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1	config ARCH
2	string
3	option env="ARCH"
4
5	config KERNELVERSION
6	string
7	option env="KERNELVERSION"
8
9	config DEFCONFIG_LIST
10	string
11	depends on !UML
12	option defconfig_list
13	default "/lib/modules/$UNAME_RELEASE/.config"
14	default "/etc/kernel-config"
15	default "/boot/config-$UNAME_RELEASE"
16	default "$ARCH_DEFCONFIG"
17	default "arch/$ARCH/defconfig"
18
19	config CONSTRUCTORS
20	bool
21	depends on !UML
22	default y
23
24	menu "General setup"
25
26	config 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47	drivers that have been replaced by something else, and/or are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
57	config BROKEN
58	bool
59
60	config BROKEN_ON_SMP
61	bool
62	depends on BROKEN \|\| !SMP
63	default y
64
65	config LOCK_KERNEL
66	bool
67	depends on SMP \|\| PREEMPT
68	default y
69
70	config 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
79	config 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
89	config 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
109	config HAVE_KERNEL_GZIP
110	bool
111
112	config HAVE_KERNEL_BZIP2
113	bool
114
115	config HAVE_KERNEL_LZMA
116	bool
117
118	config HAVE_KERNEL_LZO
119	bool
120
121	choice
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
143	config 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
150	config 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
160	config 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
169	config 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
177	endchoice
178
179	config 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
189	config 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
204	config SYSVIPC_SYSCTL
205	bool
206	depends on SYSVIPC
207	depends on SYSCTL
208	default y
209
210	config 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
226	config POSIX_MQUEUE_SYSCTL
227	bool
228	depends on POSIX_MQUEUE
229	depends on SYSCTL
230	default y
231
232	config 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
245	config 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
257	config 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
270	config 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
281	config 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
290	config 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
299	config 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
308	config 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
318	config AUDIT_TREE
319	def_bool y
320	depends on AUDITSYSCALL
321	select INOTIFY
322
323	menu "RCU Subsystem"
324
325	choice
326	prompt "RCU Implementation"
327	default TREE_RCU
328
329	config 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
337	config 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
347	endchoice
348
349	config RCU_TRACE
350	bool "Enable tracing for RCU"
351	depends on TREE_RCU \|\| TREE_PREEMPT_RCU
352	help
353	This option provides tracing in RCU which presents stats
354	in debugfs for debugging RCU implementation.
355
356	Say Y here if you want to enable RCU tracing
357	Say N if you are unsure.
358
359	config RCU_FANOUT
360	int "Tree-based hierarchical RCU fanout value"
361	range 2 64 if 64BIT
362	range 2 32 if !64BIT
363	depends on TREE_RCU \|\| TREE_PREEMPT_RCU
364	default 64 if 64BIT
365	default 32 if !64BIT
366	help
367	This option controls the fanout of hierarchical implementations
368	of RCU, allowing RCU to work efficiently on machines with
369	large numbers of CPUs. This value must be at least the cube
370	root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
371	systems and up to 262,144 for 64-bit systems.
372
373	Select a specific number if testing RCU itself.
374	Take the default if unsure.
375
376	config RCU_FANOUT_EXACT
377	bool "Disable tree-based hierarchical RCU auto-balancing"
378	depends on TREE_RCU \|\| TREE_PREEMPT_RCU
379	default n
380	help
381	This option forces use of the exact RCU_FANOUT value specified,
382	regardless of imbalances in the hierarchy. This is useful for
383	testing RCU itself, and might one day be useful on systems with
384	strong NUMA behavior.
385
386	Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
387
388	Say N if unsure.
389
390	config TREE_RCU_TRACE
391	def_bool RCU_TRACE && ( TREE_RCU \|\| TREE_PREEMPT_RCU )
392	select DEBUG_FS
393	help
394	This option provides tracing for the TREE_RCU and
395	TREE_PREEMPT_RCU implementations, permitting Makefile to
396	trivially select kernel/rcutree_trace.c.
397
398	endmenu # "RCU Subsystem"
399
400	config IKCONFIG
401	tristate "Kernel .config support"
402	---help---
403	This option enables the complete Linux kernel ".config" file
404	contents to be saved in the kernel. It provides documentation
405	of which kernel options are used in a running kernel or in an
406	on-disk kernel. This information can be extracted from the kernel
407	image file with the script scripts/extract-ikconfig and used as
408	input to rebuild the current kernel or to build another kernel.
409	It can also be extracted from a running kernel by reading
410	/proc/config.gz if enabled (below).
411
412	config IKCONFIG_PROC
413	bool "Enable access to .config through /proc/config.gz"
414	depends on IKCONFIG && PROC_FS
415	---help---
416	This option enables access to the kernel configuration file
417	through /proc/config.gz.
418
419	config LOG_BUF_SHIFT
420	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
421	range 12 21
422	default 17
423	help
424	Select kernel log buffer size as a power of 2.
425	Examples:
426	17 => 128 KB
427	16 => 64 KB
428	15 => 32 KB
429	14 => 16 KB
430	13 => 8 KB
431	12 => 4 KB
432
433	#
434	# Architectures with an unreliable sched_clock() should select this:
435	#
436	config HAVE_UNSTABLE_SCHED_CLOCK
437	bool
438
439	config GROUP_SCHED
440	bool "Group CPU scheduler"
441	depends on EXPERIMENTAL
442	default n
443	help
444	This feature lets CPU scheduler recognize task groups and control CPU
445	bandwidth allocation to such task groups.
446	In order to create a group from arbitrary set of processes, use
447	CONFIG_CGROUPS. (See Control Group support.)
448
449	config FAIR_GROUP_SCHED
450	bool "Group scheduling for SCHED_OTHER"
451	depends on GROUP_SCHED
452	default GROUP_SCHED
453
454	config RT_GROUP_SCHED
455	bool "Group scheduling for SCHED_RR/FIFO"
456	depends on EXPERIMENTAL
457	depends on GROUP_SCHED
458	default n
459	help
460	This feature lets you explicitly allocate real CPU bandwidth
461	to users or control groups (depending on the "Basis for grouping tasks"
462	setting below. If enabled, it will also make it impossible to
463	schedule realtime tasks for non-root users until you allocate
464	realtime bandwidth for them.
465	See Documentation/scheduler/sched-rt-group.txt for more information.
466
467	choice
468	depends on GROUP_SCHED
469	prompt "Basis for grouping tasks"
470	default USER_SCHED
471
472	config USER_SCHED
473	bool "user id"
474	help
475	This option will choose userid as the basis for grouping
476	tasks, thus providing equal CPU bandwidth to each user.
477
478	config CGROUP_SCHED
479	bool "Control groups"
480	depends on CGROUPS
481	help
482	This option allows you to create arbitrary task groups
483	using the "cgroup" pseudo filesystem and control
484	the cpu bandwidth allocated to each such task group.
485	Refer to Documentation/cgroups/cgroups.txt for more
486	information on "cgroup" pseudo filesystem.
487
488	endchoice
489
490	menuconfig CGROUPS
491	boolean "Control Group support"
492	help
493	This option adds support for grouping sets of processes together, for
494	use with process control subsystems such as Cpusets, CFS, memory
495	controls or device isolation.
496	See
497	- Documentation/scheduler/sched-design-CFS.txt (CFS)
498	- Documentation/cgroups/ (features for grouping, isolation
499	and resource control)
500
501	Say N if unsure.
502
503	if CGROUPS
504
505	config CGROUP_DEBUG
506	bool "Example debug cgroup subsystem"
507	depends on CGROUPS
508	default n
509	help
510	This option enables a simple cgroup subsystem that
511	exports useful debugging information about the cgroups
512	framework.
513
514	Say N if unsure.
515
516	config CGROUP_NS
517	bool "Namespace cgroup subsystem"
518	depends on CGROUPS
519	help
520	Provides a simple namespace cgroup subsystem to
521	provide hierarchical naming of sets of namespaces,
522	for instance virtual servers and checkpoint/restart
523	jobs.
524
525	config CGROUP_FREEZER
526	bool "Freezer cgroup subsystem"
527	depends on CGROUPS
528	help
529	Provides a way to freeze and unfreeze all tasks in a
530	cgroup.
531
532	config CGROUP_DEVICE
533	bool "Device controller for cgroups"
534	depends on CGROUPS && EXPERIMENTAL
535	help
536	Provides a cgroup implementing whitelists for devices which
537	a process in the cgroup can mknod or open.
538
539	config CPUSETS
540	bool "Cpuset support"
541	depends on CGROUPS
542	help
543	This option will let you create and manage CPUSETs which
544	allow dynamically partitioning a system into sets of CPUs and
545	Memory Nodes and assigning tasks to run only within those sets.
546	This is primarily useful on large SMP or NUMA systems.
547
548	Say N if unsure.
549
550	config PROC_PID_CPUSET
551	bool "Include legacy /proc/<pid>/cpuset file"
552	depends on CPUSETS
553	default y
554
555	config CGROUP_CPUACCT
556	bool "Simple CPU accounting cgroup subsystem"
557	depends on CGROUPS
558	help
559	Provides a simple Resource Controller for monitoring the
560	total CPU consumed by the tasks in a cgroup.
561
562	config RESOURCE_COUNTERS
563	bool "Resource counters"
564	help
565	This option enables controller independent resource accounting
566	infrastructure that works with cgroups.
567	depends on CGROUPS
568
569	config CGROUP_MEM_RES_CTLR
570	bool "Memory Resource Controller for Control Groups"
571	depends on CGROUPS && RESOURCE_COUNTERS
572	select MM_OWNER
573	help
574	Provides a memory resource controller that manages both anonymous
575	memory and page cache. (See Documentation/cgroups/memory.txt)
576
577	Note that setting this option increases fixed memory overhead
578	associated with each page of memory in the system. By this,
579	20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
580	usage tracking struct at boot. Total amount of this is printed out
581	at boot.
582
583	Only enable when you're ok with these trade offs and really
584	sure you need the memory resource controller. Even when you enable
585	this, you can set "cgroup_disable=memory" at your boot option to
586	disable memory resource controller and you can avoid overheads.
587	(and lose benefits of memory resource controller)
588
589	This config option also selects MM_OWNER config option, which
590	could in turn add some fork/exit overhead.
591
592	config CGROUP_MEM_RES_CTLR_SWAP
593	bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
594	depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
595	help
596	Add swap management feature to memory resource controller. When you
597	enable this, you can limit mem+swap usage per cgroup. In other words,
598	when you disable this, memory resource controller has no cares to
599	usage of swap...a process can exhaust all of the swap. This extension
600	is useful when you want to avoid exhaustion swap but this itself
601	adds more overheads and consumes memory for remembering information.
602	Especially if you use 32bit system or small memory system, please
603	be careful about enabling this. When memory resource controller
604	is disabled by boot option, this will be automatically disabled and
605	there will be no overhead from this. Even when you set this config=y,
606	if boot option "noswapaccount" is set, swap will not be accounted.
607	Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
608	size is 4096bytes, 512k per 1Gbytes of swap.
609
610	endif # CGROUPS
611
612	config MM_OWNER
613	bool
614
615	config SYSFS_DEPRECATED
616	bool
617
618	config SYSFS_DEPRECATED_V2
619	bool "enable deprecated sysfs features which may confuse old userspace tools"
620	depends on SYSFS
621	default n
622	select SYSFS_DEPRECATED
623	help
624	This option switches the layout of sysfs to the deprecated
625	version. Do not use it on recent distributions.
626
627	The current sysfs layout features a unified device tree at
628	/sys/devices/, which is able to express a hierarchy between
629	class devices. If the deprecated option is set to Y, the
630	unified device tree is split into a bus device tree at
631	/sys/devices/ and several individual class device trees at
632	/sys/class/. The class and bus devices will be connected by
633	"<subsystem>:<name>" and the "device" links. The "block"
634	class devices, will not show up in /sys/class/block/. Some
635	subsystems will suppress the creation of some devices which
636	depend on the unified device tree.
637
638	This option is not a pure compatibility option that can
639	be safely enabled on newer distributions. It will change the
640	layout of sysfs to the non-extensible deprecated version,
641	and disable some features, which can not be exported without
642	confusing older userspace tools. Since 2007/2008 all major
643	distributions do not enable this option, and ship no tools which
644	depend on the deprecated layout or this option.
645
646	If you are using a new kernel on an older distribution, or use
647	older userspace tools, you might need to say Y here. Do not say Y,
648	if the original kernel, that came with your distribution, has
649	this option set to N.
650
651	config RELAY
652	bool "Kernel->user space relay support (formerly relayfs)"
653	help
654	This option enables support for relay interface support in
655	certain file systems (such as debugfs).
656	It is designed to provide an efficient mechanism for tools and
657	facilities to relay large amounts of data from kernel space to
658	user space.
659
660	If unsure, say N.
661
662	config NAMESPACES
663	bool "Namespaces support" if EMBEDDED
664	default !EMBEDDED
665	help
666	Provides the way to make tasks work with different objects using
667	the same id. For example same IPC id may refer to different objects
668	or same user id or pid may refer to different tasks when used in
669	different namespaces.
670
671	config UTS_NS
672	bool "UTS namespace"
673	depends on NAMESPACES
674	help
675	In this namespace tasks see different info provided with the
676	uname() system call
677
678	config IPC_NS
679	bool "IPC namespace"
680	depends on NAMESPACES && (SYSVIPC \|\| POSIX_MQUEUE)
681	help
682	In this namespace tasks work with IPC ids which correspond to
683	different IPC objects in different namespaces.
684
685	config USER_NS
686	bool "User namespace (EXPERIMENTAL)"
687	depends on NAMESPACES && EXPERIMENTAL
688	help
689	This allows containers, i.e. vservers, to use user namespaces
690	to provide different user info for different servers.
691	If unsure, say N.
692
693	config PID_NS
694	bool "PID Namespaces (EXPERIMENTAL)"
695	default n
696	depends on NAMESPACES && EXPERIMENTAL
697	help
698	Support process id namespaces. This allows having multiple
699	processes with the same pid as long as they are in different
700	pid namespaces. This is a building block of containers.
701
702	Unless you want to work with an experimental feature
703	say N here.
704
705	config NET_NS
706	bool "Network namespace"
707	default n
708	depends on NAMESPACES && EXPERIMENTAL && NET
709	help
710	Allow user space to create what appear to be multiple instances
711	of the network stack.
712
713	config BLK_DEV_INITRD
714	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
715	depends on BROKEN \|\| !FRV
716	help
717	The initial RAM filesystem is a ramfs which is loaded by the
718	boot loader (loadlin or lilo) and that is mounted as root
719	before the normal boot procedure. It is typically used to
720	load modules needed to mount the "real" root file system,
721	etc. See <file:Documentation/initrd.txt> for details.
722
723	If RAM disk support (BLK_DEV_RAM) is also included, this
724	also enables initial RAM disk (initrd) support and adds
725	15 Kbytes (more on some other architectures) to the kernel size.
726
727	If unsure say Y.
728
729	if BLK_DEV_INITRD
730
731	source "usr/Kconfig"
732
733	endif
734
735	config CC_OPTIMIZE_FOR_SIZE
736	bool "Optimize for size"
737	default y
738	help
739	Enabling this option will pass "-Os" instead of "-O2" to gcc
740	resulting in a smaller kernel.
741
742	If unsure, say Y.
743
744	config SYSCTL
745	bool
746
747	config ANON_INODES
748	bool
749
750	menuconfig EMBEDDED
751	bool "Configure standard kernel features (for small systems)"
752	help
753	This option allows certain base kernel options and settings
754	to be disabled or tweaked. This is for specialized
755	environments which can tolerate a "non-standard" kernel.
756	Only use this if you really know what you are doing.
757
758	config UID16
759	bool "Enable 16-bit UID system calls" if EMBEDDED
760	depends on ARM \|\| BLACKFIN \|\| CRIS \|\| FRV \|\| H8300 \|\| X86_32 \|\| M68K \|\| (S390 && !64BIT) \|\| SUPERH \|\| SPARC32 \|\| (SPARC64 && COMPAT) \|\| UML \|\| (X86_64 && IA32_EMULATION)
761	default y
762	help
763	This enables the legacy 16-bit UID syscall wrappers.
764
765	config SYSCTL_SYSCALL
766	bool "Sysctl syscall support" if EMBEDDED
767	default y
768	select SYSCTL
769	---help---
770	sys_sysctl uses binary paths that have been found challenging
771	to properly maintain and use. The interface in /proc/sys
772	using paths with ascii names is now the primary path to this
773	information.
774
775	Almost nothing using the binary sysctl interface so if you are
776	trying to save some space it is probably safe to disable this,
777	making your kernel marginally smaller.
778
779	If unsure say Y here.
780
781	config KALLSYMS
782	bool "Load all symbols for debugging/ksymoops" if EMBEDDED
783	default y
784	help
785	Say Y here to let the kernel print out symbolic crash information and
786	symbolic stack backtraces. This increases the size of the kernel
787	somewhat, as all symbols have to be loaded into the kernel image.
788
789	config KALLSYMS_ALL
790	bool "Include all symbols in kallsyms"
791	depends on DEBUG_KERNEL && KALLSYMS
792	help
793	Normally kallsyms only contains the symbols of functions, for nicer
794	OOPS messages. Some debuggers can use kallsyms for other
795	symbols too: say Y here to include all symbols, if you need them
796	and you don't care about adding 300k to the size of your kernel.
797
798	Say N.
799
800	config KALLSYMS_EXTRA_PASS
801	bool "Do an extra kallsyms pass"
802	depends on KALLSYMS
803	help
804	If kallsyms is not working correctly, the build will fail with
805	inconsistent kallsyms data. If that occurs, log a bug report and
806	turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
807	Always say N here unless you find a bug in kallsyms, which must be
808	reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
809	you wait for kallsyms to be fixed.
810
811
812	config HOTPLUG
813	bool "Support for hot-pluggable devices" if EMBEDDED
814	default y
815	help
816	This option is provided for the case where no hotplug or uevent
817	capabilities is wanted by the kernel. You should only consider
818	disabling this option for embedded systems that do not use modules, a
819	dynamic /dev tree, or dynamic device discovery. Just say Y.
820
821	config PRINTK
822	default y
823	bool "Enable support for printk" if EMBEDDED
824	help
825	This option enables normal printk support. Removing it
826	eliminates most of the message strings from the kernel image
827	and makes the kernel more or less silent. As this makes it
828	very difficult to diagnose system problems, saying N here is
829	strongly discouraged.
830
831	config BUG
832	bool "BUG() support" if EMBEDDED
833	default y
834	help
835	Disabling this option eliminates support for BUG and WARN, reducing
836	the size of your kernel image and potentially quietly ignoring
837	numerous fatal conditions. You should only consider disabling this
838	option for embedded systems with no facilities for reporting errors.
839	Just say Y.
840
841	config ELF_CORE
842	default y
843	bool "Enable ELF core dumps" if EMBEDDED
844	help
845	Enable support for generating core dumps. Disabling saves about 4k.
846
847	config PCSPKR_PLATFORM
848	bool "Enable PC-Speaker support" if EMBEDDED
849	depends on ALPHA \|\| X86 \|\| MIPS \|\| PPC_PREP \|\| PPC_CHRP \|\| PPC_PSERIES
850	default y
851	help
852	This option allows to disable the internal PC-Speaker
853	support, saving some memory.
854
855	config BASE_FULL
856	default y
857	bool "Enable full-sized data structures for core" if EMBEDDED
858	help
859	Disabling this option reduces the size of miscellaneous core
860	kernel data structures. This saves memory on small machines,
861	but may reduce performance.
862
863	config FUTEX
864	bool "Enable futex support" if EMBEDDED
865	default y
866	select RT_MUTEXES
867	help
868	Disabling this option will cause the kernel to be built without
869	support for "fast userspace mutexes". The resulting kernel may not
870	run glibc-based applications correctly.
871
872	config EPOLL
873	bool "Enable eventpoll support" if EMBEDDED
874	default y
875	select ANON_INODES
876	help
877	Disabling this option will cause the kernel to be built without
878	support for epoll family of system calls.
879
880	config SIGNALFD
881	bool "Enable signalfd() system call" if EMBEDDED
882	select ANON_INODES
883	default y
884	help
885	Enable the signalfd() system call that allows to receive signals
886	on a file descriptor.
887
888	If unsure, say Y.
889
890	config TIMERFD
891	bool "Enable timerfd() system call" if EMBEDDED
892	select ANON_INODES
893	default y
894	help
895	Enable the timerfd() system call that allows to receive timer
896	events on a file descriptor.
897
898	If unsure, say Y.
899
900	config EVENTFD
901	bool "Enable eventfd() system call" if EMBEDDED
902	select ANON_INODES
903	default y
904	help
905	Enable the eventfd() system call that allows to receive both
906	kernel notification (ie. KAIO) or userspace notifications.
907
908	If unsure, say Y.
909
910	config SHMEM
911	bool "Use full shmem filesystem" if EMBEDDED
912	default y
913	depends on MMU
914	help
915	The shmem is an internal filesystem used to manage shared memory.
916	It is backed by swap and manages resource limits. It is also exported
917	to userspace as tmpfs if TMPFS is enabled. Disabling this
918	option replaces shmem and tmpfs with the much simpler ramfs code,
919	which may be appropriate on small systems without swap.
920
921	config AIO
922	bool "Enable AIO support" if EMBEDDED
923	default y
924	help
925	This option enables POSIX asynchronous I/O which may by used
926	by some high performance threaded applications. Disabling
927	this option saves about 7k.
928
929	config HAVE_PERF_EVENTS
930	bool
931	help
932	See tools/perf/design.txt for details.
933
934	config PERF_USE_VMALLOC
935	bool
936	help
937	See tools/perf/design.txt for details
938
939	menu "Kernel Performance Events And Counters"
940
941	config PERF_EVENTS
942	bool "Kernel performance events and counters"
943	default y if (PROFILING \|\| PERF_COUNTERS)
944	depends on HAVE_PERF_EVENTS
945	select ANON_INODES
946	help
947	Enable kernel support for various performance events provided
948	by software and hardware.
949
950	Software events are supported either built-in or via the
951	use of generic tracepoints.
952
953	Most modern CPUs support performance events via performance
954	counter registers. These registers count the number of certain
955	types of hw events: such as instructions executed, cachemisses
956	suffered, or branches mis-predicted - without slowing down the
957	kernel or applications. These registers can also trigger interrupts
958	when a threshold number of events have passed - and can thus be
959	used to profile the code that runs on that CPU.
960
961	The Linux Performance Event subsystem provides an abstraction of
962	these software and hardware event capabilities, available via a
963	system call and used by the "perf" utility in tools/perf/. It
964	provides per task and per CPU counters, and it provides event
965	capabilities on top of those.
966
967	Say Y if unsure.
968
969	config EVENT_PROFILE
970	bool "Tracepoint profiling sources"
971	depends on PERF_EVENTS && EVENT_TRACING
972	default y
973	help
974	Allow the use of tracepoints as software performance events.
975
976	When this is enabled, you can create perf events based on
977	tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
978	found in debugfs://tracing/events///id. (The -e/--events
979	option to the perf tool can parse and interpret symbolic
980	tracepoints, in the subsystem:tracepoint_name format.)
981
982	config PERF_COUNTERS
983	bool "Kernel performance counters (old config option)"
984	depends on HAVE_PERF_EVENTS
985	help
986	This config has been obsoleted by the PERF_EVENTS
987	config option - please see that one for details.
988
989	It has no effect on the kernel whether you enable
990	it or not, it is a compatibility placeholder.
991
992	Say N if unsure.
993
994	config DEBUG_PERF_USE_VMALLOC
995	default n
996	bool "Debug: use vmalloc to back perf mmap() buffers"
997	depends on PERF_EVENTS && DEBUG_KERNEL
998	select PERF_USE_VMALLOC
999	help
1000	Use vmalloc memory to back perf mmap() buffers.
1001
1002	Mostly useful for debugging the vmalloc code on platforms
1003	that don't require it.
1004
1005	Say N if unsure.
1006
1007	endmenu
1008
1009	config VM_EVENT_COUNTERS
1010	default y
1011	bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1012	help
1013	VM event counters are needed for event counts to be shown.
1014	This option allows the disabling of the VM event counters
1015	on EMBEDDED systems. /proc/vmstat will only show page counts
1016	if VM event counters are disabled.
1017
1018	config PCI_QUIRKS
1019	default y
1020	bool "Enable PCI quirk workarounds" if EMBEDDED
1021	depends on PCI
1022	help
1023	This enables workarounds for various PCI chipset
1024	bugs/quirks. Disable this only if your target machine is
1025	unaffected by PCI quirks.
1026
1027	config SLUB_DEBUG
1028	default y
1029	bool "Enable SLUB debugging support" if EMBEDDED
1030	depends on SLUB && SYSFS
1031	help
1032	SLUB has extensive debug support features. Disabling these can
1033	result in significant savings in code size. This also disables
1034	SLUB sysfs support. /sys/slab will not exist and there will be
1035	no support for cache validation etc.
1036
1037	config COMPAT_BRK
1038	bool "Disable heap randomization"
1039	default y
1040	help
1041	Randomizing heap placement makes heap exploits harder, but it
1042	also breaks ancient binaries (including anything libc5 based).
1043	This option changes the bootup default to heap randomization
1044	disabled, and can be overridden at runtime by setting
1045	/proc/sys/kernel/randomize_va_space to 2.
1046
1047	On non-ancient distros (post-2000 ones) N is usually a safe choice.
1048
1049	choice
1050	prompt "Choose SLAB allocator"
1051	default SLUB
1052	help
1053	This option allows to select a slab allocator.
1054
1055	config SLAB
1056	bool "SLAB"
1057	help
1058	The regular slab allocator that is established and known to work
1059	well in all environments. It organizes cache hot objects in
1060	per cpu and per node queues.
1061
1062	config SLUB
1063	bool "SLUB (Unqueued Allocator)"
1064	help
1065	SLUB is a slab allocator that minimizes cache line usage
1066	instead of managing queues of cached objects (SLAB approach).
1067	Per cpu caching is realized using slabs of objects instead
1068	of queues of objects. SLUB can use memory efficiently
1069	and has enhanced diagnostics. SLUB is the default choice for
1070	a slab allocator.
1071
1072	config SLOB
1073	depends on EMBEDDED
1074	bool "SLOB (Simple Allocator)"
1075	help
1076	SLOB replaces the stock allocator with a drastically simpler
1077	allocator. SLOB is generally more space efficient but
1078	does not perform as well on large systems.
1079
1080	endchoice
1081
1082	config PROFILING
1083	bool "Profiling support (EXPERIMENTAL)"
1084	help
1085	Say Y here to enable the extended profiling support mechanisms used
1086	by profilers such as OProfile.
1087
1088	#
1089	# Place an empty function call at each tracepoint site. Can be
1090	# dynamically changed for a probe function.
1091	#
1092	config TRACEPOINTS
1093	bool
1094
1095	source "arch/Kconfig"
1096
1097	config SLOW_WORK
1098	default n
1099	bool
1100	help
1101	The slow work thread pool provides a number of dynamically allocated
1102	threads that can be used by the kernel to perform operations that
1103	take a relatively long time.
1104
1105	An example of this would be CacheFiles doing a path lookup followed
1106	by a series of mkdirs and a create call, all of which have to touch
1107	disk.
1108
1109	See Documentation/slow-work.txt.
1110
1111	config SLOW_WORK_DEBUG
1112	bool "Slow work debugging through debugfs"
1113	default n
1114	depends on SLOW_WORK && DEBUG_FS
1115	help
1116	Display the contents of the slow work run queue through debugfs,
1117	including items currently executing.
1118
1119	See Documentation/slow-work.txt.
1120
1121	endmenu # General setup
1122
1123	config HAVE_GENERIC_DMA_COHERENT
1124	bool
1125	default n
1126
1127	config SLABINFO
1128	bool
1129	depends on PROC_FS
1130	depends on SLAB \|\| SLUB_DEBUG
1131	default y
1132
1133	config RT_MUTEXES
1134	boolean
1135
1136	config BASE_SMALL
1137	int
1138	default 0 if BASE_FULL
1139	default 1 if !BASE_FULL
1140
1141	menuconfig MODULES
1142	bool "Enable loadable module support"
1143	help
1144	Kernel modules are small pieces of compiled code which can
1145	be inserted in the running kernel, rather than being
1146	permanently built into the kernel. You use the "modprobe"
1147	tool to add (and sometimes remove) them. If you say Y here,
1148	many parts of the kernel can be built as modules (by
1149	answering M instead of Y where indicated): this is most
1150	useful for infrequently used options which are not required
1151	for booting. For more information, see the man pages for
1152	modprobe, lsmod, modinfo, insmod and rmmod.
1153
1154	If you say Y here, you will need to run "make
1155	modules_install" to put the modules under /lib/modules/
1156	where modprobe can find them (you may need to be root to do
1157	this).
1158
1159	If unsure, say Y.
1160
1161	if MODULES
1162
1163	config MODULE_FORCE_LOAD
1164	bool "Forced module loading"
1165	default n
1166	help
1167	Allow loading of modules without version information (ie. modprobe
1168	--force). Forced module loading sets the 'F' (forced) taint flag and
1169	is usually a really bad idea.
1170
1171	config MODULE_UNLOAD
1172	bool "Module unloading"
1173	help
1174	Without this option you will not be able to unload any
1175	modules (note that some modules may not be unloadable
1176	anyway), which makes your kernel smaller, faster
1177	and simpler. If unsure, say Y.
1178
1179	config MODULE_FORCE_UNLOAD
1180	bool "Forced module unloading"
1181	depends on MODULE_UNLOAD && EXPERIMENTAL
1182	help
1183	This option allows you to force a module to unload, even if the
1184	kernel believes it is unsafe: the kernel will remove the module
1185	without waiting for anyone to stop using it (using the -f option to
1186	rmmod). This is mainly for kernel developers and desperate users.
1187	If unsure, say N.
1188
1189	config MODVERSIONS
1190	bool "Module versioning support"
1191	help
1192	Usually, you have to use modules compiled with your kernel.
1193	Saying Y here makes it sometimes possible to use modules
1194	compiled for different kernels, by adding enough information
1195	to the modules to (hopefully) spot any changes which would
1196	make them incompatible with the kernel you are running. If
1197	unsure, say N.
1198
1199	config MODULE_SRCVERSION_ALL
1200	bool "Source checksum for all modules"
1201	help
1202	Modules which contain a MODULE_VERSION get an extra "srcversion"
1203	field inserted into their modinfo section, which contains a
1204	sum of the source files which made it. This helps maintainers
1205	see exactly which source was used to build a module (since
1206	others sometimes change the module source without updating
1207	the version). With this option, such a "srcversion" field
1208	will be created for all modules. If unsure, say N.
1209
1210	endif # MODULES
1211
1212	config INIT_ALL_POSSIBLE
1213	bool
1214	help
1215	Back when each arch used to define their own cpu_online_map and
1216	cpu_possible_map, some of them chose to initialize cpu_possible_map
1217	with all 1s, and others with all 0s. When they were centralised,
1218	it was better to provide this option than to break all the archs
1219	and have several arch maintainers pursuing me down dark alleys.
1220
1221	config STOP_MACHINE
1222	bool
1223	default y
1224	depends on (SMP && MODULE_UNLOAD) \|\| HOTPLUG_CPU
1225	help
1226	Need stop_machine() primitive.
1227
1228	source "block/Kconfig"
1229
1230	config PREEMPT_NOTIFIERS
1231	bool
1232
1233

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