| blob | 455c5203d1c1461b7ab6122e7d64e3b08ddc1647 |
1 config ARCH
2 string
3 option env="ARCH"
5 config KERNELVERSION
6 string
7 option env="KERNELVERSION"
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"
19 menu "General setup"
21 config EXPERIMENTAL
22 bool "Prompt for development and/or incomplete code/drivers"
23 ---help---
24 Some of the various things that Linux supports (such as network
25 drivers, file systems, network protocols, etc.) can be in a state
26 of development where the functionality, stability, or the level of
27 testing is not yet high enough for general use. This is usually
28 known as the "alpha-test" phase among developers. If a feature is
29 currently in alpha-test, then the developers usually discourage
30 uninformed widespread use of this feature by the general public to
31 avoid "Why doesn't this work?" type mail messages. However, active
32 testing and use of these systems is welcomed. Just be aware that it
33 may not meet the normal level of reliability or it may fail to work
34 in some special cases. Detailed bug reports from people familiar
35 with the kernel internals are usually welcomed by the developers
36 (before submitting bug reports, please read the documents
37 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
38 <file:Documentation/BUG-HUNTING>, and
39 <file:Documentation/oops-tracing.txt> in the kernel source).
41 This option will also make obsoleted drivers available. These are
42 drivers that have been replaced by something else, and/or are
43 scheduled to be removed in a future kernel release.
45 Unless you intend to help test and develop a feature or driver that
46 falls into this category, or you have a situation that requires
47 using these features, you should probably say N here, which will
48 cause the configurator to present you with fewer choices. If
49 you say Y here, you will be offered the choice of using features or
50 drivers that are currently considered to be in the alpha-test phase.
52 config BROKEN
53 bool
55 config BROKEN_ON_SMP
56 bool
57 depends on BROKEN || !SMP
58 default y
60 config LOCK_KERNEL
61 bool
62 depends on SMP || PREEMPT
63 default y
65 config INIT_ENV_ARG_LIMIT
66 int
67 default 32 if !UML
68 default 128 if UML
69 help
70 Maximum of each of the number of arguments and environment
71 variables passed to init from the kernel command line.
74 config LOCALVERSION
75 string "Local version - append to kernel release"
76 help
77 Append an extra string to the end of your kernel version.
78 This will show up when you type uname, for example.
79 The string you set here will be appended after the contents of
80 any files with a filename matching localversion* in your
81 object and source tree, in that order. Your total string can
82 be a maximum of 64 characters.
84 config LOCALVERSION_AUTO
85 bool "Automatically append version information to the version string"
86 default y
87 help
88 This will try to automatically determine if the current tree is a
89 release tree by looking for git tags that belong to the current
90 top of tree revision.
92 A string of the format -gxxxxxxxx will be added to the localversion
93 if a git-based tree is found. The string generated by this will be
94 appended after any matching localversion* files, and after the value
95 set in CONFIG_LOCALVERSION.
97 (The actual string used here is the first eight characters produced
98 by running the command:
100 $ git rev-parse --verify HEAD
102 which is done within the script "scripts/setlocalversion".)
104 config HAVE_KERNEL_GZIP
105 bool
107 config HAVE_KERNEL_BZIP2
108 bool
110 config HAVE_KERNEL_LZMA
111 bool
113 choice
114 prompt "Kernel compression mode"
115 default KERNEL_GZIP
116 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
117 help
118 The linux kernel is a kind of self-extracting executable.
119 Several compression algorithms are available, which differ
120 in efficiency, compression and decompression speed.
121 Compression speed is only relevant when building a kernel.
122 Decompression speed is relevant at each boot.
124 If you have any problems with bzip2 or lzma compressed
125 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
126 version of this functionality (bzip2 only), for 2.4, was
127 supplied by Christian Ludwig)
129 High compression options are mostly useful for users, who
130 are low on disk space (embedded systems), but for whom ram
131 size matters less.
133 If in doubt, select 'gzip'
135 config KERNEL_GZIP
136 bool "Gzip"
137 depends on HAVE_KERNEL_GZIP
138 help
139 The old and tried gzip compression. Its compression ratio is
140 the poorest among the 3 choices; however its speed (both
141 compression and decompression) is the fastest.
143 config KERNEL_BZIP2
144 bool "Bzip2"
145 depends on HAVE_KERNEL_BZIP2
146 help
147 Its compression ratio and speed is intermediate.
148 Decompression speed is slowest among the three. The kernel
149 size is about 10% smaller with bzip2, in comparison to gzip.
150 Bzip2 uses a large amount of memory. For modern kernels you
151 will need at least 8MB RAM or more for booting.
153 config KERNEL_LZMA
154 bool "LZMA"
155 depends on HAVE_KERNEL_LZMA
156 help
157 The most recent compression algorithm.
158 Its ratio is best, decompression speed is between the other
159 two. Compression is slowest. The kernel size is about 33%
160 smaller with LZMA in comparison to gzip.
162 endchoice
164 config SWAP
165 bool "Support for paging of anonymous memory (swap)"
166 depends on MMU && BLOCK
167 default y
168 help
169 This option allows you to choose whether you want to have support
170 for so called swap devices or swap files in your kernel that are
171 used to provide more virtual memory than the actual RAM present
172 in your computer. If unsure say Y.
174 config SYSVIPC
175 bool "System V IPC"
176 ---help---
177 Inter Process Communication is a suite of library functions and
178 system calls which let processes (running programs) synchronize and
179 exchange information. It is generally considered to be a good thing,
180 and some programs won't run unless you say Y here. In particular, if
181 you want to run the DOS emulator dosemu under Linux (read the
182 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
183 you'll need to say Y here.
185 You can find documentation about IPC with "info ipc" and also in
186 section 6.4 of the Linux Programmer's Guide, available from
187 <http://www.tldp.org/guides.html>.
189 config SYSVIPC_SYSCTL
190 bool
191 depends on SYSVIPC
192 depends on SYSCTL
193 default y
195 config POSIX_MQUEUE
196 bool "POSIX Message Queues"
197 depends on NET && EXPERIMENTAL
198 ---help---
199 POSIX variant of message queues is a part of IPC. In POSIX message
200 queues every message has a priority which decides about succession
201 of receiving it by a process. If you want to compile and run
202 programs written e.g. for Solaris with use of its POSIX message
203 queues (functions mq_*) say Y here.
205 POSIX message queues are visible as a filesystem called 'mqueue'
206 and can be mounted somewhere if you want to do filesystem
207 operations on message queues.
209 If unsure, say Y.
211 config BSD_PROCESS_ACCT
212 bool "BSD Process Accounting"
213 help
214 If you say Y here, a user level program will be able to instruct the
215 kernel (via a special system call) to write process accounting
216 information to a file: whenever a process exits, information about
217 that process will be appended to the file by the kernel. The
218 information includes things such as creation time, owning user,
219 command name, memory usage, controlling terminal etc. (the complete
220 list is in the struct acct in <file:include/linux/acct.h>). It is
221 up to the user level program to do useful things with this
222 information. This is generally a good idea, so say Y.
224 config BSD_PROCESS_ACCT_V3
225 bool "BSD Process Accounting version 3 file format"
226 depends on BSD_PROCESS_ACCT
227 default n
228 help
229 If you say Y here, the process accounting information is written
230 in a new file format that also logs the process IDs of each
231 process and it's parent. Note that this file format is incompatible
232 with previous v0/v1/v2 file formats, so you will need updated tools
233 for processing it. A preliminary version of these tools is available
234 at <http://www.gnu.org/software/acct/>.
236 config TASKSTATS
237 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
238 depends on NET
239 default n
240 help
241 Export selected statistics for tasks/processes through the
242 generic netlink interface. Unlike BSD process accounting, the
243 statistics are available during the lifetime of tasks/processes as
244 responses to commands. Like BSD accounting, they are sent to user
245 space on task exit.
247 Say N if unsure.
249 config TASK_DELAY_ACCT
250 bool "Enable per-task delay accounting (EXPERIMENTAL)"
251 depends on TASKSTATS
252 help
253 Collect information on time spent by a task waiting for system
254 resources like cpu, synchronous block I/O completion and swapping
255 in pages. Such statistics can help in setting a task's priorities
256 relative to other tasks for cpu, io, rss limits etc.
258 Say N if unsure.
260 config TASK_XACCT
261 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
262 depends on TASKSTATS
263 help
264 Collect extended task accounting data and send the data
265 to userland for processing over the taskstats interface.
267 Say N if unsure.
269 config TASK_IO_ACCOUNTING
270 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
271 depends on TASK_XACCT
272 help
273 Collect information on the number of bytes of storage I/O which this
274 task has caused.
276 Say N if unsure.
278 config AUDIT
279 bool "Auditing support"
280 depends on NET
281 help
282 Enable auditing infrastructure that can be used with another
283 kernel subsystem, such as SELinux (which requires this for
284 logging of avc messages output). Does not do system-call
285 auditing without CONFIG_AUDITSYSCALL.
287 config AUDITSYSCALL
288 bool "Enable system-call auditing support"
289 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
290 default y if SECURITY_SELINUX
291 help
292 Enable low-overhead system-call auditing infrastructure that
293 can be used independently or with another kernel subsystem,
294 such as SELinux. To use audit's filesystem watch feature, please
295 ensure that INOTIFY is configured.
297 config AUDIT_TREE
298 def_bool y
299 depends on AUDITSYSCALL && INOTIFY
301 menu "RCU Subsystem"
303 choice
304 prompt "RCU Implementation"
305 default CLASSIC_RCU
307 config CLASSIC_RCU
308 bool "Classic RCU"
309 depends on !PREEMPT_RT
310 help
311 This option selects the classic RCU implementation that is
312 designed for best read-side performance on non-realtime
313 systems.
315 Select this option if you are unsure.
317 config TREE_RCU
318 bool "Tree-based hierarchical RCU"
319 depends on !PREEMPT_RT
320 help
321 This option selects the RCU implementation that is
322 designed for very large SMP system with hundreds or
323 thousands of CPUs.
325 config PREEMPT_RCU
326 bool "Preemptible RCU"
327 depends on PREEMPT
328 help
329 This option reduces the latency of the kernel by making certain
330 RCU sections preemptible. Normally RCU code is non-preemptible, if
331 this option is selected then read-only RCU sections become
332 preemptible. This helps latency, but may expose bugs due to
333 now-naive assumptions about each RCU read-side critical section
334 remaining on a given CPU through its execution.
336 endchoice
338 config RCU_TRACE
339 bool "Enable tracing for RCU"
340 depends on TREE_RCU || PREEMPT_RCU
341 help
342 This option provides tracing in RCU which presents stats
343 in debugfs for debugging RCU implementation.
345 Say Y here if you want to enable RCU tracing
346 Say N if you are unsure.
348 config RCU_FANOUT
349 int "Tree-based hierarchical RCU fanout value"
350 range 2 64 if 64BIT
351 range 2 32 if !64BIT
352 depends on TREE_RCU
353 default 64 if 64BIT
354 default 32 if !64BIT
355 help
356 This option controls the fanout of hierarchical implementations
357 of RCU, allowing RCU to work efficiently on machines with
358 large numbers of CPUs. This value must be at least the cube
359 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
360 systems and up to 262,144 for 64-bit systems.
362 Select a specific number if testing RCU itself.
363 Take the default if unsure.
365 config RCU_FANOUT_EXACT
366 bool "Disable tree-based hierarchical RCU auto-balancing"
367 depends on TREE_RCU
368 default n
369 help
370 This option forces use of the exact RCU_FANOUT value specified,
371 regardless of imbalances in the hierarchy. This is useful for
372 testing RCU itself, and might one day be useful on systems with
373 strong NUMA behavior.
375 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
377 Say N if unsure.
379 config TREE_RCU_TRACE
380 def_bool RCU_TRACE && TREE_RCU
381 select DEBUG_FS
382 help
383 This option provides tracing for the TREE_RCU implementation,
384 permitting Makefile to trivially select kernel/rcutree_trace.c.
386 config PREEMPT_RCU_TRACE
387 def_bool RCU_TRACE && PREEMPT_RCU
388 select DEBUG_FS
389 help
390 This option provides tracing for the PREEMPT_RCU implementation,
391 permitting Makefile to trivially select kernel/rcupreempt_trace.c.
393 endmenu # "RCU Subsystem"
395 config IKCONFIG
396 tristate "Kernel .config support"
397 ---help---
398 This option enables the complete Linux kernel ".config" file
399 contents to be saved in the kernel. It provides documentation
400 of which kernel options are used in a running kernel or in an
401 on-disk kernel. This information can be extracted from the kernel
402 image file with the script scripts/extract-ikconfig and used as
403 input to rebuild the current kernel or to build another kernel.
404 It can also be extracted from a running kernel by reading
405 /proc/config.gz if enabled (below).
407 config IKCONFIG_PROC
408 bool "Enable access to .config through /proc/config.gz"
409 depends on IKCONFIG && PROC_FS
410 ---help---
411 This option enables access to the kernel configuration file
412 through /proc/config.gz.
414 config LOG_BUF_SHIFT
415 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
416 range 12 21
417 default 17
418 help
419 Select kernel log buffer size as a power of 2.
420 Examples:
421 17 => 128 KB
422 16 => 64 KB
423 15 => 32 KB
424 14 => 16 KB
425 13 => 8 KB
426 12 => 4 KB
428 #
429 # Architectures with an unreliable sched_clock() should select this:
430 #
431 config HAVE_UNSTABLE_SCHED_CLOCK
432 bool
434 config GROUP_SCHED
435 bool "Group CPU scheduler"
436 depends on EXPERIMENTAL
437 default n
438 help
439 This feature lets CPU scheduler recognize task groups and control CPU
440 bandwidth allocation to such task groups.
441 In order to create a group from arbitrary set of processes, use
442 CONFIG_CGROUPS. (See Control Group support.)
444 config FAIR_GROUP_SCHED
445 bool "Group scheduling for SCHED_OTHER"
446 depends on GROUP_SCHED
447 default GROUP_SCHED
449 config RT_GROUP_SCHED
450 bool "Group scheduling for SCHED_RR/FIFO"
451 depends on EXPERIMENTAL
452 depends on GROUP_SCHED
453 default n
454 help
455 This feature lets you explicitly allocate real CPU bandwidth
456 to users or control groups (depending on the "Basis for grouping tasks"
457 setting below. If enabled, it will also make it impossible to
458 schedule realtime tasks for non-root users until you allocate
459 realtime bandwidth for them.
460 See Documentation/scheduler/sched-rt-group.txt for more information.
462 choice
463 depends on GROUP_SCHED
464 prompt "Basis for grouping tasks"
465 default USER_SCHED
467 config USER_SCHED
468 bool "user id"
469 help
470 This option will choose userid as the basis for grouping
471 tasks, thus providing equal CPU bandwidth to each user.
473 config CGROUP_SCHED
474 bool "Control groups"
475 depends on CGROUPS
476 help
477 This option allows you to create arbitrary task groups
478 using the "cgroup" pseudo filesystem and control
479 the cpu bandwidth allocated to each such task group.
480 Refer to Documentation/cgroups/cgroups.txt for more
481 information on "cgroup" pseudo filesystem.
483 endchoice
485 menuconfig CGROUPS
486 boolean "Control Group support"
487 help
488 This option adds support for grouping sets of processes together, for
489 use with process control subsystems such as Cpusets, CFS, memory
490 controls or device isolation.
491 See
492 - Documentation/scheduler/sched-design-CFS.txt (CFS)
493 - Documentation/cgroups/ (features for grouping, isolation
494 and resource control)
496 Say N if unsure.
498 if CGROUPS
500 config CGROUP_DEBUG
501 bool "Example debug cgroup subsystem"
502 depends on CGROUPS
503 default n
504 help
505 This option enables a simple cgroup subsystem that
506 exports useful debugging information about the cgroups
507 framework.
509 Say N if unsure.
511 config CGROUP_NS
512 bool "Namespace cgroup subsystem"
513 depends on CGROUPS
514 help
515 Provides a simple namespace cgroup subsystem to
516 provide hierarchical naming of sets of namespaces,
517 for instance virtual servers and checkpoint/restart
518 jobs.
520 config CGROUP_FREEZER
521 bool "Freezer cgroup subsystem"
522 depends on CGROUPS
523 help
524 Provides a way to freeze and unfreeze all tasks in a
525 cgroup.
527 config CGROUP_DEVICE
528 bool "Device controller for cgroups"
529 depends on CGROUPS && EXPERIMENTAL
530 help
531 Provides a cgroup implementing whitelists for devices which
532 a process in the cgroup can mknod or open.
534 config CPUSETS
535 bool "Cpuset support"
536 depends on SMP && CGROUPS
537 help
538 This option will let you create and manage CPUSETs which
539 allow dynamically partitioning a system into sets of CPUs and
540 Memory Nodes and assigning tasks to run only within those sets.
541 This is primarily useful on large SMP or NUMA systems.
543 Say N if unsure.
545 config PROC_PID_CPUSET
546 bool "Include legacy /proc/<pid>/cpuset file"
547 depends on CPUSETS
548 default y
550 config SCHED_CBS
551 bool "CBS Scheduling Class"
552 help
553 Here is the CBS...
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.
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
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/controllers/memory.txt)
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.
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)
589 This config option also selects MM_OWNER config option, which
590 could in turn add some fork/exit overhead.
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.
608 endif # CGROUPS
610 config MM_OWNER
611 bool
613 config SYSFS_DEPRECATED
614 bool
616 config SYSFS_DEPRECATED_V2
617 bool "Create deprecated sysfs layout for older userspace tools"
618 depends on SYSFS
619 default y
620 select SYSFS_DEPRECATED
621 help
622 This option switches the layout of sysfs to the deprecated
623 version.
625 The current sysfs layout features a unified device tree at
626 /sys/devices/, which is able to express a hierarchy between
627 class devices. If the deprecated option is set to Y, the
628 unified device tree is split into a bus device tree at
629 /sys/devices/ and several individual class device trees at
630 /sys/class/. The class and bus devices will be connected by
631 "<subsystem>:<name>" and the "device" links. The "block"
632 class devices, will not show up in /sys/class/block/. Some
633 subsystems will suppress the creation of some devices which
634 depend on the unified device tree.
636 This option is not a pure compatibility option that can
637 be safely enabled on newer distributions. It will change the
638 layout of sysfs to the non-extensible deprecated version,
639 and disable some features, which can not be exported without
640 confusing older userspace tools. Since 2007/2008 all major
641 distributions do not enable this option, and ship no tools which
642 depend on the deprecated layout or this option.
644 If you are using a new kernel on an older distribution, or use
645 older userspace tools, you might need to say Y here. Do not say Y,
646 if the original kernel, that came with your distribution, has
647 this option set to N.
649 config RELAY
650 bool "Kernel->user space relay support (formerly relayfs)"
651 help
652 This option enables support for relay interface support in
653 certain file systems (such as debugfs).
654 It is designed to provide an efficient mechanism for tools and
655 facilities to relay large amounts of data from kernel space to
656 user space.
658 If unsure, say N.
660 config NAMESPACES
661 bool "Namespaces support" if EMBEDDED
662 default !EMBEDDED
663 help
664 Provides the way to make tasks work with different objects using
665 the same id. For example same IPC id may refer to different objects
666 or same user id or pid may refer to different tasks when used in
667 different namespaces.
669 config UTS_NS
670 bool "UTS namespace"
671 depends on NAMESPACES
672 help
673 In this namespace tasks see different info provided with the
674 uname() system call
676 config IPC_NS
677 bool "IPC namespace"
678 depends on NAMESPACES && SYSVIPC
679 help
680 In this namespace tasks work with IPC ids which correspond to
681 different IPC objects in different namespaces
683 config USER_NS
684 bool "User namespace (EXPERIMENTAL)"
685 depends on NAMESPACES && EXPERIMENTAL
686 help
687 This allows containers, i.e. vservers, to use user namespaces
688 to provide different user info for different servers.
689 If unsure, say N.
691 config PID_NS
692 bool "PID Namespaces (EXPERIMENTAL)"
693 default n
694 depends on NAMESPACES && EXPERIMENTAL
695 help
696 Support process id namespaces. This allows having multiple
697 process with the same pid as long as they are in different
698 pid namespaces. This is a building block of containers.
700 Unless you want to work with an experimental feature
701 say N here.
703 config NET_NS
704 bool "Network namespace"
705 default n
706 depends on NAMESPACES && EXPERIMENTAL && NET
707 help
708 Allow user space to create what appear to be multiple instances
709 of the network stack.
711 config BLK_DEV_INITRD
712 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
713 depends on BROKEN || !FRV
714 help
715 The initial RAM filesystem is a ramfs which is loaded by the
716 boot loader (loadlin or lilo) and that is mounted as root
717 before the normal boot procedure. It is typically used to
718 load modules needed to mount the "real" root file system,
719 etc. See <file:Documentation/initrd.txt> for details.
721 If RAM disk support (BLK_DEV_RAM) is also included, this
722 also enables initial RAM disk (initrd) support and adds
723 15 Kbytes (more on some other architectures) to the kernel size.
725 If unsure say Y.
727 if BLK_DEV_INITRD
729 source "usr/Kconfig"
731 endif
733 config CC_OPTIMIZE_FOR_SIZE
734 bool "Optimize for size"
735 default y
736 help
737 Enabling this option will pass "-Os" instead of "-O2" to gcc
738 resulting in a smaller kernel.
740 If unsure, say Y.
742 config SYSCTL
743 bool
745 config ANON_INODES
746 bool
748 menuconfig EMBEDDED
749 bool "Configure standard kernel features (for small systems)"
750 help
751 This option allows certain base kernel options and settings
752 to be disabled or tweaked. This is for specialized
753 environments which can tolerate a "non-standard" kernel.
754 Only use this if you really know what you are doing.
756 config UID16
757 bool "Enable 16-bit UID system calls" if EMBEDDED
758 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
759 default y
760 help
761 This enables the legacy 16-bit UID syscall wrappers.
763 config SYSCTL_SYSCALL
764 bool "Sysctl syscall support" if EMBEDDED
765 default y
766 select SYSCTL
767 ---help---
768 sys_sysctl uses binary paths that have been found challenging
769 to properly maintain and use. The interface in /proc/sys
770 using paths with ascii names is now the primary path to this
771 information.
773 Almost nothing using the binary sysctl interface so if you are
774 trying to save some space it is probably safe to disable this,
775 making your kernel marginally smaller.
777 If unsure say Y here.
779 config KALLSYMS
780 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
781 default y
782 help
783 Say Y here to let the kernel print out symbolic crash information and
784 symbolic stack backtraces. This increases the size of the kernel
785 somewhat, as all symbols have to be loaded into the kernel image.
787 config KALLSYMS_ALL
788 bool "Include all symbols in kallsyms"
789 depends on DEBUG_KERNEL && KALLSYMS
790 help
791 Normally kallsyms only contains the symbols of functions, for nicer
792 OOPS messages. Some debuggers can use kallsyms for other
793 symbols too: say Y here to include all symbols, if you need them
794 and you don't care about adding 300k to the size of your kernel.
796 Say N.
798 config KALLSYMS_EXTRA_PASS
799 bool "Do an extra kallsyms pass"
800 depends on KALLSYMS
801 help
802 If kallsyms is not working correctly, the build will fail with
803 inconsistent kallsyms data. If that occurs, log a bug report and
804 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
805 Always say N here unless you find a bug in kallsyms, which must be
806 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
807 you wait for kallsyms to be fixed.
810 config HOTPLUG
811 bool "Support for hot-pluggable devices" if EMBEDDED
812 default y
813 help
814 This option is provided for the case where no hotplug or uevent
815 capabilities is wanted by the kernel. You should only consider
816 disabling this option for embedded systems that do not use modules, a
817 dynamic /dev tree, or dynamic device discovery. Just say Y.
819 config PRINTK
820 default y
821 bool "Enable support for printk" if EMBEDDED
822 help
823 This option enables normal printk support. Removing it
824 eliminates most of the message strings from the kernel image
825 and makes the kernel more or less silent. As this makes it
826 very difficult to diagnose system problems, saying N here is
827 strongly discouraged.
829 config BUG
830 bool "BUG() support" if EMBEDDED
831 default y
832 help
833 Disabling this option eliminates support for BUG and WARN, reducing
834 the size of your kernel image and potentially quietly ignoring
835 numerous fatal conditions. You should only consider disabling this
836 option for embedded systems with no facilities for reporting errors.
837 Just say Y.
839 config ELF_CORE
840 default y
841 bool "Enable ELF core dumps" if EMBEDDED
842 help
843 Enable support for generating core dumps. Disabling saves about 4k.
845 config PCSPKR_PLATFORM
846 bool "Enable PC-Speaker support" if EMBEDDED
847 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
848 default y
849 help
850 This option allows to disable the internal PC-Speaker
851 support, saving some memory.
853 config BASE_FULL
854 default y
855 bool "Enable full-sized data structures for core" if EMBEDDED
856 help
857 Disabling this option reduces the size of miscellaneous core
858 kernel data structures. This saves memory on small machines,
859 but may reduce performance.
861 config FUTEX
862 bool "Enable futex support" if EMBEDDED
863 default y
864 select RT_MUTEXES
865 help
866 Disabling this option will cause the kernel to be built without
867 support for "fast userspace mutexes". The resulting kernel may not
868 run glibc-based applications correctly.
870 config EPOLL
871 bool "Enable eventpoll support" if EMBEDDED
872 default y
873 select ANON_INODES
874 help
875 Disabling this option will cause the kernel to be built without
876 support for epoll family of system calls.
878 config SIGNALFD
879 bool "Enable signalfd() system call" if EMBEDDED
880 select ANON_INODES
881 default y
882 help
883 Enable the signalfd() system call that allows to receive signals
884 on a file descriptor.
886 If unsure, say Y.
888 config TIMERFD
889 bool "Enable timerfd() system call" if EMBEDDED
890 select ANON_INODES
891 default y
892 help
893 Enable the timerfd() system call that allows to receive timer
894 events on a file descriptor.
896 If unsure, say Y.
898 config EVENTFD
899 bool "Enable eventfd() system call" if EMBEDDED
900 select ANON_INODES
901 default y
902 help
903 Enable the eventfd() system call that allows to receive both
904 kernel notification (ie. KAIO) or userspace notifications.
906 If unsure, say Y.
908 config SHMEM
909 bool "Use full shmem filesystem" if EMBEDDED
910 default y
911 depends on MMU
912 help
913 The shmem is an internal filesystem used to manage shared memory.
914 It is backed by swap and manages resource limits. It is also exported
915 to userspace as tmpfs if TMPFS is enabled. Disabling this
916 option replaces shmem and tmpfs with the much simpler ramfs code,
917 which may be appropriate on small systems without swap.
919 config AIO
920 bool "Enable AIO support" if EMBEDDED
921 default y
922 help
923 This option enables POSIX asynchronous I/O which may by used
924 by some high performance threaded applications. Disabling
925 this option saves about 7k.
927 config HAVE_PERF_COUNTERS
928 bool
930 menu "Performance Counters"
932 config PERF_COUNTERS
933 bool "Kernel Performance Counters"
934 depends on HAVE_PERF_COUNTERS
935 default y
936 select ANON_INODES
937 help
938 Enable kernel support for performance counter hardware.
940 Performance counters are special hardware registers available
941 on most modern CPUs. These registers count the number of certain
942 types of hw events: such as instructions executed, cachemisses
943 suffered, or branches mis-predicted - without slowing down the
944 kernel or applications. These registers can also trigger interrupts
945 when a threshold number of events have passed - and can thus be
946 used to profile the code that runs on that CPU.
948 The Linux Performance Counter subsystem provides an abstraction of
949 these hardware capabilities, available via a system call. It
950 provides per task and per CPU counters, and it provides event
951 capabilities on top of those.
953 Say Y if unsure.
955 config EVENT_PROFILE
956 bool "Tracepoint profile sources"
957 depends on PERF_COUNTERS && EVENT_TRACER
958 default y
960 endmenu
962 config VM_EVENT_COUNTERS
963 default y
964 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
965 help
966 VM event counters are needed for event counts to be shown.
967 This option allows the disabling of the VM event counters
968 on EMBEDDED systems. /proc/vmstat will only show page counts
969 if VM event counters are disabled.
971 config PCI_QUIRKS
972 default y
973 bool "Enable PCI quirk workarounds" if EMBEDDED
974 depends on PCI
975 help
976 This enables workarounds for various PCI chipset
977 bugs/quirks. Disable this only if your target machine is
978 unaffected by PCI quirks.
980 config SLUB_DEBUG
981 default y
982 bool "Enable SLUB debugging support" if EMBEDDED
983 depends on SLUB && SYSFS
984 help
985 SLUB has extensive debug support features. Disabling these can
986 result in significant savings in code size. This also disables
987 SLUB sysfs support. /sys/slab will not exist and there will be
988 no support for cache validation etc.
990 config COMPAT_BRK
991 bool "Disable heap randomization"
992 default y
993 help
994 Randomizing heap placement makes heap exploits harder, but it
995 also breaks ancient binaries (including anything libc5 based).
996 This option changes the bootup default to heap randomization
997 disabled, and can be overriden runtime by setting
998 /proc/sys/kernel/randomize_va_space to 2.
1000 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1002 choice
1003 prompt "Choose SLAB allocator"
1004 default SLUB
1005 help
1006 This option allows to select a slab allocator.
1008 config SLAB
1009 bool "SLAB"
1010 help
1011 The regular slab allocator that is established and known to work
1012 well in all environments. It organizes cache hot objects in
1013 per cpu and per node queues.
1015 config SLUB
1016 bool "SLUB (Unqueued Allocator)"
1017 depends on !PREEMPT_RT
1018 help
1019 SLUB is a slab allocator that minimizes cache line usage
1020 instead of managing queues of cached objects (SLAB approach).
1021 Per cpu caching is realized using slabs of objects instead
1022 of queues of objects. SLUB can use memory efficiently
1023 and has enhanced diagnostics. SLUB is the default choice for
1024 a slab allocator.
1026 config SLOB
1027 depends on EMBEDDED
1028 # lockups observed:
1029 depends on 0
1030 bool "SLOB (Simple Allocator)"
1031 help
1032 SLOB replaces the stock allocator with a drastically simpler
1033 allocator. SLOB is generally more space efficient but
1034 does not perform as well on large systems.
1036 endchoice
1038 config PROFILING
1039 bool "Profiling support (EXPERIMENTAL)"
1040 help
1041 Say Y here to enable the extended profiling support mechanisms used
1042 by profilers such as OProfile.
1044 #
1045 # Place an empty function call at each tracepoint site. Can be
1046 # dynamically changed for a probe function.
1047 #
1048 config TRACEPOINTS
1049 bool
1051 config MARKERS
1052 bool "Activate markers"
1053 select TRACEPOINTS
1054 help
1055 Place an empty function call at each marker site. Can be
1056 dynamically changed for a probe function.
1058 source "arch/Kconfig"
1060 endmenu # General setup
1062 config HAVE_GENERIC_DMA_COHERENT
1063 bool
1064 default n
1066 config SLABINFO
1067 bool
1068 depends on PROC_FS
1069 depends on SLAB || SLUB_DEBUG
1070 default y
1072 config RT_MUTEXES
1073 boolean
1075 config BASE_SMALL
1076 int
1077 default 0 if BASE_FULL
1078 default 1 if !BASE_FULL
1080 menuconfig MODULES
1081 bool "Enable loadable module support"
1082 help
1083 Kernel modules are small pieces of compiled code which can
1084 be inserted in the running kernel, rather than being
1085 permanently built into the kernel. You use the "modprobe"
1086 tool to add (and sometimes remove) them. If you say Y here,
1087 many parts of the kernel can be built as modules (by
1088 answering M instead of Y where indicated): this is most
1089 useful for infrequently used options which are not required
1090 for booting. For more information, see the man pages for
1091 modprobe, lsmod, modinfo, insmod and rmmod.
1093 If you say Y here, you will need to run "make
1094 modules_install" to put the modules under /lib/modules/
1095 where modprobe can find them (you may need to be root to do
1096 this).
1098 If unsure, say Y.
1100 if MODULES
1102 config MODULE_FORCE_LOAD
1103 bool "Forced module loading"
1104 default n
1105 help
1106 Allow loading of modules without version information (ie. modprobe
1107 --force). Forced module loading sets the 'F' (forced) taint flag and
1108 is usually a really bad idea.
1110 config MODULE_UNLOAD
1111 bool "Module unloading"
1112 help
1113 Without this option you will not be able to unload any
1114 modules (note that some modules may not be unloadable
1115 anyway), which makes your kernel smaller, faster
1116 and simpler. If unsure, say Y.
1118 config MODULE_FORCE_UNLOAD
1119 bool "Forced module unloading"
1120 depends on MODULE_UNLOAD && EXPERIMENTAL
1121 help
1122 This option allows you to force a module to unload, even if the
1123 kernel believes it is unsafe: the kernel will remove the module
1124 without waiting for anyone to stop using it (using the -f option to
1125 rmmod). This is mainly for kernel developers and desperate users.
1126 If unsure, say N.
1128 config MODVERSIONS
1129 bool "Module versioning support"
1130 help
1131 Usually, you have to use modules compiled with your kernel.
1132 Saying Y here makes it sometimes possible to use modules
1133 compiled for different kernels, by adding enough information
1134 to the modules to (hopefully) spot any changes which would
1135 make them incompatible with the kernel you are running. If
1136 unsure, say N.
1138 config MODULE_SRCVERSION_ALL
1139 bool "Source checksum for all modules"
1140 help
1141 Modules which contain a MODULE_VERSION get an extra "srcversion"
1142 field inserted into their modinfo section, which contains a
1143 sum of the source files which made it. This helps maintainers
1144 see exactly which source was used to build a module (since
1145 others sometimes change the module source without updating
1146 the version). With this option, such a "srcversion" field
1147 will be created for all modules. If unsure, say N.
1149 endif # MODULES
1151 config INIT_ALL_POSSIBLE
1152 bool
1153 help
1154 Back when each arch used to define their own cpu_online_map and
1155 cpu_possible_map, some of them chose to initialize cpu_possible_map
1156 with all 1s, and others with all 0s. When they were centralised,
1157 it was better to provide this option than to break all the archs
1158 and have several arch maintainers persuing me down dark alleys.
1160 config STOP_MACHINE
1161 bool
1162 default y
1163 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1164 help
1165 Need stop_machine() primitive.
1167 source "block/Kconfig"
1169 config PREEMPT_NOTIFIERS
1170 bool