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 These are 54 drivers that have been replaced by something else, and/or are 55 scheduled to be removed in a future kernel release. 56 57 Unless you intend to help test and develop a feature or driver that 58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_XZ 134 bool 135 136config HAVE_KERNEL_LZO 137 bool 138 139choice 140 prompt "Kernel compression mode" 141 default KERNEL_GZIP 142 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 143 help 144 The linux kernel is a kind of self-extracting executable. 145 Several compression algorithms are available, which differ 146 in efficiency, compression and decompression speed. 147 Compression speed is only relevant when building a kernel. 148 Decompression speed is relevant at each boot. 149 150 If you have any problems with bzip2 or lzma compressed 151 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 152 version of this functionality (bzip2 only), for 2.4, was 153 supplied by Christian Ludwig) 154 155 High compression options are mostly useful for users, who 156 are low on disk space (embedded systems), but for whom ram 157 size matters less. 158 159 If in doubt, select 'gzip' 160 161config KERNEL_GZIP 162 bool "Gzip" 163 depends on HAVE_KERNEL_GZIP 164 help 165 The old and tried gzip compression. It provides a good balance 166 between compression ratio and decompression speed. 167 168config KERNEL_BZIP2 169 bool "Bzip2" 170 depends on HAVE_KERNEL_BZIP2 171 help 172 Its compression ratio and speed is intermediate. 173 Decompression speed is slowest among the three. The kernel 174 size is about 10% smaller with bzip2, in comparison to gzip. 175 Bzip2 uses a large amount of memory. For modern kernels you 176 will need at least 8MB RAM or more for booting. 177 178config KERNEL_LZMA 179 bool "LZMA" 180 depends on HAVE_KERNEL_LZMA 181 help 182 The most recent compression algorithm. 183 Its ratio is best, decompression speed is between the other 184 two. Compression is slowest. The kernel size is about 33% 185 smaller with LZMA in comparison to gzip. 186 187config KERNEL_XZ 188 bool "XZ" 189 depends on HAVE_KERNEL_XZ 190 help 191 XZ uses the LZMA2 algorithm and instruction set specific 192 BCJ filters which can improve compression ratio of executable 193 code. The size of the kernel is about 30% smaller with XZ in 194 comparison to gzip. On architectures for which there is a BCJ 195 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 196 will create a few percent smaller kernel than plain LZMA. 197 198 The speed is about the same as with LZMA: The decompression 199 speed of XZ is better than that of bzip2 but worse than gzip 200 and LZO. Compression is slow. 201 202config KERNEL_LZO 203 bool "LZO" 204 depends on HAVE_KERNEL_LZO 205 help 206 Its compression ratio is the poorest among the 4. The kernel 207 size is about 10% bigger than gzip; however its speed 208 (both compression and decompression) is the fastest. 209 210endchoice 211 212config SWAP 213 bool "Support for paging of anonymous memory (swap)" 214 depends on MMU && BLOCK 215 default y 216 help 217 This option allows you to choose whether you want to have support 218 for so called swap devices or swap files in your kernel that are 219 used to provide more virtual memory than the actual RAM present 220 in your computer. If unsure say Y. 221 222config SYSVIPC 223 bool "System V IPC" 224 ---help--- 225 Inter Process Communication is a suite of library functions and 226 system calls which let processes (running programs) synchronize and 227 exchange information. It is generally considered to be a good thing, 228 and some programs won't run unless you say Y here. In particular, if 229 you want to run the DOS emulator dosemu under Linux (read the 230 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 231 you'll need to say Y here. 232 233 You can find documentation about IPC with "info ipc" and also in 234 section 6.4 of the Linux Programmer's Guide, available from 235 <http://www.tldp.org/guides.html>. 236 237config SYSVIPC_SYSCTL 238 bool 239 depends on SYSVIPC 240 depends on SYSCTL 241 default y 242 243config POSIX_MQUEUE 244 bool "POSIX Message Queues" 245 depends on NET && EXPERIMENTAL 246 ---help--- 247 POSIX variant of message queues is a part of IPC. In POSIX message 248 queues every message has a priority which decides about succession 249 of receiving it by a process. If you want to compile and run 250 programs written e.g. for Solaris with use of its POSIX message 251 queues (functions mq_*) say Y here. 252 253 POSIX message queues are visible as a filesystem called 'mqueue' 254 and can be mounted somewhere if you want to do filesystem 255 operations on message queues. 256 257 If unsure, say Y. 258 259config POSIX_MQUEUE_SYSCTL 260 bool 261 depends on POSIX_MQUEUE 262 depends on SYSCTL 263 default y 264 265config BSD_PROCESS_ACCT 266 bool "BSD Process Accounting" 267 help 268 If you say Y here, a user level program will be able to instruct the 269 kernel (via a special system call) to write process accounting 270 information to a file: whenever a process exits, information about 271 that process will be appended to the file by the kernel. The 272 information includes things such as creation time, owning user, 273 command name, memory usage, controlling terminal etc. (the complete 274 list is in the struct acct in <file:include/linux/acct.h>). It is 275 up to the user level program to do useful things with this 276 information. This is generally a good idea, so say Y. 277 278config BSD_PROCESS_ACCT_V3 279 bool "BSD Process Accounting version 3 file format" 280 depends on BSD_PROCESS_ACCT 281 default n 282 help 283 If you say Y here, the process accounting information is written 284 in a new file format that also logs the process IDs of each 285 process and it's parent. Note that this file format is incompatible 286 with previous v0/v1/v2 file formats, so you will need updated tools 287 for processing it. A preliminary version of these tools is available 288 at <http://www.gnu.org/software/acct/>. 289 290config TASKSTATS 291 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 292 depends on NET 293 default n 294 help 295 Export selected statistics for tasks/processes through the 296 generic netlink interface. Unlike BSD process accounting, the 297 statistics are available during the lifetime of tasks/processes as 298 responses to commands. Like BSD accounting, they are sent to user 299 space on task exit. 300 301 Say N if unsure. 302 303config TASK_DELAY_ACCT 304 bool "Enable per-task delay accounting (EXPERIMENTAL)" 305 depends on TASKSTATS 306 help 307 Collect information on time spent by a task waiting for system 308 resources like cpu, synchronous block I/O completion and swapping 309 in pages. Such statistics can help in setting a task's priorities 310 relative to other tasks for cpu, io, rss limits etc. 311 312 Say N if unsure. 313 314config TASK_XACCT 315 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 316 depends on TASKSTATS 317 help 318 Collect extended task accounting data and send the data 319 to userland for processing over the taskstats interface. 320 321 Say N if unsure. 322 323config TASK_IO_ACCOUNTING 324 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 325 depends on TASK_XACCT 326 help 327 Collect information on the number of bytes of storage I/O which this 328 task has caused. 329 330 Say N if unsure. 331 332config AUDIT 333 bool "Auditing support" 334 depends on NET 335 help 336 Enable auditing infrastructure that can be used with another 337 kernel subsystem, such as SELinux (which requires this for 338 logging of avc messages output). Does not do system-call 339 auditing without CONFIG_AUDITSYSCALL. 340 341config AUDITSYSCALL 342 bool "Enable system-call auditing support" 343 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH) 344 default y if SECURITY_SELINUX 345 help 346 Enable low-overhead system-call auditing infrastructure that 347 can be used independently or with another kernel subsystem, 348 such as SELinux. 349 350config AUDIT_WATCH 351 def_bool y 352 depends on AUDITSYSCALL 353 select FSNOTIFY 354 355config AUDIT_TREE 356 def_bool y 357 depends on AUDITSYSCALL 358 select FSNOTIFY 359 360source "kernel/irq/Kconfig" 361 362menu "RCU Subsystem" 363 364choice 365 prompt "RCU Implementation" 366 default TREE_RCU 367 368config TREE_RCU 369 bool "Tree-based hierarchical RCU" 370 depends on !PREEMPT && SMP 371 help 372 This option selects the RCU implementation that is 373 designed for very large SMP system with hundreds or 374 thousands of CPUs. It also scales down nicely to 375 smaller systems. 376 377config TREE_PREEMPT_RCU 378 bool "Preemptible tree-based hierarchical RCU" 379 depends on PREEMPT 380 help 381 This option selects the RCU implementation that is 382 designed for very large SMP systems with hundreds or 383 thousands of CPUs, but for which real-time response 384 is also required. It also scales down nicely to 385 smaller systems. 386 387config TINY_RCU 388 bool "UP-only small-memory-footprint RCU" 389 depends on !SMP 390 help 391 This option selects the RCU implementation that is 392 designed for UP systems from which real-time response 393 is not required. This option greatly reduces the 394 memory footprint of RCU. 395 396config TINY_PREEMPT_RCU 397 bool "Preemptible UP-only small-memory-footprint RCU" 398 depends on !SMP && PREEMPT 399 help 400 This option selects the RCU implementation that is designed 401 for real-time UP systems. This option greatly reduces the 402 memory footprint of RCU. 403 404endchoice 405 406config PREEMPT_RCU 407 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 408 help 409 This option enables preemptible-RCU code that is common between 410 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 411 412config RCU_TRACE 413 bool "Enable tracing for RCU" 414 help 415 This option provides tracing in RCU which presents stats 416 in debugfs for debugging RCU implementation. 417 418 Say Y here if you want to enable RCU tracing 419 Say N if you are unsure. 420 421config RCU_FANOUT 422 int "Tree-based hierarchical RCU fanout value" 423 range 2 64 if 64BIT 424 range 2 32 if !64BIT 425 depends on TREE_RCU || TREE_PREEMPT_RCU 426 default 64 if 64BIT 427 default 32 if !64BIT 428 help 429 This option controls the fanout of hierarchical implementations 430 of RCU, allowing RCU to work efficiently on machines with 431 large numbers of CPUs. This value must be at least the fourth 432 root of NR_CPUS, which allows NR_CPUS to be insanely large. 433 The default value of RCU_FANOUT should be used for production 434 systems, but if you are stress-testing the RCU implementation 435 itself, small RCU_FANOUT values allow you to test large-system 436 code paths on small(er) systems. 437 438 Select a specific number if testing RCU itself. 439 Take the default if unsure. 440 441config RCU_FANOUT_EXACT 442 bool "Disable tree-based hierarchical RCU auto-balancing" 443 depends on TREE_RCU || TREE_PREEMPT_RCU 444 default n 445 help 446 This option forces use of the exact RCU_FANOUT value specified, 447 regardless of imbalances in the hierarchy. This is useful for 448 testing RCU itself, and might one day be useful on systems with 449 strong NUMA behavior. 450 451 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 452 453 Say N if unsure. 454 455config RCU_FAST_NO_HZ 456 bool "Accelerate last non-dyntick-idle CPU's grace periods" 457 depends on TREE_RCU && NO_HZ && SMP 458 default n 459 help 460 This option causes RCU to attempt to accelerate grace periods 461 in order to allow the final CPU to enter dynticks-idle state 462 more quickly. On the other hand, this option increases the 463 overhead of the dynticks-idle checking, particularly on systems 464 with large numbers of CPUs. 465 466 Say Y if energy efficiency is critically important, particularly 467 if you have relatively few CPUs. 468 469 Say N if you are unsure. 470 471config TREE_RCU_TRACE 472 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 473 select DEBUG_FS 474 help 475 This option provides tracing for the TREE_RCU and 476 TREE_PREEMPT_RCU implementations, permitting Makefile to 477 trivially select kernel/rcutree_trace.c. 478 479config RCU_BOOST 480 bool "Enable RCU priority boosting" 481 depends on RT_MUTEXES && TINY_PREEMPT_RCU 482 default n 483 help 484 This option boosts the priority of preempted RCU readers that 485 block the current preemptible RCU grace period for too long. 486 This option also prevents heavy loads from blocking RCU 487 callback invocation for all flavors of RCU. 488 489 Say Y here if you are working with real-time apps or heavy loads 490 Say N here if you are unsure. 491 492config RCU_BOOST_PRIO 493 int "Real-time priority to boost RCU readers to" 494 range 1 99 495 depends on RCU_BOOST 496 default 1 497 help 498 This option specifies the real-time priority to which preempted 499 RCU readers are to be boosted. If you are working with CPU-bound 500 real-time applications, you should specify a priority higher then 501 the highest-priority CPU-bound application. 502 503 Specify the real-time priority, or take the default if unsure. 504 505config RCU_BOOST_DELAY 506 int "Milliseconds to delay boosting after RCU grace-period start" 507 range 0 3000 508 depends on RCU_BOOST 509 default 500 510 help 511 This option specifies the time to wait after the beginning of 512 a given grace period before priority-boosting preempted RCU 513 readers blocking that grace period. Note that any RCU reader 514 blocking an expedited RCU grace period is boosted immediately. 515 516 Accept the default if unsure. 517 518config SRCU_SYNCHRONIZE_DELAY 519 int "Microseconds to delay before waiting for readers" 520 range 0 20 521 default 10 522 help 523 This option controls how long SRCU delays before entering its 524 loop waiting on SRCU readers. The purpose of this loop is 525 to avoid the unconditional context-switch penalty that would 526 otherwise be incurred if there was an active SRCU reader, 527 in a manner similar to adaptive locking schemes. This should 528 be set to be a bit longer than the common-case SRCU read-side 529 critical-section overhead. 530 531 Accept the default if unsure. 532 533endmenu # "RCU Subsystem" 534 535config IKCONFIG 536 tristate "Kernel .config support" 537 ---help--- 538 This option enables the complete Linux kernel ".config" file 539 contents to be saved in the kernel. It provides documentation 540 of which kernel options are used in a running kernel or in an 541 on-disk kernel. This information can be extracted from the kernel 542 image file with the script scripts/extract-ikconfig and used as 543 input to rebuild the current kernel or to build another kernel. 544 It can also be extracted from a running kernel by reading 545 /proc/config.gz if enabled (below). 546 547config IKCONFIG_PROC 548 bool "Enable access to .config through /proc/config.gz" 549 depends on IKCONFIG && PROC_FS 550 ---help--- 551 This option enables access to the kernel configuration file 552 through /proc/config.gz. 553 554config LOG_BUF_SHIFT 555 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 556 range 12 21 557 default 17 558 help 559 Select kernel log buffer size as a power of 2. 560 Examples: 561 17 => 128 KB 562 16 => 64 KB 563 15 => 32 KB 564 14 => 16 KB 565 13 => 8 KB 566 12 => 4 KB 567 568# 569# Architectures with an unreliable sched_clock() should select this: 570# 571config HAVE_UNSTABLE_SCHED_CLOCK 572 bool 573 574menuconfig CGROUPS 575 boolean "Control Group support" 576 depends on EVENTFD 577 help 578 This option adds support for grouping sets of processes together, for 579 use with process control subsystems such as Cpusets, CFS, memory 580 controls or device isolation. 581 See 582 - Documentation/scheduler/sched-design-CFS.txt (CFS) 583 - Documentation/cgroups/ (features for grouping, isolation 584 and resource control) 585 586 Say N if unsure. 587 588if CGROUPS 589 590config CGROUP_DEBUG 591 bool "Example debug cgroup subsystem" 592 default n 593 help 594 This option enables a simple cgroup subsystem that 595 exports useful debugging information about the cgroups 596 framework. 597 598 Say N if unsure. 599 600config CGROUP_NS 601 bool "Namespace cgroup subsystem" 602 help 603 Provides a simple namespace cgroup subsystem to 604 provide hierarchical naming of sets of namespaces, 605 for instance virtual servers and checkpoint/restart 606 jobs. 607 608config CGROUP_FREEZER 609 bool "Freezer cgroup subsystem" 610 help 611 Provides a way to freeze and unfreeze all tasks in a 612 cgroup. 613 614config CGROUP_DEVICE 615 bool "Device controller for cgroups" 616 help 617 Provides a cgroup implementing whitelists for devices which 618 a process in the cgroup can mknod or open. 619 620config CPUSETS 621 bool "Cpuset support" 622 help 623 This option will let you create and manage CPUSETs which 624 allow dynamically partitioning a system into sets of CPUs and 625 Memory Nodes and assigning tasks to run only within those sets. 626 This is primarily useful on large SMP or NUMA systems. 627 628 Say N if unsure. 629 630config PROC_PID_CPUSET 631 bool "Include legacy /proc/<pid>/cpuset file" 632 depends on CPUSETS 633 default y 634 635config CGROUP_CPUACCT 636 bool "Simple CPU accounting cgroup subsystem" 637 help 638 Provides a simple Resource Controller for monitoring the 639 total CPU consumed by the tasks in a cgroup. 640 641config RESOURCE_COUNTERS 642 bool "Resource counters" 643 help 644 This option enables controller independent resource accounting 645 infrastructure that works with cgroups. 646 647config CGROUP_MEM_RES_CTLR 648 bool "Memory Resource Controller for Control Groups" 649 depends on RESOURCE_COUNTERS 650 select MM_OWNER 651 help 652 Provides a memory resource controller that manages both anonymous 653 memory and page cache. (See Documentation/cgroups/memory.txt) 654 655 Note that setting this option increases fixed memory overhead 656 associated with each page of memory in the system. By this, 657 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 658 usage tracking struct at boot. Total amount of this is printed out 659 at boot. 660 661 Only enable when you're ok with these trade offs and really 662 sure you need the memory resource controller. Even when you enable 663 this, you can set "cgroup_disable=memory" at your boot option to 664 disable memory resource controller and you can avoid overheads. 665 (and lose benefits of memory resource controller) 666 667 This config option also selects MM_OWNER config option, which 668 could in turn add some fork/exit overhead. 669 670config CGROUP_MEM_RES_CTLR_SWAP 671 bool "Memory Resource Controller Swap Extension" 672 depends on CGROUP_MEM_RES_CTLR && SWAP 673 help 674 Add swap management feature to memory resource controller. When you 675 enable this, you can limit mem+swap usage per cgroup. In other words, 676 when you disable this, memory resource controller has no cares to 677 usage of swap...a process can exhaust all of the swap. This extension 678 is useful when you want to avoid exhaustion swap but this itself 679 adds more overheads and consumes memory for remembering information. 680 Especially if you use 32bit system or small memory system, please 681 be careful about enabling this. When memory resource controller 682 is disabled by boot option, this will be automatically disabled and 683 there will be no overhead from this. Even when you set this config=y, 684 if boot option "noswapaccount" is set, swap will not be accounted. 685 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 686 size is 4096bytes, 512k per 1Gbytes of swap. 687config CGROUP_MEM_RES_CTLR_SWAP_ENABLED 688 bool "Memory Resource Controller Swap Extension enabled by default" 689 depends on CGROUP_MEM_RES_CTLR_SWAP 690 default y 691 help 692 Memory Resource Controller Swap Extension comes with its price in 693 a bigger memory consumption. General purpose distribution kernels 694 which want to enable the feautre but keep it disabled by default 695 and let the user enable it by swapaccount boot command line 696 parameter should have this option unselected. 697 For those who want to have the feature enabled by default should 698 select this option (if, for some reason, they need to disable it 699 then noswapaccount does the trick). 700 701menuconfig CGROUP_SCHED 702 bool "Group CPU scheduler" 703 depends on EXPERIMENTAL 704 default n 705 help 706 This feature lets CPU scheduler recognize task groups and control CPU 707 bandwidth allocation to such task groups. It uses cgroups to group 708 tasks. 709 710if CGROUP_SCHED 711config FAIR_GROUP_SCHED 712 bool "Group scheduling for SCHED_OTHER" 713 depends on CGROUP_SCHED 714 default CGROUP_SCHED 715 716config RT_GROUP_SCHED 717 bool "Group scheduling for SCHED_RR/FIFO" 718 depends on EXPERIMENTAL 719 depends on CGROUP_SCHED 720 default n 721 help 722 This feature lets you explicitly allocate real CPU bandwidth 723 to task groups. If enabled, it will also make it impossible to 724 schedule realtime tasks for non-root users until you allocate 725 realtime bandwidth for them. 726 See Documentation/scheduler/sched-rt-group.txt for more information. 727 728endif #CGROUP_SCHED 729 730config BLK_CGROUP 731 tristate "Block IO controller" 732 depends on BLOCK 733 default n 734 ---help--- 735 Generic block IO controller cgroup interface. This is the common 736 cgroup interface which should be used by various IO controlling 737 policies. 738 739 Currently, CFQ IO scheduler uses it to recognize task groups and 740 control disk bandwidth allocation (proportional time slice allocation) 741 to such task groups. It is also used by bio throttling logic in 742 block layer to implement upper limit in IO rates on a device. 743 744 This option only enables generic Block IO controller infrastructure. 745 One needs to also enable actual IO controlling logic/policy. For 746 enabling proportional weight division of disk bandwidth in CFQ seti 747 CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set 748 CONFIG_BLK_THROTTLE=y. 749 750 See Documentation/cgroups/blkio-controller.txt for more information. 751 752config DEBUG_BLK_CGROUP 753 bool "Enable Block IO controller debugging" 754 depends on BLK_CGROUP 755 default n 756 ---help--- 757 Enable some debugging help. Currently it exports additional stat 758 files in a cgroup which can be useful for debugging. 759 760endif # CGROUPS 761 762menuconfig NAMESPACES 763 bool "Namespaces support" if EMBEDDED 764 default !EMBEDDED 765 help 766 Provides the way to make tasks work with different objects using 767 the same id. For example same IPC id may refer to different objects 768 or same user id or pid may refer to different tasks when used in 769 different namespaces. 770 771if NAMESPACES 772 773config UTS_NS 774 bool "UTS namespace" 775 default y 776 help 777 In this namespace tasks see different info provided with the 778 uname() system call 779 780config IPC_NS 781 bool "IPC namespace" 782 depends on (SYSVIPC || POSIX_MQUEUE) 783 default y 784 help 785 In this namespace tasks work with IPC ids which correspond to 786 different IPC objects in different namespaces. 787 788config USER_NS 789 bool "User namespace (EXPERIMENTAL)" 790 depends on EXPERIMENTAL 791 default y 792 help 793 This allows containers, i.e. vservers, to use user namespaces 794 to provide different user info for different servers. 795 If unsure, say N. 796 797config PID_NS 798 bool "PID Namespaces" 799 default y 800 help 801 Support process id namespaces. This allows having multiple 802 processes with the same pid as long as they are in different 803 pid namespaces. This is a building block of containers. 804 805config NET_NS 806 bool "Network namespace" 807 depends on NET 808 default y 809 help 810 Allow user space to create what appear to be multiple instances 811 of the network stack. 812 813endif # NAMESPACES 814 815config SCHED_AUTOGROUP 816 bool "Automatic process group scheduling" 817 select EVENTFD 818 select CGROUPS 819 select CGROUP_SCHED 820 select FAIR_GROUP_SCHED 821 help 822 This option optimizes the scheduler for common desktop workloads by 823 automatically creating and populating task groups. This separation 824 of workloads isolates aggressive CPU burners (like build jobs) from 825 desktop applications. Task group autogeneration is currently based 826 upon task session. 827 828config MM_OWNER 829 bool 830 831config SYSFS_DEPRECATED 832 bool "enable deprecated sysfs features to support old userspace tools" 833 depends on SYSFS 834 default n 835 help 836 This option adds code that switches the layout of the "block" class 837 devices, to not show up in /sys/class/block/, but only in 838 /sys/block/. 839 840 This switch is only active when the sysfs.deprecated=1 boot option is 841 passed or the SYSFS_DEPRECATED_V2 option is set. 842 843 This option allows new kernels to run on old distributions and tools, 844 which might get confused by /sys/class/block/. Since 2007/2008 all 845 major distributions and tools handle this just fine. 846 847 Recent distributions and userspace tools after 2009/2010 depend on 848 the existence of /sys/class/block/, and will not work with this 849 option enabled. 850 851 Only if you are using a new kernel on an old distribution, you might 852 need to say Y here. 853 854config SYSFS_DEPRECATED_V2 855 bool "enabled deprecated sysfs features by default" 856 default n 857 depends on SYSFS 858 depends on SYSFS_DEPRECATED 859 help 860 Enable deprecated sysfs by default. 861 862 See the CONFIG_SYSFS_DEPRECATED option for more details about this 863 option. 864 865 Only if you are using a new kernel on an old distribution, you might 866 need to say Y here. Even then, odds are you would not need it 867 enabled, you can always pass the boot option if absolutely necessary. 868 869config RELAY 870 bool "Kernel->user space relay support (formerly relayfs)" 871 help 872 This option enables support for relay interface support in 873 certain file systems (such as debugfs). 874 It is designed to provide an efficient mechanism for tools and 875 facilities to relay large amounts of data from kernel space to 876 user space. 877 878 If unsure, say N. 879 880config BLK_DEV_INITRD 881 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 882 depends on BROKEN || !FRV 883 help 884 The initial RAM filesystem is a ramfs which is loaded by the 885 boot loader (loadlin or lilo) and that is mounted as root 886 before the normal boot procedure. It is typically used to 887 load modules needed to mount the "real" root file system, 888 etc. See <file:Documentation/initrd.txt> for details. 889 890 If RAM disk support (BLK_DEV_RAM) is also included, this 891 also enables initial RAM disk (initrd) support and adds 892 15 Kbytes (more on some other architectures) to the kernel size. 893 894 If unsure say Y. 895 896if BLK_DEV_INITRD 897 898source "usr/Kconfig" 899 900endif 901 902config CC_OPTIMIZE_FOR_SIZE 903 bool "Optimize for size" 904 default y 905 help 906 Enabling this option will pass "-Os" instead of "-O2" to gcc 907 resulting in a smaller kernel. 908 909 If unsure, say Y. 910 911config SYSCTL 912 bool 913 914config ANON_INODES 915 bool 916 917menuconfig EMBEDDED 918 bool "Configure standard kernel features (for small systems)" 919 help 920 This option allows certain base kernel options and settings 921 to be disabled or tweaked. This is for specialized 922 environments which can tolerate a "non-standard" kernel. 923 Only use this if you really know what you are doing. 924 925config UID16 926 bool "Enable 16-bit UID system calls" if EMBEDDED 927 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 928 default y 929 help 930 This enables the legacy 16-bit UID syscall wrappers. 931 932config SYSCTL_SYSCALL 933 bool "Sysctl syscall support" if EMBEDDED 934 depends on PROC_SYSCTL 935 default y 936 select SYSCTL 937 ---help--- 938 sys_sysctl uses binary paths that have been found challenging 939 to properly maintain and use. The interface in /proc/sys 940 using paths with ascii names is now the primary path to this 941 information. 942 943 Almost nothing using the binary sysctl interface so if you are 944 trying to save some space it is probably safe to disable this, 945 making your kernel marginally smaller. 946 947 If unsure say Y here. 948 949config KALLSYMS 950 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 951 default y 952 help 953 Say Y here to let the kernel print out symbolic crash information and 954 symbolic stack backtraces. This increases the size of the kernel 955 somewhat, as all symbols have to be loaded into the kernel image. 956 957config KALLSYMS_ALL 958 bool "Include all symbols in kallsyms" 959 depends on DEBUG_KERNEL && KALLSYMS 960 help 961 Normally kallsyms only contains the symbols of functions, for nicer 962 OOPS messages. Some debuggers can use kallsyms for other 963 symbols too: say Y here to include all symbols, if you need them 964 and you don't care about adding 300k to the size of your kernel. 965 966 Say N. 967 968config KALLSYMS_EXTRA_PASS 969 bool "Do an extra kallsyms pass" 970 depends on KALLSYMS 971 help 972 If kallsyms is not working correctly, the build will fail with 973 inconsistent kallsyms data. If that occurs, log a bug report and 974 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 975 Always say N here unless you find a bug in kallsyms, which must be 976 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 977 you wait for kallsyms to be fixed. 978 979 980config HOTPLUG 981 bool "Support for hot-pluggable devices" if EMBEDDED 982 default y 983 help 984 This option is provided for the case where no hotplug or uevent 985 capabilities is wanted by the kernel. You should only consider 986 disabling this option for embedded systems that do not use modules, a 987 dynamic /dev tree, or dynamic device discovery. Just say Y. 988 989config PRINTK 990 default y 991 bool "Enable support for printk" if EMBEDDED 992 help 993 This option enables normal printk support. Removing it 994 eliminates most of the message strings from the kernel image 995 and makes the kernel more or less silent. As this makes it 996 very difficult to diagnose system problems, saying N here is 997 strongly discouraged. 998 999config BUG 1000 bool "BUG() support" if EMBEDDED 1001 default y 1002 help 1003 Disabling this option eliminates support for BUG and WARN, reducing 1004 the size of your kernel image and potentially quietly ignoring 1005 numerous fatal conditions. You should only consider disabling this 1006 option for embedded systems with no facilities for reporting errors. 1007 Just say Y. 1008 1009config ELF_CORE 1010 default y 1011 bool "Enable ELF core dumps" if EMBEDDED 1012 help 1013 Enable support for generating core dumps. Disabling saves about 4k. 1014 1015config PCSPKR_PLATFORM 1016 bool "Enable PC-Speaker support" if EMBEDDED 1017 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 1018 default y 1019 help 1020 This option allows to disable the internal PC-Speaker 1021 support, saving some memory. 1022 1023config BASE_FULL 1024 default y 1025 bool "Enable full-sized data structures for core" if EMBEDDED 1026 help 1027 Disabling this option reduces the size of miscellaneous core 1028 kernel data structures. This saves memory on small machines, 1029 but may reduce performance. 1030 1031config FUTEX 1032 bool "Enable futex support" if EMBEDDED 1033 default y 1034 select RT_MUTEXES 1035 help 1036 Disabling this option will cause the kernel to be built without 1037 support for "fast userspace mutexes". The resulting kernel may not 1038 run glibc-based applications correctly. 1039 1040config EPOLL 1041 bool "Enable eventpoll support" if EMBEDDED 1042 default y 1043 select ANON_INODES 1044 help 1045 Disabling this option will cause the kernel to be built without 1046 support for epoll family of system calls. 1047 1048config SIGNALFD 1049 bool "Enable signalfd() system call" if EMBEDDED 1050 select ANON_INODES 1051 default y 1052 help 1053 Enable the signalfd() system call that allows to receive signals 1054 on a file descriptor. 1055 1056 If unsure, say Y. 1057 1058config TIMERFD 1059 bool "Enable timerfd() system call" if EMBEDDED 1060 select ANON_INODES 1061 default y 1062 help 1063 Enable the timerfd() system call that allows to receive timer 1064 events on a file descriptor. 1065 1066 If unsure, say Y. 1067 1068config EVENTFD 1069 bool "Enable eventfd() system call" if EMBEDDED 1070 select ANON_INODES 1071 default y 1072 help 1073 Enable the eventfd() system call that allows to receive both 1074 kernel notification (ie. KAIO) or userspace notifications. 1075 1076 If unsure, say Y. 1077 1078config SHMEM 1079 bool "Use full shmem filesystem" if EMBEDDED 1080 default y 1081 depends on MMU 1082 help 1083 The shmem is an internal filesystem used to manage shared memory. 1084 It is backed by swap and manages resource limits. It is also exported 1085 to userspace as tmpfs if TMPFS is enabled. Disabling this 1086 option replaces shmem and tmpfs with the much simpler ramfs code, 1087 which may be appropriate on small systems without swap. 1088 1089config AIO 1090 bool "Enable AIO support" if EMBEDDED 1091 default y 1092 help 1093 This option enables POSIX asynchronous I/O which may by used 1094 by some high performance threaded applications. Disabling 1095 this option saves about 7k. 1096 1097config HAVE_PERF_EVENTS 1098 bool 1099 help 1100 See tools/perf/design.txt for details. 1101 1102config PERF_USE_VMALLOC 1103 bool 1104 help 1105 See tools/perf/design.txt for details 1106 1107menu "Kernel Performance Events And Counters" 1108 1109config PERF_EVENTS 1110 bool "Kernel performance events and counters" 1111 default y if (PROFILING || PERF_COUNTERS) 1112 depends on HAVE_PERF_EVENTS 1113 select ANON_INODES 1114 select IRQ_WORK 1115 help 1116 Enable kernel support for various performance events provided 1117 by software and hardware. 1118 1119 Software events are supported either built-in or via the 1120 use of generic tracepoints. 1121 1122 Most modern CPUs support performance events via performance 1123 counter registers. These registers count the number of certain 1124 types of hw events: such as instructions executed, cachemisses 1125 suffered, or branches mis-predicted - without slowing down the 1126 kernel or applications. These registers can also trigger interrupts 1127 when a threshold number of events have passed - and can thus be 1128 used to profile the code that runs on that CPU. 1129 1130 The Linux Performance Event subsystem provides an abstraction of 1131 these software and hardware event capabilities, available via a 1132 system call and used by the "perf" utility in tools/perf/. It 1133 provides per task and per CPU counters, and it provides event 1134 capabilities on top of those. 1135 1136 Say Y if unsure. 1137 1138config PERF_COUNTERS 1139 bool "Kernel performance counters (old config option)" 1140 depends on HAVE_PERF_EVENTS 1141 help 1142 This config has been obsoleted by the PERF_EVENTS 1143 config option - please see that one for details. 1144 1145 It has no effect on the kernel whether you enable 1146 it or not, it is a compatibility placeholder. 1147 1148 Say N if unsure. 1149 1150config DEBUG_PERF_USE_VMALLOC 1151 default n 1152 bool "Debug: use vmalloc to back perf mmap() buffers" 1153 depends on PERF_EVENTS && DEBUG_KERNEL 1154 select PERF_USE_VMALLOC 1155 help 1156 Use vmalloc memory to back perf mmap() buffers. 1157 1158 Mostly useful for debugging the vmalloc code on platforms 1159 that don't require it. 1160 1161 Say N if unsure. 1162 1163endmenu 1164 1165config VM_EVENT_COUNTERS 1166 default y 1167 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 1168 help 1169 VM event counters are needed for event counts to be shown. 1170 This option allows the disabling of the VM event counters 1171 on EMBEDDED systems. /proc/vmstat will only show page counts 1172 if VM event counters are disabled. 1173 1174config PCI_QUIRKS 1175 default y 1176 bool "Enable PCI quirk workarounds" if EMBEDDED 1177 depends on PCI 1178 help 1179 This enables workarounds for various PCI chipset 1180 bugs/quirks. Disable this only if your target machine is 1181 unaffected by PCI quirks. 1182 1183config SLUB_DEBUG 1184 default y 1185 bool "Enable SLUB debugging support" if EMBEDDED 1186 depends on SLUB && SYSFS 1187 help 1188 SLUB has extensive debug support features. Disabling these can 1189 result in significant savings in code size. This also disables 1190 SLUB sysfs support. /sys/slab will not exist and there will be 1191 no support for cache validation etc. 1192 1193config COMPAT_BRK 1194 bool "Disable heap randomization" 1195 default y 1196 help 1197 Randomizing heap placement makes heap exploits harder, but it 1198 also breaks ancient binaries (including anything libc5 based). 1199 This option changes the bootup default to heap randomization 1200 disabled, and can be overridden at runtime by setting 1201 /proc/sys/kernel/randomize_va_space to 2. 1202 1203 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1204 1205choice 1206 prompt "Choose SLAB allocator" 1207 default SLUB 1208 help 1209 This option allows to select a slab allocator. 1210 1211config SLAB 1212 bool "SLAB" 1213 help 1214 The regular slab allocator that is established and known to work 1215 well in all environments. It organizes cache hot objects in 1216 per cpu and per node queues. 1217 1218config SLUB 1219 bool "SLUB (Unqueued Allocator)" 1220 help 1221 SLUB is a slab allocator that minimizes cache line usage 1222 instead of managing queues of cached objects (SLAB approach). 1223 Per cpu caching is realized using slabs of objects instead 1224 of queues of objects. SLUB can use memory efficiently 1225 and has enhanced diagnostics. SLUB is the default choice for 1226 a slab allocator. 1227 1228config SLOB 1229 depends on EMBEDDED 1230 bool "SLOB (Simple Allocator)" 1231 help 1232 SLOB replaces the stock allocator with a drastically simpler 1233 allocator. SLOB is generally more space efficient but 1234 does not perform as well on large systems. 1235 1236endchoice 1237 1238config MMAP_ALLOW_UNINITIALIZED 1239 bool "Allow mmapped anonymous memory to be uninitialized" 1240 depends on EMBEDDED && !MMU 1241 default n 1242 help 1243 Normally, and according to the Linux spec, anonymous memory obtained 1244 from mmap() has it's contents cleared before it is passed to 1245 userspace. Enabling this config option allows you to request that 1246 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1247 providing a huge performance boost. If this option is not enabled, 1248 then the flag will be ignored. 1249 1250 This is taken advantage of by uClibc's malloc(), and also by 1251 ELF-FDPIC binfmt's brk and stack allocator. 1252 1253 Because of the obvious security issues, this option should only be 1254 enabled on embedded devices where you control what is run in 1255 userspace. Since that isn't generally a problem on no-MMU systems, 1256 it is normally safe to say Y here. 1257 1258 See Documentation/nommu-mmap.txt for more information. 1259 1260config PROFILING 1261 bool "Profiling support" 1262 help 1263 Say Y here to enable the extended profiling support mechanisms used 1264 by profilers such as OProfile. 1265 1266# 1267# Place an empty function call at each tracepoint site. Can be 1268# dynamically changed for a probe function. 1269# 1270config TRACEPOINTS 1271 bool 1272 1273source "arch/Kconfig" 1274 1275endmenu # General setup 1276 1277config HAVE_GENERIC_DMA_COHERENT 1278 bool 1279 default n 1280 1281config SLABINFO 1282 bool 1283 depends on PROC_FS 1284 depends on SLAB || SLUB_DEBUG 1285 default y 1286 1287config RT_MUTEXES 1288 boolean 1289 1290config BASE_SMALL 1291 int 1292 default 0 if BASE_FULL 1293 default 1 if !BASE_FULL 1294 1295menuconfig MODULES 1296 bool "Enable loadable module support" 1297 help 1298 Kernel modules are small pieces of compiled code which can 1299 be inserted in the running kernel, rather than being 1300 permanently built into the kernel. You use the "modprobe" 1301 tool to add (and sometimes remove) them. If you say Y here, 1302 many parts of the kernel can be built as modules (by 1303 answering M instead of Y where indicated): this is most 1304 useful for infrequently used options which are not required 1305 for booting. For more information, see the man pages for 1306 modprobe, lsmod, modinfo, insmod and rmmod. 1307 1308 If you say Y here, you will need to run "make 1309 modules_install" to put the modules under /lib/modules/ 1310 where modprobe can find them (you may need to be root to do 1311 this). 1312 1313 If unsure, say Y. 1314 1315if MODULES 1316 1317config MODULE_FORCE_LOAD 1318 bool "Forced module loading" 1319 default n 1320 help 1321 Allow loading of modules without version information (ie. modprobe 1322 --force). Forced module loading sets the 'F' (forced) taint flag and 1323 is usually a really bad idea. 1324 1325config MODULE_UNLOAD 1326 bool "Module unloading" 1327 help 1328 Without this option you will not be able to unload any 1329 modules (note that some modules may not be unloadable 1330 anyway), which makes your kernel smaller, faster 1331 and simpler. If unsure, say Y. 1332 1333config MODULE_FORCE_UNLOAD 1334 bool "Forced module unloading" 1335 depends on MODULE_UNLOAD && EXPERIMENTAL 1336 help 1337 This option allows you to force a module to unload, even if the 1338 kernel believes it is unsafe: the kernel will remove the module 1339 without waiting for anyone to stop using it (using the -f option to 1340 rmmod). This is mainly for kernel developers and desperate users. 1341 If unsure, say N. 1342 1343config MODVERSIONS 1344 bool "Module versioning support" 1345 help 1346 Usually, you have to use modules compiled with your kernel. 1347 Saying Y here makes it sometimes possible to use modules 1348 compiled for different kernels, by adding enough information 1349 to the modules to (hopefully) spot any changes which would 1350 make them incompatible with the kernel you are running. If 1351 unsure, say N. 1352 1353config MODULE_SRCVERSION_ALL 1354 bool "Source checksum for all modules" 1355 help 1356 Modules which contain a MODULE_VERSION get an extra "srcversion" 1357 field inserted into their modinfo section, which contains a 1358 sum of the source files which made it. This helps maintainers 1359 see exactly which source was used to build a module (since 1360 others sometimes change the module source without updating 1361 the version). With this option, such a "srcversion" field 1362 will be created for all modules. If unsure, say N. 1363 1364endif # MODULES 1365 1366config INIT_ALL_POSSIBLE 1367 bool 1368 help 1369 Back when each arch used to define their own cpu_online_map and 1370 cpu_possible_map, some of them chose to initialize cpu_possible_map 1371 with all 1s, and others with all 0s. When they were centralised, 1372 it was better to provide this option than to break all the archs 1373 and have several arch maintainers pursuing me down dark alleys. 1374 1375config STOP_MACHINE 1376 bool 1377 default y 1378 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1379 help 1380 Need stop_machine() primitive. 1381 1382source "block/Kconfig" 1383 1384config PREEMPT_NOTIFIERS 1385 bool 1386 1387config PADATA 1388 depends on SMP 1389 bool 1390 1391source "kernel/Kconfig.locks" 1392