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 23config HAVE_IRQ_WORK 24 bool 25 26config IRQ_WORK 27 bool 28 depends on HAVE_IRQ_WORK 29 30menu "General setup" 31 32config EXPERIMENTAL 33 bool "Prompt for development and/or incomplete code/drivers" 34 ---help--- 35 Some of the various things that Linux supports (such as network 36 drivers, file systems, network protocols, etc.) can be in a state 37 of development where the functionality, stability, or the level of 38 testing is not yet high enough for general use. This is usually 39 known as the "alpha-test" phase among developers. If a feature is 40 currently in alpha-test, then the developers usually discourage 41 uninformed widespread use of this feature by the general public to 42 avoid "Why doesn't this work?" type mail messages. However, active 43 testing and use of these systems is welcomed. Just be aware that it 44 may not meet the normal level of reliability or it may fail to work 45 in some special cases. Detailed bug reports from people familiar 46 with the kernel internals are usually welcomed by the developers 47 (before submitting bug reports, please read the documents 48 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 49 <file:Documentation/BUG-HUNTING>, and 50 <file:Documentation/oops-tracing.txt> in the kernel source). 51 52 This option will also make obsoleted drivers available. These are 53 drivers that have been replaced by something else, and/or are 54 scheduled to be removed in a future kernel release. 55 56 Unless you intend to help test and develop a feature or driver that 57 falls into this category, or you have a situation that requires 58 using these features, you should probably say N here, which will 59 cause the configurator to present you with fewer choices. If 60 you say Y here, you will be offered the choice of using features or 61 drivers that are currently considered to be in the alpha-test phase. 62 63config BROKEN 64 bool 65 66config BROKEN_ON_SMP 67 bool 68 depends on BROKEN || !SMP 69 default y 70 71config INIT_ENV_ARG_LIMIT 72 int 73 default 32 if !UML 74 default 128 if UML 75 help 76 Maximum of each of the number of arguments and environment 77 variables passed to init from the kernel command line. 78 79 80config CROSS_COMPILE 81 string "Cross-compiler tool prefix" 82 help 83 Same as running 'make CROSS_COMPILE=prefix-' but stored for 84 default make runs in this kernel build directory. You don't 85 need to set this unless you want the configured kernel build 86 directory to select the cross-compiler automatically. 87 88config LOCALVERSION 89 string "Local version - append to kernel release" 90 help 91 Append an extra string to the end of your kernel version. 92 This will show up when you type uname, for example. 93 The string you set here will be appended after the contents of 94 any files with a filename matching localversion* in your 95 object and source tree, in that order. Your total string can 96 be a maximum of 64 characters. 97 98config LOCALVERSION_AUTO 99 bool "Automatically append version information to the version string" 100 default y 101 help 102 This will try to automatically determine if the current tree is a 103 release tree by looking for git tags that belong to the current 104 top of tree revision. 105 106 A string of the format -gxxxxxxxx will be added to the localversion 107 if a git-based tree is found. The string generated by this will be 108 appended after any matching localversion* files, and after the value 109 set in CONFIG_LOCALVERSION. 110 111 (The actual string used here is the first eight characters produced 112 by running the command: 113 114 $ git rev-parse --verify HEAD 115 116 which is done within the script "scripts/setlocalversion".) 117 118config HAVE_KERNEL_GZIP 119 bool 120 121config HAVE_KERNEL_BZIP2 122 bool 123 124config HAVE_KERNEL_LZMA 125 bool 126 127config HAVE_KERNEL_XZ 128 bool 129 130config HAVE_KERNEL_LZO 131 bool 132 133choice 134 prompt "Kernel compression mode" 135 default KERNEL_GZIP 136 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 137 help 138 The linux kernel is a kind of self-extracting executable. 139 Several compression algorithms are available, which differ 140 in efficiency, compression and decompression speed. 141 Compression speed is only relevant when building a kernel. 142 Decompression speed is relevant at each boot. 143 144 If you have any problems with bzip2 or lzma compressed 145 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 146 version of this functionality (bzip2 only), for 2.4, was 147 supplied by Christian Ludwig) 148 149 High compression options are mostly useful for users, who 150 are low on disk space (embedded systems), but for whom ram 151 size matters less. 152 153 If in doubt, select 'gzip' 154 155config KERNEL_GZIP 156 bool "Gzip" 157 depends on HAVE_KERNEL_GZIP 158 help 159 The old and tried gzip compression. It provides a good balance 160 between compression ratio and decompression speed. 161 162config KERNEL_BZIP2 163 bool "Bzip2" 164 depends on HAVE_KERNEL_BZIP2 165 help 166 Its compression ratio and speed is intermediate. 167 Decompression speed is slowest among the three. The kernel 168 size is about 10% smaller with bzip2, in comparison to gzip. 169 Bzip2 uses a large amount of memory. For modern kernels you 170 will need at least 8MB RAM or more for booting. 171 172config KERNEL_LZMA 173 bool "LZMA" 174 depends on HAVE_KERNEL_LZMA 175 help 176 The most recent compression algorithm. 177 Its ratio is best, decompression speed is between the other 178 two. Compression is slowest. The kernel size is about 33% 179 smaller with LZMA in comparison to gzip. 180 181config KERNEL_XZ 182 bool "XZ" 183 depends on HAVE_KERNEL_XZ 184 help 185 XZ uses the LZMA2 algorithm and instruction set specific 186 BCJ filters which can improve compression ratio of executable 187 code. The size of the kernel is about 30% smaller with XZ in 188 comparison to gzip. On architectures for which there is a BCJ 189 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 190 will create a few percent smaller kernel than plain LZMA. 191 192 The speed is about the same as with LZMA: The decompression 193 speed of XZ is better than that of bzip2 but worse than gzip 194 and LZO. Compression is slow. 195 196config KERNEL_LZO 197 bool "LZO" 198 depends on HAVE_KERNEL_LZO 199 help 200 Its compression ratio is the poorest among the 4. The kernel 201 size is about 10% bigger than gzip; however its speed 202 (both compression and decompression) is the fastest. 203 204endchoice 205 206config DEFAULT_HOSTNAME 207 string "Default hostname" 208 default "(none)" 209 help 210 This option determines the default system hostname before userspace 211 calls sethostname(2). The kernel traditionally uses "(none)" here, 212 but you may wish to use a different default here to make a minimal 213 system more usable with less configuration. 214 215config SWAP 216 bool "Support for paging of anonymous memory (swap)" 217 depends on MMU && BLOCK 218 default y 219 help 220 This option allows you to choose whether you want to have support 221 for so called swap devices or swap files in your kernel that are 222 used to provide more virtual memory than the actual RAM present 223 in your computer. If unsure say Y. 224 225config SYSVIPC 226 bool "System V IPC" 227 ---help--- 228 Inter Process Communication is a suite of library functions and 229 system calls which let processes (running programs) synchronize and 230 exchange information. It is generally considered to be a good thing, 231 and some programs won't run unless you say Y here. In particular, if 232 you want to run the DOS emulator dosemu under Linux (read the 233 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 234 you'll need to say Y here. 235 236 You can find documentation about IPC with "info ipc" and also in 237 section 6.4 of the Linux Programmer's Guide, available from 238 <http://www.tldp.org/guides.html>. 239 240config SYSVIPC_SYSCTL 241 bool 242 depends on SYSVIPC 243 depends on SYSCTL 244 default y 245 246config POSIX_MQUEUE 247 bool "POSIX Message Queues" 248 depends on NET && EXPERIMENTAL 249 ---help--- 250 POSIX variant of message queues is a part of IPC. In POSIX message 251 queues every message has a priority which decides about succession 252 of receiving it by a process. If you want to compile and run 253 programs written e.g. for Solaris with use of its POSIX message 254 queues (functions mq_*) say Y here. 255 256 POSIX message queues are visible as a filesystem called 'mqueue' 257 and can be mounted somewhere if you want to do filesystem 258 operations on message queues. 259 260 If unsure, say Y. 261 262config POSIX_MQUEUE_SYSCTL 263 bool 264 depends on POSIX_MQUEUE 265 depends on SYSCTL 266 default y 267 268config BSD_PROCESS_ACCT 269 bool "BSD Process Accounting" 270 help 271 If you say Y here, a user level program will be able to instruct the 272 kernel (via a special system call) to write process accounting 273 information to a file: whenever a process exits, information about 274 that process will be appended to the file by the kernel. The 275 information includes things such as creation time, owning user, 276 command name, memory usage, controlling terminal etc. (the complete 277 list is in the struct acct in <file:include/linux/acct.h>). It is 278 up to the user level program to do useful things with this 279 information. This is generally a good idea, so say Y. 280 281config BSD_PROCESS_ACCT_V3 282 bool "BSD Process Accounting version 3 file format" 283 depends on BSD_PROCESS_ACCT 284 default n 285 help 286 If you say Y here, the process accounting information is written 287 in a new file format that also logs the process IDs of each 288 process and it's parent. Note that this file format is incompatible 289 with previous v0/v1/v2 file formats, so you will need updated tools 290 for processing it. A preliminary version of these tools is available 291 at <http://www.gnu.org/software/acct/>. 292 293config FHANDLE 294 bool "open by fhandle syscalls" 295 select EXPORTFS 296 help 297 If you say Y here, a user level program will be able to map 298 file names to handle and then later use the handle for 299 different file system operations. This is useful in implementing 300 userspace file servers, which now track files using handles instead 301 of names. The handle would remain the same even if file names 302 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 303 syscalls. 304 305config TASKSTATS 306 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 307 depends on NET 308 default n 309 help 310 Export selected statistics for tasks/processes through the 311 generic netlink interface. Unlike BSD process accounting, the 312 statistics are available during the lifetime of tasks/processes as 313 responses to commands. Like BSD accounting, they are sent to user 314 space on task exit. 315 316 Say N if unsure. 317 318config TASK_DELAY_ACCT 319 bool "Enable per-task delay accounting (EXPERIMENTAL)" 320 depends on TASKSTATS 321 help 322 Collect information on time spent by a task waiting for system 323 resources like cpu, synchronous block I/O completion and swapping 324 in pages. Such statistics can help in setting a task's priorities 325 relative to other tasks for cpu, io, rss limits etc. 326 327 Say N if unsure. 328 329config TASK_XACCT 330 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 331 depends on TASKSTATS 332 help 333 Collect extended task accounting data and send the data 334 to userland for processing over the taskstats interface. 335 336 Say N if unsure. 337 338config TASK_IO_ACCOUNTING 339 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 340 depends on TASK_XACCT 341 help 342 Collect information on the number of bytes of storage I/O which this 343 task has caused. 344 345 Say N if unsure. 346 347config AUDIT 348 bool "Auditing support" 349 depends on NET 350 help 351 Enable auditing infrastructure that can be used with another 352 kernel subsystem, such as SELinux (which requires this for 353 logging of avc messages output). Does not do system-call 354 auditing without CONFIG_AUDITSYSCALL. 355 356config AUDITSYSCALL 357 bool "Enable system-call auditing support" 358 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH) 359 default y if SECURITY_SELINUX 360 help 361 Enable low-overhead system-call auditing infrastructure that 362 can be used independently or with another kernel subsystem, 363 such as SELinux. 364 365config AUDIT_WATCH 366 def_bool y 367 depends on AUDITSYSCALL 368 select FSNOTIFY 369 370config AUDIT_TREE 371 def_bool y 372 depends on AUDITSYSCALL 373 select FSNOTIFY 374 375source "kernel/irq/Kconfig" 376 377menu "RCU Subsystem" 378 379choice 380 prompt "RCU Implementation" 381 default TREE_RCU 382 383config TREE_RCU 384 bool "Tree-based hierarchical RCU" 385 depends on !PREEMPT && SMP 386 help 387 This option selects the RCU implementation that is 388 designed for very large SMP system with hundreds or 389 thousands of CPUs. It also scales down nicely to 390 smaller systems. 391 392config TREE_PREEMPT_RCU 393 bool "Preemptible tree-based hierarchical RCU" 394 depends on PREEMPT && SMP 395 help 396 This option selects the RCU implementation that is 397 designed for very large SMP systems with hundreds or 398 thousands of CPUs, but for which real-time response 399 is also required. It also scales down nicely to 400 smaller systems. 401 402config TINY_RCU 403 bool "UP-only small-memory-footprint RCU" 404 depends on !PREEMPT && !SMP 405 help 406 This option selects the RCU implementation that is 407 designed for UP systems from which real-time response 408 is not required. This option greatly reduces the 409 memory footprint of RCU. 410 411config TINY_PREEMPT_RCU 412 bool "Preemptible UP-only small-memory-footprint RCU" 413 depends on PREEMPT && !SMP 414 help 415 This option selects the RCU implementation that is designed 416 for real-time UP systems. This option greatly reduces the 417 memory footprint of RCU. 418 419endchoice 420 421config PREEMPT_RCU 422 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 423 help 424 This option enables preemptible-RCU code that is common between 425 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 426 427config RCU_TRACE 428 bool "Enable tracing for RCU" 429 help 430 This option provides tracing in RCU which presents stats 431 in debugfs for debugging RCU implementation. 432 433 Say Y here if you want to enable RCU tracing 434 Say N if you are unsure. 435 436config RCU_FANOUT 437 int "Tree-based hierarchical RCU fanout value" 438 range 2 64 if 64BIT 439 range 2 32 if !64BIT 440 depends on TREE_RCU || TREE_PREEMPT_RCU 441 default 64 if 64BIT 442 default 32 if !64BIT 443 help 444 This option controls the fanout of hierarchical implementations 445 of RCU, allowing RCU to work efficiently on machines with 446 large numbers of CPUs. This value must be at least the fourth 447 root of NR_CPUS, which allows NR_CPUS to be insanely large. 448 The default value of RCU_FANOUT should be used for production 449 systems, but if you are stress-testing the RCU implementation 450 itself, small RCU_FANOUT values allow you to test large-system 451 code paths on small(er) systems. 452 453 Select a specific number if testing RCU itself. 454 Take the default if unsure. 455 456config RCU_FANOUT_EXACT 457 bool "Disable tree-based hierarchical RCU auto-balancing" 458 depends on TREE_RCU || TREE_PREEMPT_RCU 459 default n 460 help 461 This option forces use of the exact RCU_FANOUT value specified, 462 regardless of imbalances in the hierarchy. This is useful for 463 testing RCU itself, and might one day be useful on systems with 464 strong NUMA behavior. 465 466 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 467 468 Say N if unsure. 469 470config RCU_FAST_NO_HZ 471 bool "Accelerate last non-dyntick-idle CPU's grace periods" 472 depends on NO_HZ && SMP 473 default n 474 help 475 This option causes RCU to attempt to accelerate grace periods 476 in order to allow CPUs to enter dynticks-idle state more 477 quickly. On the other hand, this option increases the overhead 478 of the dynticks-idle checking, particularly on systems with 479 large numbers of CPUs. 480 481 Say Y if energy efficiency is critically important, particularly 482 if you have relatively few CPUs. 483 484 Say N if you are unsure. 485 486config TREE_RCU_TRACE 487 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 488 select DEBUG_FS 489 help 490 This option provides tracing for the TREE_RCU and 491 TREE_PREEMPT_RCU implementations, permitting Makefile to 492 trivially select kernel/rcutree_trace.c. 493 494config RCU_BOOST 495 bool "Enable RCU priority boosting" 496 depends on RT_MUTEXES && PREEMPT_RCU 497 default n 498 help 499 This option boosts the priority of preempted RCU readers that 500 block the current preemptible RCU grace period for too long. 501 This option also prevents heavy loads from blocking RCU 502 callback invocation for all flavors of RCU. 503 504 Say Y here if you are working with real-time apps or heavy loads 505 Say N here if you are unsure. 506 507config RCU_BOOST_PRIO 508 int "Real-time priority to boost RCU readers to" 509 range 1 99 510 depends on RCU_BOOST 511 default 1 512 help 513 This option specifies the real-time priority to which preempted 514 RCU readers are to be boosted. If you are working with CPU-bound 515 real-time applications, you should specify a priority higher then 516 the highest-priority CPU-bound application. 517 518 Specify the real-time priority, or take the default if unsure. 519 520config RCU_BOOST_DELAY 521 int "Milliseconds to delay boosting after RCU grace-period start" 522 range 0 3000 523 depends on RCU_BOOST 524 default 500 525 help 526 This option specifies the time to wait after the beginning of 527 a given grace period before priority-boosting preempted RCU 528 readers blocking that grace period. Note that any RCU reader 529 blocking an expedited RCU grace period is boosted immediately. 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_FREEZER 601 bool "Freezer cgroup subsystem" 602 help 603 Provides a way to freeze and unfreeze all tasks in a 604 cgroup. 605 606config CGROUP_DEVICE 607 bool "Device controller for cgroups" 608 help 609 Provides a cgroup implementing whitelists for devices which 610 a process in the cgroup can mknod or open. 611 612config CPUSETS 613 bool "Cpuset support" 614 help 615 This option will let you create and manage CPUSETs which 616 allow dynamically partitioning a system into sets of CPUs and 617 Memory Nodes and assigning tasks to run only within those sets. 618 This is primarily useful on large SMP or NUMA systems. 619 620 Say N if unsure. 621 622config PROC_PID_CPUSET 623 bool "Include legacy /proc/<pid>/cpuset file" 624 depends on CPUSETS 625 default y 626 627config CGROUP_CPUACCT 628 bool "Simple CPU accounting cgroup subsystem" 629 help 630 Provides a simple Resource Controller for monitoring the 631 total CPU consumed by the tasks in a cgroup. 632 633config RESOURCE_COUNTERS 634 bool "Resource counters" 635 help 636 This option enables controller independent resource accounting 637 infrastructure that works with cgroups. 638 639config CGROUP_MEM_RES_CTLR 640 bool "Memory Resource Controller for Control Groups" 641 depends on RESOURCE_COUNTERS 642 select MM_OWNER 643 help 644 Provides a memory resource controller that manages both anonymous 645 memory and page cache. (See Documentation/cgroups/memory.txt) 646 647 Note that setting this option increases fixed memory overhead 648 associated with each page of memory in the system. By this, 649 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 650 usage tracking struct at boot. Total amount of this is printed out 651 at boot. 652 653 Only enable when you're ok with these trade offs and really 654 sure you need the memory resource controller. Even when you enable 655 this, you can set "cgroup_disable=memory" at your boot option to 656 disable memory resource controller and you can avoid overheads. 657 (and lose benefits of memory resource controller) 658 659 This config option also selects MM_OWNER config option, which 660 could in turn add some fork/exit overhead. 661 662config CGROUP_MEM_RES_CTLR_SWAP 663 bool "Memory Resource Controller Swap Extension" 664 depends on CGROUP_MEM_RES_CTLR && SWAP 665 help 666 Add swap management feature to memory resource controller. When you 667 enable this, you can limit mem+swap usage per cgroup. In other words, 668 when you disable this, memory resource controller has no cares to 669 usage of swap...a process can exhaust all of the swap. This extension 670 is useful when you want to avoid exhaustion swap but this itself 671 adds more overheads and consumes memory for remembering information. 672 Especially if you use 32bit system or small memory system, please 673 be careful about enabling this. When memory resource controller 674 is disabled by boot option, this will be automatically disabled and 675 there will be no overhead from this. Even when you set this config=y, 676 if boot option "swapaccount=0" is set, swap will not be accounted. 677 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 678 size is 4096bytes, 512k per 1Gbytes of swap. 679config CGROUP_MEM_RES_CTLR_SWAP_ENABLED 680 bool "Memory Resource Controller Swap Extension enabled by default" 681 depends on CGROUP_MEM_RES_CTLR_SWAP 682 default y 683 help 684 Memory Resource Controller Swap Extension comes with its price in 685 a bigger memory consumption. General purpose distribution kernels 686 which want to enable the feature but keep it disabled by default 687 and let the user enable it by swapaccount boot command line 688 parameter should have this option unselected. 689 For those who want to have the feature enabled by default should 690 select this option (if, for some reason, they need to disable it 691 then swapaccount=0 does the trick). 692config CGROUP_MEM_RES_CTLR_KMEM 693 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)" 694 depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL 695 default n 696 help 697 The Kernel Memory extension for Memory Resource Controller can limit 698 the amount of memory used by kernel objects in the system. Those are 699 fundamentally different from the entities handled by the standard 700 Memory Controller, which are page-based, and can be swapped. Users of 701 the kmem extension can use it to guarantee that no group of processes 702 will ever exhaust kernel resources alone. 703 704config CGROUP_PERF 705 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 706 depends on PERF_EVENTS && CGROUPS 707 help 708 This option extends the per-cpu mode to restrict monitoring to 709 threads which belong to the cgroup specified and run on the 710 designated cpu. 711 712 Say N if unsure. 713 714menuconfig CGROUP_SCHED 715 bool "Group CPU scheduler" 716 depends on EXPERIMENTAL 717 default n 718 help 719 This feature lets CPU scheduler recognize task groups and control CPU 720 bandwidth allocation to such task groups. It uses cgroups to group 721 tasks. 722 723if CGROUP_SCHED 724config FAIR_GROUP_SCHED 725 bool "Group scheduling for SCHED_OTHER" 726 depends on CGROUP_SCHED 727 default CGROUP_SCHED 728 729config CFS_BANDWIDTH 730 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 731 depends on EXPERIMENTAL 732 depends on FAIR_GROUP_SCHED 733 default n 734 help 735 This option allows users to define CPU bandwidth rates (limits) for 736 tasks running within the fair group scheduler. Groups with no limit 737 set are considered to be unconstrained and will run with no 738 restriction. 739 See tip/Documentation/scheduler/sched-bwc.txt for more information. 740 741config RT_GROUP_SCHED 742 bool "Group scheduling for SCHED_RR/FIFO" 743 depends on EXPERIMENTAL 744 depends on CGROUP_SCHED 745 default n 746 help 747 This feature lets you explicitly allocate real CPU bandwidth 748 to task groups. If enabled, it will also make it impossible to 749 schedule realtime tasks for non-root users until you allocate 750 realtime bandwidth for them. 751 See Documentation/scheduler/sched-rt-group.txt for more information. 752 753endif #CGROUP_SCHED 754 755config BLK_CGROUP 756 tristate "Block IO controller" 757 depends on BLOCK 758 default n 759 ---help--- 760 Generic block IO controller cgroup interface. This is the common 761 cgroup interface which should be used by various IO controlling 762 policies. 763 764 Currently, CFQ IO scheduler uses it to recognize task groups and 765 control disk bandwidth allocation (proportional time slice allocation) 766 to such task groups. It is also used by bio throttling logic in 767 block layer to implement upper limit in IO rates on a device. 768 769 This option only enables generic Block IO controller infrastructure. 770 One needs to also enable actual IO controlling logic/policy. For 771 enabling proportional weight division of disk bandwidth in CFQ, set 772 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 773 CONFIG_BLK_DEV_THROTTLING=y. 774 775 See Documentation/cgroups/blkio-controller.txt for more information. 776 777config DEBUG_BLK_CGROUP 778 bool "Enable Block IO controller debugging" 779 depends on BLK_CGROUP 780 default n 781 ---help--- 782 Enable some debugging help. Currently it exports additional stat 783 files in a cgroup which can be useful for debugging. 784 785endif # CGROUPS 786 787menuconfig NAMESPACES 788 bool "Namespaces support" if EXPERT 789 default !EXPERT 790 help 791 Provides the way to make tasks work with different objects using 792 the same id. For example same IPC id may refer to different objects 793 or same user id or pid may refer to different tasks when used in 794 different namespaces. 795 796if NAMESPACES 797 798config UTS_NS 799 bool "UTS namespace" 800 default y 801 help 802 In this namespace tasks see different info provided with the 803 uname() system call 804 805config IPC_NS 806 bool "IPC namespace" 807 depends on (SYSVIPC || POSIX_MQUEUE) 808 default y 809 help 810 In this namespace tasks work with IPC ids which correspond to 811 different IPC objects in different namespaces. 812 813config USER_NS 814 bool "User namespace (EXPERIMENTAL)" 815 depends on EXPERIMENTAL 816 default y 817 help 818 This allows containers, i.e. vservers, to use user namespaces 819 to provide different user info for different servers. 820 If unsure, say N. 821 822config PID_NS 823 bool "PID Namespaces" 824 default y 825 help 826 Support process id namespaces. This allows having multiple 827 processes with the same pid as long as they are in different 828 pid namespaces. This is a building block of containers. 829 830config NET_NS 831 bool "Network namespace" 832 depends on NET 833 default y 834 help 835 Allow user space to create what appear to be multiple instances 836 of the network stack. 837 838endif # NAMESPACES 839 840config SCHED_AUTOGROUP 841 bool "Automatic process group scheduling" 842 select EVENTFD 843 select CGROUPS 844 select CGROUP_SCHED 845 select FAIR_GROUP_SCHED 846 help 847 This option optimizes the scheduler for common desktop workloads by 848 automatically creating and populating task groups. This separation 849 of workloads isolates aggressive CPU burners (like build jobs) from 850 desktop applications. Task group autogeneration is currently based 851 upon task session. 852 853config MM_OWNER 854 bool 855 856config SYSFS_DEPRECATED 857 bool "Enable deprecated sysfs features to support old userspace tools" 858 depends on SYSFS 859 default n 860 help 861 This option adds code that switches the layout of the "block" class 862 devices, to not show up in /sys/class/block/, but only in 863 /sys/block/. 864 865 This switch is only active when the sysfs.deprecated=1 boot option is 866 passed or the SYSFS_DEPRECATED_V2 option is set. 867 868 This option allows new kernels to run on old distributions and tools, 869 which might get confused by /sys/class/block/. Since 2007/2008 all 870 major distributions and tools handle this just fine. 871 872 Recent distributions and userspace tools after 2009/2010 depend on 873 the existence of /sys/class/block/, and will not work with this 874 option enabled. 875 876 Only if you are using a new kernel on an old distribution, you might 877 need to say Y here. 878 879config SYSFS_DEPRECATED_V2 880 bool "Enable deprecated sysfs features by default" 881 default n 882 depends on SYSFS 883 depends on SYSFS_DEPRECATED 884 help 885 Enable deprecated sysfs by default. 886 887 See the CONFIG_SYSFS_DEPRECATED option for more details about this 888 option. 889 890 Only if you are using a new kernel on an old distribution, you might 891 need to say Y here. Even then, odds are you would not need it 892 enabled, you can always pass the boot option if absolutely necessary. 893 894config RELAY 895 bool "Kernel->user space relay support (formerly relayfs)" 896 help 897 This option enables support for relay interface support in 898 certain file systems (such as debugfs). 899 It is designed to provide an efficient mechanism for tools and 900 facilities to relay large amounts of data from kernel space to 901 user space. 902 903 If unsure, say N. 904 905config BLK_DEV_INITRD 906 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 907 depends on BROKEN || !FRV 908 help 909 The initial RAM filesystem is a ramfs which is loaded by the 910 boot loader (loadlin or lilo) and that is mounted as root 911 before the normal boot procedure. It is typically used to 912 load modules needed to mount the "real" root file system, 913 etc. See <file:Documentation/initrd.txt> for details. 914 915 If RAM disk support (BLK_DEV_RAM) is also included, this 916 also enables initial RAM disk (initrd) support and adds 917 15 Kbytes (more on some other architectures) to the kernel size. 918 919 If unsure say Y. 920 921if BLK_DEV_INITRD 922 923source "usr/Kconfig" 924 925endif 926 927config CC_OPTIMIZE_FOR_SIZE 928 bool "Optimize for size" 929 help 930 Enabling this option will pass "-Os" instead of "-O2" to gcc 931 resulting in a smaller kernel. 932 933 If unsure, say Y. 934 935config SYSCTL 936 bool 937 938config ANON_INODES 939 bool 940 941menuconfig EXPERT 942 bool "Configure standard kernel features (expert users)" 943 # Unhide debug options, to make the on-by-default options visible 944 select DEBUG_KERNEL 945 help 946 This option allows certain base kernel options and settings 947 to be disabled or tweaked. This is for specialized 948 environments which can tolerate a "non-standard" kernel. 949 Only use this if you really know what you are doing. 950 951config UID16 952 bool "Enable 16-bit UID system calls" if EXPERT 953 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 954 default y 955 help 956 This enables the legacy 16-bit UID syscall wrappers. 957 958config SYSCTL_SYSCALL 959 bool "Sysctl syscall support" if EXPERT 960 depends on PROC_SYSCTL 961 default n 962 select SYSCTL 963 ---help--- 964 sys_sysctl uses binary paths that have been found challenging 965 to properly maintain and use. The interface in /proc/sys 966 using paths with ascii names is now the primary path to this 967 information. 968 969 Almost nothing using the binary sysctl interface so if you are 970 trying to save some space it is probably safe to disable this, 971 making your kernel marginally smaller. 972 973 If unsure say N here. 974 975config KALLSYMS 976 bool "Load all symbols for debugging/ksymoops" if EXPERT 977 default y 978 help 979 Say Y here to let the kernel print out symbolic crash information and 980 symbolic stack backtraces. This increases the size of the kernel 981 somewhat, as all symbols have to be loaded into the kernel image. 982 983config KALLSYMS_ALL 984 bool "Include all symbols in kallsyms" 985 depends on DEBUG_KERNEL && KALLSYMS 986 help 987 Normally kallsyms only contains the symbols of functions for nicer 988 OOPS messages and backtraces (i.e., symbols from the text and inittext 989 sections). This is sufficient for most cases. And only in very rare 990 cases (e.g., when a debugger is used) all symbols are required (e.g., 991 names of variables from the data sections, etc). 992 993 This option makes sure that all symbols are loaded into the kernel 994 image (i.e., symbols from all sections) in cost of increased kernel 995 size (depending on the kernel configuration, it may be 300KiB or 996 something like this). 997 998 Say N unless you really need all symbols. 999 1000config HOTPLUG 1001 bool "Support for hot-pluggable devices" if EXPERT 1002 default y 1003 help 1004 This option is provided for the case where no hotplug or uevent 1005 capabilities is wanted by the kernel. You should only consider 1006 disabling this option for embedded systems that do not use modules, a 1007 dynamic /dev tree, or dynamic device discovery. Just say Y. 1008 1009config PRINTK 1010 default y 1011 bool "Enable support for printk" if EXPERT 1012 help 1013 This option enables normal printk support. Removing it 1014 eliminates most of the message strings from the kernel image 1015 and makes the kernel more or less silent. As this makes it 1016 very difficult to diagnose system problems, saying N here is 1017 strongly discouraged. 1018 1019config BUG 1020 bool "BUG() support" if EXPERT 1021 default y 1022 help 1023 Disabling this option eliminates support for BUG and WARN, reducing 1024 the size of your kernel image and potentially quietly ignoring 1025 numerous fatal conditions. You should only consider disabling this 1026 option for embedded systems with no facilities for reporting errors. 1027 Just say Y. 1028 1029config ELF_CORE 1030 default y 1031 bool "Enable ELF core dumps" if EXPERT 1032 help 1033 Enable support for generating core dumps. Disabling saves about 4k. 1034 1035 1036config PCSPKR_PLATFORM 1037 bool "Enable PC-Speaker support" if EXPERT 1038 depends on HAVE_PCSPKR_PLATFORM 1039 select I8253_LOCK 1040 default y 1041 help 1042 This option allows to disable the internal PC-Speaker 1043 support, saving some memory. 1044 1045config HAVE_PCSPKR_PLATFORM 1046 bool 1047 1048config BASE_FULL 1049 default y 1050 bool "Enable full-sized data structures for core" if EXPERT 1051 help 1052 Disabling this option reduces the size of miscellaneous core 1053 kernel data structures. This saves memory on small machines, 1054 but may reduce performance. 1055 1056config FUTEX 1057 bool "Enable futex support" if EXPERT 1058 default y 1059 select RT_MUTEXES 1060 help 1061 Disabling this option will cause the kernel to be built without 1062 support for "fast userspace mutexes". The resulting kernel may not 1063 run glibc-based applications correctly. 1064 1065config EPOLL 1066 bool "Enable eventpoll support" if EXPERT 1067 default y 1068 select ANON_INODES 1069 help 1070 Disabling this option will cause the kernel to be built without 1071 support for epoll family of system calls. 1072 1073config SIGNALFD 1074 bool "Enable signalfd() system call" if EXPERT 1075 select ANON_INODES 1076 default y 1077 help 1078 Enable the signalfd() system call that allows to receive signals 1079 on a file descriptor. 1080 1081 If unsure, say Y. 1082 1083config TIMERFD 1084 bool "Enable timerfd() system call" if EXPERT 1085 select ANON_INODES 1086 default y 1087 help 1088 Enable the timerfd() system call that allows to receive timer 1089 events on a file descriptor. 1090 1091 If unsure, say Y. 1092 1093config EVENTFD 1094 bool "Enable eventfd() system call" if EXPERT 1095 select ANON_INODES 1096 default y 1097 help 1098 Enable the eventfd() system call that allows to receive both 1099 kernel notification (ie. KAIO) or userspace notifications. 1100 1101 If unsure, say Y. 1102 1103config SHMEM 1104 bool "Use full shmem filesystem" if EXPERT 1105 default y 1106 depends on MMU 1107 help 1108 The shmem is an internal filesystem used to manage shared memory. 1109 It is backed by swap and manages resource limits. It is also exported 1110 to userspace as tmpfs if TMPFS is enabled. Disabling this 1111 option replaces shmem and tmpfs with the much simpler ramfs code, 1112 which may be appropriate on small systems without swap. 1113 1114config AIO 1115 bool "Enable AIO support" if EXPERT 1116 default y 1117 help 1118 This option enables POSIX asynchronous I/O which may by used 1119 by some high performance threaded applications. Disabling 1120 this option saves about 7k. 1121 1122config EMBEDDED 1123 bool "Embedded system" 1124 select EXPERT 1125 help 1126 This option should be enabled if compiling the kernel for 1127 an embedded system so certain expert options are available 1128 for configuration. 1129 1130config HAVE_PERF_EVENTS 1131 bool 1132 help 1133 See tools/perf/design.txt for details. 1134 1135config PERF_USE_VMALLOC 1136 bool 1137 help 1138 See tools/perf/design.txt for details 1139 1140menu "Kernel Performance Events And Counters" 1141 1142config PERF_EVENTS 1143 bool "Kernel performance events and counters" 1144 default y if (PROFILING || PERF_COUNTERS) 1145 depends on HAVE_PERF_EVENTS 1146 select ANON_INODES 1147 select IRQ_WORK 1148 help 1149 Enable kernel support for various performance events provided 1150 by software and hardware. 1151 1152 Software events are supported either built-in or via the 1153 use of generic tracepoints. 1154 1155 Most modern CPUs support performance events via performance 1156 counter registers. These registers count the number of certain 1157 types of hw events: such as instructions executed, cachemisses 1158 suffered, or branches mis-predicted - without slowing down the 1159 kernel or applications. These registers can also trigger interrupts 1160 when a threshold number of events have passed - and can thus be 1161 used to profile the code that runs on that CPU. 1162 1163 The Linux Performance Event subsystem provides an abstraction of 1164 these software and hardware event capabilities, available via a 1165 system call and used by the "perf" utility in tools/perf/. It 1166 provides per task and per CPU counters, and it provides event 1167 capabilities on top of those. 1168 1169 Say Y if unsure. 1170 1171config PERF_COUNTERS 1172 bool "Kernel performance counters (old config option)" 1173 depends on HAVE_PERF_EVENTS 1174 help 1175 This config has been obsoleted by the PERF_EVENTS 1176 config option - please see that one for details. 1177 1178 It has no effect on the kernel whether you enable 1179 it or not, it is a compatibility placeholder. 1180 1181 Say N if unsure. 1182 1183config DEBUG_PERF_USE_VMALLOC 1184 default n 1185 bool "Debug: use vmalloc to back perf mmap() buffers" 1186 depends on PERF_EVENTS && DEBUG_KERNEL 1187 select PERF_USE_VMALLOC 1188 help 1189 Use vmalloc memory to back perf mmap() buffers. 1190 1191 Mostly useful for debugging the vmalloc code on platforms 1192 that don't require it. 1193 1194 Say N if unsure. 1195 1196endmenu 1197 1198config VM_EVENT_COUNTERS 1199 default y 1200 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1201 help 1202 VM event counters are needed for event counts to be shown. 1203 This option allows the disabling of the VM event counters 1204 on EXPERT systems. /proc/vmstat will only show page counts 1205 if VM event counters are disabled. 1206 1207config PCI_QUIRKS 1208 default y 1209 bool "Enable PCI quirk workarounds" if EXPERT 1210 depends on PCI 1211 help 1212 This enables workarounds for various PCI chipset 1213 bugs/quirks. Disable this only if your target machine is 1214 unaffected by PCI quirks. 1215 1216config SLUB_DEBUG 1217 default y 1218 bool "Enable SLUB debugging support" if EXPERT 1219 depends on SLUB && SYSFS 1220 help 1221 SLUB has extensive debug support features. Disabling these can 1222 result in significant savings in code size. This also disables 1223 SLUB sysfs support. /sys/slab will not exist and there will be 1224 no support for cache validation etc. 1225 1226config COMPAT_BRK 1227 bool "Disable heap randomization" 1228 default y 1229 help 1230 Randomizing heap placement makes heap exploits harder, but it 1231 also breaks ancient binaries (including anything libc5 based). 1232 This option changes the bootup default to heap randomization 1233 disabled, and can be overridden at runtime by setting 1234 /proc/sys/kernel/randomize_va_space to 2. 1235 1236 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1237 1238choice 1239 prompt "Choose SLAB allocator" 1240 default SLUB 1241 help 1242 This option allows to select a slab allocator. 1243 1244config SLAB 1245 bool "SLAB" 1246 help 1247 The regular slab allocator that is established and known to work 1248 well in all environments. It organizes cache hot objects in 1249 per cpu and per node queues. 1250 1251config SLUB 1252 bool "SLUB (Unqueued Allocator)" 1253 help 1254 SLUB is a slab allocator that minimizes cache line usage 1255 instead of managing queues of cached objects (SLAB approach). 1256 Per cpu caching is realized using slabs of objects instead 1257 of queues of objects. SLUB can use memory efficiently 1258 and has enhanced diagnostics. SLUB is the default choice for 1259 a slab allocator. 1260 1261config SLOB 1262 depends on EXPERT 1263 bool "SLOB (Simple Allocator)" 1264 help 1265 SLOB replaces the stock allocator with a drastically simpler 1266 allocator. SLOB is generally more space efficient but 1267 does not perform as well on large systems. 1268 1269endchoice 1270 1271config MMAP_ALLOW_UNINITIALIZED 1272 bool "Allow mmapped anonymous memory to be uninitialized" 1273 depends on EXPERT && !MMU 1274 default n 1275 help 1276 Normally, and according to the Linux spec, anonymous memory obtained 1277 from mmap() has it's contents cleared before it is passed to 1278 userspace. Enabling this config option allows you to request that 1279 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1280 providing a huge performance boost. If this option is not enabled, 1281 then the flag will be ignored. 1282 1283 This is taken advantage of by uClibc's malloc(), and also by 1284 ELF-FDPIC binfmt's brk and stack allocator. 1285 1286 Because of the obvious security issues, this option should only be 1287 enabled on embedded devices where you control what is run in 1288 userspace. Since that isn't generally a problem on no-MMU systems, 1289 it is normally safe to say Y here. 1290 1291 See Documentation/nommu-mmap.txt for more information. 1292 1293config PROFILING 1294 bool "Profiling support" 1295 help 1296 Say Y here to enable the extended profiling support mechanisms used 1297 by profilers such as OProfile. 1298 1299# 1300# Place an empty function call at each tracepoint site. Can be 1301# dynamically changed for a probe function. 1302# 1303config TRACEPOINTS 1304 bool 1305 1306source "arch/Kconfig" 1307 1308endmenu # General setup 1309 1310config HAVE_GENERIC_DMA_COHERENT 1311 bool 1312 default n 1313 1314config SLABINFO 1315 bool 1316 depends on PROC_FS 1317 depends on SLAB || SLUB_DEBUG 1318 default y 1319 1320config RT_MUTEXES 1321 boolean 1322 1323config BASE_SMALL 1324 int 1325 default 0 if BASE_FULL 1326 default 1 if !BASE_FULL 1327 1328menuconfig MODULES 1329 bool "Enable loadable module support" 1330 help 1331 Kernel modules are small pieces of compiled code which can 1332 be inserted in the running kernel, rather than being 1333 permanently built into the kernel. You use the "modprobe" 1334 tool to add (and sometimes remove) them. If you say Y here, 1335 many parts of the kernel can be built as modules (by 1336 answering M instead of Y where indicated): this is most 1337 useful for infrequently used options which are not required 1338 for booting. For more information, see the man pages for 1339 modprobe, lsmod, modinfo, insmod and rmmod. 1340 1341 If you say Y here, you will need to run "make 1342 modules_install" to put the modules under /lib/modules/ 1343 where modprobe can find them (you may need to be root to do 1344 this). 1345 1346 If unsure, say Y. 1347 1348if MODULES 1349 1350config MODULE_FORCE_LOAD 1351 bool "Forced module loading" 1352 default n 1353 help 1354 Allow loading of modules without version information (ie. modprobe 1355 --force). Forced module loading sets the 'F' (forced) taint flag and 1356 is usually a really bad idea. 1357 1358config MODULE_UNLOAD 1359 bool "Module unloading" 1360 help 1361 Without this option you will not be able to unload any 1362 modules (note that some modules may not be unloadable 1363 anyway), which makes your kernel smaller, faster 1364 and simpler. If unsure, say Y. 1365 1366config MODULE_FORCE_UNLOAD 1367 bool "Forced module unloading" 1368 depends on MODULE_UNLOAD && EXPERIMENTAL 1369 help 1370 This option allows you to force a module to unload, even if the 1371 kernel believes it is unsafe: the kernel will remove the module 1372 without waiting for anyone to stop using it (using the -f option to 1373 rmmod). This is mainly for kernel developers and desperate users. 1374 If unsure, say N. 1375 1376config MODVERSIONS 1377 bool "Module versioning support" 1378 help 1379 Usually, you have to use modules compiled with your kernel. 1380 Saying Y here makes it sometimes possible to use modules 1381 compiled for different kernels, by adding enough information 1382 to the modules to (hopefully) spot any changes which would 1383 make them incompatible with the kernel you are running. If 1384 unsure, say N. 1385 1386config MODULE_SRCVERSION_ALL 1387 bool "Source checksum for all modules" 1388 help 1389 Modules which contain a MODULE_VERSION get an extra "srcversion" 1390 field inserted into their modinfo section, which contains a 1391 sum of the source files which made it. This helps maintainers 1392 see exactly which source was used to build a module (since 1393 others sometimes change the module source without updating 1394 the version). With this option, such a "srcversion" field 1395 will be created for all modules. If unsure, say N. 1396 1397endif # MODULES 1398 1399config INIT_ALL_POSSIBLE 1400 bool 1401 help 1402 Back when each arch used to define their own cpu_online_map and 1403 cpu_possible_map, some of them chose to initialize cpu_possible_map 1404 with all 1s, and others with all 0s. When they were centralised, 1405 it was better to provide this option than to break all the archs 1406 and have several arch maintainers pursuing me down dark alleys. 1407 1408config STOP_MACHINE 1409 bool 1410 default y 1411 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1412 help 1413 Need stop_machine() primitive. 1414 1415source "block/Kconfig" 1416 1417config PREEMPT_NOTIFIERS 1418 bool 1419 1420config PADATA 1421 depends on SMP 1422 bool 1423 1424source "kernel/Kconfig.locks" 1425