1config ARCH 2 string 3 option env="ARCH" 4 5config KERNELVERSION 6 string 7 option env="KERNELVERSION" 8 9config DEFCONFIG_LIST 10 string 11 depends on !UML 12 option defconfig_list 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" 18 19config CONSTRUCTORS 20 bool 21 depends on !UML 22 default y 23 24menu "General setup" 25 26config EXPERIMENTAL 27 bool "Prompt for development and/or incomplete code/drivers" 28 ---help--- 29 Some of the various things that Linux supports (such as network 30 drivers, file systems, network protocols, etc.) can be in a state 31 of development where the functionality, stability, or the level of 32 testing is not yet high enough for general use. This is usually 33 known as the "alpha-test" phase among developers. If a feature is 34 currently in alpha-test, then the developers usually discourage 35 uninformed widespread use of this feature by the general public to 36 avoid "Why doesn't this work?" type mail messages. However, active 37 testing and use of these systems is welcomed. Just be aware that it 38 may not meet the normal level of reliability or it may fail to work 39 in some special cases. Detailed bug reports from people familiar 40 with the kernel internals are usually welcomed by the developers 41 (before submitting bug reports, please read the documents 42 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 43 <file:Documentation/BUG-HUNTING>, and 44 <file:Documentation/oops-tracing.txt> in the kernel source). 45 46 This option will also make obsoleted drivers available. These are 47 drivers that have been replaced by something else, and/or are 48 scheduled to be removed in a future kernel release. 49 50 Unless you intend to help test and develop a feature or driver that 51 falls into this category, or you have a situation that requires 52 using these features, you should probably say N here, which will 53 cause the configurator to present you with fewer choices. If 54 you say Y here, you will be offered the choice of using features or 55 drivers that are currently considered to be in the alpha-test phase. 56 57config BROKEN 58 bool 59 60config BROKEN_ON_SMP 61 bool 62 depends on BROKEN || !SMP 63 default y 64 65config LOCK_KERNEL 66 bool 67 depends on SMP || PREEMPT 68 default y 69 70config INIT_ENV_ARG_LIMIT 71 int 72 default 32 if !UML 73 default 128 if UML 74 help 75 Maximum of each of the number of arguments and environment 76 variables passed to init from the kernel command line. 77 78 79config LOCALVERSION 80 string "Local version - append to kernel release" 81 help 82 Append an extra string to the end of your kernel version. 83 This will show up when you type uname, for example. 84 The string you set here will be appended after the contents of 85 any files with a filename matching localversion* in your 86 object and source tree, in that order. Your total string can 87 be a maximum of 64 characters. 88 89config LOCALVERSION_AUTO 90 bool "Automatically append version information to the version string" 91 default y 92 help 93 This will try to automatically determine if the current tree is a 94 release tree by looking for git tags that belong to the current 95 top of tree revision. 96 97 A string of the format -gxxxxxxxx will be added to the localversion 98 if a git-based tree is found. The string generated by this will be 99 appended after any matching localversion* files, and after the value 100 set in CONFIG_LOCALVERSION. 101 102 (The actual string used here is the first eight characters produced 103 by running the command: 104 105 $ git rev-parse --verify HEAD 106 107 which is done within the script "scripts/setlocalversion".) 108 109config HAVE_KERNEL_GZIP 110 bool 111 112config HAVE_KERNEL_BZIP2 113 bool 114 115config HAVE_KERNEL_LZMA 116 bool 117 118choice 119 prompt "Kernel compression mode" 120 default KERNEL_GZIP 121 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA 122 help 123 The linux kernel is a kind of self-extracting executable. 124 Several compression algorithms are available, which differ 125 in efficiency, compression and decompression speed. 126 Compression speed is only relevant when building a kernel. 127 Decompression speed is relevant at each boot. 128 129 If you have any problems with bzip2 or lzma compressed 130 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 131 version of this functionality (bzip2 only), for 2.4, was 132 supplied by Christian Ludwig) 133 134 High compression options are mostly useful for users, who 135 are low on disk space (embedded systems), but for whom ram 136 size matters less. 137 138 If in doubt, select 'gzip' 139 140config KERNEL_GZIP 141 bool "Gzip" 142 depends on HAVE_KERNEL_GZIP 143 help 144 The old and tried gzip compression. Its compression ratio is 145 the poorest among the 3 choices; however its speed (both 146 compression and decompression) is the fastest. 147 148config KERNEL_BZIP2 149 bool "Bzip2" 150 depends on HAVE_KERNEL_BZIP2 151 help 152 Its compression ratio and speed is intermediate. 153 Decompression speed is slowest among the three. The kernel 154 size is about 10% smaller with bzip2, in comparison to gzip. 155 Bzip2 uses a large amount of memory. For modern kernels you 156 will need at least 8MB RAM or more for booting. 157 158config KERNEL_LZMA 159 bool "LZMA" 160 depends on HAVE_KERNEL_LZMA 161 help 162 The most recent compression algorithm. 163 Its ratio is best, decompression speed is between the other 164 two. Compression is slowest. The kernel size is about 33% 165 smaller with LZMA in comparison to gzip. 166 167endchoice 168 169config SWAP 170 bool "Support for paging of anonymous memory (swap)" 171 depends on MMU && BLOCK 172 default y 173 help 174 This option allows you to choose whether you want to have support 175 for so called swap devices or swap files in your kernel that are 176 used to provide more virtual memory than the actual RAM present 177 in your computer. If unsure say Y. 178 179config SYSVIPC 180 bool "System V IPC" 181 ---help--- 182 Inter Process Communication is a suite of library functions and 183 system calls which let processes (running programs) synchronize and 184 exchange information. It is generally considered to be a good thing, 185 and some programs won't run unless you say Y here. In particular, if 186 you want to run the DOS emulator dosemu under Linux (read the 187 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 188 you'll need to say Y here. 189 190 You can find documentation about IPC with "info ipc" and also in 191 section 6.4 of the Linux Programmer's Guide, available from 192 <http://www.tldp.org/guides.html>. 193 194config SYSVIPC_SYSCTL 195 bool 196 depends on SYSVIPC 197 depends on SYSCTL 198 default y 199 200config POSIX_MQUEUE 201 bool "POSIX Message Queues" 202 depends on NET && EXPERIMENTAL 203 ---help--- 204 POSIX variant of message queues is a part of IPC. In POSIX message 205 queues every message has a priority which decides about succession 206 of receiving it by a process. If you want to compile and run 207 programs written e.g. for Solaris with use of its POSIX message 208 queues (functions mq_*) say Y here. 209 210 POSIX message queues are visible as a filesystem called 'mqueue' 211 and can be mounted somewhere if you want to do filesystem 212 operations on message queues. 213 214 If unsure, say Y. 215 216config POSIX_MQUEUE_SYSCTL 217 bool 218 depends on POSIX_MQUEUE 219 depends on SYSCTL 220 default y 221 222config BSD_PROCESS_ACCT 223 bool "BSD Process Accounting" 224 help 225 If you say Y here, a user level program will be able to instruct the 226 kernel (via a special system call) to write process accounting 227 information to a file: whenever a process exits, information about 228 that process will be appended to the file by the kernel. The 229 information includes things such as creation time, owning user, 230 command name, memory usage, controlling terminal etc. (the complete 231 list is in the struct acct in <file:include/linux/acct.h>). It is 232 up to the user level program to do useful things with this 233 information. This is generally a good idea, so say Y. 234 235config BSD_PROCESS_ACCT_V3 236 bool "BSD Process Accounting version 3 file format" 237 depends on BSD_PROCESS_ACCT 238 default n 239 help 240 If you say Y here, the process accounting information is written 241 in a new file format that also logs the process IDs of each 242 process and it's parent. Note that this file format is incompatible 243 with previous v0/v1/v2 file formats, so you will need updated tools 244 for processing it. A preliminary version of these tools is available 245 at <http://www.gnu.org/software/acct/>. 246 247config TASKSTATS 248 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 249 depends on NET 250 default n 251 help 252 Export selected statistics for tasks/processes through the 253 generic netlink interface. Unlike BSD process accounting, the 254 statistics are available during the lifetime of tasks/processes as 255 responses to commands. Like BSD accounting, they are sent to user 256 space on task exit. 257 258 Say N if unsure. 259 260config TASK_DELAY_ACCT 261 bool "Enable per-task delay accounting (EXPERIMENTAL)" 262 depends on TASKSTATS 263 help 264 Collect information on time spent by a task waiting for system 265 resources like cpu, synchronous block I/O completion and swapping 266 in pages. Such statistics can help in setting a task's priorities 267 relative to other tasks for cpu, io, rss limits etc. 268 269 Say N if unsure. 270 271config TASK_XACCT 272 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 273 depends on TASKSTATS 274 help 275 Collect extended task accounting data and send the data 276 to userland for processing over the taskstats interface. 277 278 Say N if unsure. 279 280config TASK_IO_ACCOUNTING 281 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 282 depends on TASK_XACCT 283 help 284 Collect information on the number of bytes of storage I/O which this 285 task has caused. 286 287 Say N if unsure. 288 289config AUDIT 290 bool "Auditing support" 291 depends on NET 292 help 293 Enable auditing infrastructure that can be used with another 294 kernel subsystem, such as SELinux (which requires this for 295 logging of avc messages output). Does not do system-call 296 auditing without CONFIG_AUDITSYSCALL. 297 298config AUDITSYSCALL 299 bool "Enable system-call auditing support" 300 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH) 301 default y if SECURITY_SELINUX 302 help 303 Enable low-overhead system-call auditing infrastructure that 304 can be used independently or with another kernel subsystem, 305 such as SELinux. To use audit's filesystem watch feature, please 306 ensure that INOTIFY is configured. 307 308config AUDIT_TREE 309 def_bool y 310 depends on AUDITSYSCALL 311 select INOTIFY 312 313menu "RCU Subsystem" 314 315choice 316 prompt "RCU Implementation" 317 default TREE_RCU 318 319config TREE_RCU 320 bool "Tree-based hierarchical RCU" 321 help 322 This option selects the RCU implementation that is 323 designed for very large SMP system with hundreds or 324 thousands of CPUs. It also scales down nicely to 325 smaller systems. 326 327config TREE_PREEMPT_RCU 328 bool "Preemptable tree-based hierarchical RCU" 329 depends on PREEMPT 330 help 331 This option selects the RCU implementation that is 332 designed for very large SMP systems with hundreds or 333 thousands of CPUs, but for which real-time response 334 is also required. It also scales down nicely to 335 smaller systems. 336 337config TINY_RCU 338 bool "UP-only small-memory-footprint RCU" 339 depends on !SMP 340 help 341 This option selects the RCU implementation that is 342 designed for UP systems from which real-time response 343 is not required. This option greatly reduces the 344 memory footprint of RCU. 345 346endchoice 347 348config RCU_TRACE 349 bool "Enable tracing for RCU" 350 depends on TREE_RCU || TREE_PREEMPT_RCU 351 help 352 This option provides tracing in RCU which presents stats 353 in debugfs for debugging RCU implementation. 354 355 Say Y here if you want to enable RCU tracing 356 Say N if you are unsure. 357 358config RCU_FANOUT 359 int "Tree-based hierarchical RCU fanout value" 360 range 2 64 if 64BIT 361 range 2 32 if !64BIT 362 depends on TREE_RCU || TREE_PREEMPT_RCU 363 default 64 if 64BIT 364 default 32 if !64BIT 365 help 366 This option controls the fanout of hierarchical implementations 367 of RCU, allowing RCU to work efficiently on machines with 368 large numbers of CPUs. This value must be at least the cube 369 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit 370 systems and up to 262,144 for 64-bit systems. 371 372 Select a specific number if testing RCU itself. 373 Take the default if unsure. 374 375config RCU_FANOUT_EXACT 376 bool "Disable tree-based hierarchical RCU auto-balancing" 377 depends on TREE_RCU || TREE_PREEMPT_RCU 378 default n 379 help 380 This option forces use of the exact RCU_FANOUT value specified, 381 regardless of imbalances in the hierarchy. This is useful for 382 testing RCU itself, and might one day be useful on systems with 383 strong NUMA behavior. 384 385 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 386 387 Say N if unsure. 388 389config TREE_RCU_TRACE 390 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 391 select DEBUG_FS 392 help 393 This option provides tracing for the TREE_RCU and 394 TREE_PREEMPT_RCU implementations, permitting Makefile to 395 trivially select kernel/rcutree_trace.c. 396 397endmenu # "RCU Subsystem" 398 399config IKCONFIG 400 tristate "Kernel .config support" 401 ---help--- 402 This option enables the complete Linux kernel ".config" file 403 contents to be saved in the kernel. It provides documentation 404 of which kernel options are used in a running kernel or in an 405 on-disk kernel. This information can be extracted from the kernel 406 image file with the script scripts/extract-ikconfig and used as 407 input to rebuild the current kernel or to build another kernel. 408 It can also be extracted from a running kernel by reading 409 /proc/config.gz if enabled (below). 410 411config IKCONFIG_PROC 412 bool "Enable access to .config through /proc/config.gz" 413 depends on IKCONFIG && PROC_FS 414 ---help--- 415 This option enables access to the kernel configuration file 416 through /proc/config.gz. 417 418config LOG_BUF_SHIFT 419 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 420 range 12 21 421 default 17 422 help 423 Select kernel log buffer size as a power of 2. 424 Examples: 425 17 => 128 KB 426 16 => 64 KB 427 15 => 32 KB 428 14 => 16 KB 429 13 => 8 KB 430 12 => 4 KB 431 432# 433# Architectures with an unreliable sched_clock() should select this: 434# 435config HAVE_UNSTABLE_SCHED_CLOCK 436 bool 437 438config GROUP_SCHED 439 bool "Group CPU scheduler" 440 depends on EXPERIMENTAL 441 default n 442 help 443 This feature lets CPU scheduler recognize task groups and control CPU 444 bandwidth allocation to such task groups. 445 In order to create a group from arbitrary set of processes, use 446 CONFIG_CGROUPS. (See Control Group support.) 447 448config FAIR_GROUP_SCHED 449 bool "Group scheduling for SCHED_OTHER" 450 depends on GROUP_SCHED 451 default GROUP_SCHED 452 453config RT_GROUP_SCHED 454 bool "Group scheduling for SCHED_RR/FIFO" 455 depends on EXPERIMENTAL 456 depends on GROUP_SCHED 457 default n 458 help 459 This feature lets you explicitly allocate real CPU bandwidth 460 to users or control groups (depending on the "Basis for grouping tasks" 461 setting below. If enabled, it will also make it impossible to 462 schedule realtime tasks for non-root users until you allocate 463 realtime bandwidth for them. 464 See Documentation/scheduler/sched-rt-group.txt for more information. 465 466choice 467 depends on GROUP_SCHED 468 prompt "Basis for grouping tasks" 469 default USER_SCHED 470 471config USER_SCHED 472 bool "user id" 473 help 474 This option will choose userid as the basis for grouping 475 tasks, thus providing equal CPU bandwidth to each user. 476 477config CGROUP_SCHED 478 bool "Control groups" 479 depends on CGROUPS 480 help 481 This option allows you to create arbitrary task groups 482 using the "cgroup" pseudo filesystem and control 483 the cpu bandwidth allocated to each such task group. 484 Refer to Documentation/cgroups/cgroups.txt for more 485 information on "cgroup" pseudo filesystem. 486 487endchoice 488 489menuconfig CGROUPS 490 boolean "Control Group support" 491 help 492 This option adds support for grouping sets of processes together, for 493 use with process control subsystems such as Cpusets, CFS, memory 494 controls or device isolation. 495 See 496 - Documentation/scheduler/sched-design-CFS.txt (CFS) 497 - Documentation/cgroups/ (features for grouping, isolation 498 and resource control) 499 500 Say N if unsure. 501 502if CGROUPS 503 504config CGROUP_DEBUG 505 bool "Example debug cgroup subsystem" 506 depends on CGROUPS 507 default n 508 help 509 This option enables a simple cgroup subsystem that 510 exports useful debugging information about the cgroups 511 framework. 512 513 Say N if unsure. 514 515config CGROUP_NS 516 bool "Namespace cgroup subsystem" 517 depends on CGROUPS 518 help 519 Provides a simple namespace cgroup subsystem to 520 provide hierarchical naming of sets of namespaces, 521 for instance virtual servers and checkpoint/restart 522 jobs. 523 524config CGROUP_FREEZER 525 bool "Freezer cgroup subsystem" 526 depends on CGROUPS 527 help 528 Provides a way to freeze and unfreeze all tasks in a 529 cgroup. 530 531config CGROUP_DEVICE 532 bool "Device controller for cgroups" 533 depends on CGROUPS && EXPERIMENTAL 534 help 535 Provides a cgroup implementing whitelists for devices which 536 a process in the cgroup can mknod or open. 537 538config CPUSETS 539 bool "Cpuset support" 540 depends on CGROUPS 541 help 542 This option will let you create and manage CPUSETs which 543 allow dynamically partitioning a system into sets of CPUs and 544 Memory Nodes and assigning tasks to run only within those sets. 545 This is primarily useful on large SMP or NUMA systems. 546 547 Say N if unsure. 548 549config PROC_PID_CPUSET 550 bool "Include legacy /proc/<pid>/cpuset file" 551 depends on CPUSETS 552 default y 553 554config CGROUP_CPUACCT 555 bool "Simple CPU accounting cgroup subsystem" 556 depends on CGROUPS 557 help 558 Provides a simple Resource Controller for monitoring the 559 total CPU consumed by the tasks in a cgroup. 560 561config RESOURCE_COUNTERS 562 bool "Resource counters" 563 help 564 This option enables controller independent resource accounting 565 infrastructure that works with cgroups. 566 depends on CGROUPS 567 568config CGROUP_MEM_RES_CTLR 569 bool "Memory Resource Controller for Control Groups" 570 depends on CGROUPS && RESOURCE_COUNTERS 571 select MM_OWNER 572 help 573 Provides a memory resource controller that manages both anonymous 574 memory and page cache. (See Documentation/cgroups/memory.txt) 575 576 Note that setting this option increases fixed memory overhead 577 associated with each page of memory in the system. By this, 578 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 579 usage tracking struct at boot. Total amount of this is printed out 580 at boot. 581 582 Only enable when you're ok with these trade offs and really 583 sure you need the memory resource controller. Even when you enable 584 this, you can set "cgroup_disable=memory" at your boot option to 585 disable memory resource controller and you can avoid overheads. 586 (and lose benefits of memory resource controller) 587 588 This config option also selects MM_OWNER config option, which 589 could in turn add some fork/exit overhead. 590 591config CGROUP_MEM_RES_CTLR_SWAP 592 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)" 593 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL 594 help 595 Add swap management feature to memory resource controller. When you 596 enable this, you can limit mem+swap usage per cgroup. In other words, 597 when you disable this, memory resource controller has no cares to 598 usage of swap...a process can exhaust all of the swap. This extension 599 is useful when you want to avoid exhaustion swap but this itself 600 adds more overheads and consumes memory for remembering information. 601 Especially if you use 32bit system or small memory system, please 602 be careful about enabling this. When memory resource controller 603 is disabled by boot option, this will be automatically disabled and 604 there will be no overhead from this. Even when you set this config=y, 605 if boot option "noswapaccount" is set, swap will not be accounted. 606 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 607 size is 4096bytes, 512k per 1Gbytes of swap. 608 609endif # CGROUPS 610 611config MM_OWNER 612 bool 613 614config SYSFS_DEPRECATED 615 bool 616 617config SYSFS_DEPRECATED_V2 618 bool "enable deprecated sysfs features to support old userspace tools" 619 depends on SYSFS 620 default n 621 select SYSFS_DEPRECATED 622 help 623 This option switches the layout of sysfs to the deprecated 624 version. Do not use it on recent distributions. 625 626 The current sysfs layout features a unified device tree at 627 /sys/devices/, which is able to express a hierarchy between 628 class devices. If the deprecated option is set to Y, the 629 unified device tree is split into a bus device tree at 630 /sys/devices/ and several individual class device trees at 631 /sys/class/. The class and bus devices will be connected by 632 "<subsystem>:<name>" and the "device" links. The "block" 633 class devices, will not show up in /sys/class/block/. Some 634 subsystems will suppress the creation of some devices which 635 depend on the unified device tree. 636 637 This option is not a pure compatibility option that can 638 be safely enabled on newer distributions. It will change the 639 layout of sysfs to the non-extensible deprecated version, 640 and disable some features, which can not be exported without 641 confusing older userspace tools. Since 2007/2008 all major 642 distributions do not enable this option, and ship no tools which 643 depend on the deprecated layout or this option. 644 645 If you are using a new kernel on an older distribution, or use 646 older userspace tools, you might need to say Y here. Do not say Y, 647 if the original kernel, that came with your distribution, has 648 this option set to N. 649 650config RELAY 651 bool "Kernel->user space relay support (formerly relayfs)" 652 help 653 This option enables support for relay interface support in 654 certain file systems (such as debugfs). 655 It is designed to provide an efficient mechanism for tools and 656 facilities to relay large amounts of data from kernel space to 657 user space. 658 659 If unsure, say N. 660 661config NAMESPACES 662 bool "Namespaces support" if EMBEDDED 663 default !EMBEDDED 664 help 665 Provides the way to make tasks work with different objects using 666 the same id. For example same IPC id may refer to different objects 667 or same user id or pid may refer to different tasks when used in 668 different namespaces. 669 670config UTS_NS 671 bool "UTS namespace" 672 depends on NAMESPACES 673 help 674 In this namespace tasks see different info provided with the 675 uname() system call 676 677config IPC_NS 678 bool "IPC namespace" 679 depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE) 680 help 681 In this namespace tasks work with IPC ids which correspond to 682 different IPC objects in different namespaces. 683 684config USER_NS 685 bool "User namespace (EXPERIMENTAL)" 686 depends on NAMESPACES && EXPERIMENTAL 687 help 688 This allows containers, i.e. vservers, to use user namespaces 689 to provide different user info for different servers. 690 If unsure, say N. 691 692config PID_NS 693 bool "PID Namespaces (EXPERIMENTAL)" 694 default n 695 depends on NAMESPACES && EXPERIMENTAL 696 help 697 Support process id namespaces. This allows having multiple 698 processes with the same pid as long as they are in different 699 pid namespaces. This is a building block of containers. 700 701 Unless you want to work with an experimental feature 702 say N here. 703 704config NET_NS 705 bool "Network namespace" 706 default n 707 depends on NAMESPACES && EXPERIMENTAL && NET 708 help 709 Allow user space to create what appear to be multiple instances 710 of the network stack. 711 712config BLK_DEV_INITRD 713 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 714 depends on BROKEN || !FRV 715 help 716 The initial RAM filesystem is a ramfs which is loaded by the 717 boot loader (loadlin or lilo) and that is mounted as root 718 before the normal boot procedure. It is typically used to 719 load modules needed to mount the "real" root file system, 720 etc. See <file:Documentation/initrd.txt> for details. 721 722 If RAM disk support (BLK_DEV_RAM) is also included, this 723 also enables initial RAM disk (initrd) support and adds 724 15 Kbytes (more on some other architectures) to the kernel size. 725 726 If unsure say Y. 727 728if BLK_DEV_INITRD 729 730source "usr/Kconfig" 731 732endif 733 734config CC_OPTIMIZE_FOR_SIZE 735 bool "Optimize for size" 736 default y 737 help 738 Enabling this option will pass "-Os" instead of "-O2" to gcc 739 resulting in a smaller kernel. 740 741 If unsure, say Y. 742 743config SYSCTL 744 bool 745 746config ANON_INODES 747 bool 748 749menuconfig EMBEDDED 750 bool "Configure standard kernel features (for small systems)" 751 help 752 This option allows certain base kernel options and settings 753 to be disabled or tweaked. This is for specialized 754 environments which can tolerate a "non-standard" kernel. 755 Only use this if you really know what you are doing. 756 757config UID16 758 bool "Enable 16-bit UID system calls" if EMBEDDED 759 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 760 default y 761 help 762 This enables the legacy 16-bit UID syscall wrappers. 763 764config SYSCTL_SYSCALL 765 bool "Sysctl syscall support" if EMBEDDED 766 depends on PROC_SYSCTL 767 default y 768 select SYSCTL 769 ---help--- 770 sys_sysctl uses binary paths that have been found challenging 771 to properly maintain and use. The interface in /proc/sys 772 using paths with ascii names is now the primary path to this 773 information. 774 775 Almost nothing using the binary sysctl interface so if you are 776 trying to save some space it is probably safe to disable this, 777 making your kernel marginally smaller. 778 779 If unsure say Y here. 780 781config KALLSYMS 782 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 783 default y 784 help 785 Say Y here to let the kernel print out symbolic crash information and 786 symbolic stack backtraces. This increases the size of the kernel 787 somewhat, as all symbols have to be loaded into the kernel image. 788 789config KALLSYMS_ALL 790 bool "Include all symbols in kallsyms" 791 depends on DEBUG_KERNEL && KALLSYMS 792 help 793 Normally kallsyms only contains the symbols of functions, for nicer 794 OOPS messages. Some debuggers can use kallsyms for other 795 symbols too: say Y here to include all symbols, if you need them 796 and you don't care about adding 300k to the size of your kernel. 797 798 Say N. 799 800config KALLSYMS_EXTRA_PASS 801 bool "Do an extra kallsyms pass" 802 depends on KALLSYMS 803 help 804 If kallsyms is not working correctly, the build will fail with 805 inconsistent kallsyms data. If that occurs, log a bug report and 806 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 807 Always say N here unless you find a bug in kallsyms, which must be 808 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 809 you wait for kallsyms to be fixed. 810 811 812config HOTPLUG 813 bool "Support for hot-pluggable devices" if EMBEDDED 814 default y 815 help 816 This option is provided for the case where no hotplug or uevent 817 capabilities is wanted by the kernel. You should only consider 818 disabling this option for embedded systems that do not use modules, a 819 dynamic /dev tree, or dynamic device discovery. Just say Y. 820 821config PRINTK 822 default y 823 bool "Enable support for printk" if EMBEDDED 824 help 825 This option enables normal printk support. Removing it 826 eliminates most of the message strings from the kernel image 827 and makes the kernel more or less silent. As this makes it 828 very difficult to diagnose system problems, saying N here is 829 strongly discouraged. 830 831config BUG 832 bool "BUG() support" if EMBEDDED 833 default y 834 help 835 Disabling this option eliminates support for BUG and WARN, reducing 836 the size of your kernel image and potentially quietly ignoring 837 numerous fatal conditions. You should only consider disabling this 838 option for embedded systems with no facilities for reporting errors. 839 Just say Y. 840 841config ELF_CORE 842 default y 843 bool "Enable ELF core dumps" if EMBEDDED 844 help 845 Enable support for generating core dumps. Disabling saves about 4k. 846 847config PCSPKR_PLATFORM 848 bool "Enable PC-Speaker support" if EMBEDDED 849 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 850 default y 851 help 852 This option allows to disable the internal PC-Speaker 853 support, saving some memory. 854 855config BASE_FULL 856 default y 857 bool "Enable full-sized data structures for core" if EMBEDDED 858 help 859 Disabling this option reduces the size of miscellaneous core 860 kernel data structures. This saves memory on small machines, 861 but may reduce performance. 862 863config FUTEX 864 bool "Enable futex support" if EMBEDDED 865 default y 866 select RT_MUTEXES 867 help 868 Disabling this option will cause the kernel to be built without 869 support for "fast userspace mutexes". The resulting kernel may not 870 run glibc-based applications correctly. 871 872config EPOLL 873 bool "Enable eventpoll support" if EMBEDDED 874 default y 875 select ANON_INODES 876 help 877 Disabling this option will cause the kernel to be built without 878 support for epoll family of system calls. 879 880config SIGNALFD 881 bool "Enable signalfd() system call" if EMBEDDED 882 select ANON_INODES 883 default y 884 help 885 Enable the signalfd() system call that allows to receive signals 886 on a file descriptor. 887 888 If unsure, say Y. 889 890config TIMERFD 891 bool "Enable timerfd() system call" if EMBEDDED 892 select ANON_INODES 893 default y 894 help 895 Enable the timerfd() system call that allows to receive timer 896 events on a file descriptor. 897 898 If unsure, say Y. 899 900config EVENTFD 901 bool "Enable eventfd() system call" if EMBEDDED 902 select ANON_INODES 903 default y 904 help 905 Enable the eventfd() system call that allows to receive both 906 kernel notification (ie. KAIO) or userspace notifications. 907 908 If unsure, say Y. 909 910config SHMEM 911 bool "Use full shmem filesystem" if EMBEDDED 912 default y 913 depends on MMU 914 help 915 The shmem is an internal filesystem used to manage shared memory. 916 It is backed by swap and manages resource limits. It is also exported 917 to userspace as tmpfs if TMPFS is enabled. Disabling this 918 option replaces shmem and tmpfs with the much simpler ramfs code, 919 which may be appropriate on small systems without swap. 920 921config AIO 922 bool "Enable AIO support" if EMBEDDED 923 default y 924 help 925 This option enables POSIX asynchronous I/O which may by used 926 by some high performance threaded applications. Disabling 927 this option saves about 7k. 928 929config HAVE_PERF_EVENTS 930 bool 931 help 932 See tools/perf/design.txt for details. 933 934config PERF_USE_VMALLOC 935 bool 936 help 937 See tools/perf/design.txt for details 938 939menu "Kernel Performance Events And Counters" 940 941config PERF_EVENTS 942 bool "Kernel performance events and counters" 943 default y if (PROFILING || PERF_COUNTERS) 944 depends on HAVE_PERF_EVENTS 945 select ANON_INODES 946 help 947 Enable kernel support for various performance events provided 948 by software and hardware. 949 950 Software events are supported either built-in or via the 951 use of generic tracepoints. 952 953 Most modern CPUs support performance events via performance 954 counter registers. These registers count the number of certain 955 types of hw events: such as instructions executed, cachemisses 956 suffered, or branches mis-predicted - without slowing down the 957 kernel or applications. These registers can also trigger interrupts 958 when a threshold number of events have passed - and can thus be 959 used to profile the code that runs on that CPU. 960 961 The Linux Performance Event subsystem provides an abstraction of 962 these software and hardware event capabilities, available via a 963 system call and used by the "perf" utility in tools/perf/. It 964 provides per task and per CPU counters, and it provides event 965 capabilities on top of those. 966 967 Say Y if unsure. 968 969config EVENT_PROFILE 970 bool "Tracepoint profiling sources" 971 depends on PERF_EVENTS && EVENT_TRACING 972 default y 973 help 974 Allow the use of tracepoints as software performance events. 975 976 When this is enabled, you can create perf events based on 977 tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID 978 found in debugfs://tracing/events/*/*/id. (The -e/--events 979 option to the perf tool can parse and interpret symbolic 980 tracepoints, in the subsystem:tracepoint_name format.) 981 982config PERF_COUNTERS 983 bool "Kernel performance counters (old config option)" 984 depends on HAVE_PERF_EVENTS 985 help 986 This config has been obsoleted by the PERF_EVENTS 987 config option - please see that one for details. 988 989 It has no effect on the kernel whether you enable 990 it or not, it is a compatibility placeholder. 991 992 Say N if unsure. 993 994config DEBUG_PERF_USE_VMALLOC 995 default n 996 bool "Debug: use vmalloc to back perf mmap() buffers" 997 depends on PERF_EVENTS && DEBUG_KERNEL 998 select PERF_USE_VMALLOC 999 help 1000 Use vmalloc memory to back perf mmap() buffers. 1001 1002 Mostly useful for debugging the vmalloc code on platforms 1003 that don't require it. 1004 1005 Say N if unsure. 1006 1007endmenu 1008 1009config VM_EVENT_COUNTERS 1010 default y 1011 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 1012 help 1013 VM event counters are needed for event counts to be shown. 1014 This option allows the disabling of the VM event counters 1015 on EMBEDDED systems. /proc/vmstat will only show page counts 1016 if VM event counters are disabled. 1017 1018config PCI_QUIRKS 1019 default y 1020 bool "Enable PCI quirk workarounds" if EMBEDDED 1021 depends on PCI 1022 help 1023 This enables workarounds for various PCI chipset 1024 bugs/quirks. Disable this only if your target machine is 1025 unaffected by PCI quirks. 1026 1027config SLUB_DEBUG 1028 default y 1029 bool "Enable SLUB debugging support" if EMBEDDED 1030 depends on SLUB && SYSFS 1031 help 1032 SLUB has extensive debug support features. Disabling these can 1033 result in significant savings in code size. This also disables 1034 SLUB sysfs support. /sys/slab will not exist and there will be 1035 no support for cache validation etc. 1036 1037config COMPAT_BRK 1038 bool "Disable heap randomization" 1039 default y 1040 help 1041 Randomizing heap placement makes heap exploits harder, but it 1042 also breaks ancient binaries (including anything libc5 based). 1043 This option changes the bootup default to heap randomization 1044 disabled, and can be overridden at runtime by setting 1045 /proc/sys/kernel/randomize_va_space to 2. 1046 1047 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1048 1049choice 1050 prompt "Choose SLAB allocator" 1051 default SLUB 1052 help 1053 This option allows to select a slab allocator. 1054 1055config SLAB 1056 bool "SLAB" 1057 help 1058 The regular slab allocator that is established and known to work 1059 well in all environments. It organizes cache hot objects in 1060 per cpu and per node queues. 1061 1062config SLUB 1063 bool "SLUB (Unqueued Allocator)" 1064 help 1065 SLUB is a slab allocator that minimizes cache line usage 1066 instead of managing queues of cached objects (SLAB approach). 1067 Per cpu caching is realized using slabs of objects instead 1068 of queues of objects. SLUB can use memory efficiently 1069 and has enhanced diagnostics. SLUB is the default choice for 1070 a slab allocator. 1071 1072config SLOB 1073 depends on EMBEDDED 1074 bool "SLOB (Simple Allocator)" 1075 help 1076 SLOB replaces the stock allocator with a drastically simpler 1077 allocator. SLOB is generally more space efficient but 1078 does not perform as well on large systems. 1079 1080endchoice 1081 1082config PROFILING 1083 bool "Profiling support (EXPERIMENTAL)" 1084 help 1085 Say Y here to enable the extended profiling support mechanisms used 1086 by profilers such as OProfile. 1087 1088# 1089# Place an empty function call at each tracepoint site. Can be 1090# dynamically changed for a probe function. 1091# 1092config TRACEPOINTS 1093 bool 1094 1095source "arch/Kconfig" 1096 1097config SLOW_WORK 1098 default n 1099 bool 1100 help 1101 The slow work thread pool provides a number of dynamically allocated 1102 threads that can be used by the kernel to perform operations that 1103 take a relatively long time. 1104 1105 An example of this would be CacheFiles doing a path lookup followed 1106 by a series of mkdirs and a create call, all of which have to touch 1107 disk. 1108 1109 See Documentation/slow-work.txt. 1110 1111config SLOW_WORK_DEBUG 1112 bool "Slow work debugging through debugfs" 1113 default n 1114 depends on SLOW_WORK && DEBUG_FS 1115 help 1116 Display the contents of the slow work run queue through debugfs, 1117 including items currently executing. 1118 1119 See Documentation/slow-work.txt. 1120 1121endmenu # General setup 1122 1123config HAVE_GENERIC_DMA_COHERENT 1124 bool 1125 default n 1126 1127config SLABINFO 1128 bool 1129 depends on PROC_FS 1130 depends on SLAB || SLUB_DEBUG 1131 default y 1132 1133config RT_MUTEXES 1134 boolean 1135 1136config BASE_SMALL 1137 int 1138 default 0 if BASE_FULL 1139 default 1 if !BASE_FULL 1140 1141menuconfig MODULES 1142 bool "Enable loadable module support" 1143 help 1144 Kernel modules are small pieces of compiled code which can 1145 be inserted in the running kernel, rather than being 1146 permanently built into the kernel. You use the "modprobe" 1147 tool to add (and sometimes remove) them. If you say Y here, 1148 many parts of the kernel can be built as modules (by 1149 answering M instead of Y where indicated): this is most 1150 useful for infrequently used options which are not required 1151 for booting. For more information, see the man pages for 1152 modprobe, lsmod, modinfo, insmod and rmmod. 1153 1154 If you say Y here, you will need to run "make 1155 modules_install" to put the modules under /lib/modules/ 1156 where modprobe can find them (you may need to be root to do 1157 this). 1158 1159 If unsure, say Y. 1160 1161if MODULES 1162 1163config MODULE_FORCE_LOAD 1164 bool "Forced module loading" 1165 default n 1166 help 1167 Allow loading of modules without version information (ie. modprobe 1168 --force). Forced module loading sets the 'F' (forced) taint flag and 1169 is usually a really bad idea. 1170 1171config MODULE_UNLOAD 1172 bool "Module unloading" 1173 help 1174 Without this option you will not be able to unload any 1175 modules (note that some modules may not be unloadable 1176 anyway), which makes your kernel smaller, faster 1177 and simpler. If unsure, say Y. 1178 1179config MODULE_FORCE_UNLOAD 1180 bool "Forced module unloading" 1181 depends on MODULE_UNLOAD && EXPERIMENTAL 1182 help 1183 This option allows you to force a module to unload, even if the 1184 kernel believes it is unsafe: the kernel will remove the module 1185 without waiting for anyone to stop using it (using the -f option to 1186 rmmod). This is mainly for kernel developers and desperate users. 1187 If unsure, say N. 1188 1189config MODVERSIONS 1190 bool "Module versioning support" 1191 help 1192 Usually, you have to use modules compiled with your kernel. 1193 Saying Y here makes it sometimes possible to use modules 1194 compiled for different kernels, by adding enough information 1195 to the modules to (hopefully) spot any changes which would 1196 make them incompatible with the kernel you are running. If 1197 unsure, say N. 1198 1199config MODULE_SRCVERSION_ALL 1200 bool "Source checksum for all modules" 1201 help 1202 Modules which contain a MODULE_VERSION get an extra "srcversion" 1203 field inserted into their modinfo section, which contains a 1204 sum of the source files which made it. This helps maintainers 1205 see exactly which source was used to build a module (since 1206 others sometimes change the module source without updating 1207 the version). With this option, such a "srcversion" field 1208 will be created for all modules. If unsure, say N. 1209 1210endif # MODULES 1211 1212config INIT_ALL_POSSIBLE 1213 bool 1214 help 1215 Back when each arch used to define their own cpu_online_map and 1216 cpu_possible_map, some of them chose to initialize cpu_possible_map 1217 with all 1s, and others with all 0s. When they were centralised, 1218 it was better to provide this option than to break all the archs 1219 and have several arch maintainers pursuing me down dark alleys. 1220 1221config STOP_MACHINE 1222 bool 1223 default y 1224 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1225 help 1226 Need stop_machine() primitive. 1227 1228source "block/Kconfig" 1229 1230config PREEMPT_NOTIFIERS 1231 bool 1232 1233source "kernel/Kconfig.locks" 1234