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54 drivers that have been replaced by something else, and/or are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.
212 config VERSION_SIGNATURE
213 string "Arbitrary version signature"
215 This string will be created in a file, /proc/version_signature. It
216 is useful in determining arbitrary data about your kernel. For instance,
217 if you have several kernels of the same version, but need to keep track
218 of a revision of the same kernel, but not affect it's ability to load
219 compatible modules, this is the easiest way to do that.
222 bool "Support for paging of anonymous memory (swap)"
223 depends on MMU && BLOCK
226 This option allows you to choose whether you want to have support
227 for so called swap devices or swap files in your kernel that are
228 used to provide more virtual memory than the actual RAM present
229 in your computer. If unsure say Y.
234 Inter Process Communication is a suite of library functions and
235 system calls which let processes (running programs) synchronize and
236 exchange information. It is generally considered to be a good thing,
237 and some programs won't run unless you say Y here. In particular, if
238 you want to run the DOS emulator dosemu under Linux (read the
239 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
240 you'll need to say Y here.
242 You can find documentation about IPC with "info ipc" and also in
243 section 6.4 of the Linux Programmer's Guide, available from
244 <http://www.tldp.org/guides.html>.
246 config SYSVIPC_SYSCTL
253 bool "POSIX Message Queues"
254 depends on NET && EXPERIMENTAL
256 POSIX variant of message queues is a part of IPC. In POSIX message
257 queues every message has a priority which decides about succession
258 of receiving it by a process. If you want to compile and run
259 programs written e.g. for Solaris with use of its POSIX message
260 queues (functions mq_*) say Y here.
262 POSIX message queues are visible as a filesystem called 'mqueue'
263 and can be mounted somewhere if you want to do filesystem
264 operations on message queues.
268 config POSIX_MQUEUE_SYSCTL
270 depends on POSIX_MQUEUE
274 config BSD_PROCESS_ACCT
275 bool "BSD Process Accounting"
277 If you say Y here, a user level program will be able to instruct the
278 kernel (via a special system call) to write process accounting
279 information to a file: whenever a process exits, information about
280 that process will be appended to the file by the kernel. The
281 information includes things such as creation time, owning user,
282 command name, memory usage, controlling terminal etc. (the complete
283 list is in the struct acct in <file:include/linux/acct.h>). It is
284 up to the user level program to do useful things with this
285 information. This is generally a good idea, so say Y.
287 config BSD_PROCESS_ACCT_V3
288 bool "BSD Process Accounting version 3 file format"
289 depends on BSD_PROCESS_ACCT
292 If you say Y here, the process accounting information is written
293 in a new file format that also logs the process IDs of each
294 process and it's parent. Note that this file format is incompatible
295 with previous v0/v1/v2 file formats, so you will need updated tools
296 for processing it. A preliminary version of these tools is available
297 at <http://www.gnu.org/software/acct/>.
300 bool "Export task/process statistics through netlink (EXPERIMENTAL)"
304 Export selected statistics for tasks/processes through the
305 generic netlink interface. Unlike BSD process accounting, the
306 statistics are available during the lifetime of tasks/processes as
307 responses to commands. Like BSD accounting, they are sent to user
312 config TASK_DELAY_ACCT
313 bool "Enable per-task delay accounting (EXPERIMENTAL)"
316 Collect information on time spent by a task waiting for system
317 resources like cpu, synchronous block I/O completion and swapping
318 in pages. Such statistics can help in setting a task's priorities
319 relative to other tasks for cpu, io, rss limits etc.
324 bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
327 Collect extended task accounting data and send the data
328 to userland for processing over the taskstats interface.
332 config TASK_IO_ACCOUNTING
333 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
334 depends on TASK_XACCT
336 Collect information on the number of bytes of storage I/O which this
342 bool "Auditing support"
345 Enable auditing infrastructure that can be used with another
346 kernel subsystem, such as SELinux (which requires this for
347 logging of avc messages output). Does not do system-call
348 auditing without CONFIG_AUDITSYSCALL.
351 bool "Enable system-call auditing support"
352 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
353 default y if SECURITY_SELINUX
355 Enable low-overhead system-call auditing infrastructure that
356 can be used independently or with another kernel subsystem,
361 depends on AUDITSYSCALL
366 depends on AUDITSYSCALL
369 source "kernel/irq/Kconfig"
374 prompt "RCU Implementation"
378 bool "Tree-based hierarchical RCU"
379 depends on !PREEMPT && SMP
381 This option selects the RCU implementation that is
382 designed for very large SMP system with hundreds or
383 thousands of CPUs. It also scales down nicely to
386 config TREE_PREEMPT_RCU
387 bool "Preemptible tree-based hierarchical RCU"
390 This option selects the RCU implementation that is
391 designed for very large SMP systems with hundreds or
392 thousands of CPUs, but for which real-time response
393 is also required. It also scales down nicely to
397 bool "UP-only small-memory-footprint RCU"
400 This option selects the RCU implementation that is
401 designed for UP systems from which real-time response
402 is not required. This option greatly reduces the
403 memory footprint of RCU.
405 config TINY_PREEMPT_RCU
406 bool "Preemptible UP-only small-memory-footprint RCU"
407 depends on !SMP && PREEMPT
409 This option selects the RCU implementation that is designed
410 for real-time UP systems. This option greatly reduces the
411 memory footprint of RCU.
416 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
418 This option enables preemptible-RCU code that is common between
419 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
422 bool "Enable tracing for RCU"
424 This option provides tracing in RCU which presents stats
425 in debugfs for debugging RCU implementation.
427 Say Y here if you want to enable RCU tracing
428 Say N if you are unsure.
431 int "Tree-based hierarchical RCU fanout value"
434 depends on TREE_RCU || TREE_PREEMPT_RCU
438 This option controls the fanout of hierarchical implementations
439 of RCU, allowing RCU to work efficiently on machines with
440 large numbers of CPUs. This value must be at least the fourth
441 root of NR_CPUS, which allows NR_CPUS to be insanely large.
442 The default value of RCU_FANOUT should be used for production
443 systems, but if you are stress-testing the RCU implementation
444 itself, small RCU_FANOUT values allow you to test large-system
445 code paths on small(er) systems.
447 Select a specific number if testing RCU itself.
448 Take the default if unsure.
450 config RCU_FANOUT_EXACT
451 bool "Disable tree-based hierarchical RCU auto-balancing"
452 depends on TREE_RCU || TREE_PREEMPT_RCU
455 This option forces use of the exact RCU_FANOUT value specified,
456 regardless of imbalances in the hierarchy. This is useful for
457 testing RCU itself, and might one day be useful on systems with
458 strong NUMA behavior.
460 Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
464 config RCU_FAST_NO_HZ
465 bool "Accelerate last non-dyntick-idle CPU's grace periods"
466 depends on TREE_RCU && NO_HZ && SMP
469 This option causes RCU to attempt to accelerate grace periods
470 in order to allow the final CPU to enter dynticks-idle state
471 more quickly. On the other hand, this option increases the
472 overhead of the dynticks-idle checking, particularly on systems
473 with large numbers of CPUs.
475 Say Y if energy efficiency is critically important, particularly
476 if you have relatively few CPUs.
478 Say N if you are unsure.
480 config TREE_RCU_TRACE
481 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
484 This option provides tracing for the TREE_RCU and
485 TREE_PREEMPT_RCU implementations, permitting Makefile to
486 trivially select kernel/rcutree_trace.c.
489 bool "Enable RCU priority boosting"
490 depends on RT_MUTEXES && TINY_PREEMPT_RCU
493 This option boosts the priority of preempted RCU readers that
494 block the current preemptible RCU grace period for too long.
495 This option also prevents heavy loads from blocking RCU
496 callback invocation for all flavors of RCU.
498 Say Y here if you are working with real-time apps or heavy loads
499 Say N here if you are unsure.
501 config RCU_BOOST_PRIO
502 int "Real-time priority to boost RCU readers to"
507 This option specifies the real-time priority to which preempted
508 RCU readers are to be boosted. If you are working with CPU-bound
509 real-time applications, you should specify a priority higher then
510 the highest-priority CPU-bound application.
512 Specify the real-time priority, or take the default if unsure.
514 config RCU_BOOST_DELAY
515 int "Milliseconds to delay boosting after RCU grace-period start"
520 This option specifies the time to wait after the beginning of
521 a given grace period before priority-boosting preempted RCU
522 readers blocking that grace period. Note that any RCU reader
523 blocking an expedited RCU grace period is boosted immediately.
525 Accept the default if unsure.
527 endmenu # "RCU Subsystem"
530 tristate "Kernel .config support"
532 This option enables the complete Linux kernel ".config" file
533 contents to be saved in the kernel. It provides documentation
534 of which kernel options are used in a running kernel or in an
535 on-disk kernel. This information can be extracted from the kernel
536 image file with the script scripts/extract-ikconfig and used as
537 input to rebuild the current kernel or to build another kernel.
538 It can also be extracted from a running kernel by reading
539 /proc/config.gz if enabled (below).
542 bool "Enable access to .config through /proc/config.gz"
543 depends on IKCONFIG && PROC_FS
545 This option enables access to the kernel configuration file
546 through /proc/config.gz.
549 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
553 Select kernel log buffer size as a power of 2.
563 # Architectures with an unreliable sched_clock() should select this:
565 config HAVE_UNSTABLE_SCHED_CLOCK
569 boolean "Control Group support"
572 This option adds support for grouping sets of processes together, for
573 use with process control subsystems such as Cpusets, CFS, memory
574 controls or device isolation.
576 - Documentation/scheduler/sched-design-CFS.txt (CFS)
577 - Documentation/cgroups/ (features for grouping, isolation
578 and resource control)
585 bool "Example debug cgroup subsystem"
588 This option enables a simple cgroup subsystem that
589 exports useful debugging information about the cgroups
595 bool "Namespace cgroup subsystem"
597 Provides a simple namespace cgroup subsystem to
598 provide hierarchical naming of sets of namespaces,
599 for instance virtual servers and checkpoint/restart
602 config CGROUP_FREEZER
603 bool "Freezer cgroup subsystem"
605 Provides a way to freeze and unfreeze all tasks in a
609 bool "Device controller for cgroups"
611 Provides a cgroup implementing whitelists for devices which
612 a process in the cgroup can mknod or open.
615 bool "Cpuset support"
617 This option will let you create and manage CPUSETs which
618 allow dynamically partitioning a system into sets of CPUs and
619 Memory Nodes and assigning tasks to run only within those sets.
620 This is primarily useful on large SMP or NUMA systems.
624 config PROC_PID_CPUSET
625 bool "Include legacy /proc/<pid>/cpuset file"
629 config CGROUP_CPUACCT
630 bool "Simple CPU accounting cgroup subsystem"
632 Provides a simple Resource Controller for monitoring the
633 total CPU consumed by the tasks in a cgroup.
635 config RESOURCE_COUNTERS
636 bool "Resource counters"
638 This option enables controller independent resource accounting
639 infrastructure that works with cgroups.
641 config CGROUP_MEM_RES_CTLR
642 bool "Memory Resource Controller for Control Groups"
643 depends on RESOURCE_COUNTERS
646 Provides a memory resource controller that manages both anonymous
647 memory and page cache. (See Documentation/cgroups/memory.txt)
649 Note that setting this option increases fixed memory overhead
650 associated with each page of memory in the system. By this,
651 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
652 usage tracking struct at boot. Total amount of this is printed out
655 Only enable when you're ok with these trade offs and really
656 sure you need the memory resource controller. Even when you enable
657 this, you can set "cgroup_disable=memory" at your boot option to
658 disable memory resource controller and you can avoid overheads.
659 (and lose benefits of memory resource controller)
661 This config option also selects MM_OWNER config option, which
662 could in turn add some fork/exit overhead.
664 config CGROUP_MEM_RES_CTLR_SWAP
665 bool "Memory Resource Controller Swap Extension"
666 depends on CGROUP_MEM_RES_CTLR && SWAP
668 Add swap management feature to memory resource controller. When you
669 enable this, you can limit mem+swap usage per cgroup. In other words,
670 when you disable this, memory resource controller has no cares to
671 usage of swap...a process can exhaust all of the swap. This extension
672 is useful when you want to avoid exhaustion swap but this itself
673 adds more overheads and consumes memory for remembering information.
674 Especially if you use 32bit system or small memory system, please
675 be careful about enabling this. When memory resource controller
676 is disabled by boot option, this will be automatically disabled and
677 there will be no overhead from this. Even when you set this config=y,
678 if boot option "noswapaccount" is set, swap will not be accounted.
679 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
680 size is 4096bytes, 512k per 1Gbytes of swap.
681 config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
682 bool "Memory Resource Controller Swap Extension enabled by default"
683 depends on CGROUP_MEM_RES_CTLR_SWAP
686 Memory Resource Controller Swap Extension comes with its price in
687 a bigger memory consumption. General purpose distribution kernels
688 which want to enable the feature but keep it disabled by default
689 and let the user enable it by swapaccount boot command line
690 parameter should have this option unselected.
691 For those who want to have the feature enabled by default should
692 select this option (if, for some reason, they need to disable it
693 then noswapaccount does the trick).
695 menuconfig CGROUP_SCHED
696 bool "Group CPU scheduler"
697 depends on EXPERIMENTAL
700 This feature lets CPU scheduler recognize task groups and control CPU
701 bandwidth allocation to such task groups. It uses cgroups to group
705 config FAIR_GROUP_SCHED
706 bool "Group scheduling for SCHED_OTHER"
707 depends on CGROUP_SCHED
710 config RT_GROUP_SCHED
711 bool "Group scheduling for SCHED_RR/FIFO"
712 depends on EXPERIMENTAL
713 depends on CGROUP_SCHED
716 This feature lets you explicitly allocate real CPU bandwidth
717 to task groups. If enabled, it will also make it impossible to
718 schedule realtime tasks for non-root users until you allocate
719 realtime bandwidth for them.
720 See Documentation/scheduler/sched-rt-group.txt for more information.
725 tristate "Block IO controller"
729 Generic block IO controller cgroup interface. This is the common
730 cgroup interface which should be used by various IO controlling
733 Currently, CFQ IO scheduler uses it to recognize task groups and
734 control disk bandwidth allocation (proportional time slice allocation)
735 to such task groups. It is also used by bio throttling logic in
736 block layer to implement upper limit in IO rates on a device.
738 This option only enables generic Block IO controller infrastructure.
739 One needs to also enable actual IO controlling logic/policy. For
740 enabling proportional weight division of disk bandwidth in CFQ seti
741 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
742 CONFIG_BLK_THROTTLE=y.
744 See Documentation/cgroups/blkio-controller.txt for more information.
746 config DEBUG_BLK_CGROUP
747 bool "Enable Block IO controller debugging"
748 depends on BLK_CGROUP
751 Enable some debugging help. Currently it exports additional stat
752 files in a cgroup which can be useful for debugging.
756 menuconfig NAMESPACES
757 bool "Namespaces support" if EXPERT
760 Provides the way to make tasks work with different objects using
761 the same id. For example same IPC id may refer to different objects
762 or same user id or pid may refer to different tasks when used in
763 different namespaces.
771 In this namespace tasks see different info provided with the
776 depends on (SYSVIPC || POSIX_MQUEUE)
779 In this namespace tasks work with IPC ids which correspond to
780 different IPC objects in different namespaces.
783 bool "User namespace (EXPERIMENTAL)"
784 depends on EXPERIMENTAL
787 This allows containers, i.e. vservers, to use user namespaces
788 to provide different user info for different servers.
792 bool "PID Namespaces"
795 Support process id namespaces. This allows having multiple
796 processes with the same pid as long as they are in different
797 pid namespaces. This is a building block of containers.
800 bool "Network namespace"
804 Allow user space to create what appear to be multiple instances
805 of the network stack.
809 config SCHED_AUTOGROUP
810 bool "Automatic process group scheduling"
814 select FAIR_GROUP_SCHED
816 This option optimizes the scheduler for common desktop workloads by
817 automatically creating and populating task groups. This separation
818 of workloads isolates aggressive CPU burners (like build jobs) from
819 desktop applications. Task group autogeneration is currently based
825 config SYSFS_DEPRECATED
826 bool "enable deprecated sysfs features to support old userspace tools"
830 This option adds code that switches the layout of the "block" class
831 devices, to not show up in /sys/class/block/, but only in
834 This switch is only active when the sysfs.deprecated=1 boot option is
835 passed or the SYSFS_DEPRECATED_V2 option is set.
837 This option allows new kernels to run on old distributions and tools,
838 which might get confused by /sys/class/block/. Since 2007/2008 all
839 major distributions and tools handle this just fine.
841 Recent distributions and userspace tools after 2009/2010 depend on
842 the existence of /sys/class/block/, and will not work with this
845 Only if you are using a new kernel on an old distribution, you might
848 config SYSFS_DEPRECATED_V2
849 bool "enabled deprecated sysfs features by default"
852 depends on SYSFS_DEPRECATED
854 Enable deprecated sysfs by default.
856 See the CONFIG_SYSFS_DEPRECATED option for more details about this
859 Only if you are using a new kernel on an old distribution, you might
860 need to say Y here. Even then, odds are you would not need it
861 enabled, you can always pass the boot option if absolutely necessary.
864 bool "Kernel->user space relay support (formerly relayfs)"
866 This option enables support for relay interface support in
867 certain file systems (such as debugfs).
868 It is designed to provide an efficient mechanism for tools and
869 facilities to relay large amounts of data from kernel space to
874 config BLK_DEV_INITRD
875 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
876 depends on BROKEN || !FRV
878 The initial RAM filesystem is a ramfs which is loaded by the
879 boot loader (loadlin or lilo) and that is mounted as root
880 before the normal boot procedure. It is typically used to
881 load modules needed to mount the "real" root file system,
882 etc. See <file:Documentation/initrd.txt> for details.
884 If RAM disk support (BLK_DEV_RAM) is also included, this
885 also enables initial RAM disk (initrd) support and adds
886 15 Kbytes (more on some other architectures) to the kernel size.
896 config CC_OPTIMIZE_FOR_SIZE
897 bool "Optimize for size"
900 Enabling this option will pass "-Os" instead of "-O2" to gcc
901 resulting in a smaller kernel.
912 bool "Configure standard kernel features (expert users)"
914 This option allows certain base kernel options and settings
915 to be disabled or tweaked. This is for specialized
916 environments which can tolerate a "non-standard" kernel.
917 Only use this if you really know what you are doing.
920 bool "Embedded system"
923 This option should be enabled if compiling the kernel for
924 an embedded system so certain expert options are available
928 bool "Enable 16-bit UID system calls" if EXPERT
929 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
932 This enables the legacy 16-bit UID syscall wrappers.
934 config SYSCTL_SYSCALL
935 bool "Sysctl syscall support" if EXPERT
936 depends on PROC_SYSCTL
940 sys_sysctl uses binary paths that have been found challenging
941 to properly maintain and use. The interface in /proc/sys
942 using paths with ascii names is now the primary path to this
945 Almost nothing using the binary sysctl interface so if you are
946 trying to save some space it is probably safe to disable this,
947 making your kernel marginally smaller.
949 If unsure say Y here.
952 bool "Load all symbols for debugging/ksymoops" if EXPERT
955 Say Y here to let the kernel print out symbolic crash information and
956 symbolic stack backtraces. This increases the size of the kernel
957 somewhat, as all symbols have to be loaded into the kernel image.
960 bool "Include all symbols in kallsyms"
961 depends on DEBUG_KERNEL && KALLSYMS
963 Normally kallsyms only contains the symbols of functions, for nicer
964 OOPS messages. Some debuggers can use kallsyms for other
965 symbols too: say Y here to include all symbols, if you need them
966 and you don't care about adding 300k to the size of your kernel.
970 config KALLSYMS_EXTRA_PASS
971 bool "Do an extra kallsyms pass"
974 If kallsyms is not working correctly, the build will fail with
975 inconsistent kallsyms data. If that occurs, log a bug report and
976 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
977 Always say N here unless you find a bug in kallsyms, which must be
978 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
979 you wait for kallsyms to be fixed.
983 bool "Support for hot-pluggable devices" if EXPERT
986 This option is provided for the case where no hotplug or uevent
987 capabilities is wanted by the kernel. You should only consider
988 disabling this option for embedded systems that do not use modules, a
989 dynamic /dev tree, or dynamic device discovery. Just say Y.
993 bool "Enable support for printk" if EXPERT
995 This option enables normal printk support. Removing it
996 eliminates most of the message strings from the kernel image
997 and makes the kernel more or less silent. As this makes it
998 very difficult to diagnose system problems, saying N here is
999 strongly discouraged.
1002 bool "BUG() support" if EXPERT
1005 Disabling this option eliminates support for BUG and WARN, reducing
1006 the size of your kernel image and potentially quietly ignoring
1007 numerous fatal conditions. You should only consider disabling this
1008 option for embedded systems with no facilities for reporting errors.
1013 bool "Enable ELF core dumps" if EXPERT
1015 Enable support for generating core dumps. Disabling saves about 4k.
1017 config PCSPKR_PLATFORM
1018 bool "Enable PC-Speaker support" if EXPERT
1019 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
1022 This option allows to disable the internal PC-Speaker
1023 support, saving some memory.
1027 bool "Enable full-sized data structures for core" if EXPERT
1029 Disabling this option reduces the size of miscellaneous core
1030 kernel data structures. This saves memory on small machines,
1031 but may reduce performance.
1034 bool "Enable futex support" if EXPERT
1038 Disabling this option will cause the kernel to be built without
1039 support for "fast userspace mutexes". The resulting kernel may not
1040 run glibc-based applications correctly.
1043 bool "Enable eventpoll support" if EXPERT
1047 Disabling this option will cause the kernel to be built without
1048 support for epoll family of system calls.
1051 bool "Enable signalfd() system call" if EXPERT
1055 Enable the signalfd() system call that allows to receive signals
1056 on a file descriptor.
1061 bool "Enable timerfd() system call" if EXPERT
1065 Enable the timerfd() system call that allows to receive timer
1066 events on a file descriptor.
1071 bool "Enable eventfd() system call" if EXPERT
1075 Enable the eventfd() system call that allows to receive both
1076 kernel notification (ie. KAIO) or userspace notifications.
1081 bool "Use full shmem filesystem" if EXPERT
1085 The shmem is an internal filesystem used to manage shared memory.
1086 It is backed by swap and manages resource limits. It is also exported
1087 to userspace as tmpfs if TMPFS is enabled. Disabling this
1088 option replaces shmem and tmpfs with the much simpler ramfs code,
1089 which may be appropriate on small systems without swap.
1092 bool "Enable AIO support" if EXPERT
1095 This option enables POSIX asynchronous I/O which may by used
1096 by some high performance threaded applications. Disabling
1097 this option saves about 7k.
1099 config HAVE_PERF_EVENTS
1102 See tools/perf/design.txt for details.
1104 config PERF_USE_VMALLOC
1107 See tools/perf/design.txt for details
1109 menu "Kernel Performance Events And Counters"
1112 bool "Kernel performance events and counters"
1113 default y if (PROFILING || PERF_COUNTERS)
1114 depends on HAVE_PERF_EVENTS
1118 Enable kernel support for various performance events provided
1119 by software and hardware.
1121 Software events are supported either built-in or via the
1122 use of generic tracepoints.
1124 Most modern CPUs support performance events via performance
1125 counter registers. These registers count the number of certain
1126 types of hw events: such as instructions executed, cachemisses
1127 suffered, or branches mis-predicted - without slowing down the
1128 kernel or applications. These registers can also trigger interrupts
1129 when a threshold number of events have passed - and can thus be
1130 used to profile the code that runs on that CPU.
1132 The Linux Performance Event subsystem provides an abstraction of
1133 these software and hardware event capabilities, available via a
1134 system call and used by the "perf" utility in tools/perf/. It
1135 provides per task and per CPU counters, and it provides event
1136 capabilities on top of those.
1140 config PERF_COUNTERS
1141 bool "Kernel performance counters (old config option)"
1142 depends on HAVE_PERF_EVENTS
1144 This config has been obsoleted by the PERF_EVENTS
1145 config option - please see that one for details.
1147 It has no effect on the kernel whether you enable
1148 it or not, it is a compatibility placeholder.
1152 config DEBUG_PERF_USE_VMALLOC
1154 bool "Debug: use vmalloc to back perf mmap() buffers"
1155 depends on PERF_EVENTS && DEBUG_KERNEL
1156 select PERF_USE_VMALLOC
1158 Use vmalloc memory to back perf mmap() buffers.
1160 Mostly useful for debugging the vmalloc code on platforms
1161 that don't require it.
1167 config VM_EVENT_COUNTERS
1169 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1171 VM event counters are needed for event counts to be shown.
1172 This option allows the disabling of the VM event counters
1173 on EXPERT systems. /proc/vmstat will only show page counts
1174 if VM event counters are disabled.
1178 bool "Enable PCI quirk workarounds" if EXPERT
1181 This enables workarounds for various PCI chipset
1182 bugs/quirks. Disable this only if your target machine is
1183 unaffected by PCI quirks.
1187 bool "Enable SLUB debugging support" if EXPERT
1188 depends on SLUB && SYSFS
1190 SLUB has extensive debug support features. Disabling these can
1191 result in significant savings in code size. This also disables
1192 SLUB sysfs support. /sys/slab will not exist and there will be
1193 no support for cache validation etc.
1196 bool "Disable heap randomization"
1199 Randomizing heap placement makes heap exploits harder, but it
1200 also breaks ancient binaries (including anything libc5 based).
1201 This option changes the bootup default to heap randomization
1202 disabled, and can be overridden at runtime by setting
1203 /proc/sys/kernel/randomize_va_space to 2.
1205 On non-ancient distros (post-2000 ones) N is usually a safe choice.
1208 prompt "Choose SLAB allocator"
1211 This option allows to select a slab allocator.
1216 The regular slab allocator that is established and known to work
1217 well in all environments. It organizes cache hot objects in
1218 per cpu and per node queues.
1221 bool "SLUB (Unqueued Allocator)"
1223 SLUB is a slab allocator that minimizes cache line usage
1224 instead of managing queues of cached objects (SLAB approach).
1225 Per cpu caching is realized using slabs of objects instead
1226 of queues of objects. SLUB can use memory efficiently
1227 and has enhanced diagnostics. SLUB is the default choice for
1232 bool "SLOB (Simple Allocator)"
1234 SLOB replaces the stock allocator with a drastically simpler
1235 allocator. SLOB is generally more space efficient but
1236 does not perform as well on large systems.
1240 config MMAP_ALLOW_UNINITIALIZED
1241 bool "Allow mmapped anonymous memory to be uninitialized"
1242 depends on EXPERT && !MMU
1245 Normally, and according to the Linux spec, anonymous memory obtained
1246 from mmap() has it's contents cleared before it is passed to
1247 userspace. Enabling this config option allows you to request that
1248 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1249 providing a huge performance boost. If this option is not enabled,
1250 then the flag will be ignored.
1252 This is taken advantage of by uClibc's malloc(), and also by
1253 ELF-FDPIC binfmt's brk and stack allocator.
1255 Because of the obvious security issues, this option should only be
1256 enabled on embedded devices where you control what is run in
1257 userspace. Since that isn't generally a problem on no-MMU systems,
1258 it is normally safe to say Y here.
1260 See Documentation/nommu-mmap.txt for more information.
1263 bool "Profiling support"
1265 Say Y here to enable the extended profiling support mechanisms used
1266 by profilers such as OProfile.
1269 # Place an empty function call at each tracepoint site. Can be
1270 # dynamically changed for a probe function.
1275 source "arch/Kconfig"
1277 endmenu # General setup
1279 config HAVE_GENERIC_DMA_COHERENT
1286 depends on SLAB || SLUB_DEBUG
1294 default 0 if BASE_FULL
1295 default 1 if !BASE_FULL
1298 bool "Enable loadable module support"
1300 Kernel modules are small pieces of compiled code which can
1301 be inserted in the running kernel, rather than being
1302 permanently built into the kernel. You use the "modprobe"
1303 tool to add (and sometimes remove) them. If you say Y here,
1304 many parts of the kernel can be built as modules (by
1305 answering M instead of Y where indicated): this is most
1306 useful for infrequently used options which are not required
1307 for booting. For more information, see the man pages for
1308 modprobe, lsmod, modinfo, insmod and rmmod.
1310 If you say Y here, you will need to run "make
1311 modules_install" to put the modules under /lib/modules/
1312 where modprobe can find them (you may need to be root to do
1319 config MODULE_FORCE_LOAD
1320 bool "Forced module loading"
1323 Allow loading of modules without version information (ie. modprobe
1324 --force). Forced module loading sets the 'F' (forced) taint flag and
1325 is usually a really bad idea.
1327 config MODULE_UNLOAD
1328 bool "Module unloading"
1330 Without this option you will not be able to unload any
1331 modules (note that some modules may not be unloadable
1332 anyway), which makes your kernel smaller, faster
1333 and simpler. If unsure, say Y.
1335 config MODULE_FORCE_UNLOAD
1336 bool "Forced module unloading"
1337 depends on MODULE_UNLOAD && EXPERIMENTAL
1339 This option allows you to force a module to unload, even if the
1340 kernel believes it is unsafe: the kernel will remove the module
1341 without waiting for anyone to stop using it (using the -f option to
1342 rmmod). This is mainly for kernel developers and desperate users.
1346 bool "Module versioning support"
1348 Usually, you have to use modules compiled with your kernel.
1349 Saying Y here makes it sometimes possible to use modules
1350 compiled for different kernels, by adding enough information
1351 to the modules to (hopefully) spot any changes which would
1352 make them incompatible with the kernel you are running. If
1355 config MODULE_SRCVERSION_ALL
1356 bool "Source checksum for all modules"
1358 Modules which contain a MODULE_VERSION get an extra "srcversion"
1359 field inserted into their modinfo section, which contains a
1360 sum of the source files which made it. This helps maintainers
1361 see exactly which source was used to build a module (since
1362 others sometimes change the module source without updating
1363 the version). With this option, such a "srcversion" field
1364 will be created for all modules. If unsure, say N.
1368 config INIT_ALL_POSSIBLE
1371 Back when each arch used to define their own cpu_online_map and
1372 cpu_possible_map, some of them chose to initialize cpu_possible_map
1373 with all 1s, and others with all 0s. When they were centralised,
1374 it was better to provide this option than to break all the archs
1375 and have several arch maintainers pursuing me down dark alleys.
1380 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1382 Need stop_machine() primitive.
1384 source "block/Kconfig"
1386 config PREEMPT_NOTIFIERS
1393 source "kernel/Kconfig.locks"
projects / linux-flexiantxendom0-natty.git / blob