be offered the choice of using features or
64      drivers that are currently considered to be in the alpha-test phase.
65
66config BROKEN
67    bool
68
69config BROKEN_ON_SMP
70    bool
71    depends on BROKEN || !SMP
72    default y
73
74config INIT_ENV_ARG_LIMIT
75    int
76    default 32 if !UML
77    default 128 if UML
78    help
79      Maximum of each of the number of arguments and environment
80      variables passed to init from the kernel command line.
81
82
83config CROSS_COMPILE
84    string "Cross-compiler tool prefix"
85    help
86      Same as running 'make CROSS_COMPILE=prefix-' but stored for
87      default make runs in this kernel build directory. You don't
88      need to set this unless you want the configured kernel build
89      directory to select the cross-compiler automatically.
90
91config LOCALVERSION
92    string "Local version - append to kernel release"
93    help
94      Append an extra string to the end of your kernel version.
95      This will show up when you type uname, for example.
96      The string you set here will be appended after the contents of
97      any files with a filename matching localversion* in your
98      object and source tree, in that order. Your total string can
99      be a maximum of 64 characters.
100
101config LOCALVERSION_AUTO
102    bool "Automatically append version information to the version string"
103    default y
104    help
105      This will try to automatically determine if the current tree is a
106      release tree by looking for git tags that belong to the current
107      top of tree revision.
108
109      A string of the format -gxxxxxxxx will be added to the localversion
110      if a git-based tree is found. The string generated by this will be
111      appended after any matching localversion* files, and after the value
112      set in CONFIG_LOCALVERSION.
113
114      (The actual string used here is the first eight characters produced
115      by running the command:
116
117        $ git rev-parse --verify HEAD
118
119      which is done within the script "scripts/setlocalversion".)
120
121config HAVE_KERNEL_GZIP
122    bool
123
124config HAVE_KERNEL_BZIP2
125    bool
126
127config HAVE_KERNEL_LZMA
128    bool
129
130config HAVE_KERNEL_XZ
131    bool
132
133config HAVE_KERNEL_LZO
134    bool
135
136choice
137    prompt "Kernel compression mode"
138    default KERNEL_GZIP
139    depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
140    help
141      The linux kernel is a kind of self-extracting executable.
142      Several compression algorithms are available, which differ
143      in efficiency, compression and decompression speed.
144      Compression speed is only relevant when building a kernel.
145      Decompression speed is relevant at each boot.
146
147      If you have any problems with bzip2 or lzma compressed
148      kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
149      version of this functionality (bzip2 only), for 2.4, was
150      supplied by Christian Ludwig)
151
152      High compression options are mostly useful for users, who
153      are low on disk space (embedded systems), but for whom ram
154      size matters less.
155
156      If in doubt, select 'gzip'
157
158config KERNEL_GZIP
159    bool "Gzip"
160    depends on HAVE_KERNEL_GZIP
161    help
162      The old and tried gzip compression. It provides a good balance
163      between compression ratio and decompression speed.
164
165config KERNEL_BZIP2
166    bool "Bzip2"
167    depends on HAVE_KERNEL_BZIP2
168    help
169      Its compression ratio and speed is intermediate.
170      Decompression speed is slowest among the choices. The kernel
171      size is about 10% smaller with bzip2, in comparison to gzip.
172      Bzip2 uses a large amount of memory. For modern kernels you
173      will need at least 8MB RAM or more for booting.
174
175config KERNEL_LZMA
176    bool "LZMA"
177    depends on HAVE_KERNEL_LZMA
178    help
179      This compression algorithm's ratio is best. Decompression speed
180      is between gzip and bzip2. Compression is slowest.
181      The kernel size is about 33% smaller with LZMA in comparison to gzip.
182
183config KERNEL_XZ
184    bool "XZ"
185    depends on HAVE_KERNEL_XZ
186    help
187      XZ uses the LZMA2 algorithm and instruction set specific
188      BCJ filters which can improve compression ratio of executable
189      code. The size of the kernel is about 30% smaller with XZ in
190      comparison to gzip. On architectures for which there is a BCJ
191      filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
192      will create a few percent smaller kernel than plain LZMA.
193
194      The speed is about the same as with LZMA: The decompression
195      speed of XZ is better than that of bzip2 but worse than gzip
196      and LZO. Compression is slow.
197
198config KERNEL_LZO
199    bool "LZO"
200    depends on HAVE_KERNEL_LZO
201    help
202      Its compression ratio is the poorest among the choices. The kernel
203      size is about 10% bigger than gzip; however its speed
204      (both compression and decompression) is the fastest.
205
206endchoice
207
208config DEFAULT_HOSTNAME
209    string "Default hostname"
210    default "(none)"
211    help
212      This option determines the default system hostname before userspace
213      calls sethostname(2). The kernel traditionally uses "(none)" here,
214      but you may wish to use a different default here to make a minimal
215      system more usable with less configuration.
216
217config SWAP
218    bool "Support for paging of anonymous memory (swap)"
219    depends on MMU && BLOCK
220    default y
221    help
222      This option allows you to choose whether you want to have support
223      for so called swap devices or swap files in your kernel that are
224      used to provide more virtual memory than the actual RAM present
225      in your computer. If unsure say Y.
226
227config SYSVIPC
228    bool "System V IPC"
229    ---help---
230      Inter Process Communication is a suite of library functions and
231      system calls which let processes (running programs) synchronize and
232      exchange information. It is generally considered to be a good thing,
233      and some programs won't run unless you say Y here. In particular, if
234      you want to run the DOS emulator dosemu under Linux (read the
235      DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
236      you'll need to say Y here.
237
238      You can find documentation about IPC with "info ipc" and also in
239      section 6.4 of the Linux Programmer's Guide, available from
240      <http://www.tldp.org/guides.html>.
241
242config SYSVIPC_SYSCTL
243    bool
244    depends on SYSVIPC
245    depends on SYSCTL
246    default y
247
248config POSIX_MQUEUE
249    bool "POSIX Message Queues"
250    depends on NET && EXPERIMENTAL
251    ---help---
252      POSIX variant of message queues is a part of IPC. In POSIX message
253      queues every message has a priority which decides about succession
254      of receiving it by a process. If you want to compile and run
255      programs written e.g. for Solaris with use of its POSIX message
256      queues (functions mq_*) say Y here.
257
258      POSIX message queues are visible as a filesystem called 'mqueue'
259      and can be mounted somewhere if you want to do filesystem
260      operations on message queues.
261
262      If unsure, say Y.
263
264config POSIX_MQUEUE_SYSCTL
265    bool
266    depends on POSIX_MQUEUE
267    depends on SYSCTL
268    default y
269
270config BSD_PROCESS_ACCT
271    bool "BSD Process Accounting"
272    help
273      If you say Y here, a user level program will be able to instruct the
274      kernel (via a special system call) to write process accounting
275      information to a file: whenever a process exits, information about
276      that process will be appended to the file by the kernel. The
277      information includes things such as creation time, owning user,
278      command name, memory usage, controlling terminal etc. (the complete
279      list is in the struct acct in <file:include/linux/acct.h>). It is
280      up to the user level program to do useful things with this
281      information. This is generally a good idea, so say Y.
282
283config BSD_PROCESS_ACCT_V3
284    bool "BSD Process Accounting version 3 file format"
285    depends on BSD_PROCESS_ACCT
286    default n
287    help
288      If you say Y here, the process accounting information is written
289      in a new file format that also logs the process IDs of each
290      process and it's parent. Note that this file format is incompatible
291      with previous v0/v1/v2 file formats, so you will need updated tools
292      for processing it. A preliminary version of these tools is available
293      at <http://www.gnu.org/software/acct/>.
294
295config FHANDLE
296    bool "open by fhandle syscalls"
297    select EXPORTFS
298    help
299      If you say Y here, a user level program will be able to map
300      file names to handle and then later use the handle for
301      different file system operations. This is useful in implementing
302      userspace file servers, which now track files using handles instead
303      of names. The handle would remain the same even if file names
304      get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
305      syscalls.
306
307config TASKSTATS
308    bool "Export task/process statistics through netlink (EXPERIMENTAL)"
309    depends on NET
310    default n
311    help
312      Export selected statistics for tasks/processes through the
313      generic netlink interface. Unlike BSD process accounting, the
314      statistics are available during the lifetime of tasks/processes as
315      responses to commands. Like BSD accounting, they are sent to user
316      space on task exit.
317
318      Say N if unsure.
319
320config TASK_DELAY_ACCT
321    bool "Enable per-task delay accounting (EXPERIMENTAL)"
322    depends on TASKSTATS
323    help
324      Collect information on time spent by a task waiting for system
325      resources like cpu, synchronous block I/O completion and swapping
326      in pages. Such statistics can help in setting a task's priorities
327      relative to other tasks for cpu, io, rss limits etc.
328
329      Say N if unsure.
330
331config TASK_XACCT
332    bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
333    depends on TASKSTATS
334    help
335      Collect extended task accounting data and send the data
336      to userland for processing over the taskstats interface.
337
338      Say N if unsure.
339
340config TASK_IO_ACCOUNTING
341    bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
342    depends on TASK_XACCT
343    help
344      Collect information on the number of bytes of storage I/O which this
345      task has caused.
346
347      Say N if unsure.
348
349config AUDIT
350    bool "Auditing support"
351    depends on NET
352    help
353      Enable auditing infrastructure that can be used with another
354      kernel subsystem, such as SELinux (which requires this for
355      logging of avc messages output). Does not do system-call
356      auditing without CONFIG_AUDITSYSCALL.
357
358config AUDITSYSCALL
359    bool "Enable system-call auditing support"
360    depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
361    default y if SECURITY_SELINUX
362    help
363      Enable low-overhead system-call auditing infrastructure that
364      can be used independently or with another kernel subsystem,
365      such as SELinux.
366
367config AUDIT_WATCH
368    def_bool y
369    depends on AUDITSYSCALL
370    select FSNOTIFY
371
372config AUDIT_TREE
373    def_bool y
374    depends on AUDITSYSCALL
375    select FSNOTIFY
376
377config AUDIT_LOGINUID_IMMUTABLE
378    bool "Make audit loginuid immutable"
379    depends on AUDIT
380    help
381      The config option toggles if a task setting its loginuid requires
382      CAP_SYS_AUDITCONTROL or if that task should require no special permissions
383      but should instead only allow setting its loginuid if it was never
384      previously set. On systems which use systemd or a similar central
385      process to restart login services this should be set to true. On older
386      systems in which an admin would typically have to directly stop and
387      start processes this should be set to false. Setting this to true allows
388      one to drop potentially dangerous capabilites from the login tasks,
389      but may not be backwards compatible with older init systems.
390
391source "kernel/irq/Kconfig"
392source "kernel/time/Kconfig"
393
394menu "RCU Subsystem"
395
396choice
397    prompt "RCU Implementation"
398    default TREE_RCU
399
400config TREE_RCU
401    bool "Tree-based hierarchical RCU"
402    depends on !PREEMPT && SMP
403    help
404      This option selects the RCU implementation that is
405      designed for very large SMP system with hundreds or
406      thousands of CPUs. It also scales down nicely to
407      smaller systems.
408
409config TREE_PREEMPT_RCU
410    bool "Preemptible tree-based hierarchical RCU"
411    depends on PREEMPT && SMP
412    help
413      This option selects the RCU implementation that is
414      designed for very large SMP systems with hundreds or
415      thousands of CPUs, but for which real-time response
416      is also required. It also scales down nicely to
417      smaller systems.
418
419config TINY_RCU
420    bool "UP-only small-memory-footprint RCU"
421    depends on !PREEMPT && !SMP
422    help
423      This option selects the RCU implementation that is
424      designed for UP systems from which real-time response
425      is not required. This option greatly reduces the
426      memory footprint of RCU.
427
428config TINY_PREEMPT_RCU
429    bool "Preemptible UP-only small-memory-footprint RCU"
430    depends on PREEMPT && !SMP
431    help
432      This option selects the RCU implementation that is designed
433      for real-time UP systems. This option greatly reduces the
434      memory footprint of RCU.
435
436endchoice
437
438config PREEMPT_RCU
439    def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
440    help
441      This option enables preemptible-RCU code that is common between
442      the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
443
444config RCU_FANOUT
445    int "Tree-based hierarchical RCU fanout value"
446    range 2 64 if 64BIT
447    range 2 32 if !64BIT
448    depends on TREE_RCU || TREE_PREEMPT_RCU
449    default 64 if 64BIT
450    default 32 if !64BIT
451    help
452      This option controls the fanout of hierarchical implementations
453      of RCU, allowing RCU to work efficiently on machines with
454      large numbers of CPUs. This value must be at least the fourth
455      root of NR_CPUS, which allows NR_CPUS to be insanely large.
456      The default value of RCU_FANOUT should be used for production
457      systems, but if you are stress-testing the RCU implementation
458      itself, small RCU_FANOUT values allow you to test large-system
459      code paths on small(er) systems.
460
461      Select a specific number if testing RCU itself.
462      Take the default if unsure.
463
464config RCU_FANOUT_LEAF
465    int "Tree-based hierarchical RCU leaf-level fanout value"
466    range 2 RCU_FANOUT if 64BIT
467    range 2 RCU_FANOUT if !64BIT
468    depends on TREE_RCU || TREE_PREEMPT_RCU
469    default 16
470    help
471      This option controls the leaf-level fanout of hierarchical
472      implementations of RCU, and allows trading off cache misses
473      against lock contention. Systems that synchronize their
474      scheduling-clock interrupts for energy-efficiency reasons will
475      want the default because the smaller leaf-level fanout keeps
476      lock contention levels acceptably low. Very large systems
477      (hundreds or thousands of CPUs) will instead want to set this
478      value to the maximum value possible in order to reduce the
479      number of cache misses incurred during RCU's grace-period
480      initialization. These systems tend to run CPU-bound, and thus
481      are not helped by synchronized interrupts, and thus tend to
482      skew them, which reduces lock contention enough that large
483      leaf-level fanouts work well.
484
485      Select a specific number if testing RCU itself.
486
487      Select the maximum permissible value for large systems.
488
489      Take the default if unsure.
490
491config RCU_FANOUT_EXACT
492    bool "Disable tree-based hierarchical RCU auto-balancing"
493    depends on TREE_RCU || TREE_PREEMPT_RCU
494    default n
495    help
496      This option forces use of the exact RCU_FANOUT value specified,
497      regardless of imbalances in the hierarchy. This is useful for
498      testing RCU itself, and might one day be useful on systems with
499      strong NUMA behavior.
500
501      Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
502
503      Say N if unsure.
504
505config RCU_FAST_NO_HZ
506    bool "Accelerate last non-dyntick-idle CPU's grace periods"
507    depends on NO_HZ && SMP
508    default n
509    help
510      This option causes RCU to attempt to accelerate grace periods
511      in order to allow CPUs to enter dynticks-idle state more
512      quickly. On the other hand, this option increases the overhead
513      of the dynticks-idle checking, particularly on systems with
514      large numbers of CPUs.
515
516      Say Y if energy efficiency is critically important, particularly
517          if you have relatively few CPUs.
518
519      Say N if you are unsure.
520
521config TREE_RCU_TRACE
522    def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
523    select DEBUG_FS
524    help
525      This option provides tracing for the TREE_RCU and
526      TREE_PREEMPT_RCU implementations, permitting Makefile to
527      trivially select kernel/rcutree_trace.c.
528
529config RCU_BOOST
530    bool "Enable RCU priority boosting"
531    depends on RT_MUTEXES && PREEMPT_RCU
532    default n
533    help
534      This option boosts the priority of preempted RCU readers that
535      block the current preemptible RCU grace period for too long.
536      This option also prevents heavy loads from blocking RCU
537      callback invocation for all flavors of RCU.
538
539      Say Y here if you are working with real-time apps or heavy loads
540      Say N here if you are unsure.
541
542config RCU_BOOST_PRIO
543    int "Real-time priority to boost RCU readers to"
544    range 1 99
545    depends on RCU_BOOST
546    default 1
547    help
548      This option specifies the real-time priority to which long-term
549      preempted RCU readers are to be boosted. If you are working
550      with a real-time application that has one or more CPU-bound
551      threads running at a real-time priority level, you should set
552      RCU_BOOST_PRIO to a priority higher then the highest-priority
553      real-time CPU-bound thread. The default RCU_BOOST_PRIO value
554      of 1 is appropriate in the common case, which is real-time
555      applications that do not have any CPU-bound threads.
556
557      Some real-time applications might not have a single real-time
558      thread that saturates a given CPU, but instead might have
559      multiple real-time threads that, taken together, fully utilize
560      that CPU. In this case, you should set RCU_BOOST_PRIO to
561      a priority higher than the lowest-priority thread that is
562      conspiring to prevent the CPU from running any non-real-time
563      tasks. For example, if one thread at priority 10 and another
564      thread at priority 5 are between themselves fully consuming
565      the CPU time on a given CPU, then RCU_BOOST_PRIO should be
566      set to priority 6 or higher.
567
568      Specify the real-time priority, or take the default if unsure.
569
570config RCU_BOOST_DELAY
571    int "Milliseconds to delay boosting after RCU grace-period start"
572    range 0 3000
573    depends on RCU_BOOST
574    default 500
575    help
576      This option specifies the time to wait after the beginning of
577      a given grace period before priority-boosting preempted RCU
578      readers blocking that grace period. Note that any RCU reader
579      blocking an expedited RCU grace period is boosted immediately.
580
581      Accept the default if unsure.
582
583endmenu # "RCU Subsystem"
584
585config IKCONFIG
586    tristate "Kernel .config support"
587    ---help---
588      This option enables the complete Linux kernel ".config" file
589      contents to be saved in the kernel. It provides documentation
590      of which kernel options are used in a running kernel or in an
591      on-disk kernel. This information can be extracted from the kernel
592      image file with the script scripts/extract-ikconfig and used as
593      input to rebuild the current kernel or to build another kernel.
594      It can also be extracted from a running kernel by reading
595      /proc/config.gz if enabled (below).
596
597config IKCONFIG_PROC
598    bool "Enable access to .config through /proc/config.gz"
599    depends on IKCONFIG && PROC_FS
600    ---help---
601      This option enables access to the kernel configuration file
602      through /proc/config.gz.
603
604config LOG_BUF_SHIFT
605    int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
606    range 12 21
607    default 17
608    help
609      Select kernel log buffer size as a power of 2.
610      Examples:
611               17 => 128 KB
612             16 => 64 KB
613                 15 => 32 KB
614                 14 => 16 KB
615             13 => 8 KB
616             12 => 4 KB
617
618#
619# Architectures with an unreliable sched_clock() should select this:
620#
621config HAVE_UNSTABLE_SCHED_CLOCK
622    bool
623
624menuconfig CGROUPS
625    boolean "Control Group support"
626    depends on EVENTFD
627    help
628      This option adds support for grouping sets of processes together, for
629      use with process control subsystems such as Cpusets, CFS, memory
630      controls or device isolation.
631      See
632        - Documentation/scheduler/sched-design-CFS.txt (CFS)
633        - Documentation/cgroups/ (features for grouping, isolation
634                      and resource control)
635
636      Say N if unsure.
637
638if CGROUPS
639
640config CGROUP_DEBUG
641    bool "Example debug cgroup subsystem"
642    default n
643    help
644      This option enables a simple cgroup subsystem that
645      exports useful debugging information about the cgroups
646      framework.
647
648      Say N if unsure.
649
650config CGROUP_FREEZER
651    bool "Freezer cgroup subsystem"
652    help
653      Provides a way to freeze and unfreeze all tasks in a
654      cgroup.
655
656config CGROUP_DEVICE
657    bool "Device controller for cgroups"
658    help
659      Provides a cgroup implementing whitelists for devices which
660      a process in the cgroup can mknod or open.
661
662config CPUSETS
663    bool "Cpuset support"
664    help
665      This option will let you create and manage CPUSETs which
666      allow dynamically partitioning a system into sets of CPUs and
667      Memory Nodes and assigning tasks to run only within those sets.
668      This is primarily useful on large SMP or NUMA systems.
669
670      Say N if unsure.
671
672config PROC_PID_CPUSET
673    bool "Include legacy /proc/<pid>/cpuset file"
674    depends on CPUSETS
675    default y
676
677config CGROUP_CPUACCT
678    bool "Simple CPU accounting cgroup subsystem"
679    help
680      Provides a simple Resource Controller for monitoring the
681      total CPU consumed by the tasks in a cgroup.
682
683config RESOURCE_COUNTERS
684    bool "Resource counters"
685    help
686      This option enables controller independent resource accounting
687      infrastructure that works with cgroups.
688
689config MEMCG
690    bool "Memory Resource Controller for Control Groups"
691    depends on RESOURCE_COUNTERS
692    select MM_OWNER
693    help
694      Provides a memory resource controller that manages both anonymous
695      memory and page cache. (See Documentation/cgroups/memory.txt)
696
697      Note that setting this option increases fixed memory overhead
698      associated with each page of memory in the system. By this,
699      20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
700      usage tracking struct at boot. Total amount of this is printed out
701      at boot.
702
703      Only enable when you're ok with these trade offs and really
704      sure you need the memory resource controller. Even when you enable
705      this, you can set "cgroup_disable=memory" at your boot option to
706      disable memory resource controller and you can avoid overheads.
707      (and lose benefits of memory resource controller)
708
709      This config option also selects MM_OWNER config option, which
710      could in turn add some fork/exit overhead.
711
712config MEMCG_SWAP
713    bool "Memory Resource Controller Swap Extension"
714    depends on MEMCG && SWAP
715    help
716      Add swap management feature to memory resource controller. When you
717      enable this, you can limit mem+swap usage per cgroup. In other words,
718      when you disable this, memory resource controller has no cares to
719      usage of swap...a process can exhaust all of the swap. This extension
720      is useful when you want to avoid exhaustion swap but this itself
721      adds more overheads and consumes memory for remembering information.
722      Especially if you use 32bit system or small memory system, please
723      be careful about enabling this. When memory resource controller
724      is disabled by boot option, this will be automatically disabled and
725      there will be no overhead from this. Even when you set this config=y,
726      if boot option "swapaccount=0" is set, swap will not be accounted.
727      Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
728      size is 4096bytes, 512k per 1Gbytes of swap.
729config MEMCG_SWAP_ENABLED
730    bool "Memory Resource Controller Swap Extension enabled by default"
731    depends on MEMCG_SWAP
732    default y
733    help
734      Memory Resource Controller Swap Extension comes with its price in
735      a bigger memory consumption. General purpose distribution kernels
736      which want to enable the feature but keep it disabled by default
737      and let the user enable it by swapaccount boot command line
738      parameter should have this option unselected.
739      For those who want to have the feature enabled by default should
740      select this option (if, for some reason, they need to disable it
741      then swapaccount=0 does the trick).
742config MEMCG_KMEM
743    bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
744    depends on MEMCG && EXPERIMENTAL
745    default n
746    help
747      The Kernel Memory extension for Memory Resource Controller can limit
748      the amount of memory used by kernel objects in the system. Those are
749      fundamentally different from the entities handled by the standard
750      Memory Controller, which are page-based, and can be swapped. Users of
751      the kmem extension can use it to guarantee that no group of processes
752      will ever exhaust kernel resources alone.
753
754config CGROUP_HUGETLB
755    bool "HugeTLB Resource Controller for Control Groups"
756    depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL
757    default n
758    help
759      Provides a cgroup Resource Controller for HugeTLB pages.
760      When you enable this, you can put a per cgroup limit on HugeTLB usage.
761      The limit is enforced during page fault. Since HugeTLB doesn't
762      support page reclaim, enforcing the limit at page fault time implies
763      that, the application will get SIGBUS signal if it tries to access
764      HugeTLB pages beyond its limit. This requires the application to know
765      beforehand how much HugeTLB pages it would require for its use. The
766      control group is tracked in the third page lru pointer. This means
767      that we cannot use the controller with huge page less than 3 pages.
768
769config CGROUP_PERF
770    bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
771    depends on PERF_EVENTS && CGROUPS
772    help
773      This option extends the per-cpu mode to restrict monitoring to
774      threads which belong to the cgroup specified and run on the
775      designated cpu.
776
777      Say N if unsure.
778
779menuconfig CGROUP_SCHED
780    bool "Group CPU scheduler"
781    default n
782    help
783      This feature lets CPU scheduler recognize task groups and control CPU
784      bandwidth allocation to such task groups. It uses cgroups to group
785      tasks.
786
787if CGROUP_SCHED
788config FAIR_GROUP_SCHED
789    bool "Group scheduling for SCHED_OTHER"
790    depends on CGROUP_SCHED
791    default CGROUP_SCHED
792
793config CFS_BANDWIDTH
794    bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
795    depends on EXPERIMENTAL
796    depends on FAIR_GROUP_SCHED
797    default n
798    help
799      This option allows users to define CPU bandwidth rates (limits) for
800      tasks running within the fair group scheduler. Groups with no limit
801      set are considered to be unconstrained and will run with no
802      restriction.
803      See tip/Documentation/scheduler/sched-bwc.txt for more information.
804
805config RT_GROUP_SCHED
806    bool "Group scheduling for SCHED_RR/FIFO"
807    depends on EXPERIMENTAL
808    depends on CGROUP_SCHED
809    default n
810    help
811      This feature lets you explicitly allocate real CPU bandwidth
812      to task groups. If enabled, it will also make it impossible to
813      schedule realtime tasks for non-root users until you allocate
814      realtime bandwidth for them.
815      See Documentation/scheduler/sched-rt-group.txt for more information.
816
817endif #CGROUP_SCHED
818
819config BLK_CGROUP
820    bool "Block IO controller"
821    depends on BLOCK
822    default n
823    ---help---
824    Generic block IO controller cgroup interface. This is the common
825    cgroup interface which should be used by various IO controlling
826    policies.
827
828    Currently, CFQ IO scheduler uses it to recognize task groups and
829    control disk bandwidth allocation (proportional time slice allocation)
830    to such task groups. It is also used by bio throttling logic in
831    block layer to implement upper limit in IO rates on a device.
832
833    This option only enables generic Block IO controller infrastructure.
834    One needs to also enable actual IO controlling logic/policy. For
835    enabling proportional weight division of disk bandwidth in CFQ, set
836    CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
837    CONFIG_BLK_DEV_THROTTLING=y.
838
839    See Documentation/cgroups/blkio-controller.txt for more information.
840
841config DEBUG_BLK_CGROUP
842    bool "Enable Block IO controller debugging"
843    depends on BLK_CGROUP
844    default n
845    ---help---
846    Enable some debugging help. Currently it exports additional stat
847    files in a cgroup which can be useful for debugging.
848
849endif # CGROUPS
850
851config CHECKPOINT_RESTORE
852    bool "Checkpoint/restore support" if EXPERT
853    default n
854    help
855      Enables additional kernel features in a sake of checkpoint/restore.
856      In particular it adds auxiliary prctl codes to setup process text,
857      data and heap segment sizes, and a few additional /proc filesystem
858      entries.
859
860      If unsure, say N here.
861
862menuconfig NAMESPACES
863    bool "Namespaces support" if EXPERT
864    default !EXPERT
865    help
866      Provides the way to make tasks work with different objects using
867      the same id. For example same IPC id may refer to different objects
868      or same user id or pid may refer to different tasks when used in
869      different namespaces.
870
871if NAMESPACES
872
873config UTS_NS
874    bool "UTS namespace"
875    default y
876    help
877      In this namespace tasks see different info provided with the
878      uname() system call
879
880config IPC_NS
881    bool "IPC namespace"
882    depends on (SYSVIPC || POSIX_MQUEUE)
883    default y
884    help
885      In this namespace tasks work with IPC ids which correspond to
886      different IPC objects in different namespaces.
887
888config USER_NS
889    bool "User namespace (EXPERIMENTAL)"
890    depends on EXPERIMENTAL
891    depends on UIDGID_CONVERTED
892    select UIDGID_STRICT_TYPE_CHECKS
893
894    default n
895    help
896      This allows containers, i.e. vservers, to use user namespaces
897      to provide different user info for different servers.
898      If unsure, say N.
899
900config PID_NS
901    bool "PID Namespaces"
902    default y
903    help
904      Support process id namespaces. This allows having multiple
905      processes with the same pid as long as they are in different
906      pid namespaces. This is a building block of containers.
907
908config NET_NS
909    bool "Network namespace"
910    depends on NET
911    default y
912    help
913      Allow user space to create what appear to be multiple instances
914      of the network stack.
915
916endif # NAMESPACES
917
918config UIDGID_CONVERTED
919    # True if all of the selected software conmponents are known
920    # to have uid_t and gid_t converted to kuid_t and kgid_t
921    # where appropriate and are otherwise safe to use with
922    # the user namespace.
923    bool
924    default y
925
926    # List of kernel pieces that need user namespace work
927    # Features
928    depends on SYSVIPC = n
929    depends on IMA = n
930    depends on EVM = n
931    depends on KEYS = n
932    depends on AUDIT = n
933    depends on AUDITSYSCALL = n
934    depends on TASKSTATS = n
935    depends on TRACING = n
936    depends on FS_POSIX_ACL = n
937    depends on QUOTA = n
938    depends on QUOTACTL = n
939    depends on DEBUG_CREDENTIALS = n
940    depends on BSD_PROCESS_ACCT = n
941    depends on DRM = n
942    depends on PROC_EVENTS = n
943
944    # Networking
945    depends on NET = n
946    depends on NET_9P = n
947    depends on IPX = n
948    depends on PHONET = n
949    depends on NET_CLS_FLOW = n
950    depends on NETFILTER_XT_MATCH_OWNER = n
951    depends on NETFILTER_XT_MATCH_RECENT = n
952    depends on NETFILTER_XT_TARGET_LOG = n
953    depends on NETFILTER_NETLINK_LOG = n
954    depends on INET = n
955    depends on IPV6 = n
956    depends on IP_SCTP = n
957    depends on AF_RXRPC = n
958    depends on LLC2 = n
959    depends on NET_KEY = n
960    depends on INET_DIAG = n
961    depends on DNS_RESOLVER = n
962    depends on AX25 = n
963    depends on ATALK = n
964
965    # Filesystems
966    depends on USB_DEVICEFS = n
967    depends on USB_GADGETFS = n
968    depends on USB_FUNCTIONFS = n
969    depends on DEVTMPFS = n
970    depends on XENFS = n
971
972    depends on 9P_FS = n
973    depends on ADFS_FS = n
974    depends on AFFS_FS = n
975    depends on AFS_FS = n
976    depends on AUTOFS4_FS = n
977    depends on BEFS_FS = n
978    depends on BFS_FS = n
979    depends on BTRFS_FS = n
980    depends on CEPH_FS = n
981    depends on CIFS = n
982    depends on CODA_FS = n
983    depends on CONFIGFS_FS = n
984    depends on CRAMFS = n
985    depends on DEBUG_FS = n
986    depends on ECRYPT_FS = n
987    depends on EFS_FS = n
988    depends on EXOFS_FS = n
989    depends on FAT_FS = n
990    depends on FUSE_FS = n
991    depends on GFS2_FS = n
992    depends on HFS_FS = n
993    depends on HFSPLUS_FS = n
994    depends on HPFS_FS = n
995    depends on HUGETLBFS = n
996    depends on ISO9660_FS = n
997    depends on JFFS2_FS = n
998    depends on JFS_FS = n
999    depends on LOGFS = n
1000    depends on MINIX_FS = n
1001    depends on NCP_FS = n
1002    depends on NFSD = n
1003    depends on NFS_FS = n
1004    depends on NILFS2_FS = n
1005    depends on NTFS_FS = n
1006    depends on OCFS2_FS = n
1007    depends on OMFS_FS = n
1008    depends on QNX4FS_FS = n
1009    depends on QNX6FS_FS = n
1010    depends on REISERFS_FS = n
1011    depends on SQUASHFS = n
1012    depends on SYSV_FS = n
1013    depends on UBIFS_FS = n
1014    depends on UDF_FS = n
1015    depends on UFS_FS = n
1016    depends on VXFS_FS = n
1017    depends on XFS_FS = n
1018
1019    depends on !UML || HOSTFS = n
1020
1021    # The rare drivers that won't build
1022    depends on AIRO = n
1023    depends on AIRO_CS = n
1024    depends on TUN = n
1025    depends on INFINIBAND_QIB = n
1026    depends on BLK_DEV_LOOP = n
1027    depends on ANDROID_BINDER_IPC = n
1028
1029    # Security modules
1030    depends on SECURITY_TOMOYO = n
1031    depends on SECURITY_APPARMOR = n
1032
1033config UIDGID_STRICT_TYPE_CHECKS
1034    bool "Require conversions between uid/gids and their internal representation"
1035    depends on UIDGID_CONVERTED
1036    default n
1037    help
1038     While the nececessary conversions are being added to all subsystems this option allows
1039     the code to continue to build for unconverted subsystems.
1040
1041     Say Y here if you want the strict type checking enabled
1042
1043config SCHED_AUTOGROUP
1044    bool "Automatic process group scheduling"
1045    select EVENTFD
1046    select CGROUPS
1047    select CGROUP_SCHED
1048    select FAIR_GROUP_SCHED
1049    help
1050      This option optimizes the scheduler for common desktop workloads by
1051      automatically creating and populating task groups. This separation
1052      of workloads isolates aggressive CPU burners (like build jobs) from
1053      desktop applications. Task group autogeneration is currently based
1054      upon task session.
1055
1056config MM_OWNER
1057    bool
1058
1059config SYSFS_DEPRECATED
1060    bool "Enable deprecated sysfs features to support old userspace tools"
1061    depends on SYSFS
1062    default n
1063    help
1064      This option adds code that switches the layout of the "block" class
1065      devices, to not show up in /sys/class/block/, but only in
1066      /sys/block/.
1067
1068      This switch is only active when the sysfs.deprecated=1 boot option is
1069      passed or the SYSFS_DEPRECATED_V2 option is set.
1070
1071      This option allows new kernels to run on old distributions and tools,
1072      which might get confused by /sys/class/block/. Since 2007/2008 all
1073      major distributions and tools handle this just fine.
1074
1075      Recent distributions and userspace tools after 2009/2010 depend on
1076      the existence of /sys/class/block/, and will not work with this
1077      option enabled.
1078
1079      Only if you are using a new kernel on an old distribution, you might
1080      need to say Y here.
1081
1082config SYSFS_DEPRECATED_V2
1083    bool "Enable deprecated sysfs features by default"
1084    default n
1085    depends on SYSFS
1086    depends on SYSFS_DEPRECATED
1087    help
1088      Enable deprecated sysfs by default.
1089
1090      See the CONFIG_SYSFS_DEPRECATED option for more details about this
1091      option.
1092
1093      Only if you are using a new kernel on an old distribution, you might
1094      need to say Y here. Even then, odds are you would not need it
1095      enabled, you can always pass the boot option if absolutely necessary.
1096
1097config RELAY
1098    bool "Kernel->user space relay support (formerly relayfs)"
1099    help
1100      This option enables support for relay interface support in
1101      certain file systems (such as debugfs).
1102      It is designed to provide an efficient mechanism for tools and
1103      facilities to relay large amounts of data from kernel space to
1104      user space.
1105
1106      If unsure, say N.
1107
1108config BLK_DEV_INITRD
1109    bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1110    depends on BROKEN || !FRV
1111    help
1112      The initial RAM filesystem is a ramfs which is loaded by the
1113      boot loader (loadlin or lilo) and that is mounted as root
1114      before the normal boot procedure. It is typically used to
1115      load modules needed to mount the "real" root file system,
1116      etc. See <file:Documentation/initrd.txt> for details.
1117
1118      If RAM disk support (BLK_DEV_RAM) is also included, this
1119      also enables initial RAM disk (initrd) support and adds
1120      15 Kbytes (more on some other architectures) to the kernel size.
1121
1122      If unsure say Y.
1123
1124if BLK_DEV_INITRD
1125
1126source "usr/Kconfig"
1127
1128endif
1129
1130config CC_OPTIMIZE_FOR_SIZE
1131    bool "Optimize for size"
1132    help
1133      Enabling this option will pass "-Os" instead of "-O2" to gcc
1134      resulting in a smaller kernel.
1135
1136      If unsure, say Y.
1137
1138config SYSCTL
1139    bool
1140
1141config ANON_INODES
1142    bool
1143
1144menuconfig EXPERT
1145    bool "Configure standard kernel features (expert users)"
1146    # Unhide debug options, to make the on-by-default options visible
1147    select DEBUG_KERNEL
1148    help
1149      This option allows certain base kernel options and settings
1150          to be disabled or tweaked. This is for specialized
1151          environments which can tolerate a "non-standard" kernel.
1152          Only use this if you really know what you are doing.
1153
1154config UID16
1155    bool "Enable 16-bit UID system calls" if EXPERT
1156    depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
1157    default y
1158    help
1159      This enables the legacy 16-bit UID syscall wrappers.
1160
1161config SYSCTL_SYSCALL
1162    bool "Sysctl syscall support" if EXPERT
1163    depends on PROC_SYSCTL
1164    default n
1165    select SYSCTL
1166    ---help---
1167      sys_sysctl uses binary paths that have been found challenging
1168      to properly maintain and use. The interface in /proc/sys
1169      using paths with ascii names is now the primary path to this
1170      information.
1171
1172      Almost nothing using the binary sysctl interface so if you are
1173      trying to save some space it is probably safe to disable this,
1174      making your kernel marginally smaller.
1175
1176      If unsure say N here.
1177
1178config KALLSYMS
1179     bool "Load all symbols for debugging/ksymoops" if EXPERT
1180     default y
1181     help
1182       Say Y here to let the kernel print out symbolic crash information and
1183       symbolic stack backtraces. This increases the size of the kernel
1184       somewhat, as all symbols have to be loaded into the kernel image.
1185
1186config KALLSYMS_ALL
1187    bool "Include all symbols in kallsyms"
1188    depends on DEBUG_KERNEL && KALLSYMS
1189    help
1190       Normally kallsyms only contains the symbols of functions for nicer
1191       OOPS messages and backtraces (i.e., symbols from the text and inittext
1192       sections). This is sufficient for most cases. And only in very rare
1193       cases (e.g., when a debugger is used) all symbols are required (e.g.,
1194       names of variables from the data sections, etc).
1195
1196       This option makes sure that all symbols are loaded into the kernel
1197       image (i.e., symbols from all sections) in cost of increased kernel
1198       size (depending on the kernel configuration, it may be 300KiB or
1199       something like this).
1200
1201       Say N unless you really need all symbols.
1202
1203config HOTPLUG
1204    bool "Support for hot-pluggable devices" if EXPERT
1205    default y
1206    help
1207      This option is provided for the case where no hotplug or uevent
1208      capabilities is wanted by the kernel. You should only consider
1209      disabling this option for embedded systems that do not use modules, a
1210      dynamic /dev tree, or dynamic device discovery. Just say Y.
1211
1212config PRINTK
1213    default y
1214    bool "Enable support for printk" if EXPERT
1215    help
1216      This option enables normal printk support. Removing it
1217      eliminates most of the message strings from the kernel image
1218      and makes the kernel more or less silent. As this makes it
1219      very difficult to diagnose system problems, saying N here is
1220      strongly discouraged.
1221
1222config BUG
1223    bool "BUG() support" if EXPERT
1224    default y
1225    help
1226          Disabling this option eliminates support for BUG and WARN, reducing
1227          the size of your kernel image and potentially quietly ignoring
1228          numerous fatal conditions. You should only consider disabling this
1229          option for embedded systems with no facilities for reporting errors.
1230          Just say Y.
1231
1232config ELF_CORE
1233    default y
1234    bool "Enable ELF core dumps" if EXPERT
1235    help
1236      Enable support for generating core dumps. Disabling saves about 4k.
1237
1238
1239config PCSPKR_PLATFORM
1240    bool "Enable PC-Speaker support" if EXPERT
1241    depends on HAVE_PCSPKR_PLATFORM
1242    select I8253_LOCK
1243    default y
1244    help
1245          This option allows to disable the internal PC-Speaker
1246          support, saving some memory.
1247
1248config HAVE_PCSPKR_PLATFORM
1249    bool
1250
1251config BASE_FULL
1252    default y
1253    bool "Enable full-sized data structures for core" if EXPERT
1254    help
1255      Disabling this option reduces the size of miscellaneous core
1256      kernel data structures. This saves memory on small machines,
1257      but may reduce performance.
1258
1259config FUTEX
1260    bool "Enable futex support" if EXPERT
1261    default y
1262    select RT_MUTEXES
1263    help
1264      Disabling this option will cause the kernel to be built without
1265      support for "fast userspace mutexes". The resulting kernel may not
1266      run glibc-based applications correctly.
1267
1268config EPOLL
1269    bool "Enable eventpoll support" if EXPERT
1270    default y
1271    select ANON_INODES
1272    help
1273      Disabling this option will cause the kernel to be built without
1274      support for epoll family of system calls.
1275
1276config SIGNALFD
1277    bool "Enable signalfd() system call" if EXPERT
1278    select ANON_INODES
1279    default y
1280    help
1281      Enable the signalfd() system call that allows to receive signals
1282      on a file descriptor.
1283
1284      If unsure, say Y.
1285
1286config TIMERFD
1287    bool "Enable timerfd() system call" if EXPERT
1288    select ANON_INODES
1289    default y
1290    help
1291      Enable the timerfd() system call that allows to receive timer
1292      events on a file descriptor.
1293
1294      If unsure, say Y.
1295
1296config EVENTFD
1297    bool "Enable eventfd() system call" if EXPERT
1298    select ANON_INODES
1299    default y
1300    help
1301      Enable the eventfd() system call that allows to receive both
1302      kernel notification (ie. KAIO) or userspace notifications.
1303
1304      If unsure, say Y.
1305
1306config SHMEM
1307    bool "Use full shmem filesystem" if EXPERT
1308    default y
1309    depends on MMU
1310    help
1311      The shmem is an internal filesystem used to manage shared memory.
1312      It is backed by swap and manages resource limits. It is also exported
1313      to userspace as tmpfs if TMPFS is enabled. Disabling this
1314      option replaces shmem and tmpfs with the much simpler ramfs code,
1315      which may be appropriate on small systems without swap.
1316
1317config AIO
1318    bool "Enable AIO support" if EXPERT
1319    default y
1320    help
1321      This option enables POSIX asynchronous I/O which may by used
1322          by some high performance threaded applications. Disabling
1323          this option saves about 7k.
1324
1325config EMBEDDED
1326    bool "Embedded system"
1327    select EXPERT
1328    help
1329      This option should be enabled if compiling the kernel for
1330      an embedded system so certain expert options are available
1331      for configuration.
1332
1333config HAVE_PERF_EVENTS
1334    bool
1335    help
1336      See tools/perf/design.txt for details.
1337
1338config PERF_USE_VMALLOC
1339    bool
1340    help
1341      See tools/perf/design.txt for details
1342
1343menu "Kernel Performance Events And Counters"
1344
1345config PERF_EVENTS
1346    bool "Kernel performance events and counters"
1347    default y if PROFILING
1348    depends on HAVE_PERF_EVENTS
1349    select ANON_INODES
1350    select IRQ_WORK
1351    help
1352      Enable kernel support for various performance events provided
1353      by software and hardware.
1354
1355      Software events are supported either built-in or via the
1356      use of generic tracepoints.
1357
1358      Most modern CPUs support performance events via performance
1359      counter registers. These registers count the number of certain
1360      types of hw events: such as instructions executed, cachemisses
1361      suffered, or branches mis-predicted - without slowing down the
1362      kernel or applications. These registers can also trigger interrupts
1363      when a threshold number of events have passed - and can thus be
1364      used to profile the code that runs on that CPU.
1365
1366      The Linux Performance Event subsystem provides an abstraction of
1367      these software and hardware event capabilities, available via a
1368      system call and used by the "perf" utility in tools/perf/. It
1369      provides per task and per CPU counters, and it provides event
1370      capabilities on top of those.
1371
1372      Say Y if unsure.
1373
1374config DEBUG_PERF_USE_VMALLOC
1375    default n
1376    bool "Debug: use vmalloc to back perf mmap() buffers"
1377    depends on PERF_EVENTS && DEBUG_KERNEL
1378    select PERF_USE_VMALLOC
1379    help
1380     Use vmalloc memory to back perf mmap() buffers.
1381
1382     Mostly useful for debugging the vmalloc code on platforms
1383     that don't require it.
1384
1385     Say N if unsure.
1386
1387endmenu
1388
1389config VM_EVENT_COUNTERS
1390    default y
1391    bool "Enable VM event counters for /proc/vmstat" if EXPERT
1392    help
1393      VM event counters are needed for event counts to be shown.
1394      This option allows the disabling of the VM event counters
1395      on EXPERT systems. /proc/vmstat will only show page counts
1396      if VM event counters are disabled.
1397
1398config PCI_QUIRKS
1399    default y
1400    bool "Enable PCI quirk workarounds" if EXPERT
1401    depends on PCI
1402    help
1403      This enables workarounds for various PCI chipset
1404          bugs/quirks. Disable this only if your target machine is
1405          unaffected by PCI quirks.
1406
1407config SLUB_DEBUG
1408    default y
1409    bool "Enable SLUB debugging support" if EXPERT
1410    depends on SLUB && SYSFS
1411    help
1412      SLUB has extensive debug support features. Disabling these can
1413      result in significant savings in code size. This also disables
1414      SLUB sysfs support. /sys/slab will not exist and there will be
1415      no support for cache validation etc.
1416
1417config COMPAT_BRK
1418    bool "Disable heap randomization"
1419    default y
1420    help
1421      Randomizing heap placement makes heap exploits harder, but it
1422      also breaks ancient binaries (including anything libc5 based).
1423      This option changes the bootup default to heap randomization
1424      disabled, and can be overridden at runtime by setting
1425      /proc/sys/kernel/randomize_va_space to 2.
1426
1427      On non-ancient distros (post-2000 ones) N is usually a safe choice.
1428
1429choice
1430    prompt "Choose SLAB allocator"
1431    default SLUB
1432    help
1433       This option allows to select a slab allocator.
1434
1435config SLAB
1436    bool "SLAB"
1437    help
1438      The regular slab allocator that is established and known to work
1439      well in all environments. It organizes cache hot objects in
1440      per cpu and per node queues.
1441
1442config SLUB
1443    bool "SLUB (Unqueued Allocator)"
1444    help
1445       SLUB is a slab allocator that minimizes cache line usage
1446       instead of managing queues of cached objects (SLAB approach).
1447       Per cpu caching is realized using slabs of objects instead
1448       of queues of objects. SLUB can use memory efficiently
1449       and has enhanced diagnostics. SLUB is the default choice for
1450       a slab allocator.
1451
1452config SLOB
1453    depends on EXPERT
1454    bool "SLOB (Simple Allocator)"
1455    help
1456       SLOB replaces the stock allocator with a drastically simpler
1457       allocator. SLOB is generally more space efficient but
1458       does not perform as well on large systems.
1459
1460endchoice
1461
1462config MMAP_ALLOW_UNINITIALIZED
1463    bool "Allow mmapped anonymous memory to be uninitialized"
1464    depends on EXPERT && !MMU
1465    default n
1466    help
1467      Normally, and according to the Linux spec, anonymous memory obtained
1468      from mmap() has it's contents cleared before it is passed to
1469      userspace. Enabling this config option allows you to request that
1470      mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1471      providing a huge performance boost. If this option is not enabled,
1472      then the flag will be ignored.
1473
1474      This is taken advantage of by uClibc's malloc(), and also by
1475      ELF-FDPIC binfmt's brk and stack allocator.
1476
1477      Because of the obvious security issues, this option should only be
1478      enabled on embedded devices where you control what is run in
1479      userspace. Since that isn't generally a problem on no-MMU systems,
1480      it is normally safe to say Y here.
1481
1482      See Documentation/nommu-mmap.txt for more information.
1483
1484config PROFILING
1485    bool "Profiling support"
1486    help
1487      Say Y here to enable the extended profiling support mechanisms used
1488      by profilers such as OProfile.
1489
1490#
1491# Place an empty function call at each tracepoint site. Can be
1492# dynamically changed for a probe function.
1493#
1494config TRACEPOINTS
1495    bool
1496
1497source "arch/Kconfig"
1498
1499endmenu # General setup
1500
1501config HAVE_GENERIC_DMA_COHERENT
1502    bool
1503    default n
1504
1505config SLABINFO
1506    bool
1507    depends on PROC_FS
1508    depends on SLAB || SLUB_DEBUG
1509    default y
1510
1511config RT_MUTEXES
1512    boolean
1513
1514config BASE_SMALL
1515    int
1516    default 0 if BASE_FULL
1517    default 1 if !BASE_FULL
1518
1519menuconfig MODULES
1520    bool "Enable loadable module support"
1521    help
1522      Kernel modules are small pieces of compiled code which can
1523      be inserted in the running kernel, rather than being
1524      permanently built into the kernel. You use the "modprobe"
1525      tool to add (and sometimes remove) them. If you say Y here,
1526      many parts of the kernel can be built as modules (by
1527      answering M instead of Y where indicated): this is most
1528      useful for infrequently used options which are not required
1529      for booting. For more information, see the man pages for
1530      modprobe, lsmod, modinfo, insmod and rmmod.
1531
1532      If you say Y here, you will need to run "make
1533      modules_install" to put the modules under /lib/modules/
1534      where modprobe can find them (you may need to be root to do
1535      this).
1536
1537      If unsure, say Y.
1538
1539if MODULES
1540
1541config MODULE_FORCE_LOAD
1542    bool "Forced module loading"
1543    default n
1544    help
1545      Allow loading of modules without version information (ie. modprobe
1546      --force). Forced module loading sets the 'F' (forced) taint flag and
1547      is usually a really bad idea.
1548
1549config MODULE_UNLOAD
1550    bool "Module unloading"
1551    help
1552      Without this option you will not be able to unload any
1553      modules (note that some modules may not be unloadable
1554      anyway), which makes your kernel smaller, faster
1555      and simpler. If unsure, say Y.
1556
1557config MODULE_FORCE_UNLOAD
1558    bool "Forced module unloading"
1559    depends on MODULE_UNLOAD && EXPERIMENTAL
1560    help
1561      This option allows you to force a module to unload, even if the
1562      kernel believes it is unsafe: the kernel will remove the module
1563      without waiting for anyone to stop using it (using the -f option to
1564      rmmod). This is mainly for kernel developers and desperate users.
1565      If unsure, say N.
1566
1567config MODVERSIONS
1568    bool "Module versioning support"
1569    help
1570      Usually, you have to use modules compiled with your kernel.
1571      Saying Y here makes it sometimes possible to use modules
1572      compiled for different kernels, by adding enough information
1573      to the modules to (hopefully) spot any changes which would
1574      make them incompatible with the kernel you are running. If
1575      unsure, say N.
1576
1577config MODULE_SRCVERSION_ALL
1578    bool "Source checksum for all modules"
1579    help
1580      Modules which contain a MODULE_VERSION get an extra "srcversion"
1581      field inserted into their modinfo section, which contains a
1582          sum of the source files which made it. This helps maintainers
1583      see exactly which source was used to build a module (since
1584      others sometimes change the module source without updating
1585      the version). With this option, such a "srcversion" field
1586      will be created for all modules. If unsure, say N.
1587
1588endif # MODULES
1589
1590config INIT_ALL_POSSIBLE
1591    bool
1592    help
1593      Back when each arch used to define their own cpu_online_mask and
1594      cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1595      with all 1s, and others with all 0s. When they were centralised,
1596      it was better to provide this option than to break all the archs
1597      and have several arch maintainers pursuing me down dark alleys.
1598
1599config STOP_MACHINE
1600    bool
1601    default y
1602    depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1603    help
1604      Need stop_machine() primitive.
1605
1606source "block/Kconfig"
1607
1608config PREEMPT_NOTIFIERS
1609    bool
1610
1611config PADATA
1612    depends on SMP
1613    bool
1614
1615source "kernel/Kconfig.locks"
1616

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