xref: /openbmc/linux/init/Kconfig (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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	default y
23
24menu "General setup"
25
26config EXPERIMENTAL
27	bool "Prompt for development and/or incomplete code/drivers"
28	---help---
29	  Some of the various things that Linux supports (such as network
30	  drivers, file systems, network protocols, etc.) can be in a state
31	  of development where the functionality, stability, or the level of
32	  testing is not yet high enough for general use. This is usually
33	  known as the "alpha-test" phase among developers. If a feature is
34	  currently in alpha-test, then the developers usually discourage
35	  uninformed widespread use of this feature by the general public to
36	  avoid "Why doesn't this work?" type mail messages. However, active
37	  testing and use of these systems is welcomed. Just be aware that it
38	  may not meet the normal level of reliability or it may fail to work
39	  in some special cases. Detailed bug reports from people familiar
40	  with the kernel internals are usually welcomed by the developers
41	  (before submitting bug reports, please read the documents
42	  <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
43	  <file:Documentation/BUG-HUNTING>, and
44	  <file:Documentation/oops-tracing.txt> in the kernel source).
45
46	  This option will also make obsoleted drivers available. These are
47	  drivers that have been replaced by something else, and/or are
48	  scheduled to be removed in a future kernel release.
49
50	  Unless you intend to help test and develop a feature or driver that
51	  falls into this category, or you have a situation that requires
52	  using these features, you should probably say N here, which will
53	  cause the configurator to present you with fewer choices. If
54	  you say Y here, you will be offered the choice of using features or
55	  drivers that are currently considered to be in the alpha-test phase.
56
57config BROKEN
58	bool
59
60config BROKEN_ON_SMP
61	bool
62	depends on BROKEN || !SMP
63	default y
64
65config LOCK_KERNEL
66	bool
67	depends on SMP || PREEMPT
68	default y
69
70config INIT_ENV_ARG_LIMIT
71	int
72	default 32 if !UML
73	default 128 if UML
74	help
75	  Maximum of each of the number of arguments and environment
76	  variables passed to init from the kernel command line.
77
78
79config LOCALVERSION
80	string "Local version - append to kernel release"
81	help
82	  Append an extra string to the end of your kernel version.
83	  This will show up when you type uname, for example.
84	  The string you set here will be appended after the contents of
85	  any files with a filename matching localversion* in your
86	  object and source tree, in that order.  Your total string can
87	  be a maximum of 64 characters.
88
89config LOCALVERSION_AUTO
90	bool "Automatically append version information to the version string"
91	default y
92	help
93	  This will try to automatically determine if the current tree is a
94	  release tree by looking for git tags that belong to the current
95	  top of tree revision.
96
97	  A string of the format -gxxxxxxxx will be added to the localversion
98	  if a git-based tree is found.  The string generated by this will be
99	  appended after any matching localversion* files, and after the value
100	  set in CONFIG_LOCALVERSION.
101
102	  (The actual string used here is the first eight characters produced
103	  by running the command:
104
105	    $ git rev-parse --verify HEAD
106
107	  which is done within the script "scripts/setlocalversion".)
108
109config HAVE_KERNEL_GZIP
110	bool
111
112config HAVE_KERNEL_BZIP2
113	bool
114
115config HAVE_KERNEL_LZMA
116	bool
117
118config HAVE_KERNEL_LZO
119	bool
120
121choice
122	prompt "Kernel compression mode"
123	default KERNEL_GZIP
124	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
125	help
126	  The linux kernel is a kind of self-extracting executable.
127	  Several compression algorithms are available, which differ
128	  in efficiency, compression and decompression speed.
129	  Compression speed is only relevant when building a kernel.
130	  Decompression speed is relevant at each boot.
131
132	  If you have any problems with bzip2 or lzma compressed
133	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
134	  version of this functionality (bzip2 only), for 2.4, was
135	  supplied by Christian Ludwig)
136
137	  High compression options are mostly useful for users, who
138	  are low on disk space (embedded systems), but for whom ram
139	  size matters less.
140
141	  If in doubt, select 'gzip'
142
143config KERNEL_GZIP
144	bool "Gzip"
145	depends on HAVE_KERNEL_GZIP
146	help
147	  The old and tried gzip compression. It provides a good balance
148	  between compression ratio and decompression speed.
149
150config KERNEL_BZIP2
151	bool "Bzip2"
152	depends on HAVE_KERNEL_BZIP2
153	help
154	  Its compression ratio and speed is intermediate.
155	  Decompression speed is slowest among the three.  The kernel
156	  size is about 10% smaller with bzip2, in comparison to gzip.
157	  Bzip2 uses a large amount of memory. For modern kernels you
158	  will need at least 8MB RAM or more for booting.
159
160config KERNEL_LZMA
161	bool "LZMA"
162	depends on HAVE_KERNEL_LZMA
163	help
164	  The most recent compression algorithm.
165	  Its ratio is best, decompression speed is between the other
166	  two. Compression is slowest.	The kernel size is about 33%
167	  smaller with LZMA in comparison to gzip.
168
169config KERNEL_LZO
170	bool "LZO"
171	depends on HAVE_KERNEL_LZO
172	help
173	  Its compression ratio is the poorest among the 4. The kernel
174	  size is about about 10% bigger than gzip; however its speed
175	  (both compression and decompression) is the fastest.
176
177endchoice
178
179config SWAP
180	bool "Support for paging of anonymous memory (swap)"
181	depends on MMU && BLOCK
182	default y
183	help
184	  This option allows you to choose whether you want to have support
185	  for so called swap devices or swap files in your kernel that are
186	  used to provide more virtual memory than the actual RAM present
187	  in your computer.  If unsure say Y.
188
189config SYSVIPC
190	bool "System V IPC"
191	---help---
192	  Inter Process Communication is a suite of library functions and
193	  system calls which let processes (running programs) synchronize and
194	  exchange information. It is generally considered to be a good thing,
195	  and some programs won't run unless you say Y here. In particular, if
196	  you want to run the DOS emulator dosemu under Linux (read the
197	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
198	  you'll need to say Y here.
199
200	  You can find documentation about IPC with "info ipc" and also in
201	  section 6.4 of the Linux Programmer's Guide, available from
202	  <http://www.tldp.org/guides.html>.
203
204config SYSVIPC_SYSCTL
205	bool
206	depends on SYSVIPC
207	depends on SYSCTL
208	default y
209
210config POSIX_MQUEUE
211	bool "POSIX Message Queues"
212	depends on NET && EXPERIMENTAL
213	---help---
214	  POSIX variant of message queues is a part of IPC. In POSIX message
215	  queues every message has a priority which decides about succession
216	  of receiving it by a process. If you want to compile and run
217	  programs written e.g. for Solaris with use of its POSIX message
218	  queues (functions mq_*) say Y here.
219
220	  POSIX message queues are visible as a filesystem called 'mqueue'
221	  and can be mounted somewhere if you want to do filesystem
222	  operations on message queues.
223
224	  If unsure, say Y.
225
226config POSIX_MQUEUE_SYSCTL
227	bool
228	depends on POSIX_MQUEUE
229	depends on SYSCTL
230	default y
231
232config BSD_PROCESS_ACCT
233	bool "BSD Process Accounting"
234	help
235	  If you say Y here, a user level program will be able to instruct the
236	  kernel (via a special system call) to write process accounting
237	  information to a file: whenever a process exits, information about
238	  that process will be appended to the file by the kernel.  The
239	  information includes things such as creation time, owning user,
240	  command name, memory usage, controlling terminal etc. (the complete
241	  list is in the struct acct in <file:include/linux/acct.h>).  It is
242	  up to the user level program to do useful things with this
243	  information.  This is generally a good idea, so say Y.
244
245config BSD_PROCESS_ACCT_V3
246	bool "BSD Process Accounting version 3 file format"
247	depends on BSD_PROCESS_ACCT
248	default n
249	help
250	  If you say Y here, the process accounting information is written
251	  in a new file format that also logs the process IDs of each
252	  process and it's parent. Note that this file format is incompatible
253	  with previous v0/v1/v2 file formats, so you will need updated tools
254	  for processing it. A preliminary version of these tools is available
255	  at <http://www.gnu.org/software/acct/>.
256
257config TASKSTATS
258	bool "Export task/process statistics through netlink (EXPERIMENTAL)"
259	depends on NET
260	default n
261	help
262	  Export selected statistics for tasks/processes through the
263	  generic netlink interface. Unlike BSD process accounting, the
264	  statistics are available during the lifetime of tasks/processes as
265	  responses to commands. Like BSD accounting, they are sent to user
266	  space on task exit.
267
268	  Say N if unsure.
269
270config TASK_DELAY_ACCT
271	bool "Enable per-task delay accounting (EXPERIMENTAL)"
272	depends on TASKSTATS
273	help
274	  Collect information on time spent by a task waiting for system
275	  resources like cpu, synchronous block I/O completion and swapping
276	  in pages. Such statistics can help in setting a task's priorities
277	  relative to other tasks for cpu, io, rss limits etc.
278
279	  Say N if unsure.
280
281config TASK_XACCT
282	bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
283	depends on TASKSTATS
284	help
285	  Collect extended task accounting data and send the data
286	  to userland for processing over the taskstats interface.
287
288	  Say N if unsure.
289
290config TASK_IO_ACCOUNTING
291	bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
292	depends on TASK_XACCT
293	help
294	  Collect information on the number of bytes of storage I/O which this
295	  task has caused.
296
297	  Say N if unsure.
298
299config AUDIT
300	bool "Auditing support"
301	depends on NET
302	help
303	  Enable auditing infrastructure that can be used with another
304	  kernel subsystem, such as SELinux (which requires this for
305	  logging of avc messages output).  Does not do system-call
306	  auditing without CONFIG_AUDITSYSCALL.
307
308config AUDITSYSCALL
309	bool "Enable system-call auditing support"
310	depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
311	default y if SECURITY_SELINUX
312	help
313	  Enable low-overhead system-call auditing infrastructure that
314	  can be used independently or with another kernel subsystem,
315	  such as SELinux.  To use audit's filesystem watch feature, please
316	  ensure that INOTIFY is configured.
317
318config AUDIT_TREE
319	def_bool y
320	depends on AUDITSYSCALL
321	select INOTIFY
322
323menu "RCU Subsystem"
324
325choice
326	prompt "RCU Implementation"
327	default TREE_RCU
328
329config TREE_RCU
330	bool "Tree-based hierarchical RCU"
331	help
332	  This option selects the RCU implementation that is
333	  designed for very large SMP system with hundreds or
334	  thousands of CPUs.  It also scales down nicely to
335	  smaller systems.
336
337config TREE_PREEMPT_RCU
338	bool "Preemptable tree-based hierarchical RCU"
339	depends on PREEMPT
340	help
341	  This option selects the RCU implementation that is
342	  designed for very large SMP systems with hundreds or
343	  thousands of CPUs, but for which real-time response
344	  is also required.  It also scales down nicely to
345	  smaller systems.
346
347config TINY_RCU
348	bool "UP-only small-memory-footprint RCU"
349	depends on !SMP
350	help
351	  This option selects the RCU implementation that is
352	  designed for UP systems from which real-time response
353	  is not required.  This option greatly reduces the
354	  memory footprint of RCU.
355
356endchoice
357
358config RCU_TRACE
359	bool "Enable tracing for RCU"
360	depends on TREE_RCU || TREE_PREEMPT_RCU
361	help
362	  This option provides tracing in RCU which presents stats
363	  in debugfs for debugging RCU implementation.
364
365	  Say Y here if you want to enable RCU tracing
366	  Say N if you are unsure.
367
368config RCU_FANOUT
369	int "Tree-based hierarchical RCU fanout value"
370	range 2 64 if 64BIT
371	range 2 32 if !64BIT
372	depends on TREE_RCU || TREE_PREEMPT_RCU
373	default 64 if 64BIT
374	default 32 if !64BIT
375	help
376	  This option controls the fanout of hierarchical implementations
377	  of RCU, allowing RCU to work efficiently on machines with
378	  large numbers of CPUs.  This value must be at least the cube
379	  root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
380	  systems and up to 262,144 for 64-bit systems.
381
382	  Select a specific number if testing RCU itself.
383	  Take the default if unsure.
384
385config RCU_FANOUT_EXACT
386	bool "Disable tree-based hierarchical RCU auto-balancing"
387	depends on TREE_RCU || TREE_PREEMPT_RCU
388	default n
389	help
390	  This option forces use of the exact RCU_FANOUT value specified,
391	  regardless of imbalances in the hierarchy.  This is useful for
392	  testing RCU itself, and might one day be useful on systems with
393	  strong NUMA behavior.
394
395	  Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
396
397	  Say N if unsure.
398
399config TREE_RCU_TRACE
400	def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
401	select DEBUG_FS
402	help
403	  This option provides tracing for the TREE_RCU and
404	  TREE_PREEMPT_RCU implementations, permitting Makefile to
405	  trivially select kernel/rcutree_trace.c.
406
407endmenu # "RCU Subsystem"
408
409config IKCONFIG
410	tristate "Kernel .config support"
411	---help---
412	  This option enables the complete Linux kernel ".config" file
413	  contents to be saved in the kernel. It provides documentation
414	  of which kernel options are used in a running kernel or in an
415	  on-disk kernel.  This information can be extracted from the kernel
416	  image file with the script scripts/extract-ikconfig and used as
417	  input to rebuild the current kernel or to build another kernel.
418	  It can also be extracted from a running kernel by reading
419	  /proc/config.gz if enabled (below).
420
421config IKCONFIG_PROC
422	bool "Enable access to .config through /proc/config.gz"
423	depends on IKCONFIG && PROC_FS
424	---help---
425	  This option enables access to the kernel configuration file
426	  through /proc/config.gz.
427
428config LOG_BUF_SHIFT
429	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
430	range 12 21
431	default 17
432	help
433	  Select kernel log buffer size as a power of 2.
434	  Examples:
435	  	     17 => 128 KB
436		     16 => 64 KB
437	             15 => 32 KB
438	             14 => 16 KB
439		     13 =>  8 KB
440		     12 =>  4 KB
441
442#
443# Architectures with an unreliable sched_clock() should select this:
444#
445config HAVE_UNSTABLE_SCHED_CLOCK
446	bool
447
448config GROUP_SCHED
449	bool "Group CPU scheduler"
450	depends on EXPERIMENTAL
451	default n
452	help
453	  This feature lets CPU scheduler recognize task groups and control CPU
454	  bandwidth allocation to such task groups.
455	  In order to create a group from arbitrary set of processes, use
456	  CONFIG_CGROUPS. (See Control Group support.)
457
458config FAIR_GROUP_SCHED
459	bool "Group scheduling for SCHED_OTHER"
460	depends on GROUP_SCHED
461	default GROUP_SCHED
462
463config RT_GROUP_SCHED
464	bool "Group scheduling for SCHED_RR/FIFO"
465	depends on EXPERIMENTAL
466	depends on GROUP_SCHED
467	default n
468	help
469	  This feature lets you explicitly allocate real CPU bandwidth
470	  to users or control groups (depending on the "Basis for grouping tasks"
471	  setting below. If enabled, it will also make it impossible to
472	  schedule realtime tasks for non-root users until you allocate
473	  realtime bandwidth for them.
474	  See Documentation/scheduler/sched-rt-group.txt for more information.
475
476choice
477	depends on GROUP_SCHED
478	prompt "Basis for grouping tasks"
479	default USER_SCHED
480
481config USER_SCHED
482	bool "user id"
483	help
484	  This option will choose userid as the basis for grouping
485	  tasks, thus providing equal CPU bandwidth to each user.
486
487config CGROUP_SCHED
488	bool "Control groups"
489 	depends on CGROUPS
490 	help
491	  This option allows you to create arbitrary task groups
492	  using the "cgroup" pseudo filesystem and control
493	  the cpu bandwidth allocated to each such task group.
494	  Refer to Documentation/cgroups/cgroups.txt for more
495	  information on "cgroup" pseudo filesystem.
496
497endchoice
498
499menuconfig CGROUPS
500	boolean "Control Group support"
501	help
502	  This option adds support for grouping sets of processes together, for
503	  use with process control subsystems such as Cpusets, CFS, memory
504	  controls or device isolation.
505	  See
506		- Documentation/scheduler/sched-design-CFS.txt	(CFS)
507		- Documentation/cgroups/ (features for grouping, isolation
508					  and resource control)
509
510	  Say N if unsure.
511
512if CGROUPS
513
514config CGROUP_DEBUG
515	bool "Example debug cgroup subsystem"
516	depends on CGROUPS
517	default n
518	help
519	  This option enables a simple cgroup subsystem that
520	  exports useful debugging information about the cgroups
521	  framework.
522
523	  Say N if unsure.
524
525config CGROUP_NS
526	bool "Namespace cgroup subsystem"
527	depends on CGROUPS
528	help
529	  Provides a simple namespace cgroup subsystem to
530	  provide hierarchical naming of sets of namespaces,
531	  for instance virtual servers and checkpoint/restart
532	  jobs.
533
534config CGROUP_FREEZER
535	bool "Freezer cgroup subsystem"
536	depends on CGROUPS
537	help
538	  Provides a way to freeze and unfreeze all tasks in a
539	  cgroup.
540
541config CGROUP_DEVICE
542	bool "Device controller for cgroups"
543	depends on CGROUPS && EXPERIMENTAL
544	help
545	  Provides a cgroup implementing whitelists for devices which
546	  a process in the cgroup can mknod or open.
547
548config CPUSETS
549	bool "Cpuset support"
550	depends on CGROUPS
551	help
552	  This option will let you create and manage CPUSETs which
553	  allow dynamically partitioning a system into sets of CPUs and
554	  Memory Nodes and assigning tasks to run only within those sets.
555	  This is primarily useful on large SMP or NUMA systems.
556
557	  Say N if unsure.
558
559config PROC_PID_CPUSET
560	bool "Include legacy /proc/<pid>/cpuset file"
561	depends on CPUSETS
562	default y
563
564config CGROUP_CPUACCT
565	bool "Simple CPU accounting cgroup subsystem"
566	depends on CGROUPS
567	help
568	  Provides a simple Resource Controller for monitoring the
569	  total CPU consumed by the tasks in a cgroup.
570
571config RESOURCE_COUNTERS
572	bool "Resource counters"
573	help
574	  This option enables controller independent resource accounting
575	  infrastructure that works with cgroups.
576	depends on CGROUPS
577
578config CGROUP_MEM_RES_CTLR
579	bool "Memory Resource Controller for Control Groups"
580	depends on CGROUPS && RESOURCE_COUNTERS
581	select MM_OWNER
582	help
583	  Provides a memory resource controller that manages both anonymous
584	  memory and page cache. (See Documentation/cgroups/memory.txt)
585
586	  Note that setting this option increases fixed memory overhead
587	  associated with each page of memory in the system. By this,
588	  20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
589	  usage tracking struct at boot. Total amount of this is printed out
590	  at boot.
591
592	  Only enable when you're ok with these trade offs and really
593	  sure you need the memory resource controller. Even when you enable
594	  this, you can set "cgroup_disable=memory" at your boot option to
595	  disable memory resource controller and you can avoid overheads.
596	  (and lose benefits of memory resource controller)
597
598	  This config option also selects MM_OWNER config option, which
599	  could in turn add some fork/exit overhead.
600
601config CGROUP_MEM_RES_CTLR_SWAP
602	bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
603	depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
604	help
605	  Add swap management feature to memory resource controller. When you
606	  enable this, you can limit mem+swap usage per cgroup. In other words,
607	  when you disable this, memory resource controller has no cares to
608	  usage of swap...a process can exhaust all of the swap. This extension
609	  is useful when you want to avoid exhaustion swap but this itself
610	  adds more overheads and consumes memory for remembering information.
611	  Especially if you use 32bit system or small memory system, please
612	  be careful about enabling this. When memory resource controller
613	  is disabled by boot option, this will be automatically disabled and
614	  there will be no overhead from this. Even when you set this config=y,
615	  if boot option "noswapaccount" is set, swap will not be accounted.
616	  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
617	  size is 4096bytes, 512k per 1Gbytes of swap.
618
619endif # CGROUPS
620
621config MM_OWNER
622	bool
623
624config SYSFS_DEPRECATED
625	bool
626
627config SYSFS_DEPRECATED_V2
628	bool "enable deprecated sysfs features to support old userspace tools"
629	depends on SYSFS
630	default n
631	select SYSFS_DEPRECATED
632	help
633	  This option switches the layout of sysfs to the deprecated
634	  version. Do not use it on recent distributions.
635
636	  The current sysfs layout features a unified device tree at
637	  /sys/devices/, which is able to express a hierarchy between
638	  class devices. If the deprecated option is set to Y, the
639	  unified device tree is split into a bus device tree at
640	  /sys/devices/ and several individual class device trees at
641	  /sys/class/. The class and bus devices will be connected by
642	  "<subsystem>:<name>" and the "device" links. The "block"
643	  class devices, will not show up in /sys/class/block/. Some
644	  subsystems will suppress the creation of some devices which
645	  depend on the unified device tree.
646
647	  This option is not a pure compatibility option that can
648	  be safely enabled on newer distributions. It will change the
649	  layout of sysfs to the non-extensible deprecated version,
650	  and disable some features, which can not be exported without
651	  confusing older userspace tools. Since 2007/2008 all major
652	  distributions do not enable this option, and ship no tools which
653	  depend on the deprecated layout or this option.
654
655	  If you are using a new kernel on an older distribution, or use
656	  older userspace tools, you might need to say Y here. Do not say Y,
657	  if the original kernel, that came with your distribution, has
658	  this option set to N.
659
660config RELAY
661	bool "Kernel->user space relay support (formerly relayfs)"
662	help
663	  This option enables support for relay interface support in
664	  certain file systems (such as debugfs).
665	  It is designed to provide an efficient mechanism for tools and
666	  facilities to relay large amounts of data from kernel space to
667	  user space.
668
669	  If unsure, say N.
670
671config NAMESPACES
672	bool "Namespaces support" if EMBEDDED
673	default !EMBEDDED
674	help
675	  Provides the way to make tasks work with different objects using
676	  the same id. For example same IPC id may refer to different objects
677	  or same user id or pid may refer to different tasks when used in
678	  different namespaces.
679
680config UTS_NS
681	bool "UTS namespace"
682	depends on NAMESPACES
683	help
684	  In this namespace tasks see different info provided with the
685	  uname() system call
686
687config IPC_NS
688	bool "IPC namespace"
689	depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
690	help
691	  In this namespace tasks work with IPC ids which correspond to
692	  different IPC objects in different namespaces.
693
694config USER_NS
695	bool "User namespace (EXPERIMENTAL)"
696	depends on NAMESPACES && EXPERIMENTAL
697	help
698	  This allows containers, i.e. vservers, to use user namespaces
699	  to provide different user info for different servers.
700	  If unsure, say N.
701
702config PID_NS
703	bool "PID Namespaces (EXPERIMENTAL)"
704	default n
705	depends on NAMESPACES && EXPERIMENTAL
706	help
707	  Support process id namespaces.  This allows having multiple
708	  processes with the same pid as long as they are in different
709	  pid namespaces.  This is a building block of containers.
710
711	  Unless you want to work with an experimental feature
712	  say N here.
713
714config NET_NS
715	bool "Network namespace"
716	default n
717	depends on NAMESPACES && EXPERIMENTAL && NET
718	help
719	  Allow user space to create what appear to be multiple instances
720	  of the network stack.
721
722config BLK_DEV_INITRD
723	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
724	depends on BROKEN || !FRV
725	help
726	  The initial RAM filesystem is a ramfs which is loaded by the
727	  boot loader (loadlin or lilo) and that is mounted as root
728	  before the normal boot procedure. It is typically used to
729	  load modules needed to mount the "real" root file system,
730	  etc. See <file:Documentation/initrd.txt> for details.
731
732	  If RAM disk support (BLK_DEV_RAM) is also included, this
733	  also enables initial RAM disk (initrd) support and adds
734	  15 Kbytes (more on some other architectures) to the kernel size.
735
736	  If unsure say Y.
737
738if BLK_DEV_INITRD
739
740source "usr/Kconfig"
741
742endif
743
744config CC_OPTIMIZE_FOR_SIZE
745	bool "Optimize for size"
746	default y
747	help
748	  Enabling this option will pass "-Os" instead of "-O2" to gcc
749	  resulting in a smaller kernel.
750
751	  If unsure, say Y.
752
753config SYSCTL
754	bool
755
756config ANON_INODES
757	bool
758
759menuconfig EMBEDDED
760	bool "Configure standard kernel features (for small systems)"
761	help
762	  This option allows certain base kernel options and settings
763          to be disabled or tweaked. This is for specialized
764          environments which can tolerate a "non-standard" kernel.
765          Only use this if you really know what you are doing.
766
767config UID16
768	bool "Enable 16-bit UID system calls" if EMBEDDED
769	depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
770	default y
771	help
772	  This enables the legacy 16-bit UID syscall wrappers.
773
774config SYSCTL_SYSCALL
775	bool "Sysctl syscall support" if EMBEDDED
776	depends on PROC_SYSCTL
777	default y
778	select SYSCTL
779	---help---
780	  sys_sysctl uses binary paths that have been found challenging
781	  to properly maintain and use.  The interface in /proc/sys
782	  using paths with ascii names is now the primary path to this
783	  information.
784
785	  Almost nothing using the binary sysctl interface so if you are
786	  trying to save some space it is probably safe to disable this,
787	  making your kernel marginally smaller.
788
789	  If unsure say Y here.
790
791config KALLSYMS
792	 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
793	 default y
794	 help
795	   Say Y here to let the kernel print out symbolic crash information and
796	   symbolic stack backtraces. This increases the size of the kernel
797	   somewhat, as all symbols have to be loaded into the kernel image.
798
799config KALLSYMS_ALL
800	bool "Include all symbols in kallsyms"
801	depends on DEBUG_KERNEL && KALLSYMS
802	help
803	   Normally kallsyms only contains the symbols of functions, for nicer
804	   OOPS messages.  Some debuggers can use kallsyms for other
805	   symbols too: say Y here to include all symbols, if you need them
806	   and you don't care about adding 300k to the size of your kernel.
807
808	   Say N.
809
810config KALLSYMS_EXTRA_PASS
811	bool "Do an extra kallsyms pass"
812	depends on KALLSYMS
813	help
814	   If kallsyms is not working correctly, the build will fail with
815	   inconsistent kallsyms data.  If that occurs, log a bug report and
816	   turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
817	   Always say N here unless you find a bug in kallsyms, which must be
818	   reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
819	   you wait for kallsyms to be fixed.
820
821
822config HOTPLUG
823	bool "Support for hot-pluggable devices" if EMBEDDED
824	default y
825	help
826	  This option is provided for the case where no hotplug or uevent
827	  capabilities is wanted by the kernel.  You should only consider
828	  disabling this option for embedded systems that do not use modules, a
829	  dynamic /dev tree, or dynamic device discovery.  Just say Y.
830
831config PRINTK
832	default y
833	bool "Enable support for printk" if EMBEDDED
834	help
835	  This option enables normal printk support. Removing it
836	  eliminates most of the message strings from the kernel image
837	  and makes the kernel more or less silent. As this makes it
838	  very difficult to diagnose system problems, saying N here is
839	  strongly discouraged.
840
841config BUG
842	bool "BUG() support" if EMBEDDED
843	default y
844	help
845          Disabling this option eliminates support for BUG and WARN, reducing
846          the size of your kernel image and potentially quietly ignoring
847          numerous fatal conditions. You should only consider disabling this
848          option for embedded systems with no facilities for reporting errors.
849          Just say Y.
850
851config ELF_CORE
852	default y
853	bool "Enable ELF core dumps" if EMBEDDED
854	help
855	  Enable support for generating core dumps. Disabling saves about 4k.
856
857config PCSPKR_PLATFORM
858	bool "Enable PC-Speaker support" if EMBEDDED
859	depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
860	default y
861	help
862          This option allows to disable the internal PC-Speaker
863          support, saving some memory.
864
865config BASE_FULL
866	default y
867	bool "Enable full-sized data structures for core" if EMBEDDED
868	help
869	  Disabling this option reduces the size of miscellaneous core
870	  kernel data structures. This saves memory on small machines,
871	  but may reduce performance.
872
873config FUTEX
874	bool "Enable futex support" if EMBEDDED
875	default y
876	select RT_MUTEXES
877	help
878	  Disabling this option will cause the kernel to be built without
879	  support for "fast userspace mutexes".  The resulting kernel may not
880	  run glibc-based applications correctly.
881
882config EPOLL
883	bool "Enable eventpoll support" if EMBEDDED
884	default y
885	select ANON_INODES
886	help
887	  Disabling this option will cause the kernel to be built without
888	  support for epoll family of system calls.
889
890config SIGNALFD
891	bool "Enable signalfd() system call" if EMBEDDED
892	select ANON_INODES
893	default y
894	help
895	  Enable the signalfd() system call that allows to receive signals
896	  on a file descriptor.
897
898	  If unsure, say Y.
899
900config TIMERFD
901	bool "Enable timerfd() system call" if EMBEDDED
902	select ANON_INODES
903	default y
904	help
905	  Enable the timerfd() system call that allows to receive timer
906	  events on a file descriptor.
907
908	  If unsure, say Y.
909
910config EVENTFD
911	bool "Enable eventfd() system call" if EMBEDDED
912	select ANON_INODES
913	default y
914	help
915	  Enable the eventfd() system call that allows to receive both
916	  kernel notification (ie. KAIO) or userspace notifications.
917
918	  If unsure, say Y.
919
920config SHMEM
921	bool "Use full shmem filesystem" if EMBEDDED
922	default y
923	depends on MMU
924	help
925	  The shmem is an internal filesystem used to manage shared memory.
926	  It is backed by swap and manages resource limits. It is also exported
927	  to userspace as tmpfs if TMPFS is enabled. Disabling this
928	  option replaces shmem and tmpfs with the much simpler ramfs code,
929	  which may be appropriate on small systems without swap.
930
931config AIO
932	bool "Enable AIO support" if EMBEDDED
933	default y
934	help
935	  This option enables POSIX asynchronous I/O which may by used
936          by some high performance threaded applications. Disabling
937          this option saves about 7k.
938
939config HAVE_PERF_EVENTS
940	bool
941	help
942	  See tools/perf/design.txt for details.
943
944config PERF_USE_VMALLOC
945	bool
946	help
947	  See tools/perf/design.txt for details
948
949menu "Kernel Performance Events And Counters"
950
951config PERF_EVENTS
952	bool "Kernel performance events and counters"
953	default y if (PROFILING || PERF_COUNTERS)
954	depends on HAVE_PERF_EVENTS
955	select ANON_INODES
956	help
957	  Enable kernel support for various performance events provided
958	  by software and hardware.
959
960	  Software events are supported either built-in or via the
961	  use of generic tracepoints.
962
963	  Most modern CPUs support performance events via performance
964	  counter registers. These registers count the number of certain
965	  types of hw events: such as instructions executed, cachemisses
966	  suffered, or branches mis-predicted - without slowing down the
967	  kernel or applications. These registers can also trigger interrupts
968	  when a threshold number of events have passed - and can thus be
969	  used to profile the code that runs on that CPU.
970
971	  The Linux Performance Event subsystem provides an abstraction of
972	  these software and hardware event capabilities, available via a
973	  system call and used by the "perf" utility in tools/perf/. It
974	  provides per task and per CPU counters, and it provides event
975	  capabilities on top of those.
976
977	  Say Y if unsure.
978
979config EVENT_PROFILE
980	bool "Tracepoint profiling sources"
981	depends on PERF_EVENTS && EVENT_TRACING
982	default y
983	help
984	 Allow the use of tracepoints as software performance events.
985
986	 When this is enabled, you can create perf events based on
987	 tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
988	 found in debugfs://tracing/events/*/*/id. (The -e/--events
989	 option to the perf tool can parse and interpret symbolic
990	 tracepoints, in the subsystem:tracepoint_name format.)
991
992config PERF_COUNTERS
993	bool "Kernel performance counters (old config option)"
994	depends on HAVE_PERF_EVENTS
995	help
996	  This config has been obsoleted by the PERF_EVENTS
997	  config option - please see that one for details.
998
999	  It has no effect on the kernel whether you enable
1000	  it or not, it is a compatibility placeholder.
1001
1002	  Say N if unsure.
1003
1004config DEBUG_PERF_USE_VMALLOC
1005	default n
1006	bool "Debug: use vmalloc to back perf mmap() buffers"
1007	depends on PERF_EVENTS && DEBUG_KERNEL
1008	select PERF_USE_VMALLOC
1009	help
1010	 Use vmalloc memory to back perf mmap() buffers.
1011
1012	 Mostly useful for debugging the vmalloc code on platforms
1013	 that don't require it.
1014
1015	 Say N if unsure.
1016
1017endmenu
1018
1019config VM_EVENT_COUNTERS
1020	default y
1021	bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1022	help
1023	  VM event counters are needed for event counts to be shown.
1024	  This option allows the disabling of the VM event counters
1025	  on EMBEDDED systems.  /proc/vmstat will only show page counts
1026	  if VM event counters are disabled.
1027
1028config PCI_QUIRKS
1029	default y
1030	bool "Enable PCI quirk workarounds" if EMBEDDED
1031	depends on PCI
1032	help
1033	  This enables workarounds for various PCI chipset
1034          bugs/quirks. Disable this only if your target machine is
1035          unaffected by PCI quirks.
1036
1037config SLUB_DEBUG
1038	default y
1039	bool "Enable SLUB debugging support" if EMBEDDED
1040	depends on SLUB && SYSFS
1041	help
1042	  SLUB has extensive debug support features. Disabling these can
1043	  result in significant savings in code size. This also disables
1044	  SLUB sysfs support. /sys/slab will not exist and there will be
1045	  no support for cache validation etc.
1046
1047config COMPAT_BRK
1048	bool "Disable heap randomization"
1049	default y
1050	help
1051	  Randomizing heap placement makes heap exploits harder, but it
1052	  also breaks ancient binaries (including anything libc5 based).
1053	  This option changes the bootup default to heap randomization
1054	  disabled, and can be overridden at runtime by setting
1055	  /proc/sys/kernel/randomize_va_space to 2.
1056
1057	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
1058
1059choice
1060	prompt "Choose SLAB allocator"
1061	default SLUB
1062	help
1063	   This option allows to select a slab allocator.
1064
1065config SLAB
1066	bool "SLAB"
1067	help
1068	  The regular slab allocator that is established and known to work
1069	  well in all environments. It organizes cache hot objects in
1070	  per cpu and per node queues.
1071
1072config SLUB
1073	bool "SLUB (Unqueued Allocator)"
1074	help
1075	   SLUB is a slab allocator that minimizes cache line usage
1076	   instead of managing queues of cached objects (SLAB approach).
1077	   Per cpu caching is realized using slabs of objects instead
1078	   of queues of objects. SLUB can use memory efficiently
1079	   and has enhanced diagnostics. SLUB is the default choice for
1080	   a slab allocator.
1081
1082config SLOB
1083	depends on EMBEDDED
1084	bool "SLOB (Simple Allocator)"
1085	help
1086	   SLOB replaces the stock allocator with a drastically simpler
1087	   allocator. SLOB is generally more space efficient but
1088	   does not perform as well on large systems.
1089
1090endchoice
1091
1092config MMAP_ALLOW_UNINITIALIZED
1093	bool "Allow mmapped anonymous memory to be uninitialized"
1094	depends on EMBEDDED && !MMU
1095	default n
1096	help
1097	  Normally, and according to the Linux spec, anonymous memory obtained
1098	  from mmap() has it's contents cleared before it is passed to
1099	  userspace.  Enabling this config option allows you to request that
1100	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1101	  providing a huge performance boost.  If this option is not enabled,
1102	  then the flag will be ignored.
1103
1104	  This is taken advantage of by uClibc's malloc(), and also by
1105	  ELF-FDPIC binfmt's brk and stack allocator.
1106
1107	  Because of the obvious security issues, this option should only be
1108	  enabled on embedded devices where you control what is run in
1109	  userspace.  Since that isn't generally a problem on no-MMU systems,
1110	  it is normally safe to say Y here.
1111
1112	  See Documentation/nommu-mmap.txt for more information.
1113
1114config PROFILING
1115	bool "Profiling support (EXPERIMENTAL)"
1116	help
1117	  Say Y here to enable the extended profiling support mechanisms used
1118	  by profilers such as OProfile.
1119
1120#
1121# Place an empty function call at each tracepoint site. Can be
1122# dynamically changed for a probe function.
1123#
1124config TRACEPOINTS
1125	bool
1126
1127source "arch/Kconfig"
1128
1129config SLOW_WORK
1130	default n
1131	bool
1132	help
1133	  The slow work thread pool provides a number of dynamically allocated
1134	  threads that can be used by the kernel to perform operations that
1135	  take a relatively long time.
1136
1137	  An example of this would be CacheFiles doing a path lookup followed
1138	  by a series of mkdirs and a create call, all of which have to touch
1139	  disk.
1140
1141	  See Documentation/slow-work.txt.
1142
1143config SLOW_WORK_DEBUG
1144	bool "Slow work debugging through debugfs"
1145	default n
1146	depends on SLOW_WORK && DEBUG_FS
1147	help
1148	  Display the contents of the slow work run queue through debugfs,
1149	  including items currently executing.
1150
1151	  See Documentation/slow-work.txt.
1152
1153endmenu		# General setup
1154
1155config HAVE_GENERIC_DMA_COHERENT
1156	bool
1157	default n
1158
1159config SLABINFO
1160	bool
1161	depends on PROC_FS
1162	depends on SLAB || SLUB_DEBUG
1163	default y
1164
1165config RT_MUTEXES
1166	boolean
1167
1168config BASE_SMALL
1169	int
1170	default 0 if BASE_FULL
1171	default 1 if !BASE_FULL
1172
1173menuconfig MODULES
1174	bool "Enable loadable module support"
1175	help
1176	  Kernel modules are small pieces of compiled code which can
1177	  be inserted in the running kernel, rather than being
1178	  permanently built into the kernel.  You use the "modprobe"
1179	  tool to add (and sometimes remove) them.  If you say Y here,
1180	  many parts of the kernel can be built as modules (by
1181	  answering M instead of Y where indicated): this is most
1182	  useful for infrequently used options which are not required
1183	  for booting.  For more information, see the man pages for
1184	  modprobe, lsmod, modinfo, insmod and rmmod.
1185
1186	  If you say Y here, you will need to run "make
1187	  modules_install" to put the modules under /lib/modules/
1188	  where modprobe can find them (you may need to be root to do
1189	  this).
1190
1191	  If unsure, say Y.
1192
1193if MODULES
1194
1195config MODULE_FORCE_LOAD
1196	bool "Forced module loading"
1197	default n
1198	help
1199	  Allow loading of modules without version information (ie. modprobe
1200	  --force).  Forced module loading sets the 'F' (forced) taint flag and
1201	  is usually a really bad idea.
1202
1203config MODULE_UNLOAD
1204	bool "Module unloading"
1205	help
1206	  Without this option you will not be able to unload any
1207	  modules (note that some modules may not be unloadable
1208	  anyway), which makes your kernel smaller, faster
1209	  and simpler.  If unsure, say Y.
1210
1211config MODULE_FORCE_UNLOAD
1212	bool "Forced module unloading"
1213	depends on MODULE_UNLOAD && EXPERIMENTAL
1214	help
1215	  This option allows you to force a module to unload, even if the
1216	  kernel believes it is unsafe: the kernel will remove the module
1217	  without waiting for anyone to stop using it (using the -f option to
1218	  rmmod).  This is mainly for kernel developers and desperate users.
1219	  If unsure, say N.
1220
1221config MODVERSIONS
1222	bool "Module versioning support"
1223	help
1224	  Usually, you have to use modules compiled with your kernel.
1225	  Saying Y here makes it sometimes possible to use modules
1226	  compiled for different kernels, by adding enough information
1227	  to the modules to (hopefully) spot any changes which would
1228	  make them incompatible with the kernel you are running.  If
1229	  unsure, say N.
1230
1231config MODULE_SRCVERSION_ALL
1232	bool "Source checksum for all modules"
1233	help
1234	  Modules which contain a MODULE_VERSION get an extra "srcversion"
1235	  field inserted into their modinfo section, which contains a
1236    	  sum of the source files which made it.  This helps maintainers
1237	  see exactly which source was used to build a module (since
1238	  others sometimes change the module source without updating
1239	  the version).  With this option, such a "srcversion" field
1240	  will be created for all modules.  If unsure, say N.
1241
1242endif # MODULES
1243
1244config INIT_ALL_POSSIBLE
1245	bool
1246	help
1247	  Back when each arch used to define their own cpu_online_map and
1248	  cpu_possible_map, some of them chose to initialize cpu_possible_map
1249	  with all 1s, and others with all 0s.  When they were centralised,
1250	  it was better to provide this option than to break all the archs
1251	  and have several arch maintainers pursuing me down dark alleys.
1252
1253config STOP_MACHINE
1254	bool
1255	default y
1256	depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1257	help
1258	  Need stop_machine() primitive.
1259
1260source "block/Kconfig"
1261
1262config PREEMPT_NOTIFIERS
1263	bool
1264
1265source "kernel/Kconfig.locks"
1266