1config DEFCONFIG_LIST 2 string 3 depends on !UML 4 option defconfig_list 5 default "/lib/modules/$UNAME_RELEASE/.config" 6 default "/etc/kernel-config" 7 default "/boot/config-$UNAME_RELEASE" 8 default "arch/$ARCH/defconfig" 9 10menu "Code maturity level options" 11 12config EXPERIMENTAL 13 bool "Prompt for development and/or incomplete code/drivers" 14 ---help--- 15 Some of the various things that Linux supports (such as network 16 drivers, file systems, network protocols, etc.) can be in a state 17 of development where the functionality, stability, or the level of 18 testing is not yet high enough for general use. This is usually 19 known as the "alpha-test" phase among developers. If a feature is 20 currently in alpha-test, then the developers usually discourage 21 uninformed widespread use of this feature by the general public to 22 avoid "Why doesn't this work?" type mail messages. However, active 23 testing and use of these systems is welcomed. Just be aware that it 24 may not meet the normal level of reliability or it may fail to work 25 in some special cases. Detailed bug reports from people familiar 26 with the kernel internals are usually welcomed by the developers 27 (before submitting bug reports, please read the documents 28 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 29 <file:Documentation/BUG-HUNTING>, and 30 <file:Documentation/oops-tracing.txt> in the kernel source). 31 32 This option will also make obsoleted drivers available. These are 33 drivers that have been replaced by something else, and/or are 34 scheduled to be removed in a future kernel release. 35 36 Unless you intend to help test and develop a feature or driver that 37 falls into this category, or you have a situation that requires 38 using these features, you should probably say N here, which will 39 cause the configurator to present you with fewer choices. If 40 you say Y here, you will be offered the choice of using features or 41 drivers that are currently considered to be in the alpha-test phase. 42 43config BROKEN 44 bool 45 46config BROKEN_ON_SMP 47 bool 48 depends on BROKEN || !SMP 49 default y 50 51config LOCK_KERNEL 52 bool 53 depends on SMP || PREEMPT 54 default y 55 56config INIT_ENV_ARG_LIMIT 57 int 58 default 32 if !UML 59 default 128 if UML 60 help 61 Maximum of each of the number of arguments and environment 62 variables passed to init from the kernel command line. 63 64endmenu 65 66menu "General setup" 67 68config LOCALVERSION 69 string "Local version - append to kernel release" 70 help 71 Append an extra string to the end of your kernel version. 72 This will show up when you type uname, for example. 73 The string you set here will be appended after the contents of 74 any files with a filename matching localversion* in your 75 object and source tree, in that order. Your total string can 76 be a maximum of 64 characters. 77 78config LOCALVERSION_AUTO 79 bool "Automatically append version information to the version string" 80 default y 81 help 82 This will try to automatically determine if the current tree is a 83 release tree by looking for git tags that belong to the current 84 top of tree revision. 85 86 A string of the format -gxxxxxxxx will be added to the localversion 87 if a git-based tree is found. The string generated by this will be 88 appended after any matching localversion* files, and after the value 89 set in CONFIG_LOCALVERSION. 90 91 (The actual string used here is the first eight characters produced 92 by running the command: 93 94 $ git rev-parse --verify HEAD 95 96 which is done within the script "scripts/setlocalversion".) 97 98config SWAP 99 bool "Support for paging of anonymous memory (swap)" 100 depends on MMU && BLOCK 101 default y 102 help 103 This option allows you to choose whether you want to have support 104 for so called swap devices or swap files in your kernel that are 105 used to provide more virtual memory than the actual RAM present 106 in your computer. If unsure say Y. 107 108config SYSVIPC 109 bool "System V IPC" 110 ---help--- 111 Inter Process Communication is a suite of library functions and 112 system calls which let processes (running programs) synchronize and 113 exchange information. It is generally considered to be a good thing, 114 and some programs won't run unless you say Y here. In particular, if 115 you want to run the DOS emulator dosemu under Linux (read the 116 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 117 you'll need to say Y here. 118 119 You can find documentation about IPC with "info ipc" and also in 120 section 6.4 of the Linux Programmer's Guide, available from 121 <http://www.tldp.org/guides.html>. 122 123config SYSVIPC_SYSCTL 124 bool 125 depends on SYSVIPC 126 depends on SYSCTL 127 default y 128 129config POSIX_MQUEUE 130 bool "POSIX Message Queues" 131 depends on NET && EXPERIMENTAL 132 ---help--- 133 POSIX variant of message queues is a part of IPC. In POSIX message 134 queues every message has a priority which decides about succession 135 of receiving it by a process. If you want to compile and run 136 programs written e.g. for Solaris with use of its POSIX message 137 queues (functions mq_*) say Y here. 138 139 POSIX message queues are visible as a filesystem called 'mqueue' 140 and can be mounted somewhere if you want to do filesystem 141 operations on message queues. 142 143 If unsure, say Y. 144 145config BSD_PROCESS_ACCT 146 bool "BSD Process Accounting" 147 help 148 If you say Y here, a user level program will be able to instruct the 149 kernel (via a special system call) to write process accounting 150 information to a file: whenever a process exits, information about 151 that process will be appended to the file by the kernel. The 152 information includes things such as creation time, owning user, 153 command name, memory usage, controlling terminal etc. (the complete 154 list is in the struct acct in <file:include/linux/acct.h>). It is 155 up to the user level program to do useful things with this 156 information. This is generally a good idea, so say Y. 157 158config BSD_PROCESS_ACCT_V3 159 bool "BSD Process Accounting version 3 file format" 160 depends on BSD_PROCESS_ACCT 161 default n 162 help 163 If you say Y here, the process accounting information is written 164 in a new file format that also logs the process IDs of each 165 process and it's parent. Note that this file format is incompatible 166 with previous v0/v1/v2 file formats, so you will need updated tools 167 for processing it. A preliminary version of these tools is available 168 at <http://www.physik3.uni-rostock.de/tim/kernel/utils/acct/>. 169 170config TASKSTATS 171 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 172 depends on NET 173 default n 174 help 175 Export selected statistics for tasks/processes through the 176 generic netlink interface. Unlike BSD process accounting, the 177 statistics are available during the lifetime of tasks/processes as 178 responses to commands. Like BSD accounting, they are sent to user 179 space on task exit. 180 181 Say N if unsure. 182 183config TASK_DELAY_ACCT 184 bool "Enable per-task delay accounting (EXPERIMENTAL)" 185 depends on TASKSTATS 186 help 187 Collect information on time spent by a task waiting for system 188 resources like cpu, synchronous block I/O completion and swapping 189 in pages. Such statistics can help in setting a task's priorities 190 relative to other tasks for cpu, io, rss limits etc. 191 192 Say N if unsure. 193 194config TASK_XACCT 195 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 196 depends on TASKSTATS 197 help 198 Collect extended task accounting data and send the data 199 to userland for processing over the taskstats interface. 200 201 Say N if unsure. 202 203config TASK_IO_ACCOUNTING 204 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 205 depends on TASK_XACCT 206 help 207 Collect information on the number of bytes of storage I/O which this 208 task has caused. 209 210 Say N if unsure. 211 212config USER_NS 213 bool "User Namespaces (EXPERIMENTAL)" 214 default n 215 depends on EXPERIMENTAL 216 help 217 Support user namespaces. This allows containers, i.e. 218 vservers, to use user namespaces to provide different 219 user info for different servers. If unsure, say N. 220 221config AUDIT 222 bool "Auditing support" 223 depends on NET 224 help 225 Enable auditing infrastructure that can be used with another 226 kernel subsystem, such as SELinux (which requires this for 227 logging of avc messages output). Does not do system-call 228 auditing without CONFIG_AUDITSYSCALL. 229 230config AUDITSYSCALL 231 bool "Enable system-call auditing support" 232 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64) 233 default y if SECURITY_SELINUX 234 help 235 Enable low-overhead system-call auditing infrastructure that 236 can be used independently or with another kernel subsystem, 237 such as SELinux. To use audit's filesystem watch feature, please 238 ensure that INOTIFY is configured. 239 240config IKCONFIG 241 tristate "Kernel .config support" 242 ---help--- 243 This option enables the complete Linux kernel ".config" file 244 contents to be saved in the kernel. It provides documentation 245 of which kernel options are used in a running kernel or in an 246 on-disk kernel. This information can be extracted from the kernel 247 image file with the script scripts/extract-ikconfig and used as 248 input to rebuild the current kernel or to build another kernel. 249 It can also be extracted from a running kernel by reading 250 /proc/config.gz if enabled (below). 251 252config IKCONFIG_PROC 253 bool "Enable access to .config through /proc/config.gz" 254 depends on IKCONFIG && PROC_FS 255 ---help--- 256 This option enables access to the kernel configuration file 257 through /proc/config.gz. 258 259config LOG_BUF_SHIFT 260 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 261 range 12 21 262 default 17 if S390 || LOCKDEP 263 default 16 if X86_NUMAQ || IA64 264 default 15 if SMP 265 default 14 266 help 267 Select kernel log buffer size as a power of 2. 268 Defaults and Examples: 269 17 => 128 KB for S/390 270 16 => 64 KB for x86 NUMAQ or IA-64 271 15 => 32 KB for SMP 272 14 => 16 KB for uniprocessor 273 13 => 8 KB 274 12 => 4 KB 275 276config CPUSETS 277 bool "Cpuset support" 278 depends on SMP 279 help 280 This option will let you create and manage CPUSETs which 281 allow dynamically partitioning a system into sets of CPUs and 282 Memory Nodes and assigning tasks to run only within those sets. 283 This is primarily useful on large SMP or NUMA systems. 284 285 Say N if unsure. 286 287config SYSFS_DEPRECATED 288 bool "Create deprecated sysfs files" 289 default y 290 help 291 This option creates deprecated symlinks such as the 292 "device"-link, the <subsystem>:<name>-link, and the 293 "bus"-link. It may also add deprecated key in the 294 uevent environment. 295 None of these features or values should be used today, as 296 they export driver core implementation details to userspace 297 or export properties which can't be kept stable across kernel 298 releases. 299 300 If enabled, this option will also move any device structures 301 that belong to a class, back into the /sys/class hierarchy, in 302 order to support older versions of udev. 303 304 If you are using a distro that was released in 2006 or later, 305 it should be safe to say N here. 306 307config RELAY 308 bool "Kernel->user space relay support (formerly relayfs)" 309 help 310 This option enables support for relay interface support in 311 certain file systems (such as debugfs). 312 It is designed to provide an efficient mechanism for tools and 313 facilities to relay large amounts of data from kernel space to 314 user space. 315 316 If unsure, say N. 317 318config BLK_DEV_INITRD 319 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 320 depends on BROKEN || !FRV 321 help 322 The initial RAM filesystem is a ramfs which is loaded by the 323 boot loader (loadlin or lilo) and that is mounted as root 324 before the normal boot procedure. It is typically used to 325 load modules needed to mount the "real" root file system, 326 etc. See <file:Documentation/initrd.txt> for details. 327 328 If RAM disk support (BLK_DEV_RAM) is also included, this 329 also enables initial RAM disk (initrd) support and adds 330 15 Kbytes (more on some other architectures) to the kernel size. 331 332 If unsure say Y. 333 334if BLK_DEV_INITRD 335 336source "usr/Kconfig" 337 338endif 339 340config CC_OPTIMIZE_FOR_SIZE 341 bool "Optimize for size (Look out for broken compilers!)" 342 default y 343 depends on ARM || H8300 || SUPERH || EXPERIMENTAL 344 help 345 Enabling this option will pass "-Os" instead of "-O2" to gcc 346 resulting in a smaller kernel. 347 348 WARNING: some versions of gcc may generate incorrect code with this 349 option. If problems are observed, a gcc upgrade may be needed. 350 351 If unsure, say N. 352 353config SYSCTL 354 bool 355 356menuconfig EMBEDDED 357 bool "Configure standard kernel features (for small systems)" 358 help 359 This option allows certain base kernel options and settings 360 to be disabled or tweaked. This is for specialized 361 environments which can tolerate a "non-standard" kernel. 362 Only use this if you really know what you are doing. 363 364config UID16 365 bool "Enable 16-bit UID system calls" if EMBEDDED 366 depends on ARM || BFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && SPARC32_COMPAT) || UML || (X86_64 && IA32_EMULATION) 367 default y 368 help 369 This enables the legacy 16-bit UID syscall wrappers. 370 371config SYSCTL_SYSCALL 372 bool "Sysctl syscall support" if EMBEDDED 373 default y 374 select SYSCTL 375 ---help--- 376 sys_sysctl uses binary paths that have been found challenging 377 to properly maintain and use. The interface in /proc/sys 378 using paths with ascii names is now the primary path to this 379 information. 380 381 Almost nothing using the binary sysctl interface so if you are 382 trying to save some space it is probably safe to disable this, 383 making your kernel marginally smaller. 384 385 If unsure say Y here. 386 387config KALLSYMS 388 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 389 default y 390 help 391 Say Y here to let the kernel print out symbolic crash information and 392 symbolic stack backtraces. This increases the size of the kernel 393 somewhat, as all symbols have to be loaded into the kernel image. 394 395config KALLSYMS_ALL 396 bool "Include all symbols in kallsyms" 397 depends on DEBUG_KERNEL && KALLSYMS 398 help 399 Normally kallsyms only contains the symbols of functions, for nicer 400 OOPS messages. Some debuggers can use kallsyms for other 401 symbols too: say Y here to include all symbols, if you need them 402 and you don't care about adding 300k to the size of your kernel. 403 404 Say N. 405 406config KALLSYMS_EXTRA_PASS 407 bool "Do an extra kallsyms pass" 408 depends on KALLSYMS 409 help 410 If kallsyms is not working correctly, the build will fail with 411 inconsistent kallsyms data. If that occurs, log a bug report and 412 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 413 Always say N here unless you find a bug in kallsyms, which must be 414 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 415 you wait for kallsyms to be fixed. 416 417 418config HOTPLUG 419 bool "Support for hot-pluggable devices" if EMBEDDED 420 default y 421 help 422 This option is provided for the case where no hotplug or uevent 423 capabilities is wanted by the kernel. You should only consider 424 disabling this option for embedded systems that do not use modules, a 425 dynamic /dev tree, or dynamic device discovery. Just say Y. 426 427config PRINTK 428 default y 429 bool "Enable support for printk" if EMBEDDED 430 help 431 This option enables normal printk support. Removing it 432 eliminates most of the message strings from the kernel image 433 and makes the kernel more or less silent. As this makes it 434 very difficult to diagnose system problems, saying N here is 435 strongly discouraged. 436 437config BUG 438 bool "BUG() support" if EMBEDDED 439 default y 440 help 441 Disabling this option eliminates support for BUG and WARN, reducing 442 the size of your kernel image and potentially quietly ignoring 443 numerous fatal conditions. You should only consider disabling this 444 option for embedded systems with no facilities for reporting errors. 445 Just say Y. 446 447config ELF_CORE 448 default y 449 bool "Enable ELF core dumps" if EMBEDDED 450 help 451 Enable support for generating core dumps. Disabling saves about 4k. 452 453config BASE_FULL 454 default y 455 bool "Enable full-sized data structures for core" if EMBEDDED 456 help 457 Disabling this option reduces the size of miscellaneous core 458 kernel data structures. This saves memory on small machines, 459 but may reduce performance. 460 461config FUTEX 462 bool "Enable futex support" if EMBEDDED 463 default y 464 select RT_MUTEXES 465 help 466 Disabling this option will cause the kernel to be built without 467 support for "fast userspace mutexes". The resulting kernel may not 468 run glibc-based applications correctly. 469 470config ANON_INODES 471 bool "Enable anonymous inode source" if EMBEDDED 472 default y 473 help 474 Anonymous inode source for pseudo-files like epoll, signalfd, 475 timerfd and eventfd. 476 477 If unsure, say Y. 478 479config EPOLL 480 bool "Enable eventpoll support" if EMBEDDED 481 default y 482 depends on ANON_INODES 483 help 484 Disabling this option will cause the kernel to be built without 485 support for epoll family of system calls. 486 487config SIGNALFD 488 bool "Enable signalfd() system call" if EMBEDDED 489 depends on ANON_INODES 490 default y 491 help 492 Enable the signalfd() system call that allows to receive signals 493 on a file descriptor. 494 495 If unsure, say Y. 496 497config TIMERFD 498 bool "Enable timerfd() system call" if EMBEDDED 499 depends on ANON_INODES 500 default y 501 help 502 Enable the timerfd() system call that allows to receive timer 503 events on a file descriptor. 504 505 If unsure, say Y. 506 507config EVENTFD 508 bool "Enable eventfd() system call" if EMBEDDED 509 depends on ANON_INODES 510 default y 511 help 512 Enable the eventfd() system call that allows to receive both 513 kernel notification (ie. KAIO) or userspace notifications. 514 515 If unsure, say Y. 516 517config SHMEM 518 bool "Use full shmem filesystem" if EMBEDDED 519 default y 520 depends on MMU 521 help 522 The shmem is an internal filesystem used to manage shared memory. 523 It is backed by swap and manages resource limits. It is also exported 524 to userspace as tmpfs if TMPFS is enabled. Disabling this 525 option replaces shmem and tmpfs with the much simpler ramfs code, 526 which may be appropriate on small systems without swap. 527 528config VM_EVENT_COUNTERS 529 default y 530 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 531 help 532 VM event counters are needed for event counts to be shown. 533 This option allows the disabling of the VM event counters 534 on EMBEDDED systems. /proc/vmstat will only show page counts 535 if VM event counters are disabled. 536 537config SLUB_DEBUG 538 default y 539 bool "Enable SLUB debugging support" if EMBEDDED 540 depends on SLUB 541 help 542 SLUB has extensive debug support features. Disabling these can 543 result in significant savings in code size. This also disables 544 SLUB sysfs support. /sys/slab will not exist and there will be 545 no support for cache validation etc. 546 547choice 548 prompt "Choose SLAB allocator" 549 default SLUB 550 help 551 This option allows to select a slab allocator. 552 553config SLAB 554 bool "SLAB" 555 help 556 The regular slab allocator that is established and known to work 557 well in all environments. It organizes cache hot objects in 558 per cpu and per node queues. SLAB is the default choice for 559 a slab allocator. 560 561config SLUB 562 bool "SLUB (Unqueued Allocator)" 563 help 564 SLUB is a slab allocator that minimizes cache line usage 565 instead of managing queues of cached objects (SLAB approach). 566 Per cpu caching is realized using slabs of objects instead 567 of queues of objects. SLUB can use memory efficiently 568 and has enhanced diagnostics. 569 570config SLOB 571 depends on EMBEDDED 572 bool "SLOB (Simple Allocator)" 573 help 574 SLOB replaces the SLAB allocator with a drastically simpler 575 allocator. SLOB is more space efficient than SLAB but does not 576 scale well (single lock for all operations) and is also highly 577 susceptible to fragmentation. SLUB can accomplish a higher object 578 density. It is usually better to use SLUB instead of SLOB. 579 580endchoice 581 582endmenu # General setup 583 584config RT_MUTEXES 585 boolean 586 select PLIST 587 588config TINY_SHMEM 589 default !SHMEM 590 bool 591 592config BASE_SMALL 593 int 594 default 0 if BASE_FULL 595 default 1 if !BASE_FULL 596 597menuconfig MODULES 598 bool "Enable loadable module support" 599 help 600 Kernel modules are small pieces of compiled code which can 601 be inserted in the running kernel, rather than being 602 permanently built into the kernel. You use the "modprobe" 603 tool to add (and sometimes remove) them. If you say Y here, 604 many parts of the kernel can be built as modules (by 605 answering M instead of Y where indicated): this is most 606 useful for infrequently used options which are not required 607 for booting. For more information, see the man pages for 608 modprobe, lsmod, modinfo, insmod and rmmod. 609 610 If you say Y here, you will need to run "make 611 modules_install" to put the modules under /lib/modules/ 612 where modprobe can find them (you may need to be root to do 613 this). 614 615 If unsure, say Y. 616 617config MODULE_UNLOAD 618 bool "Module unloading" 619 depends on MODULES 620 help 621 Without this option you will not be able to unload any 622 modules (note that some modules may not be unloadable 623 anyway), which makes your kernel slightly smaller and 624 simpler. If unsure, say Y. 625 626config MODULE_FORCE_UNLOAD 627 bool "Forced module unloading" 628 depends on MODULE_UNLOAD && EXPERIMENTAL 629 help 630 This option allows you to force a module to unload, even if the 631 kernel believes it is unsafe: the kernel will remove the module 632 without waiting for anyone to stop using it (using the -f option to 633 rmmod). This is mainly for kernel developers and desperate users. 634 If unsure, say N. 635 636config MODVERSIONS 637 bool "Module versioning support" 638 depends on MODULES 639 help 640 Usually, you have to use modules compiled with your kernel. 641 Saying Y here makes it sometimes possible to use modules 642 compiled for different kernels, by adding enough information 643 to the modules to (hopefully) spot any changes which would 644 make them incompatible with the kernel you are running. If 645 unsure, say N. 646 647config MODULE_SRCVERSION_ALL 648 bool "Source checksum for all modules" 649 depends on MODULES 650 help 651 Modules which contain a MODULE_VERSION get an extra "srcversion" 652 field inserted into their modinfo section, which contains a 653 sum of the source files which made it. This helps maintainers 654 see exactly which source was used to build a module (since 655 others sometimes change the module source without updating 656 the version). With this option, such a "srcversion" field 657 will be created for all modules. If unsure, say N. 658 659config KMOD 660 bool "Automatic kernel module loading" 661 depends on MODULES 662 help 663 Normally when you have selected some parts of the kernel to 664 be created as kernel modules, you must load them (using the 665 "modprobe" command) before you can use them. If you say Y 666 here, some parts of the kernel will be able to load modules 667 automatically: when a part of the kernel needs a module, it 668 runs modprobe with the appropriate arguments, thereby 669 loading the module if it is available. If unsure, say Y. 670 671config STOP_MACHINE 672 bool 673 default y 674 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 675 help 676 Need stop_machine() primitive. 677 678source "block/Kconfig" 679