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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
23 config IRQ_WORK
24 bool
26 config BUILDTIME_EXTABLE_SORT
27 bool
29 menu "General setup"
31 config BROKEN
32 bool
34 config BROKEN_ON_SMP
35 bool
36 depends on BROKEN || !SMP
37 default y
39 config INIT_ENV_ARG_LIMIT
40 int
41 default 32 if !UML
42 default 128 if UML
43 help
44 Maximum of each of the number of arguments and environment
45 variables passed to init from the kernel command line.
48 config CROSS_COMPILE
49 string "Cross-compiler tool prefix"
50 help
51 Same as running 'make CROSS_COMPILE=prefix-' but stored for
52 default make runs in this kernel build directory. You don't
53 need to set this unless you want the configured kernel build
54 directory to select the cross-compiler automatically.
56 config LOCALVERSION
57 string "Local version - append to kernel release"
58 help
59 Append an extra string to the end of your kernel version.
60 This will show up when you type uname, for example.
61 The string you set here will be appended after the contents of
62 any files with a filename matching localversion* in your
63 object and source tree, in that order. Your total string can
64 be a maximum of 64 characters.
66 config LOCALVERSION_AUTO
67 bool "Automatically append version information to the version string"
68 default y
69 help
70 This will try to automatically determine if the current tree is a
71 release tree by looking for git tags that belong to the current
72 top of tree revision.
74 A string of the format -gxxxxxxxx will be added to the localversion
75 if a git-based tree is found. The string generated by this will be
76 appended after any matching localversion* files, and after the value
77 set in CONFIG_LOCALVERSION.
79 (The actual string used here is the first eight characters produced
80 by running the command:
82 $ git rev-parse --verify HEAD
84 which is done within the script "scripts/setlocalversion".)
86 config HAVE_KERNEL_GZIP
87 bool
89 config HAVE_KERNEL_BZIP2
90 bool
92 config HAVE_KERNEL_LZMA
93 bool
95 config HAVE_KERNEL_XZ
96 bool
98 config HAVE_KERNEL_LZO
99 bool
101 choice
102 prompt "Kernel compression mode"
103 default KERNEL_GZIP
104 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
105 help
106 The linux kernel is a kind of self-extracting executable.
107 Several compression algorithms are available, which differ
108 in efficiency, compression and decompression speed.
109 Compression speed is only relevant when building a kernel.
110 Decompression speed is relevant at each boot.
112 If you have any problems with bzip2 or lzma compressed
113 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
114 version of this functionality (bzip2 only), for 2.4, was
115 supplied by Christian Ludwig)
117 High compression options are mostly useful for users, who
118 are low on disk space (embedded systems), but for whom ram
119 size matters less.
121 If in doubt, select 'gzip'
123 config KERNEL_GZIP
124 bool "Gzip"
125 depends on HAVE_KERNEL_GZIP
126 help
127 The old and tried gzip compression. It provides a good balance
128 between compression ratio and decompression speed.
130 config KERNEL_BZIP2
131 bool "Bzip2"
132 depends on HAVE_KERNEL_BZIP2
133 help
134 Its compression ratio and speed is intermediate.
135 Decompression speed is slowest among the choices. The kernel
136 size is about 10% smaller with bzip2, in comparison to gzip.
137 Bzip2 uses a large amount of memory. For modern kernels you
138 will need at least 8MB RAM or more for booting.
140 config KERNEL_LZMA
141 bool "LZMA"
142 depends on HAVE_KERNEL_LZMA
143 help
144 This compression algorithm's ratio is best. Decompression speed
145 is between gzip and bzip2. Compression is slowest.
146 The kernel size is about 33% smaller with LZMA in comparison to gzip.
148 config KERNEL_XZ
149 bool "XZ"
150 depends on HAVE_KERNEL_XZ
151 help
152 XZ uses the LZMA2 algorithm and instruction set specific
153 BCJ filters which can improve compression ratio of executable
154 code. The size of the kernel is about 30% smaller with XZ in
155 comparison to gzip. On architectures for which there is a BCJ
156 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
157 will create a few percent smaller kernel than plain LZMA.
159 The speed is about the same as with LZMA: The decompression
160 speed of XZ is better than that of bzip2 but worse than gzip
161 and LZO. Compression is slow.
163 config KERNEL_LZO
164 bool "LZO"
165 depends on HAVE_KERNEL_LZO
166 help
167 Its compression ratio is the poorest among the choices. The kernel
168 size is about 10% bigger than gzip; however its speed
169 (both compression and decompression) is the fastest.
171 endchoice
173 config DEFAULT_HOSTNAME
174 string "Default hostname"
175 default "(none)"
176 help
177 This option determines the default system hostname before userspace
178 calls sethostname(2). The kernel traditionally uses "(none)" here,
179 but you may wish to use a different default here to make a minimal
180 system more usable with less configuration.
182 config SWAP
183 bool "Support for paging of anonymous memory (swap)"
184 depends on MMU && BLOCK
185 default y
186 help
187 This option allows you to choose whether you want to have support
188 for so called swap devices or swap files in your kernel that are
189 used to provide more virtual memory than the actual RAM present
190 in your computer. If unsure say Y.
192 config SYSVIPC
193 bool "System V IPC"
194 ---help---
195 Inter Process Communication is a suite of library functions and
196 system calls which let processes (running programs) synchronize and
197 exchange information. It is generally considered to be a good thing,
198 and some programs won't run unless you say Y here. In particular, if
199 you want to run the DOS emulator dosemu under Linux (read the
200 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
201 you'll need to say Y here.
203 You can find documentation about IPC with "info ipc" and also in
204 section 6.4 of the Linux Programmer's Guide, available from
205 <http://www.tldp.org/guides.html>.
207 config SYSVIPC_SYSCTL
208 bool
209 depends on SYSVIPC
210 depends on SYSCTL
211 default y
213 config POSIX_MQUEUE
214 bool "POSIX Message Queues"
215 depends on NET
216 ---help---
217 POSIX variant of message queues is a part of IPC. In POSIX message
218 queues every message has a priority which decides about succession
219 of receiving it by a process. If you want to compile and run
220 programs written e.g. for Solaris with use of its POSIX message
221 queues (functions mq_*) say Y here.
223 POSIX message queues are visible as a filesystem called 'mqueue'
224 and can be mounted somewhere if you want to do filesystem
225 operations on message queues.
227 If unsure, say Y.
229 config POSIX_MQUEUE_SYSCTL
230 bool
231 depends on POSIX_MQUEUE
232 depends on SYSCTL
233 default y
235 config FHANDLE
236 bool "open by fhandle syscalls"
237 select EXPORTFS
238 help
239 If you say Y here, a user level program will be able to map
240 file names to handle and then later use the handle for
241 different file system operations. This is useful in implementing
242 userspace file servers, which now track files using handles instead
243 of names. The handle would remain the same even if file names
244 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
245 syscalls.
247 config AUDIT
248 bool "Auditing support"
249 depends on NET
250 help
251 Enable auditing infrastructure that can be used with another
252 kernel subsystem, such as SELinux (which requires this for
253 logging of avc messages output). Does not do system-call
254 auditing without CONFIG_AUDITSYSCALL.
256 config AUDITSYSCALL
257 bool "Enable system-call auditing support"
258 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT))
259 default y if SECURITY_SELINUX
260 help
261 Enable low-overhead system-call auditing infrastructure that
262 can be used independently or with another kernel subsystem,
263 such as SELinux.
265 config AUDIT_WATCH
266 def_bool y
267 depends on AUDITSYSCALL
268 select FSNOTIFY
270 config AUDIT_TREE
271 def_bool y
272 depends on AUDITSYSCALL
273 select FSNOTIFY
275 config AUDIT_LOGINUID_IMMUTABLE
276 bool "Make audit loginuid immutable"
277 depends on AUDIT
278 help
279 The config option toggles if a task setting its loginuid requires
280 CAP_SYS_AUDITCONTROL or if that task should require no special permissions
281 but should instead only allow setting its loginuid if it was never
282 previously set. On systems which use systemd or a similar central
283 process to restart login services this should be set to true. On older
284 systems in which an admin would typically have to directly stop and
285 start processes this should be set to false. Setting this to true allows
286 one to drop potentially dangerous capabilites from the login tasks,
287 but may not be backwards compatible with older init systems.
289 source "kernel/irq/Kconfig"
290 source "kernel/time/Kconfig"
292 menu "CPU/Task time and stats accounting"
294 config VIRT_CPU_ACCOUNTING
295 bool
297 choice
298 prompt "Cputime accounting"
299 default TICK_CPU_ACCOUNTING if !PPC64
300 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
302 # Kind of a stub config for the pure tick based cputime accounting
303 config TICK_CPU_ACCOUNTING
304 bool "Simple tick based cputime accounting"
305 depends on !S390
306 help
307 This is the basic tick based cputime accounting that maintains
308 statistics about user, system and idle time spent on per jiffies
309 granularity.
311 If unsure, say Y.
313 config VIRT_CPU_ACCOUNTING_NATIVE
314 bool "Deterministic task and CPU time accounting"
315 depends on HAVE_VIRT_CPU_ACCOUNTING
316 select VIRT_CPU_ACCOUNTING
317 help
318 Select this option to enable more accurate task and CPU time
319 accounting. This is done by reading a CPU counter on each
320 kernel entry and exit and on transitions within the kernel
321 between system, softirq and hardirq state, so there is a
322 small performance impact. In the case of s390 or IBM POWER > 5,
323 this also enables accounting of stolen time on logically-partitioned
324 systems.
326 config VIRT_CPU_ACCOUNTING_GEN
327 bool "Full dynticks CPU time accounting"
328 depends on HAVE_CONTEXT_TRACKING && 64BIT
329 select VIRT_CPU_ACCOUNTING
330 select CONTEXT_TRACKING
331 help
332 Select this option to enable task and CPU time accounting on full
333 dynticks systems. This accounting is implemented by watching every
334 kernel-user boundaries using the context tracking subsystem.
335 The accounting is thus performed at the expense of some significant
336 overhead.
338 For now this is only useful if you are working on the full
339 dynticks subsystem development.
341 If unsure, say N.
343 config IRQ_TIME_ACCOUNTING
344 bool "Fine granularity task level IRQ time accounting"
345 depends on HAVE_IRQ_TIME_ACCOUNTING
346 help
347 Select this option to enable fine granularity task irq time
348 accounting. This is done by reading a timestamp on each
349 transitions between softirq and hardirq state, so there can be a
350 small performance impact.
352 If in doubt, say N here.
354 endchoice
356 config BSD_PROCESS_ACCT
357 bool "BSD Process Accounting"
358 help
359 If you say Y here, a user level program will be able to instruct the
360 kernel (via a special system call) to write process accounting
361 information to a file: whenever a process exits, information about
362 that process will be appended to the file by the kernel. The
363 information includes things such as creation time, owning user,
364 command name, memory usage, controlling terminal etc. (the complete
365 list is in the struct acct in <file:include/linux/acct.h>). It is
366 up to the user level program to do useful things with this
367 information. This is generally a good idea, so say Y.
369 config BSD_PROCESS_ACCT_V3
370 bool "BSD Process Accounting version 3 file format"
371 depends on BSD_PROCESS_ACCT
372 default n
373 help
374 If you say Y here, the process accounting information is written
375 in a new file format that also logs the process IDs of each
376 process and it's parent. Note that this file format is incompatible
377 with previous v0/v1/v2 file formats, so you will need updated tools
378 for processing it. A preliminary version of these tools is available
379 at <http://www.gnu.org/software/acct/>.
381 config TASKSTATS
382 bool "Export task/process statistics through netlink"
383 depends on NET
384 default n
385 help
386 Export selected statistics for tasks/processes through the
387 generic netlink interface. Unlike BSD process accounting, the
388 statistics are available during the lifetime of tasks/processes as
389 responses to commands. Like BSD accounting, they are sent to user
390 space on task exit.
392 Say N if unsure.
394 config TASK_DELAY_ACCT
395 bool "Enable per-task delay accounting"
396 depends on TASKSTATS
397 help
398 Collect information on time spent by a task waiting for system
399 resources like cpu, synchronous block I/O completion and swapping
400 in pages. Such statistics can help in setting a task's priorities
401 relative to other tasks for cpu, io, rss limits etc.
403 Say N if unsure.
405 config TASK_XACCT
406 bool "Enable extended accounting over taskstats"
407 depends on TASKSTATS
408 help
409 Collect extended task accounting data and send the data
410 to userland for processing over the taskstats interface.
412 Say N if unsure.
414 config TASK_IO_ACCOUNTING
415 bool "Enable per-task storage I/O accounting"
416 depends on TASK_XACCT
417 help
418 Collect information on the number of bytes of storage I/O which this
419 task has caused.
421 Say N if unsure.
423 endmenu # "CPU/Task time and stats accounting"
425 menu "RCU Subsystem"
427 choice
428 prompt "RCU Implementation"
429 default TREE_RCU
431 config TREE_RCU
432 bool "Tree-based hierarchical RCU"
433 depends on !PREEMPT && SMP
434 help
435 This option selects the RCU implementation that is
436 designed for very large SMP system with hundreds or
437 thousands of CPUs. It also scales down nicely to
438 smaller systems.
440 config TREE_PREEMPT_RCU
441 bool "Preemptible tree-based hierarchical RCU"
442 depends on PREEMPT
443 help
444 This option selects the RCU implementation that is
445 designed for very large SMP systems with hundreds or
446 thousands of CPUs, but for which real-time response
447 is also required. It also scales down nicely to
448 smaller systems.
450 Select this option if you are unsure.
452 config TINY_RCU
453 bool "UP-only small-memory-footprint RCU"
454 depends on !PREEMPT && !SMP
455 help
456 This option selects the RCU implementation that is
457 designed for UP systems from which real-time response
458 is not required. This option greatly reduces the
459 memory footprint of RCU.
461 config TINY_PREEMPT_RCU
462 bool "Preemptible UP-only small-memory-footprint RCU"
463 depends on PREEMPT && !SMP
464 help
465 This option selects the RCU implementation that is designed
466 for real-time UP systems. This option greatly reduces the
467 memory footprint of RCU.
469 endchoice
471 config PREEMPT_RCU
472 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
473 help
474 This option enables preemptible-RCU code that is common between
475 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
477 config RCU_STALL_COMMON
478 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
479 help
480 This option enables RCU CPU stall code that is common between
481 the TINY and TREE variants of RCU. The purpose is to allow
482 the tiny variants to disable RCU CPU stall warnings, while
483 making these warnings mandatory for the tree variants.
485 config CONTEXT_TRACKING
486 bool
488 config RCU_USER_QS
489 bool "Consider userspace as in RCU extended quiescent state"
490 depends on HAVE_CONTEXT_TRACKING && SMP
491 select CONTEXT_TRACKING
492 help
493 This option sets hooks on kernel / userspace boundaries and
494 puts RCU in extended quiescent state when the CPU runs in
495 userspace. It means that when a CPU runs in userspace, it is
496 excluded from the global RCU state machine and thus doesn't
497 try to keep the timer tick on for RCU.
499 Unless you want to hack and help the development of the full
500 dynticks mode, you shouldn't enable this option. It also
501 adds unnecessary overhead.
503 If unsure say N
505 config CONTEXT_TRACKING_FORCE
506 bool "Force context tracking"
507 depends on CONTEXT_TRACKING
508 help
509 Probe on user/kernel boundaries by default in order to
510 test the features that rely on it such as userspace RCU extended
511 quiescent states.
512 This test is there for debugging until we have a real user like the
513 full dynticks mode.
515 config RCU_FANOUT
516 int "Tree-based hierarchical RCU fanout value"
517 range 2 64 if 64BIT
518 range 2 32 if !64BIT
519 depends on TREE_RCU || TREE_PREEMPT_RCU
520 default 64 if 64BIT
521 default 32 if !64BIT
522 help
523 This option controls the fanout of hierarchical implementations
524 of RCU, allowing RCU to work efficiently on machines with
525 large numbers of CPUs. This value must be at least the fourth
526 root of NR_CPUS, which allows NR_CPUS to be insanely large.
527 The default value of RCU_FANOUT should be used for production
528 systems, but if you are stress-testing the RCU implementation
529 itself, small RCU_FANOUT values allow you to test large-system
530 code paths on small(er) systems.
532 Select a specific number if testing RCU itself.
533 Take the default if unsure.
535 config RCU_FANOUT_LEAF
536 int "Tree-based hierarchical RCU leaf-level fanout value"
537 range 2 RCU_FANOUT if 64BIT
538 range 2 RCU_FANOUT if !64BIT
539 depends on TREE_RCU || TREE_PREEMPT_RCU
540 default 16
541 help
542 This option controls the leaf-level fanout of hierarchical
543 implementations of RCU, and allows trading off cache misses
544 against lock contention. Systems that synchronize their
545 scheduling-clock interrupts for energy-efficiency reasons will
546 want the default because the smaller leaf-level fanout keeps
547 lock contention levels acceptably low. Very large systems
548 (hundreds or thousands of CPUs) will instead want to set this
549 value to the maximum value possible in order to reduce the
550 number of cache misses incurred during RCU's grace-period
551 initialization. These systems tend to run CPU-bound, and thus
552 are not helped by synchronized interrupts, and thus tend to
553 skew them, which reduces lock contention enough that large
554 leaf-level fanouts work well.
556 Select a specific number if testing RCU itself.
558 Select the maximum permissible value for large systems.
560 Take the default if unsure.
562 config RCU_FANOUT_EXACT
563 bool "Disable tree-based hierarchical RCU auto-balancing"
564 depends on TREE_RCU || TREE_PREEMPT_RCU
565 default n
566 help
567 This option forces use of the exact RCU_FANOUT value specified,
568 regardless of imbalances in the hierarchy. This is useful for
569 testing RCU itself, and might one day be useful on systems with
570 strong NUMA behavior.
572 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
574 Say N if unsure.
576 config RCU_FAST_NO_HZ
577 bool "Accelerate last non-dyntick-idle CPU's grace periods"
578 depends on NO_HZ && SMP
579 default n
580 help
581 This option causes RCU to attempt to accelerate grace periods in
582 order to allow CPUs to enter dynticks-idle state more quickly.
583 On the other hand, this option increases the overhead of the
584 dynticks-idle checking, thus degrading scheduling latency.
586 Say Y if energy efficiency is critically important, and you don't
587 care about real-time response.
589 Say N if you are unsure.
591 config TREE_RCU_TRACE
592 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
593 select DEBUG_FS
594 help
595 This option provides tracing for the TREE_RCU and
596 TREE_PREEMPT_RCU implementations, permitting Makefile to
597 trivially select kernel/rcutree_trace.c.
599 config RCU_BOOST
600 bool "Enable RCU priority boosting"
601 depends on RT_MUTEXES && PREEMPT_RCU
602 default n
603 help
604 This option boosts the priority of preempted RCU readers that
605 block the current preemptible RCU grace period for too long.
606 This option also prevents heavy loads from blocking RCU
607 callback invocation for all flavors of RCU.
609 Say Y here if you are working with real-time apps or heavy loads
610 Say N here if you are unsure.
612 config RCU_BOOST_PRIO
613 int "Real-time priority to boost RCU readers to"
614 range 1 99
615 depends on RCU_BOOST
616 default 1
617 help
618 This option specifies the real-time priority to which long-term
619 preempted RCU readers are to be boosted. If you are working
620 with a real-time application that has one or more CPU-bound
621 threads running at a real-time priority level, you should set
622 RCU_BOOST_PRIO to a priority higher then the highest-priority
623 real-time CPU-bound thread. The default RCU_BOOST_PRIO value
624 of 1 is appropriate in the common case, which is real-time
625 applications that do not have any CPU-bound threads.
627 Some real-time applications might not have a single real-time
628 thread that saturates a given CPU, but instead might have
629 multiple real-time threads that, taken together, fully utilize
630 that CPU. In this case, you should set RCU_BOOST_PRIO to
631 a priority higher than the lowest-priority thread that is
632 conspiring to prevent the CPU from running any non-real-time
633 tasks. For example, if one thread at priority 10 and another
634 thread at priority 5 are between themselves fully consuming
635 the CPU time on a given CPU, then RCU_BOOST_PRIO should be
636 set to priority 6 or higher.
638 Specify the real-time priority, or take the default if unsure.
640 config RCU_BOOST_DELAY
641 int "Milliseconds to delay boosting after RCU grace-period start"
642 range 0 3000
643 depends on RCU_BOOST
644 default 500
645 help
646 This option specifies the time to wait after the beginning of
647 a given grace period before priority-boosting preempted RCU
648 readers blocking that grace period. Note that any RCU reader
649 blocking an expedited RCU grace period is boosted immediately.
651 Accept the default if unsure.
653 config RCU_NOCB_CPU
654 bool "Offload RCU callback processing from boot-selected CPUs"
655 depends on TREE_RCU || TREE_PREEMPT_RCU
656 default n
657 help
658 Use this option to reduce OS jitter for aggressive HPC or
659 real-time workloads. It can also be used to offload RCU
660 callback invocation to energy-efficient CPUs in battery-powered
661 asymmetric multiprocessors.
663 This option offloads callback invocation from the set of
664 CPUs specified at boot time by the rcu_nocbs parameter.
665 For each such CPU, a kthread ("rcuoN") will be created to
666 invoke callbacks, where the "N" is the CPU being offloaded.
667 Nothing prevents this kthread from running on the specified
668 CPUs, but (1) the kthreads may be preempted between each
669 callback, and (2) affinity or cgroups can be used to force
670 the kthreads to run on whatever set of CPUs is desired.
672 Say Y here if you want reduced OS jitter on selected CPUs.
673 Say N here if you are unsure.
675 endmenu # "RCU Subsystem"
677 config IKCONFIG
678 tristate "Kernel .config support"
679 ---help---
680 This option enables the complete Linux kernel ".config" file
681 contents to be saved in the kernel. It provides documentation
682 of which kernel options are used in a running kernel or in an
683 on-disk kernel. This information can be extracted from the kernel
684 image file with the script scripts/extract-ikconfig and used as
685 input to rebuild the current kernel or to build another kernel.
686 It can also be extracted from a running kernel by reading
687 /proc/config.gz if enabled (below).
689 config IKCONFIG_PROC
690 bool "Enable access to .config through /proc/config.gz"
691 depends on IKCONFIG && PROC_FS
692 ---help---
693 This option enables access to the kernel configuration file
694 through /proc/config.gz.
696 config LOG_BUF_SHIFT
697 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
698 range 12 21
699 default 17
700 help
701 Select kernel log buffer size as a power of 2.
702 Examples:
703 17 => 128 KB
704 16 => 64 KB
705 15 => 32 KB
706 14 => 16 KB
707 13 => 8 KB
708 12 => 4 KB
710 #
711 # Architectures with an unreliable sched_clock() should select this:
712 #
713 config HAVE_UNSTABLE_SCHED_CLOCK
714 bool
716 #
717 # For architectures that want to enable the support for NUMA-affine scheduler
718 # balancing logic:
719 #
720 config ARCH_SUPPORTS_NUMA_BALANCING
721 bool
723 # For architectures that (ab)use NUMA to represent different memory regions
724 # all cpu-local but of different latencies, such as SuperH.
725 #
726 config ARCH_WANT_NUMA_VARIABLE_LOCALITY
727 bool
729 #
730 # For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE
731 config ARCH_WANTS_PROT_NUMA_PROT_NONE
732 bool
734 config ARCH_USES_NUMA_PROT_NONE
735 bool
736 default y
737 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE
738 depends on NUMA_BALANCING
740 config NUMA_BALANCING_DEFAULT_ENABLED
741 bool "Automatically enable NUMA aware memory/task placement"
742 default y
743 depends on NUMA_BALANCING
744 help
745 If set, autonumic NUMA balancing will be enabled if running on a NUMA
746 machine.
748 config NUMA_BALANCING
749 bool "Memory placement aware NUMA scheduler"
750 depends on ARCH_SUPPORTS_NUMA_BALANCING
751 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
752 depends on SMP && NUMA && MIGRATION
753 help
754 This option adds support for automatic NUMA aware memory/task placement.
755 The mechanism is quite primitive and is based on migrating memory when
756 it is references to the node the task is running on.
758 This system will be inactive on UMA systems.
760 menuconfig CGROUPS
761 boolean "Control Group support"
762 depends on EVENTFD
763 help
764 This option adds support for grouping sets of processes together, for
765 use with process control subsystems such as Cpusets, CFS, memory
766 controls or device isolation.
767 See
768 - Documentation/scheduler/sched-design-CFS.txt (CFS)
769 - Documentation/cgroups/ (features for grouping, isolation
770 and resource control)
772 Say N if unsure.
774 if CGROUPS
776 config CGROUP_DEBUG
777 bool "Example debug cgroup subsystem"
778 default n
779 help
780 This option enables a simple cgroup subsystem that
781 exports useful debugging information about the cgroups
782 framework.
784 Say N if unsure.
786 config CGROUP_FREEZER
787 bool "Freezer cgroup subsystem"
788 help
789 Provides a way to freeze and unfreeze all tasks in a
790 cgroup.
792 config CGROUP_DEVICE
793 bool "Device controller for cgroups"
794 help
795 Provides a cgroup implementing whitelists for devices which
796 a process in the cgroup can mknod or open.
798 config CPUSETS
799 bool "Cpuset support"
800 help
801 This option will let you create and manage CPUSETs which
802 allow dynamically partitioning a system into sets of CPUs and
803 Memory Nodes and assigning tasks to run only within those sets.
804 This is primarily useful on large SMP or NUMA systems.
806 Say N if unsure.
808 config PROC_PID_CPUSET
809 bool "Include legacy /proc/<pid>/cpuset file"
810 depends on CPUSETS
811 default y
813 config CGROUP_CPUACCT
814 bool "Simple CPU accounting cgroup subsystem"
815 help
816 Provides a simple Resource Controller for monitoring the
817 total CPU consumed by the tasks in a cgroup.
819 config RESOURCE_COUNTERS
820 bool "Resource counters"
821 help
822 This option enables controller independent resource accounting
823 infrastructure that works with cgroups.
825 config MEMCG
826 bool "Memory Resource Controller for Control Groups"
827 depends on RESOURCE_COUNTERS
828 select MM_OWNER
829 help
830 Provides a memory resource controller that manages both anonymous
831 memory and page cache. (See Documentation/cgroups/memory.txt)
833 Note that setting this option increases fixed memory overhead
834 associated with each page of memory in the system. By this,
835 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
836 usage tracking struct at boot. Total amount of this is printed out
837 at boot.
839 Only enable when you're ok with these trade offs and really
840 sure you need the memory resource controller. Even when you enable
841 this, you can set "cgroup_disable=memory" at your boot option to
842 disable memory resource controller and you can avoid overheads.
843 (and lose benefits of memory resource controller)
845 This config option also selects MM_OWNER config option, which
846 could in turn add some fork/exit overhead.
848 config MEMCG_SWAP
849 bool "Memory Resource Controller Swap Extension"
850 depends on MEMCG && SWAP
851 help
852 Add swap management feature to memory resource controller. When you
853 enable this, you can limit mem+swap usage per cgroup. In other words,
854 when you disable this, memory resource controller has no cares to
855 usage of swap...a process can exhaust all of the swap. This extension
856 is useful when you want to avoid exhaustion swap but this itself
857 adds more overheads and consumes memory for remembering information.
858 Especially if you use 32bit system or small memory system, please
859 be careful about enabling this. When memory resource controller
860 is disabled by boot option, this will be automatically disabled and
861 there will be no overhead from this. Even when you set this config=y,
862 if boot option "swapaccount=0" is set, swap will not be accounted.
863 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
864 size is 4096bytes, 512k per 1Gbytes of swap.
865 config MEMCG_SWAP_ENABLED
866 bool "Memory Resource Controller Swap Extension enabled by default"
867 depends on MEMCG_SWAP
868 default y
869 help
870 Memory Resource Controller Swap Extension comes with its price in
871 a bigger memory consumption. General purpose distribution kernels
872 which want to enable the feature but keep it disabled by default
873 and let the user enable it by swapaccount boot command line
874 parameter should have this option unselected.
875 For those who want to have the feature enabled by default should
876 select this option (if, for some reason, they need to disable it
877 then swapaccount=0 does the trick).
878 config MEMCG_KMEM
879 bool "Memory Resource Controller Kernel Memory accounting"
880 depends on MEMCG
881 depends on SLUB || SLAB
882 help
883 The Kernel Memory extension for Memory Resource Controller can limit
884 the amount of memory used by kernel objects in the system. Those are
885 fundamentally different from the entities handled by the standard
886 Memory Controller, which are page-based, and can be swapped. Users of
887 the kmem extension can use it to guarantee that no group of processes
888 will ever exhaust kernel resources alone.
890 config CGROUP_HUGETLB
891 bool "HugeTLB Resource Controller for Control Groups"
892 depends on RESOURCE_COUNTERS && HUGETLB_PAGE
893 default n
894 help
895 Provides a cgroup Resource Controller for HugeTLB pages.
896 When you enable this, you can put a per cgroup limit on HugeTLB usage.
897 The limit is enforced during page fault. Since HugeTLB doesn't
898 support page reclaim, enforcing the limit at page fault time implies
899 that, the application will get SIGBUS signal if it tries to access
900 HugeTLB pages beyond its limit. This requires the application to know
901 beforehand how much HugeTLB pages it would require for its use. The
902 control group is tracked in the third page lru pointer. This means
903 that we cannot use the controller with huge page less than 3 pages.
905 config CGROUP_PERF
906 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
907 depends on PERF_EVENTS && CGROUPS
908 help
909 This option extends the per-cpu mode to restrict monitoring to
910 threads which belong to the cgroup specified and run on the
911 designated cpu.
913 Say N if unsure.
915 menuconfig CGROUP_SCHED
916 bool "Group CPU scheduler"
917 default n
918 help
919 This feature lets CPU scheduler recognize task groups and control CPU
920 bandwidth allocation to such task groups. It uses cgroups to group
921 tasks.
923 if CGROUP_SCHED
924 config FAIR_GROUP_SCHED
925 bool "Group scheduling for SCHED_OTHER"
926 depends on CGROUP_SCHED
927 default CGROUP_SCHED
929 config CFS_BANDWIDTH
930 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
931 depends on FAIR_GROUP_SCHED
932 default n
933 help
934 This option allows users to define CPU bandwidth rates (limits) for
935 tasks running within the fair group scheduler. Groups with no limit
936 set are considered to be unconstrained and will run with no
937 restriction.
938 See tip/Documentation/scheduler/sched-bwc.txt for more information.
940 config RT_GROUP_SCHED
941 bool "Group scheduling for SCHED_RR/FIFO"
942 depends on CGROUP_SCHED
943 default n
944 help
945 This feature lets you explicitly allocate real CPU bandwidth
946 to task groups. If enabled, it will also make it impossible to
947 schedule realtime tasks for non-root users until you allocate
948 realtime bandwidth for them.
949 See Documentation/scheduler/sched-rt-group.txt for more information.
951 endif #CGROUP_SCHED
953 config BLK_CGROUP
954 bool "Block IO controller"
955 depends on BLOCK
956 default n
957 ---help---
958 Generic block IO controller cgroup interface. This is the common
959 cgroup interface which should be used by various IO controlling
960 policies.
962 Currently, CFQ IO scheduler uses it to recognize task groups and
963 control disk bandwidth allocation (proportional time slice allocation)
964 to such task groups. It is also used by bio throttling logic in
965 block layer to implement upper limit in IO rates on a device.
967 This option only enables generic Block IO controller infrastructure.
968 One needs to also enable actual IO controlling logic/policy. For
969 enabling proportional weight division of disk bandwidth in CFQ, set
970 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
971 CONFIG_BLK_DEV_THROTTLING=y.
973 See Documentation/cgroups/blkio-controller.txt for more information.
975 config DEBUG_BLK_CGROUP
976 bool "Enable Block IO controller debugging"
977 depends on BLK_CGROUP
978 default n
979 ---help---
980 Enable some debugging help. Currently it exports additional stat
981 files in a cgroup which can be useful for debugging.
983 endif # CGROUPS
985 config CHECKPOINT_RESTORE
986 bool "Checkpoint/restore support" if EXPERT
987 default n
988 help
989 Enables additional kernel features in a sake of checkpoint/restore.
990 In particular it adds auxiliary prctl codes to setup process text,
991 data and heap segment sizes, and a few additional /proc filesystem
992 entries.
994 If unsure, say N here.
996 menuconfig NAMESPACES
997 bool "Namespaces support" if EXPERT
998 default !EXPERT
999 help
1000 Provides the way to make tasks work with different objects using
1001 the same id. For example same IPC id may refer to different objects
1002 or same user id or pid may refer to different tasks when used in
1003 different namespaces.
1005 if NAMESPACES
1007 config UTS_NS
1008 bool "UTS namespace"
1009 default y
1010 help
1011 In this namespace tasks see different info provided with the
1012 uname() system call
1014 config IPC_NS
1015 bool "IPC namespace"
1016 depends on (SYSVIPC || POSIX_MQUEUE)
1017 default y
1018 help
1019 In this namespace tasks work with IPC ids which correspond to
1020 different IPC objects in different namespaces.
1022 config USER_NS
1023 bool "User namespace"
1024 depends on UIDGID_CONVERTED
1025 select UIDGID_STRICT_TYPE_CHECKS
1027 default n
1028 help
1029 This allows containers, i.e. vservers, to use user namespaces
1030 to provide different user info for different servers.
1032 When user namespaces are enabled in the kernel it is
1033 recommended that the MEMCG and MEMCG_KMEM options also be
1034 enabled and that user-space use the memory control groups to
1035 limit the amount of memory a memory unprivileged users can
1036 use.
1038 If unsure, say N.
1040 config PID_NS
1041 bool "PID Namespaces"
1042 default y
1043 help
1044 Support process id namespaces. This allows having multiple
1045 processes with the same pid as long as they are in different
1046 pid namespaces. This is a building block of containers.
1048 config NET_NS
1049 bool "Network namespace"
1050 depends on NET
1051 default y
1052 help
1053 Allow user space to create what appear to be multiple instances
1054 of the network stack.
1056 endif # NAMESPACES
1058 config UIDGID_CONVERTED
1059 # True if all of the selected software conmponents are known
1060 # to have uid_t and gid_t converted to kuid_t and kgid_t
1061 # where appropriate and are otherwise safe to use with
1062 # the user namespace.
1063 bool
1064 default y
1066 # Filesystems
1067 depends on XFS_FS = n
1069 config UIDGID_STRICT_TYPE_CHECKS
1070 bool "Require conversions between uid/gids and their internal representation"
1071 depends on UIDGID_CONVERTED
1072 default n
1073 help
1074 While the nececessary conversions are being added to all subsystems this option allows
1075 the code to continue to build for unconverted subsystems.
1077 Say Y here if you want the strict type checking enabled
1079 config SCHED_AUTOGROUP
1080 bool "Automatic process group scheduling"
1081 select EVENTFD
1082 select CGROUPS
1083 select CGROUP_SCHED
1084 select FAIR_GROUP_SCHED
1085 help
1086 This option optimizes the scheduler for common desktop workloads by
1087 automatically creating and populating task groups. This separation
1088 of workloads isolates aggressive CPU burners (like build jobs) from
1089 desktop applications. Task group autogeneration is currently based
1090 upon task session.
1092 config MM_OWNER
1093 bool
1095 config SYSFS_DEPRECATED
1096 bool "Enable deprecated sysfs features to support old userspace tools"
1097 depends on SYSFS
1098 default n
1099 help
1100 This option adds code that switches the layout of the "block" class
1101 devices, to not show up in /sys/class/block/, but only in
1102 /sys/block/.
1104 This switch is only active when the sysfs.deprecated=1 boot option is
1105 passed or the SYSFS_DEPRECATED_V2 option is set.
1107 This option allows new kernels to run on old distributions and tools,
1108 which might get confused by /sys/class/block/. Since 2007/2008 all
1109 major distributions and tools handle this just fine.
1111 Recent distributions and userspace tools after 2009/2010 depend on
1112 the existence of /sys/class/block/, and will not work with this
1113 option enabled.
1115 Only if you are using a new kernel on an old distribution, you might
1116 need to say Y here.
1118 config SYSFS_DEPRECATED_V2
1119 bool "Enable deprecated sysfs features by default"
1120 default n
1121 depends on SYSFS
1122 depends on SYSFS_DEPRECATED
1123 help
1124 Enable deprecated sysfs by default.
1126 See the CONFIG_SYSFS_DEPRECATED option for more details about this
1127 option.
1129 Only if you are using a new kernel on an old distribution, you might
1130 need to say Y here. Even then, odds are you would not need it
1131 enabled, you can always pass the boot option if absolutely necessary.
1133 config RELAY
1134 bool "Kernel->user space relay support (formerly relayfs)"
1135 help
1136 This option enables support for relay interface support in
1137 certain file systems (such as debugfs).
1138 It is designed to provide an efficient mechanism for tools and
1139 facilities to relay large amounts of data from kernel space to
1140 user space.
1142 If unsure, say N.
1144 config BLK_DEV_INITRD
1145 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1146 depends on BROKEN || !FRV
1147 help
1148 The initial RAM filesystem is a ramfs which is loaded by the
1149 boot loader (loadlin or lilo) and that is mounted as root
1150 before the normal boot procedure. It is typically used to
1151 load modules needed to mount the "real" root file system,
1152 etc. See <file:Documentation/initrd.txt> for details.
1154 If RAM disk support (BLK_DEV_RAM) is also included, this
1155 also enables initial RAM disk (initrd) support and adds
1156 15 Kbytes (more on some other architectures) to the kernel size.
1158 If unsure say Y.
1160 if BLK_DEV_INITRD
1162 source "usr/Kconfig"
1164 endif
1166 config CC_OPTIMIZE_FOR_SIZE
1167 bool "Optimize for size"
1168 help
1169 Enabling this option will pass "-Os" instead of "-O2" to gcc
1170 resulting in a smaller kernel.
1172 If unsure, say N.
1174 config SYSCTL
1175 bool
1177 config ANON_INODES
1178 bool
1180 menuconfig EXPERT
1181 bool "Configure standard kernel features (expert users)"
1182 # Unhide debug options, to make the on-by-default options visible
1183 select DEBUG_KERNEL
1184 help
1185 This option allows certain base kernel options and settings
1186 to be disabled or tweaked. This is for specialized
1187 environments which can tolerate a "non-standard" kernel.
1188 Only use this if you really know what you are doing.
1190 config HAVE_UID16
1191 bool
1193 config UID16
1194 bool "Enable 16-bit UID system calls" if EXPERT
1195 depends on HAVE_UID16
1196 default y
1197 help
1198 This enables the legacy 16-bit UID syscall wrappers.
1200 config SYSCTL_SYSCALL
1201 bool "Sysctl syscall support" if EXPERT
1202 depends on PROC_SYSCTL
1203 default n
1204 select SYSCTL
1205 ---help---
1206 sys_sysctl uses binary paths that have been found challenging
1207 to properly maintain and use. The interface in /proc/sys
1208 using paths with ascii names is now the primary path to this
1209 information.
1211 Almost nothing using the binary sysctl interface so if you are
1212 trying to save some space it is probably safe to disable this,
1213 making your kernel marginally smaller.
1215 If unsure say N here.
1217 config SYSCTL_EXCEPTION_TRACE
1218 bool
1219 help
1220 Enable support for /proc/sys/debug/exception-trace.
1222 config SYSCTL_ARCH_UNALIGN_NO_WARN
1223 bool
1224 help
1225 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1226 Allows arch to define/use @no_unaligned_warning to possibly warn
1227 about unaligned access emulation going on under the hood.
1229 config SYSCTL_ARCH_UNALIGN_ALLOW
1230 bool
1231 help
1232 Enable support for /proc/sys/kernel/unaligned-trap
1233 Allows arches to define/use @unaligned_enabled to runtime toggle
1234 the unaligned access emulation.
1235 see arch/parisc/kernel/unaligned.c for reference
1237 config KALLSYMS
1238 bool "Load all symbols for debugging/ksymoops" if EXPERT
1239 default y
1240 help
1241 Say Y here to let the kernel print out symbolic crash information and
1242 symbolic stack backtraces. This increases the size of the kernel
1243 somewhat, as all symbols have to be loaded into the kernel image.
1245 config KALLSYMS_ALL
1246 bool "Include all symbols in kallsyms"
1247 depends on DEBUG_KERNEL && KALLSYMS
1248 help
1249 Normally kallsyms only contains the symbols of functions for nicer
1250 OOPS messages and backtraces (i.e., symbols from the text and inittext
1251 sections). This is sufficient for most cases. And only in very rare
1252 cases (e.g., when a debugger is used) all symbols are required (e.g.,
1253 names of variables from the data sections, etc).
1255 This option makes sure that all symbols are loaded into the kernel
1256 image (i.e., symbols from all sections) in cost of increased kernel
1257 size (depending on the kernel configuration, it may be 300KiB or
1258 something like this).
1260 Say N unless you really need all symbols.
1262 config HOTPLUG
1263 def_bool y
1265 config PRINTK
1266 default y
1267 bool "Enable support for printk" if EXPERT
1268 select IRQ_WORK
1269 help
1270 This option enables normal printk support. Removing it
1271 eliminates most of the message strings from the kernel image
1272 and makes the kernel more or less silent. As this makes it
1273 very difficult to diagnose system problems, saying N here is
1274 strongly discouraged.
1276 config BUG
1277 bool "BUG() support" if EXPERT
1278 default y
1279 help
1280 Disabling this option eliminates support for BUG and WARN, reducing
1281 the size of your kernel image and potentially quietly ignoring
1282 numerous fatal conditions. You should only consider disabling this
1283 option for embedded systems with no facilities for reporting errors.
1284 Just say Y.
1286 config ELF_CORE
1287 depends on COREDUMP
1288 default y
1289 bool "Enable ELF core dumps" if EXPERT
1290 help
1291 Enable support for generating core dumps. Disabling saves about 4k.
1294 config PCSPKR_PLATFORM
1295 bool "Enable PC-Speaker support" if EXPERT
1296 depends on HAVE_PCSPKR_PLATFORM
1297 select I8253_LOCK
1298 default y
1299 help
1300 This option allows to disable the internal PC-Speaker
1301 support, saving some memory.
1303 config HAVE_PCSPKR_PLATFORM
1304 bool
1306 config BASE_FULL
1307 default y
1308 bool "Enable full-sized data structures for core" if EXPERT
1309 help
1310 Disabling this option reduces the size of miscellaneous core
1311 kernel data structures. This saves memory on small machines,
1312 but may reduce performance.
1314 config FUTEX
1315 bool "Enable futex support" if EXPERT
1316 default y
1317 select RT_MUTEXES
1318 help
1319 Disabling this option will cause the kernel to be built without
1320 support for "fast userspace mutexes". The resulting kernel may not
1321 run glibc-based applications correctly.
1323 config EPOLL
1324 bool "Enable eventpoll support" if EXPERT
1325 default y
1326 select ANON_INODES
1327 help
1328 Disabling this option will cause the kernel to be built without
1329 support for epoll family of system calls.
1331 config SIGNALFD
1332 bool "Enable signalfd() system call" if EXPERT
1333 select ANON_INODES
1334 default y
1335 help
1336 Enable the signalfd() system call that allows to receive signals
1337 on a file descriptor.
1339 If unsure, say Y.
1341 config TIMERFD
1342 bool "Enable timerfd() system call" if EXPERT
1343 select ANON_INODES
1344 default y
1345 help
1346 Enable the timerfd() system call that allows to receive timer
1347 events on a file descriptor.
1349 If unsure, say Y.
1351 config EVENTFD
1352 bool "Enable eventfd() system call" if EXPERT
1353 select ANON_INODES
1354 default y
1355 help
1356 Enable the eventfd() system call that allows to receive both
1357 kernel notification (ie. KAIO) or userspace notifications.
1359 If unsure, say Y.
1361 config SHMEM
1362 bool "Use full shmem filesystem" if EXPERT
1363 default y
1364 depends on MMU
1365 help
1366 The shmem is an internal filesystem used to manage shared memory.
1367 It is backed by swap and manages resource limits. It is also exported
1368 to userspace as tmpfs if TMPFS is enabled. Disabling this
1369 option replaces shmem and tmpfs with the much simpler ramfs code,
1370 which may be appropriate on small systems without swap.
1372 config AIO
1373 bool "Enable AIO support" if EXPERT
1374 default y
1375 help
1376 This option enables POSIX asynchronous I/O which may by used
1377 by some high performance threaded applications. Disabling
1378 this option saves about 7k.
1380 config EMBEDDED
1381 bool "Embedded system"
1382 select EXPERT
1383 help
1384 This option should be enabled if compiling the kernel for
1385 an embedded system so certain expert options are available
1386 for configuration.
1388 config HAVE_PERF_EVENTS
1389 bool
1390 help
1391 See tools/perf/design.txt for details.
1393 config PERF_USE_VMALLOC
1394 bool
1395 help
1396 See tools/perf/design.txt for details
1398 menu "Kernel Performance Events And Counters"
1400 config PERF_EVENTS
1401 bool "Kernel performance events and counters"
1402 default y if PROFILING
1403 depends on HAVE_PERF_EVENTS
1404 select ANON_INODES
1405 select IRQ_WORK
1406 help
1407 Enable kernel support for various performance events provided
1408 by software and hardware.
1410 Software events are supported either built-in or via the
1411 use of generic tracepoints.
1413 Most modern CPUs support performance events via performance
1414 counter registers. These registers count the number of certain
1415 types of hw events: such as instructions executed, cachemisses
1416 suffered, or branches mis-predicted - without slowing down the
1417 kernel or applications. These registers can also trigger interrupts
1418 when a threshold number of events have passed - and can thus be
1419 used to profile the code that runs on that CPU.
1421 The Linux Performance Event subsystem provides an abstraction of
1422 these software and hardware event capabilities, available via a
1423 system call and used by the "perf" utility in tools/perf/. It
1424 provides per task and per CPU counters, and it provides event
1425 capabilities on top of those.
1427 Say Y if unsure.
1429 config DEBUG_PERF_USE_VMALLOC
1430 default n
1431 bool "Debug: use vmalloc to back perf mmap() buffers"
1432 depends on PERF_EVENTS && DEBUG_KERNEL
1433 select PERF_USE_VMALLOC
1434 help
1435 Use vmalloc memory to back perf mmap() buffers.
1437 Mostly useful for debugging the vmalloc code on platforms
1438 that don't require it.
1440 Say N if unsure.
1442 endmenu
1444 config VM_EVENT_COUNTERS
1445 default y
1446 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1447 help
1448 VM event counters are needed for event counts to be shown.
1449 This option allows the disabling of the VM event counters
1450 on EXPERT systems. /proc/vmstat will only show page counts
1451 if VM event counters are disabled.
1453 config PCI_QUIRKS
1454 default y
1455 bool "Enable PCI quirk workarounds" if EXPERT
1456 depends on PCI
1457 help
1458 This enables workarounds for various PCI chipset
1459 bugs/quirks. Disable this only if your target machine is
1460 unaffected by PCI quirks.
1462 config SLUB_DEBUG
1463 default y
1464 bool "Enable SLUB debugging support" if EXPERT
1465 depends on SLUB && SYSFS
1466 help
1467 SLUB has extensive debug support features. Disabling these can
1468 result in significant savings in code size. This also disables
1469 SLUB sysfs support. /sys/slab will not exist and there will be
1470 no support for cache validation etc.
1472 config COMPAT_BRK
1473 bool "Disable heap randomization"
1474 default y
1475 help
1476 Randomizing heap placement makes heap exploits harder, but it
1477 also breaks ancient binaries (including anything libc5 based).
1478 This option changes the bootup default to heap randomization
1479 disabled, and can be overridden at runtime by setting
1480 /proc/sys/kernel/randomize_va_space to 2.
1482 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1484 choice
1485 prompt "Choose SLAB allocator"
1486 default SLUB
1487 help
1488 This option allows to select a slab allocator.
1490 config SLAB
1491 bool "SLAB"
1492 help
1493 The regular slab allocator that is established and known to work
1494 well in all environments. It organizes cache hot objects in
1495 per cpu and per node queues.
1497 config SLUB
1498 bool "SLUB (Unqueued Allocator)"
1499 help
1500 SLUB is a slab allocator that minimizes cache line usage
1501 instead of managing queues of cached objects (SLAB approach).
1502 Per cpu caching is realized using slabs of objects instead
1503 of queues of objects. SLUB can use memory efficiently
1504 and has enhanced diagnostics. SLUB is the default choice for
1505 a slab allocator.
1507 config SLOB
1508 depends on EXPERT
1509 bool "SLOB (Simple Allocator)"
1510 help
1511 SLOB replaces the stock allocator with a drastically simpler
1512 allocator. SLOB is generally more space efficient but
1513 does not perform as well on large systems.
1515 endchoice
1517 config MMAP_ALLOW_UNINITIALIZED
1518 bool "Allow mmapped anonymous memory to be uninitialized"
1519 depends on EXPERT && !MMU
1520 default n
1521 help
1522 Normally, and according to the Linux spec, anonymous memory obtained
1523 from mmap() has it's contents cleared before it is passed to
1524 userspace. Enabling this config option allows you to request that
1525 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1526 providing a huge performance boost. If this option is not enabled,
1527 then the flag will be ignored.
1529 This is taken advantage of by uClibc's malloc(), and also by
1530 ELF-FDPIC binfmt's brk and stack allocator.
1532 Because of the obvious security issues, this option should only be
1533 enabled on embedded devices where you control what is run in
1534 userspace. Since that isn't generally a problem on no-MMU systems,
1535 it is normally safe to say Y here.
1537 See Documentation/nommu-mmap.txt for more information.
1539 config PROFILING
1540 bool "Profiling support"
1541 help
1542 Say Y here to enable the extended profiling support mechanisms used
1543 by profilers such as OProfile.
1545 #
1546 # Place an empty function call at each tracepoint site. Can be
1547 # dynamically changed for a probe function.
1548 #
1549 config TRACEPOINTS
1550 bool
1552 source "arch/Kconfig"
1554 endmenu # General setup
1556 config HAVE_GENERIC_DMA_COHERENT
1557 bool
1558 default n
1560 config SLABINFO
1561 bool
1562 depends on PROC_FS
1563 depends on SLAB || SLUB_DEBUG
1564 default y
1566 config RT_MUTEXES
1567 boolean
1569 config BASE_SMALL
1570 int
1571 default 0 if BASE_FULL
1572 default 1 if !BASE_FULL
1574 menuconfig MODULES
1575 bool "Enable loadable module support"
1576 help
1577 Kernel modules are small pieces of compiled code which can
1578 be inserted in the running kernel, rather than being
1579 permanently built into the kernel. You use the "modprobe"
1580 tool to add (and sometimes remove) them. If you say Y here,
1581 many parts of the kernel can be built as modules (by
1582 answering M instead of Y where indicated): this is most
1583 useful for infrequently used options which are not required
1584 for booting. For more information, see the man pages for
1585 modprobe, lsmod, modinfo, insmod and rmmod.
1587 If you say Y here, you will need to run "make
1588 modules_install" to put the modules under /lib/modules/
1589 where modprobe can find them (you may need to be root to do
1590 this).
1592 If unsure, say Y.
1594 if MODULES
1596 config MODULE_FORCE_LOAD
1597 bool "Forced module loading"
1598 default n
1599 help
1600 Allow loading of modules without version information (ie. modprobe
1601 --force). Forced module loading sets the 'F' (forced) taint flag and
1602 is usually a really bad idea.
1604 config MODULE_UNLOAD
1605 bool "Module unloading"
1606 help
1607 Without this option you will not be able to unload any
1608 modules (note that some modules may not be unloadable
1609 anyway), which makes your kernel smaller, faster
1610 and simpler. If unsure, say Y.
1612 config MODULE_FORCE_UNLOAD
1613 bool "Forced module unloading"
1614 depends on MODULE_UNLOAD
1615 help
1616 This option allows you to force a module to unload, even if the
1617 kernel believes it is unsafe: the kernel will remove the module
1618 without waiting for anyone to stop using it (using the -f option to
1619 rmmod). This is mainly for kernel developers and desperate users.
1620 If unsure, say N.
1622 config MODVERSIONS
1623 bool "Module versioning support"
1624 help
1625 Usually, you have to use modules compiled with your kernel.
1626 Saying Y here makes it sometimes possible to use modules
1627 compiled for different kernels, by adding enough information
1628 to the modules to (hopefully) spot any changes which would
1629 make them incompatible with the kernel you are running. If
1630 unsure, say N.
1632 config MODULE_SRCVERSION_ALL
1633 bool "Source checksum for all modules"
1634 help
1635 Modules which contain a MODULE_VERSION get an extra "srcversion"
1636 field inserted into their modinfo section, which contains a
1637 sum of the source files which made it. This helps maintainers
1638 see exactly which source was used to build a module (since
1639 others sometimes change the module source without updating
1640 the version). With this option, such a "srcversion" field
1641 will be created for all modules. If unsure, say N.
1643 config MODULE_SIG
1644 bool "Module signature verification"
1645 depends on MODULES
1646 select KEYS
1647 select CRYPTO
1648 select ASYMMETRIC_KEY_TYPE
1649 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1650 select PUBLIC_KEY_ALGO_RSA
1651 select ASN1
1652 select OID_REGISTRY
1653 select X509_CERTIFICATE_PARSER
1654 help
1655 Check modules for valid signatures upon load: the signature
1656 is simply appended to the module. For more information see
1657 Documentation/module-signing.txt.
1659 !!!WARNING!!! If you enable this option, you MUST make sure that the
1660 module DOES NOT get stripped after being signed. This includes the
1661 debuginfo strip done by some packagers (such as rpmbuild) and
1662 inclusion into an initramfs that wants the module size reduced.
1664 config MODULE_SIG_FORCE
1665 bool "Require modules to be validly signed"
1666 depends on MODULE_SIG
1667 help
1668 Reject unsigned modules or signed modules for which we don't have a
1669 key. Without this, such modules will simply taint the kernel.
1671 config MODULE_SIG_ALL
1672 bool "Automatically sign all modules"
1673 default y
1674 depends on MODULE_SIG
1675 help
1676 Sign all modules during make modules_install. Without this option,
1677 modules must be signed manually, using the scripts/sign-file tool.
1679 comment "Do not forget to sign required modules with scripts/sign-file"
1680 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1682 choice
1683 prompt "Which hash algorithm should modules be signed with?"
1684 depends on MODULE_SIG
1685 help
1686 This determines which sort of hashing algorithm will be used during
1687 signature generation. This algorithm _must_ be built into the kernel
1688 directly so that signature verification can take place. It is not
1689 possible to load a signed module containing the algorithm to check
1690 the signature on that module.
1692 config MODULE_SIG_SHA1
1693 bool "Sign modules with SHA-1"
1694 select CRYPTO_SHA1
1696 config MODULE_SIG_SHA224
1697 bool "Sign modules with SHA-224"
1698 select CRYPTO_SHA256
1700 config MODULE_SIG_SHA256
1701 bool "Sign modules with SHA-256"
1702 select CRYPTO_SHA256
1704 config MODULE_SIG_SHA384
1705 bool "Sign modules with SHA-384"
1706 select CRYPTO_SHA512
1708 config MODULE_SIG_SHA512
1709 bool "Sign modules with SHA-512"
1710 select CRYPTO_SHA512
1712 endchoice
1714 config MODULE_SIG_HASH
1715 string
1716 depends on MODULE_SIG
1717 default "sha1" if MODULE_SIG_SHA1
1718 default "sha224" if MODULE_SIG_SHA224
1719 default "sha256" if MODULE_SIG_SHA256
1720 default "sha384" if MODULE_SIG_SHA384
1721 default "sha512" if MODULE_SIG_SHA512
1723 endif # MODULES
1725 config INIT_ALL_POSSIBLE
1726 bool
1727 help
1728 Back when each arch used to define their own cpu_online_mask and
1729 cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1730 with all 1s, and others with all 0s. When they were centralised,
1731 it was better to provide this option than to break all the archs
1732 and have several arch maintainers pursuing me down dark alleys.
1734 config STOP_MACHINE
1735 bool
1736 default y
1737 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1738 help
1739 Need stop_machine() primitive.
1741 source "block/Kconfig"
1743 config PREEMPT_NOTIFIERS
1744 bool
1746 config PADATA
1747 depends on SMP
1748 bool
1750 # Can be selected by architectures with broken toolchains
1751 # that get confused by correct const<->read_only section
1752 # mappings
1753 config BROKEN_RODATA
1754 bool
1756 config ASN1
1757 tristate
1758 help
1759 Build a simple ASN.1 grammar compiler that produces a bytecode output
1760 that can be interpreted by the ASN.1 stream decoder and used to
1761 inform it as to what tags are to be expected in a stream and what
1762 functions to call on what tags.
1764 source "kernel/Kconfig.locks"