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1 menu "Code maturity level options"
3 config EXPERIMENTAL
4 bool "Prompt for development and/or incomplete code/drivers"
5 ---help---
6 Some of the various things that Linux supports (such as network
7 drivers, file systems, network protocols, etc.) can be in a state
8 of development where the functionality, stability, or the level of
9 testing is not yet high enough for general use. This is usually
10 known as the "alpha-test" phase among developers. If a feature is
11 currently in alpha-test, then the developers usually discourage
12 uninformed widespread use of this feature by the general public to
13 avoid "Why doesn't this work?" type mail messages. However, active
14 testing and use of these systems is welcomed. Just be aware that it
15 may not meet the normal level of reliability or it may fail to work
16 in some special cases. Detailed bug reports from people familiar
17 with the kernel internals are usually welcomed by the developers
18 (before submitting bug reports, please read the documents
19 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
20 <file:Documentation/BUG-HUNTING>, and
21 <file:Documentation/oops-tracing.txt> in the kernel source).
23 This option will also make obsoleted drivers available. These are
24 drivers that have been replaced by something else, and/or are
25 scheduled to be removed in a future kernel release.
27 Unless you intend to help test and develop a feature or driver that
28 falls into this category, or you have a situation that requires
29 using these features, you should probably say N here, which will
30 cause the configurator to present you with fewer choices. If
31 you say Y here, you will be offered the choice of using features or
32 drivers that are currently considered to be in the alpha-test phase.
34 config BROKEN
35 bool
37 config BROKEN_ON_SMP
38 bool
39 depends on BROKEN || !SMP
40 default y
42 config LOCK_KERNEL
43 bool
44 depends on SMP || PREEMPT
45 default y
47 config INIT_ENV_ARG_LIMIT
48 int
49 default 32 if !USERMODE
50 default 128 if USERMODE
51 help
52 Maximum of each of the number of arguments and environment
53 variables passed to init from the kernel command line.
55 endmenu
57 menu "General setup"
59 config LOCALVERSION
60 string "Local version - append to kernel release"
61 help
62 Append an extra string to the end of your kernel version.
63 This will show up when you type uname, for example.
64 The string you set here will be appended after the contents of
65 any files with a filename matching localversion* in your
66 object and source tree, in that order. Your total string can
67 be a maximum of 64 characters.
69 config LOCALVERSION_AUTO
70 bool "Automatically append version information to the version string"
71 default y
72 help
73 This will try to automatically determine if the current tree is a
74 release tree by looking for git tags that
75 belong to the current top of tree revision.
77 A string of the format -gxxxxxxxx will be added to the localversion
78 if a git based tree is found. The string generated by this will be
79 appended after any matching localversion* files, and after the value
80 set in CONFIG_LOCALVERSION
82 Note: This requires Perl, and a git repository, but not necessarily
83 the git or cogito tools to be installed.
85 config SWAP
86 bool "Support for paging of anonymous memory (swap)"
87 depends on MMU
88 default y
89 help
90 This option allows you to choose whether you want to have support
91 for so called swap devices or swap files in your kernel that are
92 used to provide more virtual memory than the actual RAM present
93 in your computer. If unsure say Y.
95 config SYSVIPC
96 bool "System V IPC"
97 ---help---
98 Inter Process Communication is a suite of library functions and
99 system calls which let processes (running programs) synchronize and
100 exchange information. It is generally considered to be a good thing,
101 and some programs won't run unless you say Y here. In particular, if
102 you want to run the DOS emulator dosemu under Linux (read the
103 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
104 you'll need to say Y here.
106 You can find documentation about IPC with "info ipc" and also in
107 section 6.4 of the Linux Programmer's Guide, available from
108 <http://www.tldp.org/guides.html>.
110 config POSIX_MQUEUE
111 bool "POSIX Message Queues"
112 depends on NET && EXPERIMENTAL
113 ---help---
114 POSIX variant of message queues is a part of IPC. In POSIX message
115 queues every message has a priority which decides about succession
116 of receiving it by a process. If you want to compile and run
117 programs written e.g. for Solaris with use of its POSIX message
118 queues (functions mq_*) say Y here. To use this feature you will
119 also need mqueue library, available from
120 <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
122 POSIX message queues are visible as a filesystem called 'mqueue'
123 and can be mounted somewhere if you want to do filesystem
124 operations on message queues.
126 If unsure, say Y.
128 config BSD_PROCESS_ACCT
129 bool "BSD Process Accounting"
130 help
131 If you say Y here, a user level program will be able to instruct the
132 kernel (via a special system call) to write process accounting
133 information to a file: whenever a process exits, information about
134 that process will be appended to the file by the kernel. The
135 information includes things such as creation time, owning user,
136 command name, memory usage, controlling terminal etc. (the complete
137 list is in the struct acct in <file:include/linux/acct.h>). It is
138 up to the user level program to do useful things with this
139 information. This is generally a good idea, so say Y.
141 config BSD_PROCESS_ACCT_V3
142 bool "BSD Process Accounting version 3 file format"
143 depends on BSD_PROCESS_ACCT
144 default n
145 help
146 If you say Y here, the process accounting information is written
147 in a new file format that also logs the process IDs of each
148 process and it's parent. Note that this file format is incompatible
149 with previous v0/v1/v2 file formats, so you will need updated tools
150 for processing it. A preliminary version of these tools is available
151 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
153 config SYSCTL
154 bool "Sysctl support"
155 ---help---
156 The sysctl interface provides a means of dynamically changing
157 certain kernel parameters and variables on the fly without requiring
158 a recompile of the kernel or reboot of the system. The primary
159 interface consists of a system call, but if you say Y to "/proc
160 file system support", a tree of modifiable sysctl entries will be
161 generated beneath the /proc/sys directory. They are explained in the
162 files in <file:Documentation/sysctl/>. Note that enabling this
163 option will enlarge the kernel by at least 8 KB.
165 As it is generally a good thing, you should say Y here unless
166 building a kernel for install/rescue disks or your system is very
167 limited in memory.
169 config AUDIT
170 bool "Auditing support"
171 depends on NET
172 help
173 Enable auditing infrastructure that can be used with another
174 kernel subsystem, such as SELinux (which requires this for
175 logging of avc messages output). Does not do system-call
176 auditing without CONFIG_AUDITSYSCALL.
178 config AUDITSYSCALL
179 bool "Enable system-call auditing support"
180 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64)
181 default y if SECURITY_SELINUX
182 help
183 Enable low-overhead system-call auditing infrastructure that
184 can be used independently or with another kernel subsystem,
185 such as SELinux.
187 config IKCONFIG
188 bool "Kernel .config support"
189 ---help---
190 This option enables the complete Linux kernel ".config" file
191 contents to be saved in the kernel. It provides documentation
192 of which kernel options are used in a running kernel or in an
193 on-disk kernel. This information can be extracted from the kernel
194 image file with the script scripts/extract-ikconfig and used as
195 input to rebuild the current kernel or to build another kernel.
196 It can also be extracted from a running kernel by reading
197 /proc/config.gz if enabled (below).
199 config IKCONFIG_PROC
200 bool "Enable access to .config through /proc/config.gz"
201 depends on IKCONFIG && PROC_FS
202 ---help---
203 This option enables access to the kernel configuration file
204 through /proc/config.gz.
206 config CPUSETS
207 bool "Cpuset support"
208 depends on SMP
209 help
210 This option will let you create and manage CPUSETs which
211 allow dynamically partitioning a system into sets of CPUs and
212 Memory Nodes and assigning tasks to run only within those sets.
213 This is primarily useful on large SMP or NUMA systems.
215 Say N if unsure.
217 source "usr/Kconfig"
219 config UID16
220 bool "Enable 16-bit UID system calls" if EMBEDDED
221 depends on ARM || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION)
222 default y
223 help
224 This enables the legacy 16-bit UID syscall wrappers.
226 config VM86
227 depends X86
228 default y
229 bool "Enable VM86 support" if EMBEDDED
230 help
231 This option is required by programs like DOSEMU to run 16-bit legacy
232 code on X86 processors. It also may be needed by software like
233 XFree86 to initialize some video cards via BIOS. Disabling this
234 option saves about 6k.
236 config CC_OPTIMIZE_FOR_SIZE
237 bool "Optimize for size (Look out for broken compilers!)"
238 default y
239 depends on ARM || H8300 || EXPERIMENTAL
240 help
241 Enabling this option will pass "-Os" instead of "-O2" to gcc
242 resulting in a smaller kernel.
244 WARNING: some versions of gcc may generate incorrect code with this
245 option. If problems are observed, a gcc upgrade may be needed.
247 If unsure, say N.
249 menuconfig EMBEDDED
250 bool "Configure standard kernel features (for small systems)"
251 help
252 This option allows certain base kernel options and settings
253 to be disabled or tweaked. This is for specialized
254 environments which can tolerate a "non-standard" kernel.
255 Only use this if you really know what you are doing.
257 config KALLSYMS
258 bool "Load all symbols for debugging/kksymoops" if EMBEDDED
259 default y
260 help
261 Say Y here to let the kernel print out symbolic crash information and
262 symbolic stack backtraces. This increases the size of the kernel
263 somewhat, as all symbols have to be loaded into the kernel image.
265 config KALLSYMS_ALL
266 bool "Include all symbols in kallsyms"
267 depends on DEBUG_KERNEL && KALLSYMS
268 help
269 Normally kallsyms only contains the symbols of functions, for nicer
270 OOPS messages. Some debuggers can use kallsyms for other
271 symbols too: say Y here to include all symbols, if you need them
272 and you don't care about adding 300k to the size of your kernel.
274 Say N.
276 config KALLSYMS_EXTRA_PASS
277 bool "Do an extra kallsyms pass"
278 depends on KALLSYMS
279 help
280 If kallsyms is not working correctly, the build will fail with
281 inconsistent kallsyms data. If that occurs, log a bug report and
282 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
283 Always say N here unless you find a bug in kallsyms, which must be
284 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
285 you wait for kallsyms to be fixed.
288 config HOTPLUG
289 bool "Support for hot-pluggable devices" if EMBEDDED
290 default y
291 help
292 This option is provided for the case where no hotplug or uevent
293 capabilities is wanted by the kernel. You should only consider
294 disabling this option for embedded systems that do not use modules, a
295 dynamic /dev tree, or dynamic device discovery. Just say Y.
297 config PRINTK
298 default y
299 bool "Enable support for printk" if EMBEDDED
300 help
301 This option enables normal printk support. Removing it
302 eliminates most of the message strings from the kernel image
303 and makes the kernel more or less silent. As this makes it
304 very difficult to diagnose system problems, saying N here is
305 strongly discouraged.
307 config BUG
308 bool "BUG() support" if EMBEDDED
309 default y
310 help
311 Disabling this option eliminates support for BUG and WARN, reducing
312 the size of your kernel image and potentially quietly ignoring
313 numerous fatal conditions. You should only consider disabling this
314 option for embedded systems with no facilities for reporting errors.
315 Just say Y.
317 config ELF_CORE
318 default y
319 bool "Enable ELF core dumps" if EMBEDDED
320 help
321 Enable support for generating core dumps. Disabling saves about 4k.
323 config BASE_FULL
324 default y
325 bool "Enable full-sized data structures for core" if EMBEDDED
326 help
327 Disabling this option reduces the size of miscellaneous core
328 kernel data structures. This saves memory on small machines,
329 but may reduce performance.
331 config FUTEX
332 bool "Enable futex support" if EMBEDDED
333 default y
334 help
335 Disabling this option will cause the kernel to be built without
336 support for "fast userspace mutexes". The resulting kernel may not
337 run glibc-based applications correctly.
339 config EPOLL
340 bool "Enable eventpoll support" if EMBEDDED
341 default y
342 help
343 Disabling this option will cause the kernel to be built without
344 support for epoll family of system calls.
346 config SHMEM
347 bool "Use full shmem filesystem" if EMBEDDED
348 default y
349 depends on MMU
350 help
351 The shmem is an internal filesystem used to manage shared memory.
352 It is backed by swap and manages resource limits. It is also exported
353 to userspace as tmpfs if TMPFS is enabled. Disabling this
354 option replaces shmem and tmpfs with the much simpler ramfs code,
355 which may be appropriate on small systems without swap.
357 config CC_ALIGN_FUNCTIONS
358 int "Function alignment" if EMBEDDED
359 default 0
360 help
361 Align the start of functions to the next power-of-two greater than n,
362 skipping up to n bytes. For instance, 32 aligns functions
363 to the next 32-byte boundary, but 24 would align to the next
364 32-byte boundary only if this can be done by skipping 23 bytes or less.
365 Zero means use compiler's default.
367 config CC_ALIGN_LABELS
368 int "Label alignment" if EMBEDDED
369 default 0
370 help
371 Align all branch targets to a power-of-two boundary, skipping
372 up to n bytes like ALIGN_FUNCTIONS. This option can easily
373 make code slower, because it must insert dummy operations for
374 when the branch target is reached in the usual flow of the code.
375 Zero means use compiler's default.
377 config CC_ALIGN_LOOPS
378 int "Loop alignment" if EMBEDDED
379 default 0
380 help
381 Align loops to a power-of-two boundary, skipping up to n bytes.
382 Zero means use compiler's default.
384 config CC_ALIGN_JUMPS
385 int "Jump alignment" if EMBEDDED
386 default 0
387 help
388 Align branch targets to a power-of-two boundary, for branch
389 targets where the targets can only be reached by jumping,
390 skipping up to n bytes like ALIGN_FUNCTIONS. In this case,
391 no dummy operations need be executed.
392 Zero means use compiler's default.
394 config SLAB
395 default y
396 bool "Use full SLAB allocator" if EMBEDDED
397 help
398 Disabling this replaces the advanced SLAB allocator and
399 kmalloc support with the drastically simpler SLOB allocator.
400 SLOB is more space efficient but does not scale well and is
401 more susceptible to fragmentation.
403 endmenu # General setup
405 config TINY_SHMEM
406 default !SHMEM
407 bool
409 config BASE_SMALL
410 int
411 default 0 if BASE_FULL
412 default 1 if !BASE_FULL
414 config SLOB
415 default !SLAB
416 bool
418 config OBSOLETE_INTERMODULE
419 tristate
421 menu "Loadable module support"
423 config MODULES
424 bool "Enable loadable module support"
425 help
426 Kernel modules are small pieces of compiled code which can
427 be inserted in the running kernel, rather than being
428 permanently built into the kernel. You use the "modprobe"
429 tool to add (and sometimes remove) them. If you say Y here,
430 many parts of the kernel can be built as modules (by
431 answering M instead of Y where indicated): this is most
432 useful for infrequently used options which are not required
433 for booting. For more information, see the man pages for
434 modprobe, lsmod, modinfo, insmod and rmmod.
436 If you say Y here, you will need to run "make
437 modules_install" to put the modules under /lib/modules/
438 where modprobe can find them (you may need to be root to do
439 this).
441 If unsure, say Y.
443 config MODULE_UNLOAD
444 bool "Module unloading"
445 depends on MODULES
446 help
447 Without this option you will not be able to unload any
448 modules (note that some modules may not be unloadable
449 anyway), which makes your kernel slightly smaller and
450 simpler. If unsure, say Y.
452 config MODULE_FORCE_UNLOAD
453 bool "Forced module unloading"
454 depends on MODULE_UNLOAD && EXPERIMENTAL
455 help
456 This option allows you to force a module to unload, even if the
457 kernel believes it is unsafe: the kernel will remove the module
458 without waiting for anyone to stop using it (using the -f option to
459 rmmod). This is mainly for kernel developers and desperate users.
460 If unsure, say N.
462 config OBSOLETE_MODPARM
463 bool
464 default y
465 depends on MODULES
466 help
467 You need this option to use module parameters on modules which
468 have not been converted to the new module parameter system yet.
469 If unsure, say Y.
471 config MODVERSIONS
472 bool "Module versioning support"
473 depends on MODULES
474 help
475 Usually, you have to use modules compiled with your kernel.
476 Saying Y here makes it sometimes possible to use modules
477 compiled for different kernels, by adding enough information
478 to the modules to (hopefully) spot any changes which would
479 make them incompatible with the kernel you are running. If
480 unsure, say N.
482 config MODULE_SRCVERSION_ALL
483 bool "Source checksum for all modules"
484 depends on MODULES
485 help
486 Modules which contain a MODULE_VERSION get an extra "srcversion"
487 field inserted into their modinfo section, which contains a
488 sum of the source files which made it. This helps maintainers
489 see exactly which source was used to build a module (since
490 others sometimes change the module source without updating
491 the version). With this option, such a "srcversion" field
492 will be created for all modules. If unsure, say N.
494 config KMOD
495 bool "Automatic kernel module loading"
496 depends on MODULES
497 help
498 Normally when you have selected some parts of the kernel to
499 be created as kernel modules, you must load them (using the
500 "modprobe" command) before you can use them. If you say Y
501 here, some parts of the kernel will be able to load modules
502 automatically: when a part of the kernel needs a module, it
503 runs modprobe with the appropriate arguments, thereby
504 loading the module if it is available. If unsure, say Y.
506 config STOP_MACHINE
507 bool
508 default y
509 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
510 help
511 Need stop_machine() primitive.
512 endmenu
514 menu "Block layer"
515 source "block/Kconfig"
516 endmenu