| blob | c7bac39d6c61b7da35e5ee1e9a8c9e33a2033807 |
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 config CONSTRUCTORS
20 bool
21 depends on !UML
22 default y
24 menu "General setup"
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).
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47 drivers that have been replaced by something else, and/or are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.
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.
57 config BROKEN
58 bool
60 config BROKEN_ON_SMP
61 bool
62 depends on BROKEN || !SMP
63 default y
65 config LOCK_KERNEL
66 bool
67 depends on SMP || PREEMPT
68 default y
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.
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.
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.
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.
102 (The actual string used here is the first eight characters produced
103 by running the command:
105 $ git rev-parse --verify HEAD
107 which is done within the script "scripts/setlocalversion".)
109 config HAVE_KERNEL_GZIP
110 bool
112 config HAVE_KERNEL_BZIP2
113 bool
115 config HAVE_KERNEL_LZMA
116 bool
118 choice
119 prompt "Kernel compression mode"
120 default KERNEL_GZIP
121 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
122 help
123 The linux kernel is a kind of self-extracting executable.
124 Several compression algorithms are available, which differ
125 in efficiency, compression and decompression speed.
126 Compression speed is only relevant when building a kernel.
127 Decompression speed is relevant at each boot.
129 If you have any problems with bzip2 or lzma compressed
130 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
131 version of this functionality (bzip2 only), for 2.4, was
132 supplied by Christian Ludwig)
134 High compression options are mostly useful for users, who
135 are low on disk space (embedded systems), but for whom ram
136 size matters less.
138 If in doubt, select 'gzip'
140 config KERNEL_GZIP
141 bool "Gzip"
142 depends on HAVE_KERNEL_GZIP
143 help
144 The old and tried gzip compression. Its compression ratio is
145 the poorest among the 3 choices; however its speed (both
146 compression and decompression) is the fastest.
148 config KERNEL_BZIP2
149 bool "Bzip2"
150 depends on HAVE_KERNEL_BZIP2
151 help
152 Its compression ratio and speed is intermediate.
153 Decompression speed is slowest among the three. The kernel
154 size is about 10% smaller with bzip2, in comparison to gzip.
155 Bzip2 uses a large amount of memory. For modern kernels you
156 will need at least 8MB RAM or more for booting.
158 config KERNEL_LZMA
159 bool "LZMA"
160 depends on HAVE_KERNEL_LZMA
161 help
162 The most recent compression algorithm.
163 Its ratio is best, decompression speed is between the other
164 two. Compression is slowest. The kernel size is about 33%
165 smaller with LZMA in comparison to gzip.
167 endchoice
169 config SWAP
170 bool "Support for paging of anonymous memory (swap)"
171 depends on MMU && BLOCK
172 default y
173 help
174 This option allows you to choose whether you want to have support
175 for so called swap devices or swap files in your kernel that are
176 used to provide more virtual memory than the actual RAM present
177 in your computer. If unsure say Y.
179 config SYSVIPC
180 bool "System V IPC"
181 ---help---
182 Inter Process Communication is a suite of library functions and
183 system calls which let processes (running programs) synchronize and
184 exchange information. It is generally considered to be a good thing,
185 and some programs won't run unless you say Y here. In particular, if
186 you want to run the DOS emulator dosemu under Linux (read the
187 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
188 you'll need to say Y here.
190 You can find documentation about IPC with "info ipc" and also in
191 section 6.4 of the Linux Programmer's Guide, available from
192 <http://www.tldp.org/guides.html>.
194 config SYSVIPC_SYSCTL
195 bool
196 depends on SYSVIPC
197 depends on SYSCTL
198 default y
200 config POSIX_MQUEUE
201 bool "POSIX Message Queues"
202 depends on NET && EXPERIMENTAL
203 ---help---
204 POSIX variant of message queues is a part of IPC. In POSIX message
205 queues every message has a priority which decides about succession
206 of receiving it by a process. If you want to compile and run
207 programs written e.g. for Solaris with use of its POSIX message
208 queues (functions mq_*) say Y here.
210 POSIX message queues are visible as a filesystem called 'mqueue'
211 and can be mounted somewhere if you want to do filesystem
212 operations on message queues.
214 If unsure, say Y.
216 config POSIX_MQUEUE_SYSCTL
217 bool
218 depends on POSIX_MQUEUE
219 depends on SYSCTL
220 default y
222 config BSD_PROCESS_ACCT
223 bool "BSD Process Accounting"
224 help
225 If you say Y here, a user level program will be able to instruct the
226 kernel (via a special system call) to write process accounting
227 information to a file: whenever a process exits, information about
228 that process will be appended to the file by the kernel. The
229 information includes things such as creation time, owning user,
230 command name, memory usage, controlling terminal etc. (the complete
231 list is in the struct acct in <file:include/linux/acct.h>). It is
232 up to the user level program to do useful things with this
233 information. This is generally a good idea, so say Y.
235 config BSD_PROCESS_ACCT_V3
236 bool "BSD Process Accounting version 3 file format"
237 depends on BSD_PROCESS_ACCT
238 default n
239 help
240 If you say Y here, the process accounting information is written
241 in a new file format that also logs the process IDs of each
242 process and it's parent. Note that this file format is incompatible
243 with previous v0/v1/v2 file formats, so you will need updated tools
244 for processing it. A preliminary version of these tools is available
245 at <http://www.gnu.org/software/acct/>.
247 config TASKSTATS
248 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
249 depends on NET
250 default n
251 help
252 Export selected statistics for tasks/processes through the
253 generic netlink interface. Unlike BSD process accounting, the
254 statistics are available during the lifetime of tasks/processes as
255 responses to commands. Like BSD accounting, they are sent to user
256 space on task exit.
258 Say N if unsure.
260 config TASK_DELAY_ACCT
261 bool "Enable per-task delay accounting (EXPERIMENTAL)"
262 depends on TASKSTATS
263 help
264 Collect information on time spent by a task waiting for system
265 resources like cpu, synchronous block I/O completion and swapping
266 in pages. Such statistics can help in setting a task's priorities
267 relative to other tasks for cpu, io, rss limits etc.
269 Say N if unsure.
271 config TASK_XACCT
272 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
273 depends on TASKSTATS
274 help
275 Collect extended task accounting data and send the data
276 to userland for processing over the taskstats interface.
278 Say N if unsure.
280 config TASK_IO_ACCOUNTING
281 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
282 depends on TASK_XACCT
283 help
284 Collect information on the number of bytes of storage I/O which this
285 task has caused.
287 Say N if unsure.
289 config AUDIT
290 bool "Auditing support"
291 depends on NET
292 help
293 Enable auditing infrastructure that can be used with another
294 kernel subsystem, such as SELinux (which requires this for
295 logging of avc messages output). Does not do system-call
296 auditing without CONFIG_AUDITSYSCALL.
298 config AUDITSYSCALL
299 bool "Enable system-call auditing support"
300 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
301 default y if SECURITY_SELINUX
302 help
303 Enable low-overhead system-call auditing infrastructure that
304 can be used independently or with another kernel subsystem,
305 such as SELinux. To use audit's filesystem watch feature, please
306 ensure that INOTIFY is configured.
308 config AUDIT_TREE
309 def_bool y
310 depends on AUDITSYSCALL
311 select INOTIFY
313 menu "RCU Subsystem"
315 choice
316 prompt "RCU Implementation"
317 default TREE_RCU
319 config TREE_RCU
320 bool "Tree-based hierarchical RCU"
321 help
322 This option selects the RCU implementation that is
323 designed for very large SMP system with hundreds or
324 thousands of CPUs. It also scales down nicely to
325 smaller systems.
327 config TREE_PREEMPT_RCU
328 bool "Preemptable tree-based hierarchical RCU"
329 depends on PREEMPT
330 help
331 This option selects the RCU implementation that is
332 designed for very large SMP systems with hundreds or
333 thousands of CPUs, but for which real-time response
334 is also required. It also scales down nicely to
335 smaller systems.
337 endchoice
339 config RCU_TRACE
340 bool "Enable tracing for RCU"
341 depends on TREE_RCU || TREE_PREEMPT_RCU
342 help
343 This option provides tracing in RCU which presents stats
344 in debugfs for debugging RCU implementation.
346 Say Y here if you want to enable RCU tracing
347 Say N if you are unsure.
349 config RCU_FANOUT
350 int "Tree-based hierarchical RCU fanout value"
351 range 2 64 if 64BIT
352 range 2 32 if !64BIT
353 depends on TREE_RCU || TREE_PREEMPT_RCU
354 default 64 if 64BIT
355 default 32 if !64BIT
356 help
357 This option controls the fanout of hierarchical implementations
358 of RCU, allowing RCU to work efficiently on machines with
359 large numbers of CPUs. This value must be at least the cube
360 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
361 systems and up to 262,144 for 64-bit systems.
363 Select a specific number if testing RCU itself.
364 Take the default if unsure.
366 config RCU_FANOUT_EXACT
367 bool "Disable tree-based hierarchical RCU auto-balancing"
368 depends on TREE_RCU || TREE_PREEMPT_RCU
369 default n
370 help
371 This option forces use of the exact RCU_FANOUT value specified,
372 regardless of imbalances in the hierarchy. This is useful for
373 testing RCU itself, and might one day be useful on systems with
374 strong NUMA behavior.
376 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
378 Say N if unsure.
380 config TREE_RCU_TRACE
381 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
382 select DEBUG_FS
383 help
384 This option provides tracing for the TREE_RCU and
385 TREE_PREEMPT_RCU implementations, permitting Makefile to
386 trivially select kernel/rcutree_trace.c.
388 endmenu # "RCU Subsystem"
390 config IKCONFIG
391 tristate "Kernel .config support"
392 ---help---
393 This option enables the complete Linux kernel ".config" file
394 contents to be saved in the kernel. It provides documentation
395 of which kernel options are used in a running kernel or in an
396 on-disk kernel. This information can be extracted from the kernel
397 image file with the script scripts/extract-ikconfig and used as
398 input to rebuild the current kernel or to build another kernel.
399 It can also be extracted from a running kernel by reading
400 /proc/config.gz if enabled (below).
402 config IKCONFIG_PROC
403 bool "Enable access to .config through /proc/config.gz"
404 depends on IKCONFIG && PROC_FS
405 ---help---
406 This option enables access to the kernel configuration file
407 through /proc/config.gz.
409 config LOG_BUF_SHIFT
410 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
411 range 12 21
412 default 17
413 help
414 Select kernel log buffer size as a power of 2.
415 Examples:
416 17 => 128 KB
417 16 => 64 KB
418 15 => 32 KB
419 14 => 16 KB
420 13 => 8 KB
421 12 => 4 KB
423 #
424 # Architectures with an unreliable sched_clock() should select this:
425 #
426 config HAVE_UNSTABLE_SCHED_CLOCK
427 bool
429 config GROUP_SCHED
430 bool "Group CPU scheduler"
431 depends on EXPERIMENTAL
432 default n
433 help
434 This feature lets CPU scheduler recognize task groups and control CPU
435 bandwidth allocation to such task groups.
436 In order to create a group from arbitrary set of processes, use
437 CONFIG_CGROUPS. (See Control Group support.)
439 config FAIR_GROUP_SCHED
440 bool "Group scheduling for SCHED_OTHER"
441 depends on GROUP_SCHED
442 default GROUP_SCHED
444 config RT_GROUP_SCHED
445 bool "Group scheduling for SCHED_RR/FIFO"
446 depends on EXPERIMENTAL
447 depends on GROUP_SCHED
448 default n
449 help
450 This feature lets you explicitly allocate real CPU bandwidth
451 to users or control groups (depending on the "Basis for grouping tasks"
452 setting below. If enabled, it will also make it impossible to
453 schedule realtime tasks for non-root users until you allocate
454 realtime bandwidth for them.
455 See Documentation/scheduler/sched-rt-group.txt for more information.
457 choice
458 depends on GROUP_SCHED
459 prompt "Basis for grouping tasks"
460 default USER_SCHED
462 config USER_SCHED
463 bool "user id"
464 help
465 This option will choose userid as the basis for grouping
466 tasks, thus providing equal CPU bandwidth to each user.
468 config CGROUP_SCHED
469 bool "Control groups"
470 depends on CGROUPS
471 help
472 This option allows you to create arbitrary task groups
473 using the "cgroup" pseudo filesystem and control
474 the cpu bandwidth allocated to each such task group.
475 Refer to Documentation/cgroups/cgroups.txt for more
476 information on "cgroup" pseudo filesystem.
478 endchoice
480 menuconfig CGROUPS
481 boolean "Control Group support"
482 help
483 This option adds support for grouping sets of processes together, for
484 use with process control subsystems such as Cpusets, CFS, memory
485 controls or device isolation.
486 See
487 - Documentation/scheduler/sched-design-CFS.txt (CFS)
488 - Documentation/cgroups/ (features for grouping, isolation
489 and resource control)
491 Say N if unsure.
493 if CGROUPS
495 config CGROUP_DEBUG
496 bool "Example debug cgroup subsystem"
497 depends on CGROUPS
498 default n
499 help
500 This option enables a simple cgroup subsystem that
501 exports useful debugging information about the cgroups
502 framework.
504 Say N if unsure.
506 config CGROUP_NS
507 bool "Namespace cgroup subsystem"
508 depends on CGROUPS
509 help
510 Provides a simple namespace cgroup subsystem to
511 provide hierarchical naming of sets of namespaces,
512 for instance virtual servers and checkpoint/restart
513 jobs.
515 config CGROUP_FREEZER
516 bool "Freezer cgroup subsystem"
517 depends on CGROUPS
518 help
519 Provides a way to freeze and unfreeze all tasks in a
520 cgroup.
522 config CGROUP_DEVICE
523 bool "Device controller for cgroups"
524 depends on CGROUPS && EXPERIMENTAL
525 help
526 Provides a cgroup implementing whitelists for devices which
527 a process in the cgroup can mknod or open.
529 config CPUSETS
530 bool "Cpuset support"
531 depends on CGROUPS
532 help
533 This option will let you create and manage CPUSETs which
534 allow dynamically partitioning a system into sets of CPUs and
535 Memory Nodes and assigning tasks to run only within those sets.
536 This is primarily useful on large SMP or NUMA systems.
538 Say N if unsure.
540 config PROC_PID_CPUSET
541 bool "Include legacy /proc/<pid>/cpuset file"
542 depends on CPUSETS
543 default y
545 config CGROUP_CPUACCT
546 bool "Simple CPU accounting cgroup subsystem"
547 depends on CGROUPS
548 help
549 Provides a simple Resource Controller for monitoring the
550 total CPU consumed by the tasks in a cgroup.
552 config RESOURCE_COUNTERS
553 bool "Resource counters"
554 help
555 This option enables controller independent resource accounting
556 infrastructure that works with cgroups.
557 depends on CGROUPS
559 config CGROUP_MEM_RES_CTLR
560 bool "Memory Resource Controller for Control Groups"
561 depends on CGROUPS && RESOURCE_COUNTERS
562 select MM_OWNER
563 help
564 Provides a memory resource controller that manages both anonymous
565 memory and page cache. (See Documentation/cgroups/memory.txt)
567 Note that setting this option increases fixed memory overhead
568 associated with each page of memory in the system. By this,
569 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
570 usage tracking struct at boot. Total amount of this is printed out
571 at boot.
573 Only enable when you're ok with these trade offs and really
574 sure you need the memory resource controller. Even when you enable
575 this, you can set "cgroup_disable=memory" at your boot option to
576 disable memory resource controller and you can avoid overheads.
577 (and lose benefits of memory resource controller)
579 This config option also selects MM_OWNER config option, which
580 could in turn add some fork/exit overhead.
582 config CGROUP_MEM_RES_CTLR_SWAP
583 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
584 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
585 help
586 Add swap management feature to memory resource controller. When you
587 enable this, you can limit mem+swap usage per cgroup. In other words,
588 when you disable this, memory resource controller has no cares to
589 usage of swap...a process can exhaust all of the swap. This extension
590 is useful when you want to avoid exhaustion swap but this itself
591 adds more overheads and consumes memory for remembering information.
592 Especially if you use 32bit system or small memory system, please
593 be careful about enabling this. When memory resource controller
594 is disabled by boot option, this will be automatically disabled and
595 there will be no overhead from this. Even when you set this config=y,
596 if boot option "noswapaccount" is set, swap will not be accounted.
597 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
598 size is 4096bytes, 512k per 1Gbytes of swap.
600 endif # CGROUPS
602 config MM_OWNER
603 bool
605 config SYSFS_DEPRECATED
606 bool
608 config SYSFS_DEPRECATED_V2
609 bool "remove sysfs features which may confuse old userspace tools"
610 depends on SYSFS
611 default n
612 select SYSFS_DEPRECATED
613 help
614 This option switches the layout of sysfs to the deprecated
615 version. Do not use it on recent distributions.
617 The current sysfs layout features a unified device tree at
618 /sys/devices/, which is able to express a hierarchy between
619 class devices. If the deprecated option is set to Y, the
620 unified device tree is split into a bus device tree at
621 /sys/devices/ and several individual class device trees at
622 /sys/class/. The class and bus devices will be connected by
623 "<subsystem>:<name>" and the "device" links. The "block"
624 class devices, will not show up in /sys/class/block/. Some
625 subsystems will suppress the creation of some devices which
626 depend on the unified device tree.
628 This option is not a pure compatibility option that can
629 be safely enabled on newer distributions. It will change the
630 layout of sysfs to the non-extensible deprecated version,
631 and disable some features, which can not be exported without
632 confusing older userspace tools. Since 2007/2008 all major
633 distributions do not enable this option, and ship no tools which
634 depend on the deprecated layout or this option.
636 If you are using a new kernel on an older distribution, or use
637 older userspace tools, you might need to say Y here. Do not say Y,
638 if the original kernel, that came with your distribution, has
639 this option set to N.
641 config RELAY
642 bool "Kernel->user space relay support (formerly relayfs)"
643 help
644 This option enables support for relay interface support in
645 certain file systems (such as debugfs).
646 It is designed to provide an efficient mechanism for tools and
647 facilities to relay large amounts of data from kernel space to
648 user space.
650 If unsure, say N.
652 config NAMESPACES
653 bool "Namespaces support" if EMBEDDED
654 default !EMBEDDED
655 help
656 Provides the way to make tasks work with different objects using
657 the same id. For example same IPC id may refer to different objects
658 or same user id or pid may refer to different tasks when used in
659 different namespaces.
661 config UTS_NS
662 bool "UTS namespace"
663 depends on NAMESPACES
664 help
665 In this namespace tasks see different info provided with the
666 uname() system call
668 config IPC_NS
669 bool "IPC namespace"
670 depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
671 help
672 In this namespace tasks work with IPC ids which correspond to
673 different IPC objects in different namespaces.
675 config USER_NS
676 bool "User namespace (EXPERIMENTAL)"
677 depends on NAMESPACES && EXPERIMENTAL
678 help
679 This allows containers, i.e. vservers, to use user namespaces
680 to provide different user info for different servers.
681 If unsure, say N.
683 config PID_NS
684 bool "PID Namespaces (EXPERIMENTAL)"
685 default n
686 depends on NAMESPACES && EXPERIMENTAL
687 help
688 Support process id namespaces. This allows having multiple
689 processes with the same pid as long as they are in different
690 pid namespaces. This is a building block of containers.
692 Unless you want to work with an experimental feature
693 say N here.
695 config NET_NS
696 bool "Network namespace"
697 default n
698 depends on NAMESPACES && EXPERIMENTAL && NET
699 help
700 Allow user space to create what appear to be multiple instances
701 of the network stack.
703 config BLK_DEV_INITRD
704 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
705 depends on BROKEN || !FRV
706 help
707 The initial RAM filesystem is a ramfs which is loaded by the
708 boot loader (loadlin or lilo) and that is mounted as root
709 before the normal boot procedure. It is typically used to
710 load modules needed to mount the "real" root file system,
711 etc. See <file:Documentation/initrd.txt> for details.
713 If RAM disk support (BLK_DEV_RAM) is also included, this
714 also enables initial RAM disk (initrd) support and adds
715 15 Kbytes (more on some other architectures) to the kernel size.
717 If unsure say Y.
719 if BLK_DEV_INITRD
721 source "usr/Kconfig"
723 endif
725 config CC_OPTIMIZE_FOR_SIZE
726 bool "Optimize for size"
727 default y
728 help
729 Enabling this option will pass "-Os" instead of "-O2" to gcc
730 resulting in a smaller kernel.
732 If unsure, say Y.
734 config SYSCTL
735 bool
737 config ANON_INODES
738 bool
740 menuconfig EMBEDDED
741 bool "Configure standard kernel features (for small systems)"
742 help
743 This option allows certain base kernel options and settings
744 to be disabled or tweaked. This is for specialized
745 environments which can tolerate a "non-standard" kernel.
746 Only use this if you really know what you are doing.
748 config UID16
749 bool "Enable 16-bit UID system calls" if EMBEDDED
750 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
751 default y
752 help
753 This enables the legacy 16-bit UID syscall wrappers.
755 config SYSCTL_SYSCALL
756 bool "Sysctl syscall support" if EMBEDDED
757 default y
758 select SYSCTL
759 ---help---
760 sys_sysctl uses binary paths that have been found challenging
761 to properly maintain and use. The interface in /proc/sys
762 using paths with ascii names is now the primary path to this
763 information.
765 Almost nothing using the binary sysctl interface so if you are
766 trying to save some space it is probably safe to disable this,
767 making your kernel marginally smaller.
769 If unsure say Y here.
771 config KALLSYMS
772 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
773 default y
774 help
775 Say Y here to let the kernel print out symbolic crash information and
776 symbolic stack backtraces. This increases the size of the kernel
777 somewhat, as all symbols have to be loaded into the kernel image.
779 config KALLSYMS_ALL
780 bool "Include all symbols in kallsyms"
781 depends on DEBUG_KERNEL && KALLSYMS
782 help
783 Normally kallsyms only contains the symbols of functions, for nicer
784 OOPS messages. Some debuggers can use kallsyms for other
785 symbols too: say Y here to include all symbols, if you need them
786 and you don't care about adding 300k to the size of your kernel.
788 Say N.
790 config KALLSYMS_EXTRA_PASS
791 bool "Do an extra kallsyms pass"
792 depends on KALLSYMS
793 help
794 If kallsyms is not working correctly, the build will fail with
795 inconsistent kallsyms data. If that occurs, log a bug report and
796 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
797 Always say N here unless you find a bug in kallsyms, which must be
798 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
799 you wait for kallsyms to be fixed.
802 config HOTPLUG
803 bool "Support for hot-pluggable devices" if EMBEDDED
804 default y
805 help
806 This option is provided for the case where no hotplug or uevent
807 capabilities is wanted by the kernel. You should only consider
808 disabling this option for embedded systems that do not use modules, a
809 dynamic /dev tree, or dynamic device discovery. Just say Y.
811 config PRINTK
812 default y
813 bool "Enable support for printk" if EMBEDDED
814 help
815 This option enables normal printk support. Removing it
816 eliminates most of the message strings from the kernel image
817 and makes the kernel more or less silent. As this makes it
818 very difficult to diagnose system problems, saying N here is
819 strongly discouraged.
821 config BUG
822 bool "BUG() support" if EMBEDDED
823 default y
824 help
825 Disabling this option eliminates support for BUG and WARN, reducing
826 the size of your kernel image and potentially quietly ignoring
827 numerous fatal conditions. You should only consider disabling this
828 option for embedded systems with no facilities for reporting errors.
829 Just say Y.
831 config ELF_CORE
832 default y
833 bool "Enable ELF core dumps" if EMBEDDED
834 help
835 Enable support for generating core dumps. Disabling saves about 4k.
837 config PCSPKR_PLATFORM
838 bool "Enable PC-Speaker support" if EMBEDDED
839 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
840 default y
841 help
842 This option allows to disable the internal PC-Speaker
843 support, saving some memory.
845 config BASE_FULL
846 default y
847 bool "Enable full-sized data structures for core" if EMBEDDED
848 help
849 Disabling this option reduces the size of miscellaneous core
850 kernel data structures. This saves memory on small machines,
851 but may reduce performance.
853 config FUTEX
854 bool "Enable futex support" if EMBEDDED
855 default y
856 select RT_MUTEXES
857 help
858 Disabling this option will cause the kernel to be built without
859 support for "fast userspace mutexes". The resulting kernel may not
860 run glibc-based applications correctly.
862 config EPOLL
863 bool "Enable eventpoll support" if EMBEDDED
864 default y
865 select ANON_INODES
866 help
867 Disabling this option will cause the kernel to be built without
868 support for epoll family of system calls.
870 config SIGNALFD
871 bool "Enable signalfd() system call" if EMBEDDED
872 select ANON_INODES
873 default y
874 help
875 Enable the signalfd() system call that allows to receive signals
876 on a file descriptor.
878 If unsure, say Y.
880 config TIMERFD
881 bool "Enable timerfd() system call" if EMBEDDED
882 select ANON_INODES
883 default y
884 help
885 Enable the timerfd() system call that allows to receive timer
886 events on a file descriptor.
888 If unsure, say Y.
890 config EVENTFD
891 bool "Enable eventfd() system call" if EMBEDDED
892 select ANON_INODES
893 default y
894 help
895 Enable the eventfd() system call that allows to receive both
896 kernel notification (ie. KAIO) or userspace notifications.
898 If unsure, say Y.
900 config SHMEM
901 bool "Use full shmem filesystem" if EMBEDDED
902 default y
903 depends on MMU
904 help
905 The shmem is an internal filesystem used to manage shared memory.
906 It is backed by swap and manages resource limits. It is also exported
907 to userspace as tmpfs if TMPFS is enabled. Disabling this
908 option replaces shmem and tmpfs with the much simpler ramfs code,
909 which may be appropriate on small systems without swap.
911 config AIO
912 bool "Enable AIO support" if EMBEDDED
913 default y
914 help
915 This option enables POSIX asynchronous I/O which may by used
916 by some high performance threaded applications. Disabling
917 this option saves about 7k.
919 config HAVE_PERF_EVENTS
920 bool
921 help
922 See tools/perf/design.txt for details.
924 menu "Kernel Performance Events And Counters"
926 config PERF_EVENTS
927 bool "Kernel performance events and counters"
928 default y if (PROFILING || PERF_COUNTERS)
929 depends on HAVE_PERF_EVENTS
930 select ANON_INODES
931 help
932 Enable kernel support for various performance events provided
933 by software and hardware.
935 Software events are supported either build-in or via the
936 use of generic tracepoints.
938 Most modern CPUs support performance events via performance
939 counter registers. These registers count the number of certain
940 types of hw events: such as instructions executed, cachemisses
941 suffered, or branches mis-predicted - without slowing down the
942 kernel or applications. These registers can also trigger interrupts
943 when a threshold number of events have passed - and can thus be
944 used to profile the code that runs on that CPU.
946 The Linux Performance Event subsystem provides an abstraction of
947 these software and hardware cevent apabilities, available via a
948 system call and used by the "perf" utility in tools/perf/. It
949 provides per task and per CPU counters, and it provides event
950 capabilities on top of those.
952 Say Y if unsure.
954 config EVENT_PROFILE
955 bool "Tracepoint profiling sources"
956 depends on PERF_EVENTS && EVENT_TRACING
957 default y
958 help
959 Allow the use of tracepoints as software performance events.
961 When this is enabled, you can create perf events based on
962 tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
963 found in debugfs://tracing/events/*/*/id. (The -e/--events
964 option to the perf tool can parse and interpret symbolic
965 tracepoints, in the subsystem:tracepoint_name format.)
967 config PERF_COUNTERS
968 bool "Kernel performance counters (old config option)"
969 depends on HAVE_PERF_EVENTS
970 help
971 This config has been obsoleted by the PERF_EVENTS
972 config option - please see that one for details.
974 It has no effect on the kernel whether you enable
975 it or not, it is a compatibility placeholder.
977 Say N if unsure.
979 endmenu
981 config VM_EVENT_COUNTERS
982 default y
983 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
984 help
985 VM event counters are needed for event counts to be shown.
986 This option allows the disabling of the VM event counters
987 on EMBEDDED systems. /proc/vmstat will only show page counts
988 if VM event counters are disabled.
990 config PCI_QUIRKS
991 default y
992 bool "Enable PCI quirk workarounds" if EMBEDDED
993 depends on PCI
994 help
995 This enables workarounds for various PCI chipset
996 bugs/quirks. Disable this only if your target machine is
997 unaffected by PCI quirks.
999 config SLUB_DEBUG
1000 default y
1001 bool "Enable SLUB debugging support" if EMBEDDED
1002 depends on SLUB && SYSFS
1003 help
1004 SLUB has extensive debug support features. Disabling these can
1005 result in significant savings in code size. This also disables
1006 SLUB sysfs support. /sys/slab will not exist and there will be
1007 no support for cache validation etc.
1009 config COMPAT_BRK
1010 bool "Disable heap randomization"
1011 default y
1012 help
1013 Randomizing heap placement makes heap exploits harder, but it
1014 also breaks ancient binaries (including anything libc5 based).
1015 This option changes the bootup default to heap randomization
1016 disabled, and can be overridden at runtime by setting
1017 /proc/sys/kernel/randomize_va_space to 2.
1019 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1021 choice
1022 prompt "Choose SLAB allocator"
1023 default SLUB
1024 help
1025 This option allows to select a slab allocator.
1027 config SLAB
1028 bool "SLAB"
1029 help
1030 The regular slab allocator that is established and known to work
1031 well in all environments. It organizes cache hot objects in
1032 per cpu and per node queues.
1034 config SLUB
1035 bool "SLUB (Unqueued Allocator)"
1036 help
1037 SLUB is a slab allocator that minimizes cache line usage
1038 instead of managing queues of cached objects (SLAB approach).
1039 Per cpu caching is realized using slabs of objects instead
1040 of queues of objects. SLUB can use memory efficiently
1041 and has enhanced diagnostics. SLUB is the default choice for
1042 a slab allocator.
1044 config SLOB
1045 depends on EMBEDDED
1046 bool "SLOB (Simple Allocator)"
1047 help
1048 SLOB replaces the stock allocator with a drastically simpler
1049 allocator. SLOB is generally more space efficient but
1050 does not perform as well on large systems.
1052 endchoice
1054 config PROFILING
1055 bool "Profiling support (EXPERIMENTAL)"
1056 help
1057 Say Y here to enable the extended profiling support mechanisms used
1058 by profilers such as OProfile.
1060 #
1061 # Place an empty function call at each tracepoint site. Can be
1062 # dynamically changed for a probe function.
1063 #
1064 config TRACEPOINTS
1065 bool
1067 source "arch/Kconfig"
1069 config SLOW_WORK
1070 default n
1071 bool
1072 help
1073 The slow work thread pool provides a number of dynamically allocated
1074 threads that can be used by the kernel to perform operations that
1075 take a relatively long time.
1077 An example of this would be CacheFiles doing a path lookup followed
1078 by a series of mkdirs and a create call, all of which have to touch
1079 disk.
1081 See Documentation/slow-work.txt.
1083 endmenu # General setup
1085 config HAVE_GENERIC_DMA_COHERENT
1086 bool
1087 default n
1089 config SLABINFO
1090 bool
1091 depends on PROC_FS
1092 depends on SLAB || SLUB_DEBUG
1093 default y
1095 config RT_MUTEXES
1096 boolean
1098 config BASE_SMALL
1099 int
1100 default 0 if BASE_FULL
1101 default 1 if !BASE_FULL
1103 menuconfig MODULES
1104 bool "Enable loadable module support"
1105 help
1106 Kernel modules are small pieces of compiled code which can
1107 be inserted in the running kernel, rather than being
1108 permanently built into the kernel. You use the "modprobe"
1109 tool to add (and sometimes remove) them. If you say Y here,
1110 many parts of the kernel can be built as modules (by
1111 answering M instead of Y where indicated): this is most
1112 useful for infrequently used options which are not required
1113 for booting. For more information, see the man pages for
1114 modprobe, lsmod, modinfo, insmod and rmmod.
1116 If you say Y here, you will need to run "make
1117 modules_install" to put the modules under /lib/modules/
1118 where modprobe can find them (you may need to be root to do
1119 this).
1121 If unsure, say Y.
1123 if MODULES
1125 config MODULE_FORCE_LOAD
1126 bool "Forced module loading"
1127 default n
1128 help
1129 Allow loading of modules without version information (ie. modprobe
1130 --force). Forced module loading sets the 'F' (forced) taint flag and
1131 is usually a really bad idea.
1133 config MODULE_UNLOAD
1134 bool "Module unloading"
1135 help
1136 Without this option you will not be able to unload any
1137 modules (note that some modules may not be unloadable
1138 anyway), which makes your kernel smaller, faster
1139 and simpler. If unsure, say Y.
1141 config MODULE_FORCE_UNLOAD
1142 bool "Forced module unloading"
1143 depends on MODULE_UNLOAD && EXPERIMENTAL
1144 help
1145 This option allows you to force a module to unload, even if the
1146 kernel believes it is unsafe: the kernel will remove the module
1147 without waiting for anyone to stop using it (using the -f option to
1148 rmmod). This is mainly for kernel developers and desperate users.
1149 If unsure, say N.
1151 config MODVERSIONS
1152 bool "Module versioning support"
1153 help
1154 Usually, you have to use modules compiled with your kernel.
1155 Saying Y here makes it sometimes possible to use modules
1156 compiled for different kernels, by adding enough information
1157 to the modules to (hopefully) spot any changes which would
1158 make them incompatible with the kernel you are running. If
1159 unsure, say N.
1161 config MODULE_SRCVERSION_ALL
1162 bool "Source checksum for all modules"
1163 help
1164 Modules which contain a MODULE_VERSION get an extra "srcversion"
1165 field inserted into their modinfo section, which contains a
1166 sum of the source files which made it. This helps maintainers
1167 see exactly which source was used to build a module (since
1168 others sometimes change the module source without updating
1169 the version). With this option, such a "srcversion" field
1170 will be created for all modules. If unsure, say N.
1172 endif # MODULES
1174 config INIT_ALL_POSSIBLE
1175 bool
1176 help
1177 Back when each arch used to define their own cpu_online_map and
1178 cpu_possible_map, some of them chose to initialize cpu_possible_map
1179 with all 1s, and others with all 0s. When they were centralised,
1180 it was better to provide this option than to break all the archs
1181 and have several arch maintainers pursuing me down dark alleys.
1183 config STOP_MACHINE
1184 bool
1185 default y
1186 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1187 help
1188 Need stop_machine() primitive.
1190 source "block/Kconfig"
1192 config PREEMPT_NOTIFIERS
1193 bool