1 menu "Code maturity level options"
4 bool "Prompt for development and/or incomplete code/drivers"
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24 drivers that have been replaced by something else, and/or are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.
35 bool "Select only drivers expected to compile cleanly" if EXPERIMENTAL
38 Select this option if you don't even want to see the option
39 to configure known-broken drivers.
45 depends on !CLEAN_COMPILE
50 depends on BROKEN || !SMP
55 depends on SMP || PREEMPT
58 config INIT_ENV_ARG_LIMIT
60 default 32 if !USERMODE
61 default 128 if USERMODE
63 This is the value of the two limits on the number of argument and of
64 env.var passed to init from the kernel command line.
71 string "Local version - append to kernel release"
73 Append an extra string to the end of your kernel version.
74 This will show up when you type uname, for example.
75 The string you set here will be appended after the contents of
76 any files with a filename matching localversion* in your
77 object and source tree, in that order. Your total string can
78 be a maximum of 64 characters.
81 bool "Support for paging of anonymous memory (swap)"
85 This option allows you to choose whether you want to have support
86 for socalled swap devices or swap files in your kernel that are
87 used to provide more virtual memory than the actual RAM present
88 in your computer. If unsure say Y.
94 Inter Process Communication is a suite of library functions and
95 system calls which let processes (running programs) synchronize and
96 exchange information. It is generally considered to be a good thing,
97 and some programs won't run unless you say Y here. In particular, if
98 you want to run the DOS emulator dosemu under Linux (read the
99 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
100 you'll need to say Y here.
102 You can find documentation about IPC with "info ipc" and also in
103 section 6.4 of the Linux Programmer's Guide, available from
104 <http://www.tldp.org/guides.html>.
107 bool "POSIX Message Queues"
108 depends on NET && EXPERIMENTAL
110 POSIX variant of message queues is a part of IPC. In POSIX message
111 queues every message has a priority which decides about succession
112 of receiving it by a process. If you want to compile and run
113 programs written e.g. for Solaris with use of its POSIX message
114 queues (functions mq_*) say Y here. To use this feature you will
115 also need mqueue library, available from
116 <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
118 POSIX message queues are visible as a filesystem called 'mqueue'
119 and can be mounted somewhere if you want to do filesystem
120 operations on message queues.
124 config BSD_PROCESS_ACCT
125 bool "BSD Process Accounting"
127 If you say Y here, a user level program will be able to instruct the
128 kernel (via a special system call) to write process accounting
129 information to a file: whenever a process exits, information about
130 that process will be appended to the file by the kernel. The
131 information includes things such as creation time, owning user,
132 command name, memory usage, controlling terminal etc. (the complete
133 list is in the struct acct in <file:include/linux/acct.h>). It is
134 up to the user level program to do useful things with this
135 information. This is generally a good idea, so say Y.
137 config BSD_PROCESS_ACCT_V3
138 bool "BSD Process Accounting version 3 file format"
139 depends on BSD_PROCESS_ACCT
142 If you say Y here, the process accounting information is written
143 in a new file format that also logs the process IDs of each
144 process and it's parent. Note that this file format is incompatible
145 with previous v0/v1/v2 file formats, so you will need updated tools
146 for processing it. A preliminary version of these tools is available
147 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>.
150 bool "Sysctl support"
152 The sysctl interface provides a means of dynamically changing
153 certain kernel parameters and variables on the fly without requiring
154 a recompile of the kernel or reboot of the system. The primary
155 interface consists of a system call, but if you say Y to "/proc
156 file system support", a tree of modifiable sysctl entries will be
157 generated beneath the /proc/sys directory. They are explained in the
158 files in <file:Documentation/sysctl/>. Note that enabling this
159 option will enlarge the kernel by at least 8 KB.
161 As it is generally a good thing, you should say Y here unless
162 building a kernel for install/rescue disks or your system is very
166 bool "Auditing support"
167 default y if SECURITY_SELINUX
169 Enable auditing infrastructure that can be used with another
170 kernel subsystem, such as SELinux (which requires this for
171 logging of avc messages output). Does not do system-call
172 auditing without CONFIG_AUDITSYSCALL.
175 bool "Enable system-call auditing support"
176 depends on AUDIT && (X86 || PPC64 || ARCH_S390 || IA64 || UML)
177 default y if SECURITY_SELINUX
179 Enable low-overhead system-call auditing infrastructure that
180 can be used independently or with another kernel subsystem,
184 bool "Support for hot-pluggable devices" if !ARCH_S390
187 This option is provided for the case where no in-kernel-tree
188 modules require HOTPLUG functionality, but a module built
189 outside the kernel tree does. Such modules require Y here.
191 config KOBJECT_UEVENT
192 bool "Kernel Userspace Events"
196 This option enables the kernel userspace event layer, which is a
197 simple mechanism for kernel-to-user communication over a netlink
199 The goal of the kernel userspace events layer is to provide a simple
200 and efficient events system, that notifies userspace about kobject
201 state changes. This will enable applications to just listen for
202 events instead of polling system devices and files.
203 Hotplug events (kobject addition and removal) are also available on
204 the netlink socket in addition to the execution of /sbin/hotplug if
205 CONFIG_HOTPLUG is enabled.
207 Say Y, unless you are building a system requiring minimal memory
211 bool "Kernel .config support"
213 This option enables the complete Linux kernel ".config" file
214 contents to be saved in the kernel. It provides documentation
215 of which kernel options are used in a running kernel or in an
216 on-disk kernel. This information can be extracted from the kernel
217 image file with the script scripts/extract-ikconfig and used as
218 input to rebuild the current kernel or to build another kernel.
219 It can also be extracted from a running kernel by reading
220 /proc/config.gz if enabled (below).
223 bool "Enable access to .config through /proc/config.gz"
224 depends on IKCONFIG && PROC_FS
226 This option enables access to the kernel configuration file
227 through /proc/config.gz.
230 bool "Cpuset support"
233 This options will let you create and manage CPUSET's which
234 allow dynamically partitioning a system into sets of CPUs and
235 Memory Nodes and assigning tasks to run only within those sets.
236 This is primarily useful on large SMP or NUMA systems.
241 bool "Configure standard kernel features (for small systems)"
243 This option allows certain base kernel options and settings
244 to be disabled or tweaked. This is for specialized
245 environments which can tolerate a "non-standard" kernel.
246 Only use this if you really know what you are doing.
249 bool "Load all symbols for debugging/kksymoops" if EMBEDDED
252 Say Y here to let the kernel print out symbolic crash information and
253 symbolic stack backtraces. This increases the size of the kernel
254 somewhat, as all symbols have to be loaded into the kernel image.
257 bool "Include all symbols in kallsyms"
258 depends on DEBUG_KERNEL && KALLSYMS
260 Normally kallsyms only contains the symbols of functions, for nicer
261 OOPS messages. Some debuggers can use kallsyms for other
262 symbols too: say Y here to include all symbols, and you
263 don't care about adding 300k to the size of your kernel.
267 config KALLSYMS_EXTRA_PASS
268 bool "Do an extra kallsyms pass"
271 If kallsyms is not working correctly, the build will fail with
272 inconsistent kallsyms data. If that occurs, log a bug report and
273 turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
274 Always say N here unless you find a bug in kallsyms, which must be
275 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while
276 you wait for kallsyms to be fixed.
281 bool "Enable support for printk" if EMBEDDED
283 This option enables normal printk support. Removing it
284 eliminates most of the message strings from the kernel image
285 and makes the kernel more or less silent. As this makes it
286 very difficult to diagnose system problems, saying N here is
287 strongly discouraged.
290 bool "BUG() support" if EMBEDDED
293 Disabling this option eliminates support for BUG and WARN, reducing
294 the size of your kernel image and potentially quietly ignoring
295 numerous fatal conditions. You should only consider disabling this
296 option for embedded systems with no facilities for reporting errors.
301 bool "Enable full-sized data structures for core" if EMBEDDED
303 Disabling this option reduces the size of miscellaneous core
304 kernel data structures. This saves memory on small machines,
305 but may reduce performance.
308 bool "Enable futex support" if EMBEDDED
311 Disabling this option will cause the kernel to be built without
312 support for "fast userspace mutexes". The resulting kernel may not
313 run glibc-based applications correctly.
316 bool "Enable eventpoll support" if EMBEDDED
319 Disabling this option will cause the kernel to be built without
320 support for epoll family of system calls.
322 config CC_OPTIMIZE_FOR_SIZE
323 bool "Optimize for size" if EMBEDDED
324 default y if ARM || H8300
326 Enabling this option will pass "-Os" instead of "-O2" to gcc
327 resulting in a smaller kernel.
329 WARNING: some versions of gcc may generate incorrect code with this
330 option. If problems are observed, a gcc upgrade may be needed.
335 bool "Use full shmem filesystem" if EMBEDDED
339 The shmem is an internal filesystem used to manage shared memory.
340 It is backed by swap and manages resource limits. It is also exported
341 to userspace as tmpfs if TMPFS is enabled. Disabling this
342 option replaces shmem and tmpfs with the much simpler ramfs code,
343 which may be appropriate on small systems without swap.
345 config CC_ALIGN_FUNCTIONS
346 int "Function alignment" if EMBEDDED
349 Align the start of functions to the next power-of-two greater than n,
350 skipping up to n bytes. For instance, 32 aligns functions
351 to the next 32-byte boundary, but 24 would align to the next
352 32-byte boundary only if this can be done by skipping 23 bytes or less.
353 Zero means use compiler's default.
355 config CC_ALIGN_LABELS
356 int "Label alignment" if EMBEDDED
359 Align all branch targets to a power-of-two boundary, skipping
360 up to n bytes like ALIGN_FUNCTIONS. This option can easily
361 make code slower, because it must insert dummy operations for
362 when the branch target is reached in the usual flow of the code.
363 Zero means use compiler's default.
365 config CC_ALIGN_LOOPS
366 int "Loop alignment" if EMBEDDED
369 Align loops to a power-of-two boundary, skipping up to n bytes.
370 Zero means use compiler's default.
372 config CC_ALIGN_JUMPS
373 int "Jump alignment" if EMBEDDED
376 Align branch targets to a power-of-two boundary, for branch
377 targets where the targets can only be reached by jumping,
378 skipping up to n bytes like ALIGN_FUNCTIONS. In this case,
379 no dummy operations need be executed.
380 Zero means use compiler's default.
382 endmenu # General setup
390 default 0 if BASE_FULL
391 default 1 if !BASE_FULL
393 menu "Loadable module support"
396 bool "Enable loadable module support"
398 Kernel modules are small pieces of compiled code which can
399 be inserted in the running kernel, rather than being
400 permanently built into the kernel. You use the "modprobe"
401 tool to add (and sometimes remove) them. If you say Y here,
402 many parts of the kernel can be built as modules (by
403 answering M instead of Y where indicated): this is most
404 useful for infrequently used options which are not required
405 for booting. For more information, see the man pages for
406 modprobe, lsmod, modinfo, insmod and rmmod.
408 If you say Y here, you will need to run "make
409 modules_install" to put the modules under /lib/modules/
410 where modprobe can find them (you may need to be root to do
416 bool "Module unloading"
419 Without this option you will not be able to unload any
420 modules (note that some modules may not be unloadable
421 anyway), which makes your kernel slightly smaller and
422 simpler. If unsure, say Y.
424 config MODULE_FORCE_UNLOAD
425 bool "Forced module unloading"
426 depends on MODULE_UNLOAD && EXPERIMENTAL
428 This option allows you to force a module to unload, even if the
429 kernel believes it is unsafe: the kernel will remove the module
430 without waiting for anyone to stop using it (using the -f option to
431 rmmod). This is mainly for kernel developers and desperate users.
434 config OBSOLETE_MODPARM
439 You need this option to use module parameters on modules which
440 have not been converted to the new module parameter system yet.
444 bool "Module versioning support (EXPERIMENTAL)"
445 depends on MODULES && EXPERIMENTAL
447 Usually, you have to use modules compiled with your kernel.
448 Saying Y here makes it sometimes possible to use modules
449 compiled for different kernels, by adding enough information
450 to the modules to (hopefully) spot any changes which would
451 make them incompatible with the kernel you are running. If
454 config MODULE_SRCVERSION_ALL
455 bool "Source checksum for all modules"
458 Modules which contain a MODULE_VERSION get an extra "srcversion"
459 field inserted into their modinfo section, which contains a
460 sum of the source files which made it. This helps maintainers
461 see exactly which source was used to build a module (since
462 others sometimes change the module source without updating
463 the version). With this option, such a "srcversion" field
464 will be created for all modules. If unsure, say N.
467 bool "Automatic kernel module loading"
470 Normally when you have selected some parts of the kernel to
471 be created as kernel modules, you must load them (using the
472 "modprobe" command) before you can use them. If you say Y
473 here, some parts of the kernel will be able to load modules
474 automatically: when a part of the kernel needs a module, it
475 runs modprobe with the appropriate arguments, thereby
476 loading the module if it is available. If unsure, say Y.
481 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
483 Need stop_machine() primitive.