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 24config HAVE_IRQ_WORK 25 bool 26 27config IRQ_WORK 28 bool 29 depends on HAVE_IRQ_WORK 30 31menu "General setup" 32 33config EXPERIMENTAL 34 bool "Prompt for development and/or incomplete code/drivers" 35 ---help--- 36 Some of the various things that Linux supports (such as network 37 drivers, file systems, network protocols, etc.) can be in a state 38 of development where the functionality, stability, or the level of 39 testing is not yet high enough for general use. This is usually 40 known as the "alpha-test" phase among developers. If a feature is 41 currently in alpha-test, then the developers usually discourage 42 uninformed widespread use of this feature by the general public to 43 avoid "Why doesn't this work?" type mail messages. However, active 44 testing and use of these systems is welcomed. Just be aware that it 45 may not meet the normal level of reliability or it may fail to work 46 in some special cases. Detailed bug reports from people familiar 47 with the kernel internals are usually welcomed by the developers 48 (before submitting bug reports, please read the documents 49 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 50 <file:Documentation/BUG-HUNTING>, and 51 <file:Documentation/oops-tracing.txt> in the kernel source). 52 53 This option will also make obsoleted drivers available. These are 54 drivers that have been replaced by something else, and/or are 55 scheduled to be removed in a future kernel release. 56 57 Unless you intend to help test and develop a feature or driver that 58 falls into this category, or you have a situation that requires 59 using these features, you should probably say N here, which will 60 cause the configurator to present you with fewer choices. If 61 you say Y here, you will be offered the choice of using features or 62 drivers that are currently considered to be in the alpha-test phase. 63 64config BROKEN 65 bool 66 67config BROKEN_ON_SMP 68 bool 69 depends on BROKEN || !SMP 70 default y 71 72config LOCK_KERNEL 73 bool 74 depends on (SMP || PREEMPT) && BKL 75 default y 76 77config INIT_ENV_ARG_LIMIT 78 int 79 default 32 if !UML 80 default 128 if UML 81 help 82 Maximum of each of the number of arguments and environment 83 variables passed to init from the kernel command line. 84 85 86config CROSS_COMPILE 87 string "Cross-compiler tool prefix" 88 help 89 Same as running 'make CROSS_COMPILE=prefix-' but stored for 90 default make runs in this kernel build directory. You don't 91 need to set this unless you want the configured kernel build 92 directory to select the cross-compiler automatically. 93 94config LOCALVERSION 95 string "Local version - append to kernel release" 96 help 97 Append an extra string to the end of your kernel version. 98 This will show up when you type uname, for example. 99 The string you set here will be appended after the contents of 100 any files with a filename matching localversion* in your 101 object and source tree, in that order. Your total string can 102 be a maximum of 64 characters. 103 104config LOCALVERSION_AUTO 105 bool "Automatically append version information to the version string" 106 default y 107 help 108 This will try to automatically determine if the current tree is a 109 release tree by looking for git tags that belong to the current 110 top of tree revision. 111 112 A string of the format -gxxxxxxxx will be added to the localversion 113 if a git-based tree is found. The string generated by this will be 114 appended after any matching localversion* files, and after the value 115 set in CONFIG_LOCALVERSION. 116 117 (The actual string used here is the first eight characters produced 118 by running the command: 119 120 $ git rev-parse --verify HEAD 121 122 which is done within the script "scripts/setlocalversion".) 123 124config HAVE_KERNEL_GZIP 125 bool 126 127config HAVE_KERNEL_BZIP2 128 bool 129 130config HAVE_KERNEL_LZMA 131 bool 132 133config HAVE_KERNEL_LZO 134 bool 135 136choice 137 prompt "Kernel compression mode" 138 default KERNEL_GZIP 139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO 140 help 141 The linux kernel is a kind of self-extracting executable. 142 Several compression algorithms are available, which differ 143 in efficiency, compression and decompression speed. 144 Compression speed is only relevant when building a kernel. 145 Decompression speed is relevant at each boot. 146 147 If you have any problems with bzip2 or lzma compressed 148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 149 version of this functionality (bzip2 only), for 2.4, was 150 supplied by Christian Ludwig) 151 152 High compression options are mostly useful for users, who 153 are low on disk space (embedded systems), but for whom ram 154 size matters less. 155 156 If in doubt, select 'gzip' 157 158config KERNEL_GZIP 159 bool "Gzip" 160 depends on HAVE_KERNEL_GZIP 161 help 162 The old and tried gzip compression. It provides a good balance 163 between compression ratio and decompression speed. 164 165config KERNEL_BZIP2 166 bool "Bzip2" 167 depends on HAVE_KERNEL_BZIP2 168 help 169 Its compression ratio and speed is intermediate. 170 Decompression speed is slowest among the three. The kernel 171 size is about 10% smaller with bzip2, in comparison to gzip. 172 Bzip2 uses a large amount of memory. For modern kernels you 173 will need at least 8MB RAM or more for booting. 174 175config KERNEL_LZMA 176 bool "LZMA" 177 depends on HAVE_KERNEL_LZMA 178 help 179 The most recent compression algorithm. 180 Its ratio is best, decompression speed is between the other 181 two. Compression is slowest. The kernel size is about 33% 182 smaller with LZMA in comparison to gzip. 183 184config KERNEL_LZO 185 bool "LZO" 186 depends on HAVE_KERNEL_LZO 187 help 188 Its compression ratio is the poorest among the 4. The kernel 189 size is about 10% bigger than gzip; however its speed 190 (both compression and decompression) is the fastest. 191 192endchoice 193 194config SWAP 195 bool "Support for paging of anonymous memory (swap)" 196 depends on MMU && BLOCK 197 default y 198 help 199 This option allows you to choose whether you want to have support 200 for so called swap devices or swap files in your kernel that are 201 used to provide more virtual memory than the actual RAM present 202 in your computer. If unsure say Y. 203 204config SYSVIPC 205 bool "System V IPC" 206 ---help--- 207 Inter Process Communication is a suite of library functions and 208 system calls which let processes (running programs) synchronize and 209 exchange information. It is generally considered to be a good thing, 210 and some programs won't run unless you say Y here. In particular, if 211 you want to run the DOS emulator dosemu under Linux (read the 212 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 213 you'll need to say Y here. 214 215 You can find documentation about IPC with "info ipc" and also in 216 section 6.4 of the Linux Programmer's Guide, available from 217 <http://www.tldp.org/guides.html>. 218 219config SYSVIPC_SYSCTL 220 bool 221 depends on SYSVIPC 222 depends on SYSCTL 223 default y 224 225config POSIX_MQUEUE 226 bool "POSIX Message Queues" 227 depends on NET && EXPERIMENTAL 228 ---help--- 229 POSIX variant of message queues is a part of IPC. In POSIX message 230 queues every message has a priority which decides about succession 231 of receiving it by a process. If you want to compile and run 232 programs written e.g. for Solaris with use of its POSIX message 233 queues (functions mq_*) say Y here. 234 235 POSIX message queues are visible as a filesystem called 'mqueue' 236 and can be mounted somewhere if you want to do filesystem 237 operations on message queues. 238 239 If unsure, say Y. 240 241config POSIX_MQUEUE_SYSCTL 242 bool 243 depends on POSIX_MQUEUE 244 depends on SYSCTL 245 default y 246 247config BSD_PROCESS_ACCT 248 bool "BSD Process Accounting" 249 help 250 If you say Y here, a user level program will be able to instruct the 251 kernel (via a special system call) to write process accounting 252 information to a file: whenever a process exits, information about 253 that process will be appended to the file by the kernel. The 254 information includes things such as creation time, owning user, 255 command name, memory usage, controlling terminal etc. (the complete 256 list is in the struct acct in <file:include/linux/acct.h>). It is 257 up to the user level program to do useful things with this 258 information. This is generally a good idea, so say Y. 259 260config BSD_PROCESS_ACCT_V3 261 bool "BSD Process Accounting version 3 file format" 262 depends on BSD_PROCESS_ACCT 263 default n 264 help 265 If you say Y here, the process accounting information is written 266 in a new file format that also logs the process IDs of each 267 process and it's parent. Note that this file format is incompatible 268 with previous v0/v1/v2 file formats, so you will need updated tools 269 for processing it. A preliminary version of these tools is available 270 at <http://www.gnu.org/software/acct/>. 271 272config TASKSTATS 273 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 274 depends on NET 275 default n 276 help 277 Export selected statistics for tasks/processes through the 278 generic netlink interface. Unlike BSD process accounting, the 279 statistics are available during the lifetime of tasks/processes as 280 responses to commands. Like BSD accounting, they are sent to user 281 space on task exit. 282 283 Say N if unsure. 284 285config TASK_DELAY_ACCT 286 bool "Enable per-task delay accounting (EXPERIMENTAL)" 287 depends on TASKSTATS 288 help 289 Collect information on time spent by a task waiting for system 290 resources like cpu, synchronous block I/O completion and swapping 291 in pages. Such statistics can help in setting a task's priorities 292 relative to other tasks for cpu, io, rss limits etc. 293 294 Say N if unsure. 295 296config TASK_XACCT 297 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 298 depends on TASKSTATS 299 help 300 Collect extended task accounting data and send the data 301 to userland for processing over the taskstats interface. 302 303 Say N if unsure. 304 305config TASK_IO_ACCOUNTING 306 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 307 depends on TASK_XACCT 308 help 309 Collect information on the number of bytes of storage I/O which this 310 task has caused. 311 312 Say N if unsure. 313 314config AUDIT 315 bool "Auditing support" 316 depends on NET 317 help 318 Enable auditing infrastructure that can be used with another 319 kernel subsystem, such as SELinux (which requires this for 320 logging of avc messages output). Does not do system-call 321 auditing without CONFIG_AUDITSYSCALL. 322 323config AUDITSYSCALL 324 bool "Enable system-call auditing support" 325 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH) 326 default y if SECURITY_SELINUX 327 help 328 Enable low-overhead system-call auditing infrastructure that 329 can be used independently or with another kernel subsystem, 330 such as SELinux. 331 332config AUDIT_WATCH 333 def_bool y 334 depends on AUDITSYSCALL 335 select FSNOTIFY 336 337config AUDIT_TREE 338 def_bool y 339 depends on AUDITSYSCALL 340 select FSNOTIFY 341 342source "kernel/irq/Kconfig" 343 344menu "RCU Subsystem" 345 346choice 347 prompt "RCU Implementation" 348 default TREE_RCU 349 350config TREE_RCU 351 bool "Tree-based hierarchical RCU" 352 depends on !PREEMPT && SMP 353 help 354 This option selects the RCU implementation that is 355 designed for very large SMP system with hundreds or 356 thousands of CPUs. It also scales down nicely to 357 smaller systems. 358 359config TREE_PREEMPT_RCU 360 bool "Preemptible tree-based hierarchical RCU" 361 depends on PREEMPT 362 help 363 This option selects the RCU implementation that is 364 designed for very large SMP systems with hundreds or 365 thousands of CPUs, but for which real-time response 366 is also required. It also scales down nicely to 367 smaller systems. 368 369config TINY_RCU 370 bool "UP-only small-memory-footprint RCU" 371 depends on !SMP 372 help 373 This option selects the RCU implementation that is 374 designed for UP systems from which real-time response 375 is not required. This option greatly reduces the 376 memory footprint of RCU. 377 378config TINY_PREEMPT_RCU 379 bool "Preemptible UP-only small-memory-footprint RCU" 380 depends on !SMP && PREEMPT 381 help 382 This option selects the RCU implementation that is designed 383 for real-time UP systems. This option greatly reduces the 384 memory footprint of RCU. 385 386endchoice 387 388config PREEMPT_RCU 389 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 390 help 391 This option enables preemptible-RCU code that is common between 392 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 393 394config RCU_TRACE 395 bool "Enable tracing for RCU" 396 help 397 This option provides tracing in RCU which presents stats 398 in debugfs for debugging RCU implementation. 399 400 Say Y here if you want to enable RCU tracing 401 Say N if you are unsure. 402 403config RCU_FANOUT 404 int "Tree-based hierarchical RCU fanout value" 405 range 2 64 if 64BIT 406 range 2 32 if !64BIT 407 depends on TREE_RCU || TREE_PREEMPT_RCU 408 default 64 if 64BIT 409 default 32 if !64BIT 410 help 411 This option controls the fanout of hierarchical implementations 412 of RCU, allowing RCU to work efficiently on machines with 413 large numbers of CPUs. This value must be at least the fourth 414 root of NR_CPUS, which allows NR_CPUS to be insanely large. 415 The default value of RCU_FANOUT should be used for production 416 systems, but if you are stress-testing the RCU implementation 417 itself, small RCU_FANOUT values allow you to test large-system 418 code paths on small(er) systems. 419 420 Select a specific number if testing RCU itself. 421 Take the default if unsure. 422 423config RCU_FANOUT_EXACT 424 bool "Disable tree-based hierarchical RCU auto-balancing" 425 depends on TREE_RCU || TREE_PREEMPT_RCU 426 default n 427 help 428 This option forces use of the exact RCU_FANOUT value specified, 429 regardless of imbalances in the hierarchy. This is useful for 430 testing RCU itself, and might one day be useful on systems with 431 strong NUMA behavior. 432 433 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 434 435 Say N if unsure. 436 437config RCU_FAST_NO_HZ 438 bool "Accelerate last non-dyntick-idle CPU's grace periods" 439 depends on TREE_RCU && NO_HZ && SMP 440 default n 441 help 442 This option causes RCU to attempt to accelerate grace periods 443 in order to allow the final CPU to enter dynticks-idle state 444 more quickly. On the other hand, this option increases the 445 overhead of the dynticks-idle checking, particularly on systems 446 with large numbers of CPUs. 447 448 Say Y if energy efficiency is critically important, particularly 449 if you have relatively few CPUs. 450 451 Say N if you are unsure. 452 453config TREE_RCU_TRACE 454 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 455 select DEBUG_FS 456 help 457 This option provides tracing for the TREE_RCU and 458 TREE_PREEMPT_RCU implementations, permitting Makefile to 459 trivially select kernel/rcutree_trace.c. 460 461config RCU_BOOST 462 bool "Enable RCU priority boosting" 463 depends on RT_MUTEXES && TINY_PREEMPT_RCU 464 default n 465 help 466 This option boosts the priority of preempted RCU readers that 467 block the current preemptible RCU grace period for too long. 468 This option also prevents heavy loads from blocking RCU 469 callback invocation for all flavors of RCU. 470 471 Say Y here if you are working with real-time apps or heavy loads 472 Say N here if you are unsure. 473 474config RCU_BOOST_PRIO 475 int "Real-time priority to boost RCU readers to" 476 range 1 99 477 depends on RCU_BOOST 478 default 1 479 help 480 This option specifies the real-time priority to which preempted 481 RCU readers are to be boosted. If you are working with CPU-bound 482 real-time applications, you should specify a priority higher then 483 the highest-priority CPU-bound application. 484 485 Specify the real-time priority, or take the default if unsure. 486 487config RCU_BOOST_DELAY 488 int "Milliseconds to delay boosting after RCU grace-period start" 489 range 0 3000 490 depends on RCU_BOOST 491 default 500 492 help 493 This option specifies the time to wait after the beginning of 494 a given grace period before priority-boosting preempted RCU 495 readers blocking that grace period. Note that any RCU reader 496 blocking an expedited RCU grace period is boosted immediately. 497 498 Accept the default if unsure. 499 500config SRCU_SYNCHRONIZE_DELAY 501 int "Microseconds to delay before waiting for readers" 502 range 0 20 503 default 10 504 help 505 This option controls how long SRCU delays before entering its 506 loop waiting on SRCU readers. The purpose of this loop is 507 to avoid the unconditional context-switch penalty that would 508 otherwise be incurred if there was an active SRCU reader, 509 in a manner similar to adaptive locking schemes. This should 510 be set to be a bit longer than the common-case SRCU read-side 511 critical-section overhead. 512 513 Accept the default if unsure. 514 515endmenu # "RCU Subsystem" 516 517config IKCONFIG 518 tristate "Kernel .config support" 519 ---help--- 520 This option enables the complete Linux kernel ".config" file 521 contents to be saved in the kernel. It provides documentation 522 of which kernel options are used in a running kernel or in an 523 on-disk kernel. This information can be extracted from the kernel 524 image file with the script scripts/extract-ikconfig and used as 525 input to rebuild the current kernel or to build another kernel. 526 It can also be extracted from a running kernel by reading 527 /proc/config.gz if enabled (below). 528 529config IKCONFIG_PROC 530 bool "Enable access to .config through /proc/config.gz" 531 depends on IKCONFIG && PROC_FS 532 ---help--- 533 This option enables access to the kernel configuration file 534 through /proc/config.gz. 535 536config LOG_BUF_SHIFT 537 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 538 range 12 21 539 default 17 540 help 541 Select kernel log buffer size as a power of 2. 542 Examples: 543 17 => 128 KB 544 16 => 64 KB 545 15 => 32 KB 546 14 => 16 KB 547 13 => 8 KB 548 12 => 4 KB 549 550# 551# Architectures with an unreliable sched_clock() should select this: 552# 553config HAVE_UNSTABLE_SCHED_CLOCK 554 bool 555 556menuconfig CGROUPS 557 boolean "Control Group support" 558 depends on EVENTFD 559 help 560 This option adds support for grouping sets of processes together, for 561 use with process control subsystems such as Cpusets, CFS, memory 562 controls or device isolation. 563 See 564 - Documentation/scheduler/sched-design-CFS.txt (CFS) 565 - Documentation/cgroups/ (features for grouping, isolation 566 and resource control) 567 568 Say N if unsure. 569 570if CGROUPS 571 572config CGROUP_DEBUG 573 bool "Example debug cgroup subsystem" 574 default n 575 help 576 This option enables a simple cgroup subsystem that 577 exports useful debugging information about the cgroups 578 framework. 579 580 Say N if unsure. 581 582config CGROUP_NS 583 bool "Namespace cgroup subsystem" 584 help 585 Provides a simple namespace cgroup subsystem to 586 provide hierarchical naming of sets of namespaces, 587 for instance virtual servers and checkpoint/restart 588 jobs. 589 590config CGROUP_FREEZER 591 bool "Freezer cgroup subsystem" 592 help 593 Provides a way to freeze and unfreeze all tasks in a 594 cgroup. 595 596config CGROUP_DEVICE 597 bool "Device controller for cgroups" 598 help 599 Provides a cgroup implementing whitelists for devices which 600 a process in the cgroup can mknod or open. 601 602config CPUSETS 603 bool "Cpuset support" 604 help 605 This option will let you create and manage CPUSETs which 606 allow dynamically partitioning a system into sets of CPUs and 607 Memory Nodes and assigning tasks to run only within those sets. 608 This is primarily useful on large SMP or NUMA systems. 609 610 Say N if unsure. 611 612config PROC_PID_CPUSET 613 bool "Include legacy /proc/<pid>/cpuset file" 614 depends on CPUSETS 615 default y 616 617config CGROUP_CPUACCT 618 bool "Simple CPU accounting cgroup subsystem" 619 help 620 Provides a simple Resource Controller for monitoring the 621 total CPU consumed by the tasks in a cgroup. 622 623config RESOURCE_COUNTERS 624 bool "Resource counters" 625 help 626 This option enables controller independent resource accounting 627 infrastructure that works with cgroups. 628 629config CGROUP_MEM_RES_CTLR 630 bool "Memory Resource Controller for Control Groups" 631 depends on RESOURCE_COUNTERS 632 select MM_OWNER 633 help 634 Provides a memory resource controller that manages both anonymous 635 memory and page cache. (See Documentation/cgroups/memory.txt) 636 637 Note that setting this option increases fixed memory overhead 638 associated with each page of memory in the system. By this, 639 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 640 usage tracking struct at boot. Total amount of this is printed out 641 at boot. 642 643 Only enable when you're ok with these trade offs and really 644 sure you need the memory resource controller. Even when you enable 645 this, you can set "cgroup_disable=memory" at your boot option to 646 disable memory resource controller and you can avoid overheads. 647 (and lose benefits of memory resource controller) 648 649 This config option also selects MM_OWNER config option, which 650 could in turn add some fork/exit overhead. 651 652config CGROUP_MEM_RES_CTLR_SWAP 653 bool "Memory Resource Controller Swap Extension" 654 depends on CGROUP_MEM_RES_CTLR && SWAP 655 help 656 Add swap management feature to memory resource controller. When you 657 enable this, you can limit mem+swap usage per cgroup. In other words, 658 when you disable this, memory resource controller has no cares to 659 usage of swap...a process can exhaust all of the swap. This extension 660 is useful when you want to avoid exhaustion swap but this itself 661 adds more overheads and consumes memory for remembering information. 662 Especially if you use 32bit system or small memory system, please 663 be careful about enabling this. When memory resource controller 664 is disabled by boot option, this will be automatically disabled and 665 there will be no overhead from this. Even when you set this config=y, 666 if boot option "noswapaccount" is set, swap will not be accounted. 667 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 668 size is 4096bytes, 512k per 1Gbytes of swap. 669config CGROUP_MEM_RES_CTLR_SWAP_ENABLED 670 bool "Memory Resource Controller Swap Extension enabled by default" 671 depends on CGROUP_MEM_RES_CTLR_SWAP 672 default y 673 help 674 Memory Resource Controller Swap Extension comes with its price in 675 a bigger memory consumption. General purpose distribution kernels 676 which want to enable the feautre but keep it disabled by default 677 and let the user enable it by swapaccount boot command line 678 parameter should have this option unselected. 679 For those who want to have the feature enabled by default should 680 select this option (if, for some reason, they need to disable it 681 then noswapaccount does the trick). 682 683menuconfig CGROUP_SCHED 684 bool "Group CPU scheduler" 685 depends on EXPERIMENTAL 686 default n 687 help 688 This feature lets CPU scheduler recognize task groups and control CPU 689 bandwidth allocation to such task groups. It uses cgroups to group 690 tasks. 691 692if CGROUP_SCHED 693config FAIR_GROUP_SCHED 694 bool "Group scheduling for SCHED_OTHER" 695 depends on CGROUP_SCHED 696 default CGROUP_SCHED 697 698config RT_GROUP_SCHED 699 bool "Group scheduling for SCHED_RR/FIFO" 700 depends on EXPERIMENTAL 701 depends on CGROUP_SCHED 702 default n 703 help 704 This feature lets you explicitly allocate real CPU bandwidth 705 to task groups. If enabled, it will also make it impossible to 706 schedule realtime tasks for non-root users until you allocate 707 realtime bandwidth for them. 708 See Documentation/scheduler/sched-rt-group.txt for more information. 709 710endif #CGROUP_SCHED 711 712config BLK_CGROUP 713 tristate "Block IO controller" 714 depends on BLOCK 715 default n 716 ---help--- 717 Generic block IO controller cgroup interface. This is the common 718 cgroup interface which should be used by various IO controlling 719 policies. 720 721 Currently, CFQ IO scheduler uses it to recognize task groups and 722 control disk bandwidth allocation (proportional time slice allocation) 723 to such task groups. It is also used by bio throttling logic in 724 block layer to implement upper limit in IO rates on a device. 725 726 This option only enables generic Block IO controller infrastructure. 727 One needs to also enable actual IO controlling logic/policy. For 728 enabling proportional weight division of disk bandwidth in CFQ seti 729 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set 730 CONFIG_BLK_THROTTLE=y. 731 732 See Documentation/cgroups/blkio-controller.txt for more information. 733 734config DEBUG_BLK_CGROUP 735 bool "Enable Block IO controller debugging" 736 depends on BLK_CGROUP 737 default n 738 ---help--- 739 Enable some debugging help. Currently it exports additional stat 740 files in a cgroup which can be useful for debugging. 741 742endif # CGROUPS 743 744menuconfig NAMESPACES 745 bool "Namespaces support" if EMBEDDED 746 default !EMBEDDED 747 help 748 Provides the way to make tasks work with different objects using 749 the same id. For example same IPC id may refer to different objects 750 or same user id or pid may refer to different tasks when used in 751 different namespaces. 752 753if NAMESPACES 754 755config UTS_NS 756 bool "UTS namespace" 757 default y 758 help 759 In this namespace tasks see different info provided with the 760 uname() system call 761 762config IPC_NS 763 bool "IPC namespace" 764 depends on (SYSVIPC || POSIX_MQUEUE) 765 default y 766 help 767 In this namespace tasks work with IPC ids which correspond to 768 different IPC objects in different namespaces. 769 770config USER_NS 771 bool "User namespace (EXPERIMENTAL)" 772 depends on EXPERIMENTAL 773 default y 774 help 775 This allows containers, i.e. vservers, to use user namespaces 776 to provide different user info for different servers. 777 If unsure, say N. 778 779config PID_NS 780 bool "PID Namespaces" 781 default y 782 help 783 Support process id namespaces. This allows having multiple 784 processes with the same pid as long as they are in different 785 pid namespaces. This is a building block of containers. 786 787config NET_NS 788 bool "Network namespace" 789 depends on NET 790 default y 791 help 792 Allow user space to create what appear to be multiple instances 793 of the network stack. 794 795endif # NAMESPACES 796 797config SCHED_AUTOGROUP 798 bool "Automatic process group scheduling" 799 select EVENTFD 800 select CGROUPS 801 select CGROUP_SCHED 802 select FAIR_GROUP_SCHED 803 help 804 This option optimizes the scheduler for common desktop workloads by 805 automatically creating and populating task groups. This separation 806 of workloads isolates aggressive CPU burners (like build jobs) from 807 desktop applications. Task group autogeneration is currently based 808 upon task session. 809 810config MM_OWNER 811 bool 812 813config SYSFS_DEPRECATED 814 bool "enable deprecated sysfs features to support old userspace tools" 815 depends on SYSFS 816 default n 817 help 818 This option adds code that switches the layout of the "block" class 819 devices, to not show up in /sys/class/block/, but only in 820 /sys/block/. 821 822 This switch is only active when the sysfs.deprecated=1 boot option is 823 passed or the SYSFS_DEPRECATED_V2 option is set. 824 825 This option allows new kernels to run on old distributions and tools, 826 which might get confused by /sys/class/block/. Since 2007/2008 all 827 major distributions and tools handle this just fine. 828 829 Recent distributions and userspace tools after 2009/2010 depend on 830 the existence of /sys/class/block/, and will not work with this 831 option enabled. 832 833 Only if you are using a new kernel on an old distribution, you might 834 need to say Y here. 835 836config SYSFS_DEPRECATED_V2 837 bool "enabled deprecated sysfs features by default" 838 default n 839 depends on SYSFS 840 depends on SYSFS_DEPRECATED 841 help 842 Enable deprecated sysfs by default. 843 844 See the CONFIG_SYSFS_DEPRECATED option for more details about this 845 option. 846 847 Only if you are using a new kernel on an old distribution, you might 848 need to say Y here. Even then, odds are you would not need it 849 enabled, you can always pass the boot option if absolutely necessary. 850 851config RELAY 852 bool "Kernel->user space relay support (formerly relayfs)" 853 help 854 This option enables support for relay interface support in 855 certain file systems (such as debugfs). 856 It is designed to provide an efficient mechanism for tools and 857 facilities to relay large amounts of data from kernel space to 858 user space. 859 860 If unsure, say N. 861 862config BLK_DEV_INITRD 863 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 864 depends on BROKEN || !FRV 865 help 866 The initial RAM filesystem is a ramfs which is loaded by the 867 boot loader (loadlin or lilo) and that is mounted as root 868 before the normal boot procedure. It is typically used to 869 load modules needed to mount the "real" root file system, 870 etc. See <file:Documentation/initrd.txt> for details. 871 872 If RAM disk support (BLK_DEV_RAM) is also included, this 873 also enables initial RAM disk (initrd) support and adds 874 15 Kbytes (more on some other architectures) to the kernel size. 875 876 If unsure say Y. 877 878if BLK_DEV_INITRD 879 880source "usr/Kconfig" 881 882endif 883 884config CC_OPTIMIZE_FOR_SIZE 885 bool "Optimize for size" 886 default y 887 help 888 Enabling this option will pass "-Os" instead of "-O2" to gcc 889 resulting in a smaller kernel. 890 891 If unsure, say Y. 892 893config SYSCTL 894 bool 895 896config ANON_INODES 897 bool 898 899menuconfig EMBEDDED 900 bool "Configure standard kernel features (for small systems)" 901 help 902 This option allows certain base kernel options and settings 903 to be disabled or tweaked. This is for specialized 904 environments which can tolerate a "non-standard" kernel. 905 Only use this if you really know what you are doing. 906 907config UID16 908 bool "Enable 16-bit UID system calls" if EMBEDDED 909 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 910 default y 911 help 912 This enables the legacy 16-bit UID syscall wrappers. 913 914config SYSCTL_SYSCALL 915 bool "Sysctl syscall support" if EMBEDDED 916 depends on PROC_SYSCTL 917 default y 918 select SYSCTL 919 ---help--- 920 sys_sysctl uses binary paths that have been found challenging 921 to properly maintain and use. The interface in /proc/sys 922 using paths with ascii names is now the primary path to this 923 information. 924 925 Almost nothing using the binary sysctl interface so if you are 926 trying to save some space it is probably safe to disable this, 927 making your kernel marginally smaller. 928 929 If unsure say Y here. 930 931config KALLSYMS 932 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 933 default y 934 help 935 Say Y here to let the kernel print out symbolic crash information and 936 symbolic stack backtraces. This increases the size of the kernel 937 somewhat, as all symbols have to be loaded into the kernel image. 938 939config KALLSYMS_ALL 940 bool "Include all symbols in kallsyms" 941 depends on DEBUG_KERNEL && KALLSYMS 942 help 943 Normally kallsyms only contains the symbols of functions, for nicer 944 OOPS messages. Some debuggers can use kallsyms for other 945 symbols too: say Y here to include all symbols, if you need them 946 and you don't care about adding 300k to the size of your kernel. 947 948 Say N. 949 950config KALLSYMS_EXTRA_PASS 951 bool "Do an extra kallsyms pass" 952 depends on KALLSYMS 953 help 954 If kallsyms is not working correctly, the build will fail with 955 inconsistent kallsyms data. If that occurs, log a bug report and 956 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 957 Always say N here unless you find a bug in kallsyms, which must be 958 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 959 you wait for kallsyms to be fixed. 960 961 962config HOTPLUG 963 bool "Support for hot-pluggable devices" if EMBEDDED 964 default y 965 help 966 This option is provided for the case where no hotplug or uevent 967 capabilities is wanted by the kernel. You should only consider 968 disabling this option for embedded systems that do not use modules, a 969 dynamic /dev tree, or dynamic device discovery. Just say Y. 970 971config PRINTK 972 default y 973 bool "Enable support for printk" if EMBEDDED 974 help 975 This option enables normal printk support. Removing it 976 eliminates most of the message strings from the kernel image 977 and makes the kernel more or less silent. As this makes it 978 very difficult to diagnose system problems, saying N here is 979 strongly discouraged. 980 981config BUG 982 bool "BUG() support" if EMBEDDED 983 default y 984 help 985 Disabling this option eliminates support for BUG and WARN, reducing 986 the size of your kernel image and potentially quietly ignoring 987 numerous fatal conditions. You should only consider disabling this 988 option for embedded systems with no facilities for reporting errors. 989 Just say Y. 990 991config ELF_CORE 992 default y 993 bool "Enable ELF core dumps" if EMBEDDED 994 help 995 Enable support for generating core dumps. Disabling saves about 4k. 996 997config PCSPKR_PLATFORM 998 bool "Enable PC-Speaker support" if EMBEDDED 999 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 1000 default y 1001 help 1002 This option allows to disable the internal PC-Speaker 1003 support, saving some memory. 1004 1005config BASE_FULL 1006 default y 1007 bool "Enable full-sized data structures for core" if EMBEDDED 1008 help 1009 Disabling this option reduces the size of miscellaneous core 1010 kernel data structures. This saves memory on small machines, 1011 but may reduce performance. 1012 1013config FUTEX 1014 bool "Enable futex support" if EMBEDDED 1015 default y 1016 select RT_MUTEXES 1017 help 1018 Disabling this option will cause the kernel to be built without 1019 support for "fast userspace mutexes". The resulting kernel may not 1020 run glibc-based applications correctly. 1021 1022config EPOLL 1023 bool "Enable eventpoll support" if EMBEDDED 1024 default y 1025 select ANON_INODES 1026 help 1027 Disabling this option will cause the kernel to be built without 1028 support for epoll family of system calls. 1029 1030config SIGNALFD 1031 bool "Enable signalfd() system call" if EMBEDDED 1032 select ANON_INODES 1033 default y 1034 help 1035 Enable the signalfd() system call that allows to receive signals 1036 on a file descriptor. 1037 1038 If unsure, say Y. 1039 1040config TIMERFD 1041 bool "Enable timerfd() system call" if EMBEDDED 1042 select ANON_INODES 1043 default y 1044 help 1045 Enable the timerfd() system call that allows to receive timer 1046 events on a file descriptor. 1047 1048 If unsure, say Y. 1049 1050config EVENTFD 1051 bool "Enable eventfd() system call" if EMBEDDED 1052 select ANON_INODES 1053 default y 1054 help 1055 Enable the eventfd() system call that allows to receive both 1056 kernel notification (ie. KAIO) or userspace notifications. 1057 1058 If unsure, say Y. 1059 1060config SHMEM 1061 bool "Use full shmem filesystem" if EMBEDDED 1062 default y 1063 depends on MMU 1064 help 1065 The shmem is an internal filesystem used to manage shared memory. 1066 It is backed by swap and manages resource limits. It is also exported 1067 to userspace as tmpfs if TMPFS is enabled. Disabling this 1068 option replaces shmem and tmpfs with the much simpler ramfs code, 1069 which may be appropriate on small systems without swap. 1070 1071config AIO 1072 bool "Enable AIO support" if EMBEDDED 1073 default y 1074 help 1075 This option enables POSIX asynchronous I/O which may by used 1076 by some high performance threaded applications. Disabling 1077 this option saves about 7k. 1078 1079config HAVE_PERF_EVENTS 1080 bool 1081 help 1082 See tools/perf/design.txt for details. 1083 1084config PERF_USE_VMALLOC 1085 bool 1086 help 1087 See tools/perf/design.txt for details 1088 1089menu "Kernel Performance Events And Counters" 1090 1091config PERF_EVENTS 1092 bool "Kernel performance events and counters" 1093 default y if (PROFILING || PERF_COUNTERS) 1094 depends on HAVE_PERF_EVENTS 1095 select ANON_INODES 1096 select IRQ_WORK 1097 help 1098 Enable kernel support for various performance events provided 1099 by software and hardware. 1100 1101 Software events are supported either built-in or via the 1102 use of generic tracepoints. 1103 1104 Most modern CPUs support performance events via performance 1105 counter registers. These registers count the number of certain 1106 types of hw events: such as instructions executed, cachemisses 1107 suffered, or branches mis-predicted - without slowing down the 1108 kernel or applications. These registers can also trigger interrupts 1109 when a threshold number of events have passed - and can thus be 1110 used to profile the code that runs on that CPU. 1111 1112 The Linux Performance Event subsystem provides an abstraction of 1113 these software and hardware event capabilities, available via a 1114 system call and used by the "perf" utility in tools/perf/. It 1115 provides per task and per CPU counters, and it provides event 1116 capabilities on top of those. 1117 1118 Say Y if unsure. 1119 1120config PERF_COUNTERS 1121 bool "Kernel performance counters (old config option)" 1122 depends on HAVE_PERF_EVENTS 1123 help 1124 This config has been obsoleted by the PERF_EVENTS 1125 config option - please see that one for details. 1126 1127 It has no effect on the kernel whether you enable 1128 it or not, it is a compatibility placeholder. 1129 1130 Say N if unsure. 1131 1132config DEBUG_PERF_USE_VMALLOC 1133 default n 1134 bool "Debug: use vmalloc to back perf mmap() buffers" 1135 depends on PERF_EVENTS && DEBUG_KERNEL 1136 select PERF_USE_VMALLOC 1137 help 1138 Use vmalloc memory to back perf mmap() buffers. 1139 1140 Mostly useful for debugging the vmalloc code on platforms 1141 that don't require it. 1142 1143 Say N if unsure. 1144 1145endmenu 1146 1147config VM_EVENT_COUNTERS 1148 default y 1149 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 1150 help 1151 VM event counters are needed for event counts to be shown. 1152 This option allows the disabling of the VM event counters 1153 on EMBEDDED systems. /proc/vmstat will only show page counts 1154 if VM event counters are disabled. 1155 1156config PCI_QUIRKS 1157 default y 1158 bool "Enable PCI quirk workarounds" if EMBEDDED 1159 depends on PCI 1160 help 1161 This enables workarounds for various PCI chipset 1162 bugs/quirks. Disable this only if your target machine is 1163 unaffected by PCI quirks. 1164 1165config SLUB_DEBUG 1166 default y 1167 bool "Enable SLUB debugging support" if EMBEDDED 1168 depends on SLUB && SYSFS 1169 help 1170 SLUB has extensive debug support features. Disabling these can 1171 result in significant savings in code size. This also disables 1172 SLUB sysfs support. /sys/slab will not exist and there will be 1173 no support for cache validation etc. 1174 1175config COMPAT_BRK 1176 bool "Disable heap randomization" 1177 default y 1178 help 1179 Randomizing heap placement makes heap exploits harder, but it 1180 also breaks ancient binaries (including anything libc5 based). 1181 This option changes the bootup default to heap randomization 1182 disabled, and can be overridden at runtime by setting 1183 /proc/sys/kernel/randomize_va_space to 2. 1184 1185 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1186 1187choice 1188 prompt "Choose SLAB allocator" 1189 default SLUB 1190 help 1191 This option allows to select a slab allocator. 1192 1193config SLAB 1194 bool "SLAB" 1195 help 1196 The regular slab allocator that is established and known to work 1197 well in all environments. It organizes cache hot objects in 1198 per cpu and per node queues. 1199 1200config SLUB 1201 bool "SLUB (Unqueued Allocator)" 1202 help 1203 SLUB is a slab allocator that minimizes cache line usage 1204 instead of managing queues of cached objects (SLAB approach). 1205 Per cpu caching is realized using slabs of objects instead 1206 of queues of objects. SLUB can use memory efficiently 1207 and has enhanced diagnostics. SLUB is the default choice for 1208 a slab allocator. 1209 1210config SLOB 1211 depends on EMBEDDED 1212 bool "SLOB (Simple Allocator)" 1213 help 1214 SLOB replaces the stock allocator with a drastically simpler 1215 allocator. SLOB is generally more space efficient but 1216 does not perform as well on large systems. 1217 1218endchoice 1219 1220config MMAP_ALLOW_UNINITIALIZED 1221 bool "Allow mmapped anonymous memory to be uninitialized" 1222 depends on EMBEDDED && !MMU 1223 default n 1224 help 1225 Normally, and according to the Linux spec, anonymous memory obtained 1226 from mmap() has it's contents cleared before it is passed to 1227 userspace. Enabling this config option allows you to request that 1228 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1229 providing a huge performance boost. If this option is not enabled, 1230 then the flag will be ignored. 1231 1232 This is taken advantage of by uClibc's malloc(), and also by 1233 ELF-FDPIC binfmt's brk and stack allocator. 1234 1235 Because of the obvious security issues, this option should only be 1236 enabled on embedded devices where you control what is run in 1237 userspace. Since that isn't generally a problem on no-MMU systems, 1238 it is normally safe to say Y here. 1239 1240 See Documentation/nommu-mmap.txt for more information. 1241 1242config PROFILING 1243 bool "Profiling support" 1244 help 1245 Say Y here to enable the extended profiling support mechanisms used 1246 by profilers such as OProfile. 1247 1248# 1249# Place an empty function call at each tracepoint site. Can be 1250# dynamically changed for a probe function. 1251# 1252config TRACEPOINTS 1253 bool 1254 1255source "arch/Kconfig" 1256 1257endmenu # General setup 1258 1259config HAVE_GENERIC_DMA_COHERENT 1260 bool 1261 default n 1262 1263config SLABINFO 1264 bool 1265 depends on PROC_FS 1266 depends on SLAB || SLUB_DEBUG 1267 default y 1268 1269config RT_MUTEXES 1270 boolean 1271 1272config BASE_SMALL 1273 int 1274 default 0 if BASE_FULL 1275 default 1 if !BASE_FULL 1276 1277menuconfig MODULES 1278 bool "Enable loadable module support" 1279 help 1280 Kernel modules are small pieces of compiled code which can 1281 be inserted in the running kernel, rather than being 1282 permanently built into the kernel. You use the "modprobe" 1283 tool to add (and sometimes remove) them. If you say Y here, 1284 many parts of the kernel can be built as modules (by 1285 answering M instead of Y where indicated): this is most 1286 useful for infrequently used options which are not required 1287 for booting. For more information, see the man pages for 1288 modprobe, lsmod, modinfo, insmod and rmmod. 1289 1290 If you say Y here, you will need to run "make 1291 modules_install" to put the modules under /lib/modules/ 1292 where modprobe can find them (you may need to be root to do 1293 this). 1294 1295 If unsure, say Y. 1296 1297if MODULES 1298 1299config MODULE_FORCE_LOAD 1300 bool "Forced module loading" 1301 default n 1302 help 1303 Allow loading of modules without version information (ie. modprobe 1304 --force). Forced module loading sets the 'F' (forced) taint flag and 1305 is usually a really bad idea. 1306 1307config MODULE_UNLOAD 1308 bool "Module unloading" 1309 help 1310 Without this option you will not be able to unload any 1311 modules (note that some modules may not be unloadable 1312 anyway), which makes your kernel smaller, faster 1313 and simpler. If unsure, say Y. 1314 1315config MODULE_FORCE_UNLOAD 1316 bool "Forced module unloading" 1317 depends on MODULE_UNLOAD && EXPERIMENTAL 1318 help 1319 This option allows you to force a module to unload, even if the 1320 kernel believes it is unsafe: the kernel will remove the module 1321 without waiting for anyone to stop using it (using the -f option to 1322 rmmod). This is mainly for kernel developers and desperate users. 1323 If unsure, say N. 1324 1325config MODVERSIONS 1326 bool "Module versioning support" 1327 help 1328 Usually, you have to use modules compiled with your kernel. 1329 Saying Y here makes it sometimes possible to use modules 1330 compiled for different kernels, by adding enough information 1331 to the modules to (hopefully) spot any changes which would 1332 make them incompatible with the kernel you are running. If 1333 unsure, say N. 1334 1335config MODULE_SRCVERSION_ALL 1336 bool "Source checksum for all modules" 1337 help 1338 Modules which contain a MODULE_VERSION get an extra "srcversion" 1339 field inserted into their modinfo section, which contains a 1340 sum of the source files which made it. This helps maintainers 1341 see exactly which source was used to build a module (since 1342 others sometimes change the module source without updating 1343 the version). With this option, such a "srcversion" field 1344 will be created for all modules. If unsure, say N. 1345 1346endif # MODULES 1347 1348config INIT_ALL_POSSIBLE 1349 bool 1350 help 1351 Back when each arch used to define their own cpu_online_map and 1352 cpu_possible_map, some of them chose to initialize cpu_possible_map 1353 with all 1s, and others with all 0s. When they were centralised, 1354 it was better to provide this option than to break all the archs 1355 and have several arch maintainers pursuing me down dark alleys. 1356 1357config STOP_MACHINE 1358 bool 1359 default y 1360 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1361 help 1362 Need stop_machine() primitive. 1363 1364source "block/Kconfig" 1365 1366config PREEMPT_NOTIFIERS 1367 bool 1368 1369config PADATA 1370 depends on SMP 1371 bool 1372 1373source "kernel/Kconfig.locks" 1374