7 option env="KERNELVERSION"
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"
29 depends on HAVE_IRQ_WORK
34 bool "Prompt for development and/or incomplete code/drivers"
36 Some of the various things that Linux supports (such as network
37 drivers, file systems, network protocols, etc.) can be in a state
38 of development where the functionality, stability, or the level of
39 testing is not yet high enough for general use. This is usually
40 known as the "alpha-test" phase among developers. If a feature is
41 currently in alpha-test, then the developers usually discourage
42 uninformed widespread use of this feature by the general public to
43 avoid "Why doesn't this work?" type mail messages. However, active
44 testing and use of these systems is welcomed. Just be aware that it
45 may not meet the normal level of reliability or it may fail to work
46 in some special cases. Detailed bug reports from people familiar
47 with the kernel internals are usually welcomed by the developers
48 (before submitting bug reports, please read the documents
49 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
50 <file:Documentation/BUG-HUNTING>, and
51 <file:Documentation/oops-tracing.txt> in the kernel source).
53 This option will also make obsoleted drivers available. These are
54 drivers that have been replaced by something else, and/or are
55 scheduled to be removed in a future kernel release.
57 Unless you intend to help test and develop a feature or driver that
58 falls into this category, or you have a situation that requires
59 using these features, you should probably say N here, which will
60 cause the configurator to present you with fewer choices. If
61 you say Y here, you will be offered the choice of using features or
62 drivers that are currently considered to be in the alpha-test phase.
69 depends on BROKEN || !SMP
74 depends on (SMP || PREEMPT) && BKL
77 config INIT_ENV_ARG_LIMIT
82 Maximum of each of the number of arguments and environment
83 variables passed to init from the kernel command line.
87 string "Cross-compiler tool prefix"
89 Same as running 'make CROSS_COMPILE=prefix-' but stored for
90 default make runs in this kernel build directory. You don't
91 need to set this unless you want the configured kernel build
92 directory to select the cross-compiler automatically.
95 string "Local version - append to kernel release"
97 Append an extra string to the end of your kernel version.
98 This will show up when you type uname, for example.
99 The string you set here will be appended after the contents of
100 any files with a filename matching localversion* in your
101 object and source tree, in that order. Your total string can
102 be a maximum of 64 characters.
104 config LOCALVERSION_AUTO
105 bool "Automatically append version information to the version string"
108 This will try to automatically determine if the current tree is a
109 release tree by looking for git tags that belong to the current
110 top of tree revision.
112 A string of the format -gxxxxxxxx will be added to the localversion
113 if a git-based tree is found. The string generated by this will be
114 appended after any matching localversion* files, and after the value
115 set in CONFIG_LOCALVERSION.
117 (The actual string used here is the first eight characters produced
118 by running the command:
120 $ git rev-parse --verify HEAD
122 which is done within the script "scripts/setlocalversion".)
124 config HAVE_KERNEL_GZIP
127 config HAVE_KERNEL_BZIP2
130 config HAVE_KERNEL_LZMA
133 config HAVE_KERNEL_XZ
136 config HAVE_KERNEL_LZO
140 prompt "Kernel compression mode"
142 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
144 The linux kernel is a kind of self-extracting executable.
145 Several compression algorithms are available, which differ
146 in efficiency, compression and decompression speed.
147 Compression speed is only relevant when building a kernel.
148 Decompression speed is relevant at each boot.
150 If you have any problems with bzip2 or lzma compressed
151 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
152 version of this functionality (bzip2 only), for 2.4, was
153 supplied by Christian Ludwig)
155 High compression options are mostly useful for users, who
156 are low on disk space (embedded systems), but for whom ram
159 If in doubt, select 'gzip'
163 depends on HAVE_KERNEL_GZIP
165 The old and tried gzip compression. It provides a good balance
166 between compression ratio and decompression speed.
170 depends on HAVE_KERNEL_BZIP2
172 Its compression ratio and speed is intermediate.
173 Decompression speed is slowest among the three. The kernel
174 size is about 10% smaller with bzip2, in comparison to gzip.
175 Bzip2 uses a large amount of memory. For modern kernels you
176 will need at least 8MB RAM or more for booting.
180 depends on HAVE_KERNEL_LZMA
182 The most recent compression algorithm.
183 Its ratio is best, decompression speed is between the other
184 two. Compression is slowest. The kernel size is about 33%
185 smaller with LZMA in comparison to gzip.
189 depends on HAVE_KERNEL_XZ
191 XZ uses the LZMA2 algorithm and instruction set specific
192 BCJ filters which can improve compression ratio of executable
193 code. The size of the kernel is about 30% smaller with XZ in
194 comparison to gzip. On architectures for which there is a BCJ
195 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
196 will create a few percent smaller kernel than plain LZMA.
198 The speed is about the same as with LZMA: The decompression
199 speed of XZ is better than that of bzip2 but worse than gzip
200 and LZO. Compression is slow.
204 depends on HAVE_KERNEL_LZO
206 Its compression ratio is the poorest among the 4. The kernel
207 size is about 10% bigger than gzip; however its speed
208 (both compression and decompression) is the fastest.
213 bool "Support for paging of anonymous memory (swap)"
214 depends on MMU && BLOCK
217 This option allows you to choose whether you want to have support
218 for so called swap devices or swap files in your kernel that are
219 used to provide more virtual memory than the actual RAM present
220 in your computer. If unsure say Y.
225 Inter Process Communication is a suite of library functions and
226 system calls which let processes (running programs) synchronize and
227 exchange information. It is generally considered to be a good thing,
228 and some programs won't run unless you say Y here. In particular, if
229 you want to run the DOS emulator dosemu under Linux (read the
230 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
231 you'll need to say Y here.
233 You can find documentation about IPC with "info ipc" and also in
234 section 6.4 of the Linux Programmer's Guide, available from
235 <http://www.tldp.org/guides.html>.
237 config SYSVIPC_SYSCTL
244 bool "POSIX Message Queues"
245 depends on NET && EXPERIMENTAL
247 POSIX variant of message queues is a part of IPC. In POSIX message
248 queues every message has a priority which decides about succession
249 of receiving it by a process. If you want to compile and run
250 programs written e.g. for Solaris with use of its POSIX message
251 queues (functions mq_*) say Y here.
253 POSIX message queues are visible as a filesystem called 'mqueue'
254 and can be mounted somewhere if you want to do filesystem
255 operations on message queues.
259 config POSIX_MQUEUE_SYSCTL
261 depends on POSIX_MQUEUE
265 config BSD_PROCESS_ACCT
266 bool "BSD Process Accounting"
268 If you say Y here, a user level program will be able to instruct the
269 kernel (via a special system call) to write process accounting
270 information to a file: whenever a process exits, information about
271 that process will be appended to the file by the kernel. The
272 information includes things such as creation time, owning user,
273 command name, memory usage, controlling terminal etc. (the complete
274 list is in the struct acct in <file:include/linux/acct.h>). It is
275 up to the user level program to do useful things with this
276 information. This is generally a good idea, so say Y.
278 config BSD_PROCESS_ACCT_V3
279 bool "BSD Process Accounting version 3 file format"
280 depends on BSD_PROCESS_ACCT
283 If you say Y here, the process accounting information is written
284 in a new file format that also logs the process IDs of each
285 process and it's parent. Note that this file format is incompatible
286 with previous v0/v1/v2 file formats, so you will need updated tools
287 for processing it. A preliminary version of these tools is available
288 at <http://www.gnu.org/software/acct/>.
291 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
295 Export selected statistics for tasks/processes through the
296 generic netlink interface. Unlike BSD process accounting, the
297 statistics are available during the lifetime of tasks/processes as
298 responses to commands. Like BSD accounting, they are sent to user
303 config TASK_DELAY_ACCT
304 bool "Enable per-task delay accounting (EXPERIMENTAL)"
307 Collect information on time spent by a task waiting for system
308 resources like cpu, synchronous block I/O completion and swapping
309 in pages. Such statistics can help in setting a task's priorities
310 relative to other tasks for cpu, io, rss limits etc.
315 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
318 Collect extended task accounting data and send the data
319 to userland for processing over the taskstats interface.
323 config TASK_IO_ACCOUNTING
324 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
325 depends on TASK_XACCT
327 Collect information on the number of bytes of storage I/O which this
333 bool "Auditing support"
336 Enable auditing infrastructure that can be used with another
337 kernel subsystem, such as SELinux (which requires this for
338 logging of avc messages output). Does not do system-call
339 auditing without CONFIG_AUDITSYSCALL.
342 bool "Enable system-call auditing support"
343 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
344 default y if SECURITY_SELINUX
346 Enable low-overhead system-call auditing infrastructure that
347 can be used independently or with another kernel subsystem,
352 depends on AUDITSYSCALL
357 depends on AUDITSYSCALL
360 source "kernel/irq/Kconfig"
365 prompt "RCU Implementation"
369 bool "Tree-based hierarchical RCU"
370 depends on !PREEMPT && SMP
372 This option selects the RCU implementation that is
373 designed for very large SMP system with hundreds or
374 thousands of CPUs. It also scales down nicely to
377 config TREE_PREEMPT_RCU
378 bool "Preemptible tree-based hierarchical RCU"
381 This option selects the RCU implementation that is
382 designed for very large SMP systems with hundreds or
383 thousands of CPUs, but for which real-time response
384 is also required. It also scales down nicely to
388 bool "UP-only small-memory-footprint RCU"
391 This option selects the RCU implementation that is
392 designed for UP systems from which real-time response
393 is not required. This option greatly reduces the
394 memory footprint of RCU.
396 config TINY_PREEMPT_RCU
397 bool "Preemptible UP-only small-memory-footprint RCU"
398 depends on !SMP && PREEMPT
400 This option selects the RCU implementation that is designed
401 for real-time UP systems. This option greatly reduces the
402 memory footprint of RCU.
407 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
409 This option enables preemptible-RCU code that is common between
410 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
413 bool "Enable tracing for RCU"
415 This option provides tracing in RCU which presents stats
416 in debugfs for debugging RCU implementation.
418 Say Y here if you want to enable RCU tracing
419 Say N if you are unsure.
422 int "Tree-based hierarchical RCU fanout value"
425 depends on TREE_RCU || TREE_PREEMPT_RCU
429 This option controls the fanout of hierarchical implementations
430 of RCU, allowing RCU to work efficiently on machines with
431 large numbers of CPUs. This value must be at least the fourth
432 root of NR_CPUS, which allows NR_CPUS to be insanely large.
433 The default value of RCU_FANOUT should be used for production
434 systems, but if you are stress-testing the RCU implementation
435 itself, small RCU_FANOUT values allow you to test large-system
436 code paths on small(er) systems.
438 Select a specific number if testing RCU itself.
439 Take the default if unsure.
441 config RCU_FANOUT_EXACT
442 bool "Disable tree-based hierarchical RCU auto-balancing"
443 depends on TREE_RCU || TREE_PREEMPT_RCU
446 This option forces use of the exact RCU_FANOUT value specified,
447 regardless of imbalances in the hierarchy. This is useful for
448 testing RCU itself, and might one day be useful on systems with
449 strong NUMA behavior.
451 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
455 config RCU_FAST_NO_HZ
456 bool "Accelerate last non-dyntick-idle CPU's grace periods"
457 depends on TREE_RCU && NO_HZ && SMP
460 This option causes RCU to attempt to accelerate grace periods
461 in order to allow the final CPU to enter dynticks-idle state
462 more quickly. On the other hand, this option increases the
463 overhead of the dynticks-idle checking, particularly on systems
464 with large numbers of CPUs.
466 Say Y if energy efficiency is critically important, particularly
467 if you have relatively few CPUs.
469 Say N if you are unsure.
471 config TREE_RCU_TRACE
472 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
475 This option provides tracing for the TREE_RCU and
476 TREE_PREEMPT_RCU implementations, permitting Makefile to
477 trivially select kernel/rcutree_trace.c.
480 bool "Enable RCU priority boosting"
481 depends on RT_MUTEXES && TINY_PREEMPT_RCU
484 This option boosts the priority of preempted RCU readers that
485 block the current preemptible RCU grace period for too long.
486 This option also prevents heavy loads from blocking RCU
487 callback invocation for all flavors of RCU.
489 Say Y here if you are working with real-time apps or heavy loads
490 Say N here if you are unsure.
492 config RCU_BOOST_PRIO
493 int "Real-time priority to boost RCU readers to"
498 This option specifies the real-time priority to which preempted
499 RCU readers are to be boosted. If you are working with CPU-bound
500 real-time applications, you should specify a priority higher then
501 the highest-priority CPU-bound application.
503 Specify the real-time priority, or take the default if unsure.
505 config RCU_BOOST_DELAY
506 int "Milliseconds to delay boosting after RCU grace-period start"
511 This option specifies the time to wait after the beginning of
512 a given grace period before priority-boosting preempted RCU
513 readers blocking that grace period. Note that any RCU reader
514 blocking an expedited RCU grace period is boosted immediately.
516 Accept the default if unsure.
518 endmenu # "RCU Subsystem"
521 tristate "Kernel .config support"
523 This option enables the complete Linux kernel ".config" file
524 contents to be saved in the kernel. It provides documentation
525 of which kernel options are used in a running kernel or in an
526 on-disk kernel. This information can be extracted from the kernel
527 image file with the script scripts/extract-ikconfig and used as
528 input to rebuild the current kernel or to build another kernel.
529 It can also be extracted from a running kernel by reading
530 /proc/config.gz if enabled (below).
533 bool "Enable access to .config through /proc/config.gz"
534 depends on IKCONFIG && PROC_FS
536 This option enables access to the kernel configuration file
537 through /proc/config.gz.
540 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
544 Select kernel log buffer size as a power of 2.
554 # Architectures with an unreliable sched_clock() should select this:
556 config HAVE_UNSTABLE_SCHED_CLOCK
560 boolean "Control Group support"
563 This option adds support for grouping sets of processes together, for
564 use with process control subsystems such as Cpusets, CFS, memory
565 controls or device isolation.
567 - Documentation/scheduler/sched-design-CFS.txt (CFS)
568 - Documentation/cgroups/ (features for grouping, isolation
569 and resource control)
576 bool "Example debug cgroup subsystem"
579 This option enables a simple cgroup subsystem that
580 exports useful debugging information about the cgroups
586 bool "Namespace cgroup subsystem"
588 Provides a simple namespace cgroup subsystem to
589 provide hierarchical naming of sets of namespaces,
590 for instance virtual servers and checkpoint/restart
593 config CGROUP_FREEZER
594 bool "Freezer cgroup subsystem"
596 Provides a way to freeze and unfreeze all tasks in a
600 bool "Device controller for cgroups"
602 Provides a cgroup implementing whitelists for devices which
603 a process in the cgroup can mknod or open.
606 bool "Cpuset support"
608 This option will let you create and manage CPUSETs which
609 allow dynamically partitioning a system into sets of CPUs and
610 Memory Nodes and assigning tasks to run only within those sets.
611 This is primarily useful on large SMP or NUMA systems.
615 config PROC_PID_CPUSET
616 bool "Include legacy /proc/<pid>/cpuset file"
620 config CGROUP_CPUACCT
621 bool "Simple CPU accounting cgroup subsystem"
623 Provides a simple Resource Controller for monitoring the
624 total CPU consumed by the tasks in a cgroup.
626 config RESOURCE_COUNTERS
627 bool "Resource counters"
629 This option enables controller independent resource accounting
630 infrastructure that works with cgroups.
632 config CGROUP_MEM_RES_CTLR
633 bool "Memory Resource Controller for Control Groups"
634 depends on RESOURCE_COUNTERS
637 Provides a memory resource controller that manages both anonymous
638 memory and page cache. (See Documentation/cgroups/memory.txt)
640 Note that setting this option increases fixed memory overhead
641 associated with each page of memory in the system. By this,
642 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
643 usage tracking struct at boot. Total amount of this is printed out
646 Only enable when you're ok with these trade offs and really
647 sure you need the memory resource controller. Even when you enable
648 this, you can set "cgroup_disable=memory" at your boot option to
649 disable memory resource controller and you can avoid overheads.
650 (and lose benefits of memory resource controller)
652 This config option also selects MM_OWNER config option, which
653 could in turn add some fork/exit overhead.
655 config CGROUP_MEM_RES_CTLR_SWAP
656 bool "Memory Resource Controller Swap Extension"
657 depends on CGROUP_MEM_RES_CTLR && SWAP
659 Add swap management feature to memory resource controller. When you
660 enable this, you can limit mem+swap usage per cgroup. In other words,
661 when you disable this, memory resource controller has no cares to
662 usage of swap...a process can exhaust all of the swap. This extension
663 is useful when you want to avoid exhaustion swap but this itself
664 adds more overheads and consumes memory for remembering information.
665 Especially if you use 32bit system or small memory system, please
666 be careful about enabling this. When memory resource controller
667 is disabled by boot option, this will be automatically disabled and
668 there will be no overhead from this. Even when you set this config=y,
669 if boot option "noswapaccount" is set, swap will not be accounted.
670 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
671 size is 4096bytes, 512k per 1Gbytes of swap.
672 config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
673 bool "Memory Resource Controller Swap Extension enabled by default"
674 depends on CGROUP_MEM_RES_CTLR_SWAP
677 Memory Resource Controller Swap Extension comes with its price in
678 a bigger memory consumption. General purpose distribution kernels
679 which want to enable the feature but keep it disabled by default
680 and let the user enable it by swapaccount boot command line
681 parameter should have this option unselected.
682 For those who want to have the feature enabled by default should
683 select this option (if, for some reason, they need to disable it
684 then noswapaccount does the trick).
686 menuconfig CGROUP_SCHED
687 bool "Group CPU scheduler"
688 depends on EXPERIMENTAL
691 This feature lets CPU scheduler recognize task groups and control CPU
692 bandwidth allocation to such task groups. It uses cgroups to group
696 config FAIR_GROUP_SCHED
697 bool "Group scheduling for SCHED_OTHER"
698 depends on CGROUP_SCHED
701 config RT_GROUP_SCHED
702 bool "Group scheduling for SCHED_RR/FIFO"
703 depends on EXPERIMENTAL
704 depends on CGROUP_SCHED
707 This feature lets you explicitly allocate real CPU bandwidth
708 to task groups. If enabled, it will also make it impossible to
709 schedule realtime tasks for non-root users until you allocate
710 realtime bandwidth for them.
711 See Documentation/scheduler/sched-rt-group.txt for more information.
716 tristate "Block IO controller"
720 Generic block IO controller cgroup interface. This is the common
721 cgroup interface which should be used by various IO controlling
724 Currently, CFQ IO scheduler uses it to recognize task groups and
725 control disk bandwidth allocation (proportional time slice allocation)
726 to such task groups. It is also used by bio throttling logic in
727 block layer to implement upper limit in IO rates on a device.
729 This option only enables generic Block IO controller infrastructure.
730 One needs to also enable actual IO controlling logic/policy. For
731 enabling proportional weight division of disk bandwidth in CFQ seti
732 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
733 CONFIG_BLK_THROTTLE=y.
735 See Documentation/cgroups/blkio-controller.txt for more information.
737 config DEBUG_BLK_CGROUP
738 bool "Enable Block IO controller debugging"
739 depends on BLK_CGROUP
742 Enable some debugging help. Currently it exports additional stat
743 files in a cgroup which can be useful for debugging.
747 menuconfig NAMESPACES
748 bool "Namespaces support" if EMBEDDED
751 Provides the way to make tasks work with different objects using
752 the same id. For example same IPC id may refer to different objects
753 or same user id or pid may refer to different tasks when used in
754 different namespaces.
762 In this namespace tasks see different info provided with the
767 depends on (SYSVIPC || POSIX_MQUEUE)
770 In this namespace tasks work with IPC ids which correspond to
771 different IPC objects in different namespaces.
774 bool "User namespace (EXPERIMENTAL)"
775 depends on EXPERIMENTAL
778 This allows containers, i.e. vservers, to use user namespaces
779 to provide different user info for different servers.
783 bool "PID Namespaces"
786 Support process id namespaces. This allows having multiple
787 processes with the same pid as long as they are in different
788 pid namespaces. This is a building block of containers.
791 bool "Network namespace"
795 Allow user space to create what appear to be multiple instances
796 of the network stack.
800 config SCHED_AUTOGROUP
801 bool "Automatic process group scheduling"
805 select FAIR_GROUP_SCHED
807 This option optimizes the scheduler for common desktop workloads by
808 automatically creating and populating task groups. This separation
809 of workloads isolates aggressive CPU burners (like build jobs) from
810 desktop applications. Task group autogeneration is currently based
816 config SYSFS_DEPRECATED
817 bool "enable deprecated sysfs features to support old userspace tools"
821 This option adds code that switches the layout of the "block" class
822 devices, to not show up in /sys/class/block/, but only in
825 This switch is only active when the sysfs.deprecated=1 boot option is
826 passed or the SYSFS_DEPRECATED_V2 option is set.
828 This option allows new kernels to run on old distributions and tools,
829 which might get confused by /sys/class/block/. Since 2007/2008 all
830 major distributions and tools handle this just fine.
832 Recent distributions and userspace tools after 2009/2010 depend on
833 the existence of /sys/class/block/, and will not work with this
836 Only if you are using a new kernel on an old distribution, you might
839 config SYSFS_DEPRECATED_V2
840 bool "enabled deprecated sysfs features by default"
843 depends on SYSFS_DEPRECATED
845 Enable deprecated sysfs by default.
847 See the CONFIG_SYSFS_DEPRECATED option for more details about this
850 Only if you are using a new kernel on an old distribution, you might
851 need to say Y here. Even then, odds are you would not need it
852 enabled, you can always pass the boot option if absolutely necessary.
855 bool "Kernel->user space relay support (formerly relayfs)"
857 This option enables support for relay interface support in
858 certain file systems (such as debugfs).
859 It is designed to provide an efficient mechanism for tools and
860 facilities to relay large amounts of data from kernel space to
865 config BLK_DEV_INITRD
866 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
867 depends on BROKEN || !FRV
869 The initial RAM filesystem is a ramfs which is loaded by the
870 boot loader (loadlin or lilo) and that is mounted as root
871 before the normal boot procedure. It is typically used to
872 load modules needed to mount the "real" root file system,
873 etc. See <file:Documentation/initrd.txt> for details.
875 If RAM disk support (BLK_DEV_RAM) is also included, this
876 also enables initial RAM disk (initrd) support and adds
877 15 Kbytes (more on some other architectures) to the kernel size.
887 config CC_OPTIMIZE_FOR_SIZE
888 bool "Optimize for size"
891 Enabling this option will pass "-Os" instead of "-O2" to gcc
892 resulting in a smaller kernel.
903 bool "Configure standard kernel features (for small systems)"
905 This option allows certain base kernel options and settings
906 to be disabled or tweaked. This is for specialized
907 environments which can tolerate a "non-standard" kernel.
908 Only use this if you really know what you are doing.
911 bool "Enable 16-bit UID system calls" if EMBEDDED
912 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
915 This enables the legacy 16-bit UID syscall wrappers.
917 config SYSCTL_SYSCALL
918 bool "Sysctl syscall support" if EMBEDDED
919 depends on PROC_SYSCTL
923 sys_sysctl uses binary paths that have been found challenging
924 to properly maintain and use. The interface in /proc/sys
925 using paths with ascii names is now the primary path to this
928 Almost nothing using the binary sysctl interface so if you are
929 trying to save some space it is probably safe to disable this,
930 making your kernel marginally smaller.
932 If unsure say Y here.
935 bool "Load all symbols for debugging/ksymoops" if EMBEDDED
938 Say Y here to let the kernel print out symbolic crash information and
939 symbolic stack backtraces. This increases the size of the kernel
940 somewhat, as all symbols have to be loaded into the kernel image.
943 bool "Include all symbols in kallsyms"
944 depends on DEBUG_KERNEL && KALLSYMS
946 Normally kallsyms only contains the symbols of functions, for nicer
947 OOPS messages. Some debuggers can use kallsyms for other
948 symbols too: say Y here to include all symbols, if you need them
949 and you don't care about adding 300k to the size of your kernel.
953 config KALLSYMS_EXTRA_PASS
954 bool "Do an extra kallsyms pass"
957 If kallsyms is not working correctly, the build will fail with
958 inconsistent kallsyms data. If that occurs, log a bug report and
959 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
960 Always say N here unless you find a bug in kallsyms, which must be
961 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
962 you wait for kallsyms to be fixed.
966 bool "Support for hot-pluggable devices" if EMBEDDED
969 This option is provided for the case where no hotplug or uevent
970 capabilities is wanted by the kernel. You should only consider
971 disabling this option for embedded systems that do not use modules, a
972 dynamic /dev tree, or dynamic device discovery. Just say Y.
976 bool "Enable support for printk" if EMBEDDED
978 This option enables normal printk support. Removing it
979 eliminates most of the message strings from the kernel image
980 and makes the kernel more or less silent. As this makes it
981 very difficult to diagnose system problems, saying N here is
982 strongly discouraged.
985 bool "BUG() support" if EMBEDDED
988 Disabling this option eliminates support for BUG and WARN, reducing
989 the size of your kernel image and potentially quietly ignoring
990 numerous fatal conditions. You should only consider disabling this
991 option for embedded systems with no facilities for reporting errors.
996 bool "Enable ELF core dumps" if EMBEDDED
998 Enable support for generating core dumps. Disabling saves about 4k.
1000 config PCSPKR_PLATFORM
1001 bool "Enable PC-Speaker support" if EMBEDDED
1002 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1005 This option allows to disable the internal PC-Speaker
1006 support, saving some memory.
1010 bool "Enable full-sized data structures for core" if EMBEDDED
1012 Disabling this option reduces the size of miscellaneous core
1013 kernel data structures. This saves memory on small machines,
1014 but may reduce performance.
1017 bool "Enable futex support" if EMBEDDED
1021 Disabling this option will cause the kernel to be built without
1022 support for "fast userspace mutexes". The resulting kernel may not
1023 run glibc-based applications correctly.
1026 bool "Enable eventpoll support" if EMBEDDED
1030 Disabling this option will cause the kernel to be built without
1031 support for epoll family of system calls.
1034 bool "Enable signalfd() system call" if EMBEDDED
1038 Enable the signalfd() system call that allows to receive signals
1039 on a file descriptor.
1044 bool "Enable timerfd() system call" if EMBEDDED
1048 Enable the timerfd() system call that allows to receive timer
1049 events on a file descriptor.
1054 bool "Enable eventfd() system call" if EMBEDDED
1058 Enable the eventfd() system call that allows to receive both
1059 kernel notification (ie. KAIO) or userspace notifications.
1064 bool "Use full shmem filesystem" if EMBEDDED
1068 The shmem is an internal filesystem used to manage shared memory.
1069 It is backed by swap and manages resource limits. It is also exported
1070 to userspace as tmpfs if TMPFS is enabled. Disabling this
1071 option replaces shmem and tmpfs with the much simpler ramfs code,
1072 which may be appropriate on small systems without swap.
1075 bool "Enable AIO support" if EMBEDDED
1078 This option enables POSIX asynchronous I/O which may by used
1079 by some high performance threaded applications. Disabling
1080 this option saves about 7k.
1082 config HAVE_PERF_EVENTS
1085 See tools/perf/design.txt for details.
1087 config PERF_USE_VMALLOC
1090 See tools/perf/design.txt for details
1092 menu "Kernel Performance Events And Counters"
1095 bool "Kernel performance events and counters"
1096 default y if (PROFILING || PERF_COUNTERS)
1097 depends on HAVE_PERF_EVENTS
1101 Enable kernel support for various performance events provided
1102 by software and hardware.
1104 Software events are supported either built-in or via the
1105 use of generic tracepoints.
1107 Most modern CPUs support performance events via performance
1108 counter registers. These registers count the number of certain
1109 types of hw events: such as instructions executed, cachemisses
1110 suffered, or branches mis-predicted - without slowing down the
1111 kernel or applications. These registers can also trigger interrupts
1112 when a threshold number of events have passed - and can thus be
1113 used to profile the code that runs on that CPU.
1115 The Linux Performance Event subsystem provides an abstraction of
1116 these software and hardware event capabilities, available via a
1117 system call and used by the "perf" utility in tools/perf/. It
1118 provides per task and per CPU counters, and it provides event
1119 capabilities on top of those.
1123 config PERF_COUNTERS
1124 bool "Kernel performance counters (old config option)"
1125 depends on HAVE_PERF_EVENTS
1127 This config has been obsoleted by the PERF_EVENTS
1128 config option - please see that one for details.
1130 It has no effect on the kernel whether you enable
1131 it or not, it is a compatibility placeholder.
1135 config DEBUG_PERF_USE_VMALLOC
1137 bool "Debug: use vmalloc to back perf mmap() buffers"
1138 depends on PERF_EVENTS && DEBUG_KERNEL
1139 select PERF_USE_VMALLOC
1141 Use vmalloc memory to back perf mmap() buffers.
1143 Mostly useful for debugging the vmalloc code on platforms
1144 that don't require it.
1150 config VM_EVENT_COUNTERS
1152 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
1154 VM event counters are needed for event counts to be shown.
1155 This option allows the disabling of the VM event counters
1156 on EMBEDDED systems. /proc/vmstat will only show page counts
1157 if VM event counters are disabled.
1161 bool "Enable PCI quirk workarounds" if EMBEDDED
1164 This enables workarounds for various PCI chipset
1165 bugs/quirks. Disable this only if your target machine is
1166 unaffected by PCI quirks.
1170 bool "Enable SLUB debugging support" if EMBEDDED
1171 depends on SLUB && SYSFS
1173 SLUB has extensive debug support features. Disabling these can
1174 result in significant savings in code size. This also disables
1175 SLUB sysfs support. /sys/slab will not exist and there will be
1176 no support for cache validation etc.
1179 bool "Disable heap randomization"
1182 Randomizing heap placement makes heap exploits harder, but it
1183 also breaks ancient binaries (including anything libc5 based).
1184 This option changes the bootup default to heap randomization
1185 disabled, and can be overridden at runtime by setting
1186 /proc/sys/kernel/randomize_va_space to 2.
1188 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1191 prompt "Choose SLAB allocator"
1194 This option allows to select a slab allocator.
1199 The regular slab allocator that is established and known to work
1200 well in all environments. It organizes cache hot objects in
1201 per cpu and per node queues.
1204 bool "SLUB (Unqueued Allocator)"
1206 SLUB is a slab allocator that minimizes cache line usage
1207 instead of managing queues of cached objects (SLAB approach).
1208 Per cpu caching is realized using slabs of objects instead
1209 of queues of objects. SLUB can use memory efficiently
1210 and has enhanced diagnostics. SLUB is the default choice for
1215 bool "SLOB (Simple Allocator)"
1217 SLOB replaces the stock allocator with a drastically simpler
1218 allocator. SLOB is generally more space efficient but
1219 does not perform as well on large systems.
1223 config MMAP_ALLOW_UNINITIALIZED
1224 bool "Allow mmapped anonymous memory to be uninitialized"
1225 depends on EMBEDDED && !MMU
1228 Normally, and according to the Linux spec, anonymous memory obtained
1229 from mmap() has it's contents cleared before it is passed to
1230 userspace. Enabling this config option allows you to request that
1231 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1232 providing a huge performance boost. If this option is not enabled,
1233 then the flag will be ignored.
1235 This is taken advantage of by uClibc's malloc(), and also by
1236 ELF-FDPIC binfmt's brk and stack allocator.
1238 Because of the obvious security issues, this option should only be
1239 enabled on embedded devices where you control what is run in
1240 userspace. Since that isn't generally a problem on no-MMU systems,
1241 it is normally safe to say Y here.
1243 See Documentation/nommu-mmap.txt for more information.
1246 bool "Profiling support"
1248 Say Y here to enable the extended profiling support mechanisms used
1249 by profilers such as OProfile.
1252 # Place an empty function call at each tracepoint site. Can be
1253 # dynamically changed for a probe function.
1258 source "arch/Kconfig"
1260 endmenu # General setup
1262 config HAVE_GENERIC_DMA_COHERENT
1269 depends on SLAB || SLUB_DEBUG
1277 default 0 if BASE_FULL
1278 default 1 if !BASE_FULL
1281 bool "Enable loadable module support"
1283 Kernel modules are small pieces of compiled code which can
1284 be inserted in the running kernel, rather than being
1285 permanently built into the kernel. You use the "modprobe"
1286 tool to add (and sometimes remove) them. If you say Y here,
1287 many parts of the kernel can be built as modules (by
1288 answering M instead of Y where indicated): this is most
1289 useful for infrequently used options which are not required
1290 for booting. For more information, see the man pages for
1291 modprobe, lsmod, modinfo, insmod and rmmod.
1293 If you say Y here, you will need to run "make
1294 modules_install" to put the modules under /lib/modules/
1295 where modprobe can find them (you may need to be root to do
1302 config MODULE_FORCE_LOAD
1303 bool "Forced module loading"
1306 Allow loading of modules without version information (ie. modprobe
1307 --force). Forced module loading sets the 'F' (forced) taint flag and
1308 is usually a really bad idea.
1310 config MODULE_UNLOAD
1311 bool "Module unloading"
1313 Without this option you will not be able to unload any
1314 modules (note that some modules may not be unloadable
1315 anyway), which makes your kernel smaller, faster
1316 and simpler. If unsure, say Y.
1318 config MODULE_FORCE_UNLOAD
1319 bool "Forced module unloading"
1320 depends on MODULE_UNLOAD && EXPERIMENTAL
1322 This option allows you to force a module to unload, even if the
1323 kernel believes it is unsafe: the kernel will remove the module
1324 without waiting for anyone to stop using it (using the -f option to
1325 rmmod). This is mainly for kernel developers and desperate users.
1329 bool "Module versioning support"
1331 Usually, you have to use modules compiled with your kernel.
1332 Saying Y here makes it sometimes possible to use modules
1333 compiled for different kernels, by adding enough information
1334 to the modules to (hopefully) spot any changes which would
1335 make them incompatible with the kernel you are running. If
1338 config MODULE_SRCVERSION_ALL
1339 bool "Source checksum for all modules"
1341 Modules which contain a MODULE_VERSION get an extra "srcversion"
1342 field inserted into their modinfo section, which contains a
1343 sum of the source files which made it. This helps maintainers
1344 see exactly which source was used to build a module (since
1345 others sometimes change the module source without updating
1346 the version). With this option, such a "srcversion" field
1347 will be created for all modules. If unsure, say N.
1351 config INIT_ALL_POSSIBLE
1354 Back when each arch used to define their own cpu_online_map and
1355 cpu_possible_map, some of them chose to initialize cpu_possible_map
1356 with all 1s, and others with all 0s. When they were centralised,
1357 it was better to provide this option than to break all the archs
1358 and have several arch maintainers pursuing me down dark alleys.
1363 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1365 Need stop_machine() primitive.
1367 source "block/Kconfig"
1369 config PREEMPT_NOTIFIERS
1376 source "kernel/Kconfig.locks"
projects / cascardo / linux.git / blob