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54 drivers that have been replaced by something else, and/or are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.
85 config INIT_PASS_ALL_PARAMS
86 bool "Pass all (known and unknown) kernel parameters to init"
89 Pass all kernel command line parameters to init, this includes
90 those consumed by kernel modules. This is useful for upstart
91 based systems. If in doubt say N.
94 string "Cross-compiler tool prefix"
96 Same as running 'make CROSS_COMPILE=prefix-' but stored for
97 default make runs in this kernel build directory. You don't
98 need to set this unless you want the configured kernel build
99 directory to select the cross-compiler automatically.
102 string "Local version - append to kernel release"
104 Append an extra string to the end of your kernel version.
105 This will show up when you type uname, for example.
106 The string you set here will be appended after the contents of
107 any files with a filename matching localversion* in your
108 object and source tree, in that order. Your total string can
109 be a maximum of 64 characters.
111 config LOCALVERSION_AUTO
112 bool "Automatically append version information to the version string"
115 This will try to automatically determine if the current tree is a
116 release tree by looking for git tags that belong to the current
117 top of tree revision.
119 A string of the format -gxxxxxxxx will be added to the localversion
120 if a git-based tree is found. The string generated by this will be
121 appended after any matching localversion* files, and after the value
122 set in CONFIG_LOCALVERSION.
124 (The actual string used here is the first eight characters produced
125 by running the command:
127 $ git rev-parse --verify HEAD
129 which is done within the script "scripts/setlocalversion".)
131 config HAVE_KERNEL_GZIP
134 config HAVE_KERNEL_BZIP2
137 config HAVE_KERNEL_LZMA
140 config HAVE_KERNEL_XZ
143 config HAVE_KERNEL_LZO
147 prompt "Kernel compression mode"
149 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
151 The linux kernel is a kind of self-extracting executable.
152 Several compression algorithms are available, which differ
153 in efficiency, compression and decompression speed.
154 Compression speed is only relevant when building a kernel.
155 Decompression speed is relevant at each boot.
157 If you have any problems with bzip2 or lzma compressed
158 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
159 version of this functionality (bzip2 only), for 2.4, was
160 supplied by Christian Ludwig)
162 High compression options are mostly useful for users, who
163 are low on disk space (embedded systems), but for whom ram
166 If in doubt, select 'gzip'
170 depends on HAVE_KERNEL_GZIP
172 The old and tried gzip compression. It provides a good balance
173 between compression ratio and decompression speed.
177 depends on HAVE_KERNEL_BZIP2
179 Its compression ratio and speed is intermediate.
180 Decompression speed is slowest among the three. The kernel
181 size is about 10% smaller with bzip2, in comparison to gzip.
182 Bzip2 uses a large amount of memory. For modern kernels you
183 will need at least 8MB RAM or more for booting.
187 depends on HAVE_KERNEL_LZMA
189 The most recent compression algorithm.
190 Its ratio is best, decompression speed is between the other
191 two. Compression is slowest. The kernel size is about 33%
192 smaller with LZMA in comparison to gzip.
196 depends on HAVE_KERNEL_XZ
198 XZ uses the LZMA2 algorithm and instruction set specific
199 BCJ filters which can improve compression ratio of executable
200 code. The size of the kernel is about 30% smaller with XZ in
201 comparison to gzip. On architectures for which there is a BCJ
202 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
203 will create a few percent smaller kernel than plain LZMA.
205 The speed is about the same as with LZMA: The decompression
206 speed of XZ is better than that of bzip2 but worse than gzip
207 and LZO. Compression is slow.
211 depends on HAVE_KERNEL_LZO
213 Its compression ratio is the poorest among the 4. The kernel
214 size is about 10% bigger than gzip; however its speed
215 (both compression and decompression) is the fastest.
219 config VERSION_SIGNATURE
220 string "Arbitrary version signature"
222 This string will be created in a file, /proc/version_signature. It
223 is useful in determining arbitrary data about your kernel. For instance,
224 if you have several kernels of the same version, but need to keep track
225 of a revision of the same kernel, but not affect it's ability to load
226 compatible modules, this is the easiest way to do that.
229 bool "Support for paging of anonymous memory (swap)"
230 depends on MMU && BLOCK
233 This option allows you to choose whether you want to have support
234 for so called swap devices or swap files in your kernel that are
235 used to provide more virtual memory than the actual RAM present
236 in your computer. If unsure say Y.
241 Inter Process Communication is a suite of library functions and
242 system calls which let processes (running programs) synchronize and
243 exchange information. It is generally considered to be a good thing,
244 and some programs won't run unless you say Y here. In particular, if
245 you want to run the DOS emulator dosemu under Linux (read the
246 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
247 you'll need to say Y here.
249 You can find documentation about IPC with "info ipc" and also in
250 section 6.4 of the Linux Programmer's Guide, available from
251 <http://www.tldp.org/guides.html>.
253 config SYSVIPC_SYSCTL
260 bool "POSIX Message Queues"
261 depends on NET && EXPERIMENTAL
263 POSIX variant of message queues is a part of IPC. In POSIX message
264 queues every message has a priority which decides about succession
265 of receiving it by a process. If you want to compile and run
266 programs written e.g. for Solaris with use of its POSIX message
267 queues (functions mq_*) say Y here.
269 POSIX message queues are visible as a filesystem called 'mqueue'
270 and can be mounted somewhere if you want to do filesystem
271 operations on message queues.
275 config POSIX_MQUEUE_SYSCTL
277 depends on POSIX_MQUEUE
281 config BSD_PROCESS_ACCT
282 bool "BSD Process Accounting"
284 If you say Y here, a user level program will be able to instruct the
285 kernel (via a special system call) to write process accounting
286 information to a file: whenever a process exits, information about
287 that process will be appended to the file by the kernel. The
288 information includes things such as creation time, owning user,
289 command name, memory usage, controlling terminal etc. (the complete
290 list is in the struct acct in <file:include/linux/acct.h>). It is
291 up to the user level program to do useful things with this
292 information. This is generally a good idea, so say Y.
294 config BSD_PROCESS_ACCT_V3
295 bool "BSD Process Accounting version 3 file format"
296 depends on BSD_PROCESS_ACCT
299 If you say Y here, the process accounting information is written
300 in a new file format that also logs the process IDs of each
301 process and it's parent. Note that this file format is incompatible
302 with previous v0/v1/v2 file formats, so you will need updated tools
303 for processing it. A preliminary version of these tools is available
304 at <http://www.gnu.org/software/acct/>.
307 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
311 Export selected statistics for tasks/processes through the
312 generic netlink interface. Unlike BSD process accounting, the
313 statistics are available during the lifetime of tasks/processes as
314 responses to commands. Like BSD accounting, they are sent to user
319 config TASK_DELAY_ACCT
320 bool "Enable per-task delay accounting (EXPERIMENTAL)"
323 Collect information on time spent by a task waiting for system
324 resources like cpu, synchronous block I/O completion and swapping
325 in pages. Such statistics can help in setting a task's priorities
326 relative to other tasks for cpu, io, rss limits etc.
331 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
334 Collect extended task accounting data and send the data
335 to userland for processing over the taskstats interface.
339 config TASK_IO_ACCOUNTING
340 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
341 depends on TASK_XACCT
343 Collect information on the number of bytes of storage I/O which this
349 bool "Auditing support"
352 Enable auditing infrastructure that can be used with another
353 kernel subsystem, such as SELinux (which requires this for
354 logging of avc messages output). Does not do system-call
355 auditing without CONFIG_AUDITSYSCALL.
358 bool "Enable system-call auditing support"
359 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
360 default y if SECURITY_SELINUX
362 Enable low-overhead system-call auditing infrastructure that
363 can be used independently or with another kernel subsystem,
368 depends on AUDITSYSCALL
373 depends on AUDITSYSCALL
376 source "kernel/irq/Kconfig"
381 prompt "RCU Implementation"
385 bool "Tree-based hierarchical RCU"
386 depends on !PREEMPT && SMP
388 This option selects the RCU implementation that is
389 designed for very large SMP system with hundreds or
390 thousands of CPUs. It also scales down nicely to
393 config TREE_PREEMPT_RCU
394 bool "Preemptible tree-based hierarchical RCU"
397 This option selects the RCU implementation that is
398 designed for very large SMP systems with hundreds or
399 thousands of CPUs, but for which real-time response
400 is also required. It also scales down nicely to
404 bool "UP-only small-memory-footprint RCU"
407 This option selects the RCU implementation that is
408 designed for UP systems from which real-time response
409 is not required. This option greatly reduces the
410 memory footprint of RCU.
412 config TINY_PREEMPT_RCU
413 bool "Preemptible UP-only small-memory-footprint RCU"
414 depends on !SMP && PREEMPT
416 This option selects the RCU implementation that is designed
417 for real-time UP systems. This option greatly reduces the
418 memory footprint of RCU.
423 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
425 This option enables preemptible-RCU code that is common between
426 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
429 bool "Enable tracing for RCU"
431 This option provides tracing in RCU which presents stats
432 in debugfs for debugging RCU implementation.
434 Say Y here if you want to enable RCU tracing
435 Say N if you are unsure.
438 int "Tree-based hierarchical RCU fanout value"
441 depends on TREE_RCU || TREE_PREEMPT_RCU
445 This option controls the fanout of hierarchical implementations
446 of RCU, allowing RCU to work efficiently on machines with
447 large numbers of CPUs. This value must be at least the fourth
448 root of NR_CPUS, which allows NR_CPUS to be insanely large.
449 The default value of RCU_FANOUT should be used for production
450 systems, but if you are stress-testing the RCU implementation
451 itself, small RCU_FANOUT values allow you to test large-system
452 code paths on small(er) systems.
454 Select a specific number if testing RCU itself.
455 Take the default if unsure.
457 config RCU_FANOUT_EXACT
458 bool "Disable tree-based hierarchical RCU auto-balancing"
459 depends on TREE_RCU || TREE_PREEMPT_RCU
462 This option forces use of the exact RCU_FANOUT value specified,
463 regardless of imbalances in the hierarchy. This is useful for
464 testing RCU itself, and might one day be useful on systems with
465 strong NUMA behavior.
467 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
471 config RCU_FAST_NO_HZ
472 bool "Accelerate last non-dyntick-idle CPU's grace periods"
473 depends on TREE_RCU && NO_HZ && SMP
476 This option causes RCU to attempt to accelerate grace periods
477 in order to allow the final CPU to enter dynticks-idle state
478 more quickly. On the other hand, this option increases the
479 overhead of the dynticks-idle checking, particularly on systems
480 with large numbers of CPUs.
482 Say Y if energy efficiency is critically important, particularly
483 if you have relatively few CPUs.
485 Say N if you are unsure.
487 config TREE_RCU_TRACE
488 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
491 This option provides tracing for the TREE_RCU and
492 TREE_PREEMPT_RCU implementations, permitting Makefile to
493 trivially select kernel/rcutree_trace.c.
496 bool "Enable RCU priority boosting"
497 depends on RT_MUTEXES && TINY_PREEMPT_RCU
500 This option boosts the priority of preempted RCU readers that
501 block the current preemptible RCU grace period for too long.
502 This option also prevents heavy loads from blocking RCU
503 callback invocation for all flavors of RCU.
505 Say Y here if you are working with real-time apps or heavy loads
506 Say N here if you are unsure.
508 config RCU_BOOST_PRIO
509 int "Real-time priority to boost RCU readers to"
514 This option specifies the real-time priority to which preempted
515 RCU readers are to be boosted. If you are working with CPU-bound
516 real-time applications, you should specify a priority higher then
517 the highest-priority CPU-bound application.
519 Specify the real-time priority, or take the default if unsure.
521 config RCU_BOOST_DELAY
522 int "Milliseconds to delay boosting after RCU grace-period start"
527 This option specifies the time to wait after the beginning of
528 a given grace period before priority-boosting preempted RCU
529 readers blocking that grace period. Note that any RCU reader
530 blocking an expedited RCU grace period is boosted immediately.
532 Accept the default if unsure.
534 endmenu # "RCU Subsystem"
537 tristate "Kernel .config support"
539 This option enables the complete Linux kernel ".config" file
540 contents to be saved in the kernel. It provides documentation
541 of which kernel options are used in a running kernel or in an
542 on-disk kernel. This information can be extracted from the kernel
543 image file with the script scripts/extract-ikconfig and used as
544 input to rebuild the current kernel or to build another kernel.
545 It can also be extracted from a running kernel by reading
546 /proc/config.gz if enabled (below).
549 bool "Enable access to .config through /proc/config.gz"
550 depends on IKCONFIG && PROC_FS
552 This option enables access to the kernel configuration file
553 through /proc/config.gz.
556 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
560 Select kernel log buffer size as a power of 2.
570 # Architectures with an unreliable sched_clock() should select this:
572 config HAVE_UNSTABLE_SCHED_CLOCK
576 boolean "Control Group support"
579 This option adds support for grouping sets of processes together, for
580 use with process control subsystems such as Cpusets, CFS, memory
581 controls or device isolation.
583 - Documentation/scheduler/sched-design-CFS.txt (CFS)
584 - Documentation/cgroups/ (features for grouping, isolation
585 and resource control)
592 bool "Example debug cgroup subsystem"
595 This option enables a simple cgroup subsystem that
596 exports useful debugging information about the cgroups
602 bool "Namespace cgroup subsystem"
604 Provides a simple namespace cgroup subsystem to
605 provide hierarchical naming of sets of namespaces,
606 for instance virtual servers and checkpoint/restart
609 config CGROUP_FREEZER
610 bool "Freezer cgroup subsystem"
612 Provides a way to freeze and unfreeze all tasks in a
616 bool "Device controller for cgroups"
618 Provides a cgroup implementing whitelists for devices which
619 a process in the cgroup can mknod or open.
622 bool "Cpuset support"
624 This option will let you create and manage CPUSETs which
625 allow dynamically partitioning a system into sets of CPUs and
626 Memory Nodes and assigning tasks to run only within those sets.
627 This is primarily useful on large SMP or NUMA systems.
631 config PROC_PID_CPUSET
632 bool "Include legacy /proc/<pid>/cpuset file"
636 config CGROUP_CPUACCT
637 bool "Simple CPU accounting cgroup subsystem"
639 Provides a simple Resource Controller for monitoring the
640 total CPU consumed by the tasks in a cgroup.
642 config RESOURCE_COUNTERS
643 bool "Resource counters"
645 This option enables controller independent resource accounting
646 infrastructure that works with cgroups.
648 config CGROUP_MEM_RES_CTLR
649 bool "Memory Resource Controller for Control Groups"
650 depends on RESOURCE_COUNTERS
653 Provides a memory resource controller that manages both anonymous
654 memory and page cache. (See Documentation/cgroups/memory.txt)
656 Note that setting this option increases fixed memory overhead
657 associated with each page of memory in the system. By this,
658 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
659 usage tracking struct at boot. Total amount of this is printed out
662 Only enable when you're ok with these trade offs and really
663 sure you need the memory resource controller. Even when you enable
664 this, you can set "cgroup_disable=memory" at your boot option to
665 disable memory resource controller and you can avoid overheads.
666 (and lose benefits of memory resource controller)
668 This config option also selects MM_OWNER config option, which
669 could in turn add some fork/exit overhead.
671 config CGROUP_MEM_RES_CTLR_SWAP
672 bool "Memory Resource Controller Swap Extension"
673 depends on CGROUP_MEM_RES_CTLR && SWAP
675 Add swap management feature to memory resource controller. When you
676 enable this, you can limit mem+swap usage per cgroup. In other words,
677 when you disable this, memory resource controller has no cares to
678 usage of swap...a process can exhaust all of the swap. This extension
679 is useful when you want to avoid exhaustion swap but this itself
680 adds more overheads and consumes memory for remembering information.
681 Especially if you use 32bit system or small memory system, please
682 be careful about enabling this. When memory resource controller
683 is disabled by boot option, this will be automatically disabled and
684 there will be no overhead from this. Even when you set this config=y,
685 if boot option "noswapaccount" is set, swap will not be accounted.
686 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
687 size is 4096bytes, 512k per 1Gbytes of swap.
688 config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
689 bool "Memory Resource Controller Swap Extension enabled by default"
690 depends on CGROUP_MEM_RES_CTLR_SWAP
693 Memory Resource Controller Swap Extension comes with its price in
694 a bigger memory consumption. General purpose distribution kernels
695 which want to enable the feature but keep it disabled by default
696 and let the user enable it by swapaccount boot command line
697 parameter should have this option unselected.
698 For those who want to have the feature enabled by default should
699 select this option (if, for some reason, they need to disable it
700 then noswapaccount does the trick).
702 menuconfig CGROUP_SCHED
703 bool "Group CPU scheduler"
704 depends on EXPERIMENTAL
707 This feature lets CPU scheduler recognize task groups and control CPU
708 bandwidth allocation to such task groups. It uses cgroups to group
712 config FAIR_GROUP_SCHED
713 bool "Group scheduling for SCHED_OTHER"
714 depends on CGROUP_SCHED
717 config RT_GROUP_SCHED
718 bool "Group scheduling for SCHED_RR/FIFO"
719 depends on EXPERIMENTAL
720 depends on CGROUP_SCHED
723 This feature lets you explicitly allocate real CPU bandwidth
724 to task groups. If enabled, it will also make it impossible to
725 schedule realtime tasks for non-root users until you allocate
726 realtime bandwidth for them.
727 See Documentation/scheduler/sched-rt-group.txt for more information.
732 tristate "Block IO controller"
736 Generic block IO controller cgroup interface. This is the common
737 cgroup interface which should be used by various IO controlling
740 Currently, CFQ IO scheduler uses it to recognize task groups and
741 control disk bandwidth allocation (proportional time slice allocation)
742 to such task groups. It is also used by bio throttling logic in
743 block layer to implement upper limit in IO rates on a device.
745 This option only enables generic Block IO controller infrastructure.
746 One needs to also enable actual IO controlling logic/policy. For
747 enabling proportional weight division of disk bandwidth in CFQ seti
748 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
749 CONFIG_BLK_THROTTLE=y.
751 See Documentation/cgroups/blkio-controller.txt for more information.
753 config DEBUG_BLK_CGROUP
754 bool "Enable Block IO controller debugging"
755 depends on BLK_CGROUP
758 Enable some debugging help. Currently it exports additional stat
759 files in a cgroup which can be useful for debugging.
763 menuconfig NAMESPACES
764 bool "Namespaces support" if EXPERT
767 Provides the way to make tasks work with different objects using
768 the same id. For example same IPC id may refer to different objects
769 or same user id or pid may refer to different tasks when used in
770 different namespaces.
778 In this namespace tasks see different info provided with the
783 depends on (SYSVIPC || POSIX_MQUEUE)
786 In this namespace tasks work with IPC ids which correspond to
787 different IPC objects in different namespaces.
790 bool "User namespace (EXPERIMENTAL)"
791 depends on EXPERIMENTAL
794 This allows containers, i.e. vservers, to use user namespaces
795 to provide different user info for different servers.
799 bool "PID Namespaces"
802 Support process id namespaces. This allows having multiple
803 processes with the same pid as long as they are in different
804 pid namespaces. This is a building block of containers.
807 bool "Network namespace"
811 Allow user space to create what appear to be multiple instances
812 of the network stack.
816 config SCHED_AUTOGROUP
817 bool "Automatic process group scheduling"
821 select FAIR_GROUP_SCHED
823 This option optimizes the scheduler for common desktop workloads by
824 automatically creating and populating task groups. This separation
825 of workloads isolates aggressive CPU burners (like build jobs) from
826 desktop applications. Task group autogeneration is currently based
832 config SYSFS_DEPRECATED
833 bool "enable deprecated sysfs features to support old userspace tools"
837 This option adds code that switches the layout of the "block" class
838 devices, to not show up in /sys/class/block/, but only in
841 This switch is only active when the sysfs.deprecated=1 boot option is
842 passed or the SYSFS_DEPRECATED_V2 option is set.
844 This option allows new kernels to run on old distributions and tools,
845 which might get confused by /sys/class/block/. Since 2007/2008 all
846 major distributions and tools handle this just fine.
848 Recent distributions and userspace tools after 2009/2010 depend on
849 the existence of /sys/class/block/, and will not work with this
852 Only if you are using a new kernel on an old distribution, you might
855 config SYSFS_DEPRECATED_V2
856 bool "enabled deprecated sysfs features by default"
859 depends on SYSFS_DEPRECATED
861 Enable deprecated sysfs by default.
863 See the CONFIG_SYSFS_DEPRECATED option for more details about this
866 Only if you are using a new kernel on an old distribution, you might
867 need to say Y here. Even then, odds are you would not need it
868 enabled, you can always pass the boot option if absolutely necessary.
871 bool "Kernel->user space relay support (formerly relayfs)"
873 This option enables support for relay interface support in
874 certain file systems (such as debugfs).
875 It is designed to provide an efficient mechanism for tools and
876 facilities to relay large amounts of data from kernel space to
881 config BLK_DEV_INITRD
882 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
883 depends on BROKEN || !FRV
885 The initial RAM filesystem is a ramfs which is loaded by the
886 boot loader (loadlin or lilo) and that is mounted as root
887 before the normal boot procedure. It is typically used to
888 load modules needed to mount the "real" root file system,
889 etc. See <file:Documentation/initrd.txt> for details.
891 If RAM disk support (BLK_DEV_RAM) is also included, this
892 also enables initial RAM disk (initrd) support and adds
893 15 Kbytes (more on some other architectures) to the kernel size.
903 config CC_OPTIMIZE_FOR_SIZE
904 bool "Optimize for size"
907 Enabling this option will pass "-Os" instead of "-O2" to gcc
908 resulting in a smaller kernel.
919 bool "Configure standard kernel features (expert users)"
921 This option allows certain base kernel options and settings
922 to be disabled or tweaked. This is for specialized
923 environments which can tolerate a "non-standard" kernel.
924 Only use this if you really know what you are doing.
927 bool "Embedded system"
930 This option should be enabled if compiling the kernel for
931 an embedded system so certain expert options are available
935 bool "Enable 16-bit UID system calls" if EXPERT
936 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
939 This enables the legacy 16-bit UID syscall wrappers.
941 config SYSCTL_SYSCALL
942 bool "Sysctl syscall support" if EXPERT
943 depends on PROC_SYSCTL
947 sys_sysctl uses binary paths that have been found challenging
948 to properly maintain and use. The interface in /proc/sys
949 using paths with ascii names is now the primary path to this
952 Almost nothing using the binary sysctl interface so if you are
953 trying to save some space it is probably safe to disable this,
954 making your kernel marginally smaller.
956 If unsure say Y here.
959 bool "Load all symbols for debugging/ksymoops" if EXPERT
962 Say Y here to let the kernel print out symbolic crash information and
963 symbolic stack backtraces. This increases the size of the kernel
964 somewhat, as all symbols have to be loaded into the kernel image.
967 bool "Include all symbols in kallsyms"
968 depends on DEBUG_KERNEL && KALLSYMS
970 Normally kallsyms only contains the symbols of functions, for nicer
971 OOPS messages. Some debuggers can use kallsyms for other
972 symbols too: say Y here to include all symbols, if you need them
973 and you don't care about adding 300k to the size of your kernel.
977 config KALLSYMS_EXTRA_PASS
978 bool "Do an extra kallsyms pass"
981 If kallsyms is not working correctly, the build will fail with
982 inconsistent kallsyms data. If that occurs, log a bug report and
983 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
984 Always say N here unless you find a bug in kallsyms, which must be
985 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
986 you wait for kallsyms to be fixed.
990 bool "Support for hot-pluggable devices" if EXPERT
993 This option is provided for the case where no hotplug or uevent
994 capabilities is wanted by the kernel. You should only consider
995 disabling this option for embedded systems that do not use modules, a
996 dynamic /dev tree, or dynamic device discovery. Just say Y.
1000 bool "Enable support for printk" if EXPERT
1002 This option enables normal printk support. Removing it
1003 eliminates most of the message strings from the kernel image
1004 and makes the kernel more or less silent. As this makes it
1005 very difficult to diagnose system problems, saying N here is
1006 strongly discouraged.
1009 bool "BUG() support" if EXPERT
1012 Disabling this option eliminates support for BUG and WARN, reducing
1013 the size of your kernel image and potentially quietly ignoring
1014 numerous fatal conditions. You should only consider disabling this
1015 option for embedded systems with no facilities for reporting errors.
1020 bool "Enable ELF core dumps" if EXPERT
1022 Enable support for generating core dumps. Disabling saves about 4k.
1024 config PCSPKR_PLATFORM
1025 bool "Enable PC-Speaker support" if EXPERT
1026 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1029 This option allows to disable the internal PC-Speaker
1030 support, saving some memory.
1034 bool "Enable full-sized data structures for core" if EXPERT
1036 Disabling this option reduces the size of miscellaneous core
1037 kernel data structures. This saves memory on small machines,
1038 but may reduce performance.
1041 bool "Enable futex support" if EXPERT
1045 Disabling this option will cause the kernel to be built without
1046 support for "fast userspace mutexes". The resulting kernel may not
1047 run glibc-based applications correctly.
1050 bool "Enable eventpoll support" if EXPERT
1054 Disabling this option will cause the kernel to be built without
1055 support for epoll family of system calls.
1058 bool "Enable signalfd() system call" if EXPERT
1062 Enable the signalfd() system call that allows to receive signals
1063 on a file descriptor.
1068 bool "Enable timerfd() system call" if EXPERT
1072 Enable the timerfd() system call that allows to receive timer
1073 events on a file descriptor.
1078 bool "Enable eventfd() system call" if EXPERT
1082 Enable the eventfd() system call that allows to receive both
1083 kernel notification (ie. KAIO) or userspace notifications.
1088 bool "Use full shmem filesystem" if EXPERT
1092 The shmem is an internal filesystem used to manage shared memory.
1093 It is backed by swap and manages resource limits. It is also exported
1094 to userspace as tmpfs if TMPFS is enabled. Disabling this
1095 option replaces shmem and tmpfs with the much simpler ramfs code,
1096 which may be appropriate on small systems without swap.
1099 bool "Enable AIO support" if EXPERT
1102 This option enables POSIX asynchronous I/O which may by used
1103 by some high performance threaded applications. Disabling
1104 this option saves about 7k.
1106 config HAVE_PERF_EVENTS
1109 See tools/perf/design.txt for details.
1111 config PERF_USE_VMALLOC
1114 See tools/perf/design.txt for details
1116 menu "Kernel Performance Events And Counters"
1119 bool "Kernel performance events and counters"
1120 default y if (PROFILING || PERF_COUNTERS)
1121 depends on HAVE_PERF_EVENTS
1125 Enable kernel support for various performance events provided
1126 by software and hardware.
1128 Software events are supported either built-in or via the
1129 use of generic tracepoints.
1131 Most modern CPUs support performance events via performance
1132 counter registers. These registers count the number of certain
1133 types of hw events: such as instructions executed, cachemisses
1134 suffered, or branches mis-predicted - without slowing down the
1135 kernel or applications. These registers can also trigger interrupts
1136 when a threshold number of events have passed - and can thus be
1137 used to profile the code that runs on that CPU.
1139 The Linux Performance Event subsystem provides an abstraction of
1140 these software and hardware event capabilities, available via a
1141 system call and used by the "perf" utility in tools/perf/. It
1142 provides per task and per CPU counters, and it provides event
1143 capabilities on top of those.
1147 config PERF_COUNTERS
1148 bool "Kernel performance counters (old config option)"
1149 depends on HAVE_PERF_EVENTS
1151 This config has been obsoleted by the PERF_EVENTS
1152 config option - please see that one for details.
1154 It has no effect on the kernel whether you enable
1155 it or not, it is a compatibility placeholder.
1159 config DEBUG_PERF_USE_VMALLOC
1161 bool "Debug: use vmalloc to back perf mmap() buffers"
1162 depends on PERF_EVENTS && DEBUG_KERNEL
1163 select PERF_USE_VMALLOC
1165 Use vmalloc memory to back perf mmap() buffers.
1167 Mostly useful for debugging the vmalloc code on platforms
1168 that don't require it.
1174 config VM_EVENT_COUNTERS
1176 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1178 VM event counters are needed for event counts to be shown.
1179 This option allows the disabling of the VM event counters
1180 on EXPERT systems. /proc/vmstat will only show page counts
1181 if VM event counters are disabled.
1185 bool "Enable PCI quirk workarounds" if EXPERT
1188 This enables workarounds for various PCI chipset
1189 bugs/quirks. Disable this only if your target machine is
1190 unaffected by PCI quirks.
1194 bool "Enable SLUB debugging support" if EXPERT
1195 depends on SLUB && SYSFS
1197 SLUB has extensive debug support features. Disabling these can
1198 result in significant savings in code size. This also disables
1199 SLUB sysfs support. /sys/slab will not exist and there will be
1200 no support for cache validation etc.
1203 bool "Disable heap randomization"
1206 Randomizing heap placement makes heap exploits harder, but it
1207 also breaks ancient binaries (including anything libc5 based).
1208 This option changes the bootup default to heap randomization
1209 disabled, and can be overridden at runtime by setting
1210 /proc/sys/kernel/randomize_va_space to 2.
1212 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1215 prompt "Choose SLAB allocator"
1218 This option allows to select a slab allocator.
1223 The regular slab allocator that is established and known to work
1224 well in all environments. It organizes cache hot objects in
1225 per cpu and per node queues.
1228 depends on BROKEN || NUMA || !DISCONTIGMEM
1229 bool "SLUB (Unqueued Allocator)"
1231 SLUB is a slab allocator that minimizes cache line usage
1232 instead of managing queues of cached objects (SLAB approach).
1233 Per cpu caching is realized using slabs of objects instead
1234 of queues of objects. SLUB can use memory efficiently
1235 and has enhanced diagnostics. SLUB is the default choice for
1240 bool "SLOB (Simple Allocator)"
1242 SLOB replaces the stock allocator with a drastically simpler
1243 allocator. SLOB is generally more space efficient but
1244 does not perform as well on large systems.
1248 config MMAP_ALLOW_UNINITIALIZED
1249 bool "Allow mmapped anonymous memory to be uninitialized"
1250 depends on EXPERT && !MMU
1253 Normally, and according to the Linux spec, anonymous memory obtained
1254 from mmap() has it's contents cleared before it is passed to
1255 userspace. Enabling this config option allows you to request that
1256 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1257 providing a huge performance boost. If this option is not enabled,
1258 then the flag will be ignored.
1260 This is taken advantage of by uClibc's malloc(), and also by
1261 ELF-FDPIC binfmt's brk and stack allocator.
1263 Because of the obvious security issues, this option should only be
1264 enabled on embedded devices where you control what is run in
1265 userspace. Since that isn't generally a problem on no-MMU systems,
1266 it is normally safe to say Y here.
1268 See Documentation/nommu-mmap.txt for more information.
1271 bool "Profiling support"
1273 Say Y here to enable the extended profiling support mechanisms used
1274 by profilers such as OProfile.
1277 # Place an empty function call at each tracepoint site. Can be
1278 # dynamically changed for a probe function.
1283 source "arch/Kconfig"
1285 endmenu # General setup
1287 config HAVE_GENERIC_DMA_COHERENT
1294 depends on SLAB || SLUB_DEBUG
1302 default 0 if BASE_FULL
1303 default 1 if !BASE_FULL
1306 bool "Enable loadable module support"
1308 Kernel modules are small pieces of compiled code which can
1309 be inserted in the running kernel, rather than being
1310 permanently built into the kernel. You use the "modprobe"
1311 tool to add (and sometimes remove) them. If you say Y here,
1312 many parts of the kernel can be built as modules (by
1313 answering M instead of Y where indicated): this is most
1314 useful for infrequently used options which are not required
1315 for booting. For more information, see the man pages for
1316 modprobe, lsmod, modinfo, insmod and rmmod.
1318 If you say Y here, you will need to run "make
1319 modules_install" to put the modules under /lib/modules/
1320 where modprobe can find them (you may need to be root to do
1327 config MODULE_FORCE_LOAD
1328 bool "Forced module loading"
1331 Allow loading of modules without version information (ie. modprobe
1332 --force). Forced module loading sets the 'F' (forced) taint flag and
1333 is usually a really bad idea.
1335 config MODULE_UNLOAD
1336 bool "Module unloading"
1338 Without this option you will not be able to unload any
1339 modules (note that some modules may not be unloadable
1340 anyway), which makes your kernel smaller, faster
1341 and simpler. If unsure, say Y.
1343 config MODULE_FORCE_UNLOAD
1344 bool "Forced module unloading"
1345 depends on MODULE_UNLOAD && EXPERIMENTAL
1347 This option allows you to force a module to unload, even if the
1348 kernel believes it is unsafe: the kernel will remove the module
1349 without waiting for anyone to stop using it (using the -f option to
1350 rmmod). This is mainly for kernel developers and desperate users.
1354 bool "Module versioning support"
1356 Usually, you have to use modules compiled with your kernel.
1357 Saying Y here makes it sometimes possible to use modules
1358 compiled for different kernels, by adding enough information
1359 to the modules to (hopefully) spot any changes which would
1360 make them incompatible with the kernel you are running. If
1363 config MODULE_SRCVERSION_ALL
1364 bool "Source checksum for all modules"
1366 Modules which contain a MODULE_VERSION get an extra "srcversion"
1367 field inserted into their modinfo section, which contains a
1368 sum of the source files which made it. This helps maintainers
1369 see exactly which source was used to build a module (since
1370 others sometimes change the module source without updating
1371 the version). With this option, such a "srcversion" field
1372 will be created for all modules. If unsure, say N.
1376 config INIT_ALL_POSSIBLE
1379 Back when each arch used to define their own cpu_online_map and
1380 cpu_possible_map, some of them chose to initialize cpu_possible_map
1381 with all 1s, and others with all 0s. When they were centralised,
1382 it was better to provide this option than to break all the archs
1383 and have several arch maintainers pursuing me down dark alleys.
1388 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1390 Need stop_machine() primitive.
1392 source "block/Kconfig"
1394 config PREEMPT_NOTIFIERS
1401 source "kernel/Kconfig.locks"
projects / linux-flexiantxendom0-natty.git / blob