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 These are 54 drivers that have been replaced by something else, and/or are 55 scheduled to be removed in a future kernel release. 56 57 Unless you intend to help test and develop a feature or driver that 58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 INIT_ENV_ARG_LIMIT 73 int 74 default 32 if !UML 75 default 128 if UML 76 help 77 Maximum of each of the number of arguments and environment 78 variables passed to init from the kernel command line. 79 80 81config CROSS_COMPILE 82 string "Cross-compiler tool prefix" 83 help 84 Same as running 'make CROSS_COMPILE=prefix-' but stored for 85 default make runs in this kernel build directory. You don't 86 need to set this unless you want the configured kernel build 87 directory to select the cross-compiler automatically. 88 89config LOCALVERSION 90 string "Local version - append to kernel release" 91 help 92 Append an extra string to the end of your kernel version. 93 This will show up when you type uname, for example. 94 The string you set here will be appended after the contents of 95 any files with a filename matching localversion* in your 96 object and source tree, in that order. Your total string can 97 be a maximum of 64 characters. 98 99config LOCALVERSION_AUTO 100 bool "Automatically append version information to the version string" 101 default y 102 help 103 This will try to automatically determine if the current tree is a 104 release tree by looking for git tags that belong to the current 105 top of tree revision. 106 107 A string of the format -gxxxxxxxx will be added to the localversion 108 if a git-based tree is found. The string generated by this will be 109 appended after any matching localversion* files, and after the value 110 set in CONFIG_LOCALVERSION. 111 112 (The actual string used here is the first eight characters produced 113 by running the command: 114 115 $ git rev-parse --verify HEAD 116 117 which is done within the script "scripts/setlocalversion".) 118 119config HAVE_KERNEL_GZIP 120 bool 121 122config HAVE_KERNEL_BZIP2 123 bool 124 125config HAVE_KERNEL_LZMA 126 bool 127 128config HAVE_KERNEL_XZ 129 bool 130 131config HAVE_KERNEL_LZO 132 bool 133 134choice 135 prompt "Kernel compression mode" 136 default KERNEL_GZIP 137 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 138 help 139 The linux kernel is a kind of self-extracting executable. 140 Several compression algorithms are available, which differ 141 in efficiency, compression and decompression speed. 142 Compression speed is only relevant when building a kernel. 143 Decompression speed is relevant at each boot. 144 145 If you have any problems with bzip2 or lzma compressed 146 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 147 version of this functionality (bzip2 only), for 2.4, was 148 supplied by Christian Ludwig) 149 150 High compression options are mostly useful for users, who 151 are low on disk space (embedded systems), but for whom ram 152 size matters less. 153 154 If in doubt, select 'gzip' 155 156config KERNEL_GZIP 157 bool "Gzip" 158 depends on HAVE_KERNEL_GZIP 159 help 160 The old and tried gzip compression. It provides a good balance 161 between compression ratio and decompression speed. 162 163config KERNEL_BZIP2 164 bool "Bzip2" 165 depends on HAVE_KERNEL_BZIP2 166 help 167 Its compression ratio and speed is intermediate. 168 Decompression speed is slowest among the three. The kernel 169 size is about 10% smaller with bzip2, in comparison to gzip. 170 Bzip2 uses a large amount of memory. For modern kernels you 171 will need at least 8MB RAM or more for booting. 172 173config KERNEL_LZMA 174 bool "LZMA" 175 depends on HAVE_KERNEL_LZMA 176 help 177 The most recent compression algorithm. 178 Its ratio is best, decompression speed is between the other 179 two. Compression is slowest. The kernel size is about 33% 180 smaller with LZMA in comparison to gzip. 181 182config KERNEL_XZ 183 bool "XZ" 184 depends on HAVE_KERNEL_XZ 185 help 186 XZ uses the LZMA2 algorithm and instruction set specific 187 BCJ filters which can improve compression ratio of executable 188 code. The size of the kernel is about 30% smaller with XZ in 189 comparison to gzip. On architectures for which there is a BCJ 190 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 191 will create a few percent smaller kernel than plain LZMA. 192 193 The speed is about the same as with LZMA: The decompression 194 speed of XZ is better than that of bzip2 but worse than gzip 195 and LZO. Compression is slow. 196 197config KERNEL_LZO 198 bool "LZO" 199 depends on HAVE_KERNEL_LZO 200 help 201 Its compression ratio is the poorest among the 4. The kernel 202 size is about 10% bigger than gzip; however its speed 203 (both compression and decompression) is the fastest. 204 205endchoice 206 207config SWAP 208 bool "Support for paging of anonymous memory (swap)" 209 depends on MMU && BLOCK 210 default y 211 help 212 This option allows you to choose whether you want to have support 213 for so called swap devices or swap files in your kernel that are 214 used to provide more virtual memory than the actual RAM present 215 in your computer. If unsure say Y. 216 217config SYSVIPC 218 bool "System V IPC" 219 ---help--- 220 Inter Process Communication is a suite of library functions and 221 system calls which let processes (running programs) synchronize and 222 exchange information. It is generally considered to be a good thing, 223 and some programs won't run unless you say Y here. In particular, if 224 you want to run the DOS emulator dosemu under Linux (read the 225 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 226 you'll need to say Y here. 227 228 You can find documentation about IPC with "info ipc" and also in 229 section 6.4 of the Linux Programmer's Guide, available from 230 <http://www.tldp.org/guides.html>. 231 232config SYSVIPC_SYSCTL 233 bool 234 depends on SYSVIPC 235 depends on SYSCTL 236 default y 237 238config POSIX_MQUEUE 239 bool "POSIX Message Queues" 240 depends on NET && EXPERIMENTAL 241 ---help--- 242 POSIX variant of message queues is a part of IPC. In POSIX message 243 queues every message has a priority which decides about succession 244 of receiving it by a process. If you want to compile and run 245 programs written e.g. for Solaris with use of its POSIX message 246 queues (functions mq_*) say Y here. 247 248 POSIX message queues are visible as a filesystem called 'mqueue' 249 and can be mounted somewhere if you want to do filesystem 250 operations on message queues. 251 252 If unsure, say Y. 253 254config POSIX_MQUEUE_SYSCTL 255 bool 256 depends on POSIX_MQUEUE 257 depends on SYSCTL 258 default y 259 260config BSD_PROCESS_ACCT 261 bool "BSD Process Accounting" 262 help 263 If you say Y here, a user level program will be able to instruct the 264 kernel (via a special system call) to write process accounting 265 information to a file: whenever a process exits, information about 266 that process will be appended to the file by the kernel. The 267 information includes things such as creation time, owning user, 268 command name, memory usage, controlling terminal etc. (the complete 269 list is in the struct acct in <file:include/linux/acct.h>). It is 270 up to the user level program to do useful things with this 271 information. This is generally a good idea, so say Y. 272 273config BSD_PROCESS_ACCT_V3 274 bool "BSD Process Accounting version 3 file format" 275 depends on BSD_PROCESS_ACCT 276 default n 277 help 278 If you say Y here, the process accounting information is written 279 in a new file format that also logs the process IDs of each 280 process and it's parent. Note that this file format is incompatible 281 with previous v0/v1/v2 file formats, so you will need updated tools 282 for processing it. A preliminary version of these tools is available 283 at <http://www.gnu.org/software/acct/>. 284 285config FHANDLE 286 bool "open by fhandle syscalls" 287 select EXPORTFS 288 help 289 If you say Y here, a user level program will be able to map 290 file names to handle and then later use the handle for 291 different file system operations. This is useful in implementing 292 userspace file servers, which now track files using handles instead 293 of names. The handle would remain the same even if file names 294 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 295 syscalls. 296 297config TASKSTATS 298 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 299 depends on NET 300 default n 301 help 302 Export selected statistics for tasks/processes through the 303 generic netlink interface. Unlike BSD process accounting, the 304 statistics are available during the lifetime of tasks/processes as 305 responses to commands. Like BSD accounting, they are sent to user 306 space on task exit. 307 308 Say N if unsure. 309 310config TASK_DELAY_ACCT 311 bool "Enable per-task delay accounting (EXPERIMENTAL)" 312 depends on TASKSTATS 313 help 314 Collect information on time spent by a task waiting for system 315 resources like cpu, synchronous block I/O completion and swapping 316 in pages. Such statistics can help in setting a task's priorities 317 relative to other tasks for cpu, io, rss limits etc. 318 319 Say N if unsure. 320 321config TASK_XACCT 322 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 323 depends on TASKSTATS 324 help 325 Collect extended task accounting data and send the data 326 to userland for processing over the taskstats interface. 327 328 Say N if unsure. 329 330config TASK_IO_ACCOUNTING 331 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 332 depends on TASK_XACCT 333 help 334 Collect information on the number of bytes of storage I/O which this 335 task has caused. 336 337 Say N if unsure. 338 339config AUDIT 340 bool "Auditing support" 341 depends on NET 342 help 343 Enable auditing infrastructure that can be used with another 344 kernel subsystem, such as SELinux (which requires this for 345 logging of avc messages output). Does not do system-call 346 auditing without CONFIG_AUDITSYSCALL. 347 348config AUDITSYSCALL 349 bool "Enable system-call auditing support" 350 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH) 351 default y if SECURITY_SELINUX 352 help 353 Enable low-overhead system-call auditing infrastructure that 354 can be used independently or with another kernel subsystem, 355 such as SELinux. 356 357config AUDIT_WATCH 358 def_bool y 359 depends on AUDITSYSCALL 360 select FSNOTIFY 361 362config AUDIT_TREE 363 def_bool y 364 depends on AUDITSYSCALL 365 select FSNOTIFY 366 367source "kernel/irq/Kconfig" 368 369menu "RCU Subsystem" 370 371choice 372 prompt "RCU Implementation" 373 default TREE_RCU 374 375config TREE_RCU 376 bool "Tree-based hierarchical RCU" 377 depends on !PREEMPT && SMP 378 help 379 This option selects the RCU implementation that is 380 designed for very large SMP system with hundreds or 381 thousands of CPUs. It also scales down nicely to 382 smaller systems. 383 384config TREE_PREEMPT_RCU 385 bool "Preemptible tree-based hierarchical RCU" 386 depends on PREEMPT 387 help 388 This option selects the RCU implementation that is 389 designed for very large SMP systems with hundreds or 390 thousands of CPUs, but for which real-time response 391 is also required. It also scales down nicely to 392 smaller systems. 393 394config TINY_RCU 395 bool "UP-only small-memory-footprint RCU" 396 depends on !SMP 397 help 398 This option selects the RCU implementation that is 399 designed for UP systems from which real-time response 400 is not required. This option greatly reduces the 401 memory footprint of RCU. 402 403config TINY_PREEMPT_RCU 404 bool "Preemptible UP-only small-memory-footprint RCU" 405 depends on !SMP && PREEMPT 406 help 407 This option selects the RCU implementation that is designed 408 for real-time UP systems. This option greatly reduces the 409 memory footprint of RCU. 410 411endchoice 412 413config PREEMPT_RCU 414 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 415 help 416 This option enables preemptible-RCU code that is common between 417 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 418 419config RCU_TRACE 420 bool "Enable tracing for RCU" 421 help 422 This option provides tracing in RCU which presents stats 423 in debugfs for debugging RCU implementation. 424 425 Say Y here if you want to enable RCU tracing 426 Say N if you are unsure. 427 428config RCU_FANOUT 429 int "Tree-based hierarchical RCU fanout value" 430 range 2 64 if 64BIT 431 range 2 32 if !64BIT 432 depends on TREE_RCU || TREE_PREEMPT_RCU 433 default 64 if 64BIT 434 default 32 if !64BIT 435 help 436 This option controls the fanout of hierarchical implementations 437 of RCU, allowing RCU to work efficiently on machines with 438 large numbers of CPUs. This value must be at least the fourth 439 root of NR_CPUS, which allows NR_CPUS to be insanely large. 440 The default value of RCU_FANOUT should be used for production 441 systems, but if you are stress-testing the RCU implementation 442 itself, small RCU_FANOUT values allow you to test large-system 443 code paths on small(er) systems. 444 445 Select a specific number if testing RCU itself. 446 Take the default if unsure. 447 448config RCU_FANOUT_EXACT 449 bool "Disable tree-based hierarchical RCU auto-balancing" 450 depends on TREE_RCU || TREE_PREEMPT_RCU 451 default n 452 help 453 This option forces use of the exact RCU_FANOUT value specified, 454 regardless of imbalances in the hierarchy. This is useful for 455 testing RCU itself, and might one day be useful on systems with 456 strong NUMA behavior. 457 458 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 459 460 Say N if unsure. 461 462config RCU_FAST_NO_HZ 463 bool "Accelerate last non-dyntick-idle CPU's grace periods" 464 depends on TREE_RCU && NO_HZ && SMP 465 default n 466 help 467 This option causes RCU to attempt to accelerate grace periods 468 in order to allow the final CPU to enter dynticks-idle state 469 more quickly. On the other hand, this option increases the 470 overhead of the dynticks-idle checking, particularly on systems 471 with large numbers of CPUs. 472 473 Say Y if energy efficiency is critically important, particularly 474 if you have relatively few CPUs. 475 476 Say N if you are unsure. 477 478config TREE_RCU_TRACE 479 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 480 select DEBUG_FS 481 help 482 This option provides tracing for the TREE_RCU and 483 TREE_PREEMPT_RCU implementations, permitting Makefile to 484 trivially select kernel/rcutree_trace.c. 485 486config RCU_BOOST 487 bool "Enable RCU priority boosting" 488 depends on RT_MUTEXES && TINY_PREEMPT_RCU 489 default n 490 help 491 This option boosts the priority of preempted RCU readers that 492 block the current preemptible RCU grace period for too long. 493 This option also prevents heavy loads from blocking RCU 494 callback invocation for all flavors of RCU. 495 496 Say Y here if you are working with real-time apps or heavy loads 497 Say N here if you are unsure. 498 499config RCU_BOOST_PRIO 500 int "Real-time priority to boost RCU readers to" 501 range 1 99 502 depends on RCU_BOOST 503 default 1 504 help 505 This option specifies the real-time priority to which preempted 506 RCU readers are to be boosted. If you are working with CPU-bound 507 real-time applications, you should specify a priority higher then 508 the highest-priority CPU-bound application. 509 510 Specify the real-time priority, or take the default if unsure. 511 512config RCU_BOOST_DELAY 513 int "Milliseconds to delay boosting after RCU grace-period start" 514 range 0 3000 515 depends on RCU_BOOST 516 default 500 517 help 518 This option specifies the time to wait after the beginning of 519 a given grace period before priority-boosting preempted RCU 520 readers blocking that grace period. Note that any RCU reader 521 blocking an expedited RCU grace period is boosted immediately. 522 523 Accept the default if unsure. 524 525endmenu # "RCU Subsystem" 526 527config IKCONFIG 528 tristate "Kernel .config support" 529 ---help--- 530 This option enables the complete Linux kernel ".config" file 531 contents to be saved in the kernel. It provides documentation 532 of which kernel options are used in a running kernel or in an 533 on-disk kernel. This information can be extracted from the kernel 534 image file with the script scripts/extract-ikconfig and used as 535 input to rebuild the current kernel or to build another kernel. 536 It can also be extracted from a running kernel by reading 537 /proc/config.gz if enabled (below). 538 539config IKCONFIG_PROC 540 bool "Enable access to .config through /proc/config.gz" 541 depends on IKCONFIG && PROC_FS 542 ---help--- 543 This option enables access to the kernel configuration file 544 through /proc/config.gz. 545 546config LOG_BUF_SHIFT 547 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 548 range 12 21 549 default 17 550 help 551 Select kernel log buffer size as a power of 2. 552 Examples: 553 17 => 128 KB 554 16 => 64 KB 555 15 => 32 KB 556 14 => 16 KB 557 13 => 8 KB 558 12 => 4 KB 559 560# 561# Architectures with an unreliable sched_clock() should select this: 562# 563config HAVE_UNSTABLE_SCHED_CLOCK 564 bool 565 566menuconfig CGROUPS 567 boolean "Control Group support" 568 depends on EVENTFD 569 help 570 This option adds support for grouping sets of processes together, for 571 use with process control subsystems such as Cpusets, CFS, memory 572 controls or device isolation. 573 See 574 - Documentation/scheduler/sched-design-CFS.txt (CFS) 575 - Documentation/cgroups/ (features for grouping, isolation 576 and resource control) 577 578 Say N if unsure. 579 580if CGROUPS 581 582config CGROUP_DEBUG 583 bool "Example debug cgroup subsystem" 584 default n 585 help 586 This option enables a simple cgroup subsystem that 587 exports useful debugging information about the cgroups 588 framework. 589 590 Say N if unsure. 591 592config CGROUP_NS 593 bool "Namespace cgroup subsystem" 594 help 595 Provides a simple namespace cgroup subsystem to 596 provide hierarchical naming of sets of namespaces, 597 for instance virtual servers and checkpoint/restart 598 jobs. 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 "noswapaccount" 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 noswapaccount does the trick). 692 693config CGROUP_PERF 694 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 695 depends on PERF_EVENTS && CGROUPS 696 help 697 This option extends the per-cpu mode to restrict monitoring to 698 threads which belong to the cgroup specified and run on the 699 designated cpu. 700 701 Say N if unsure. 702 703menuconfig CGROUP_SCHED 704 bool "Group CPU scheduler" 705 depends on EXPERIMENTAL 706 default n 707 help 708 This feature lets CPU scheduler recognize task groups and control CPU 709 bandwidth allocation to such task groups. It uses cgroups to group 710 tasks. 711 712if CGROUP_SCHED 713config FAIR_GROUP_SCHED 714 bool "Group scheduling for SCHED_OTHER" 715 depends on CGROUP_SCHED 716 default CGROUP_SCHED 717 718config RT_GROUP_SCHED 719 bool "Group scheduling for SCHED_RR/FIFO" 720 depends on EXPERIMENTAL 721 depends on CGROUP_SCHED 722 default n 723 help 724 This feature lets you explicitly allocate real CPU bandwidth 725 to task groups. If enabled, it will also make it impossible to 726 schedule realtime tasks for non-root users until you allocate 727 realtime bandwidth for them. 728 See Documentation/scheduler/sched-rt-group.txt for more information. 729 730endif #CGROUP_SCHED 731 732config BLK_CGROUP 733 tristate "Block IO controller" 734 depends on BLOCK 735 default n 736 ---help--- 737 Generic block IO controller cgroup interface. This is the common 738 cgroup interface which should be used by various IO controlling 739 policies. 740 741 Currently, CFQ IO scheduler uses it to recognize task groups and 742 control disk bandwidth allocation (proportional time slice allocation) 743 to such task groups. It is also used by bio throttling logic in 744 block layer to implement upper limit in IO rates on a device. 745 746 This option only enables generic Block IO controller infrastructure. 747 One needs to also enable actual IO controlling logic/policy. For 748 enabling proportional weight division of disk bandwidth in CFQ, set 749 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 750 CONFIG_BLK_DEV_THROTTLING=y. 751 752 See Documentation/cgroups/blkio-controller.txt for more information. 753 754config DEBUG_BLK_CGROUP 755 bool "Enable Block IO controller debugging" 756 depends on BLK_CGROUP 757 default n 758 ---help--- 759 Enable some debugging help. Currently it exports additional stat 760 files in a cgroup which can be useful for debugging. 761 762endif # CGROUPS 763 764menuconfig NAMESPACES 765 bool "Namespaces support" if EXPERT 766 default !EXPERT 767 help 768 Provides the way to make tasks work with different objects using 769 the same id. For example same IPC id may refer to different objects 770 or same user id or pid may refer to different tasks when used in 771 different namespaces. 772 773if NAMESPACES 774 775config UTS_NS 776 bool "UTS namespace" 777 default y 778 help 779 In this namespace tasks see different info provided with the 780 uname() system call 781 782config IPC_NS 783 bool "IPC namespace" 784 depends on (SYSVIPC || POSIX_MQUEUE) 785 default y 786 help 787 In this namespace tasks work with IPC ids which correspond to 788 different IPC objects in different namespaces. 789 790config USER_NS 791 bool "User namespace (EXPERIMENTAL)" 792 depends on EXPERIMENTAL 793 default y 794 help 795 This allows containers, i.e. vservers, to use user namespaces 796 to provide different user info for different servers. 797 If unsure, say N. 798 799config PID_NS 800 bool "PID Namespaces" 801 default y 802 help 803 Support process id namespaces. This allows having multiple 804 processes with the same pid as long as they are in different 805 pid namespaces. This is a building block of containers. 806 807config NET_NS 808 bool "Network namespace" 809 depends on NET 810 default y 811 help 812 Allow user space to create what appear to be multiple instances 813 of the network stack. 814 815endif # NAMESPACES 816 817config SCHED_AUTOGROUP 818 bool "Automatic process group scheduling" 819 select EVENTFD 820 select CGROUPS 821 select CGROUP_SCHED 822 select FAIR_GROUP_SCHED 823 help 824 This option optimizes the scheduler for common desktop workloads by 825 automatically creating and populating task groups. This separation 826 of workloads isolates aggressive CPU burners (like build jobs) from 827 desktop applications. Task group autogeneration is currently based 828 upon task session. 829 830config MM_OWNER 831 bool 832 833config SYSFS_DEPRECATED 834 bool "Enable deprecated sysfs features to support old userspace tools" 835 depends on SYSFS 836 default n 837 help 838 This option adds code that switches the layout of the "block" class 839 devices, to not show up in /sys/class/block/, but only in 840 /sys/block/. 841 842 This switch is only active when the sysfs.deprecated=1 boot option is 843 passed or the SYSFS_DEPRECATED_V2 option is set. 844 845 This option allows new kernels to run on old distributions and tools, 846 which might get confused by /sys/class/block/. Since 2007/2008 all 847 major distributions and tools handle this just fine. 848 849 Recent distributions and userspace tools after 2009/2010 depend on 850 the existence of /sys/class/block/, and will not work with this 851 option enabled. 852 853 Only if you are using a new kernel on an old distribution, you might 854 need to say Y here. 855 856config SYSFS_DEPRECATED_V2 857 bool "Enable deprecated sysfs features by default" 858 default n 859 depends on SYSFS 860 depends on SYSFS_DEPRECATED 861 help 862 Enable deprecated sysfs by default. 863 864 See the CONFIG_SYSFS_DEPRECATED option for more details about this 865 option. 866 867 Only if you are using a new kernel on an old distribution, you might 868 need to say Y here. Even then, odds are you would not need it 869 enabled, you can always pass the boot option if absolutely necessary. 870 871config RELAY 872 bool "Kernel->user space relay support (formerly relayfs)" 873 help 874 This option enables support for relay interface support in 875 certain file systems (such as debugfs). 876 It is designed to provide an efficient mechanism for tools and 877 facilities to relay large amounts of data from kernel space to 878 user space. 879 880 If unsure, say N. 881 882config BLK_DEV_INITRD 883 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 884 depends on BROKEN || !FRV 885 help 886 The initial RAM filesystem is a ramfs which is loaded by the 887 boot loader (loadlin or lilo) and that is mounted as root 888 before the normal boot procedure. It is typically used to 889 load modules needed to mount the "real" root file system, 890 etc. See <file:Documentation/initrd.txt> for details. 891 892 If RAM disk support (BLK_DEV_RAM) is also included, this 893 also enables initial RAM disk (initrd) support and adds 894 15 Kbytes (more on some other architectures) to the kernel size. 895 896 If unsure say Y. 897 898if BLK_DEV_INITRD 899 900source "usr/Kconfig" 901 902endif 903 904config CC_OPTIMIZE_FOR_SIZE 905 bool "Optimize for size" 906 default y 907 help 908 Enabling this option will pass "-Os" instead of "-O2" to gcc 909 resulting in a smaller kernel. 910 911 If unsure, say Y. 912 913config SYSCTL 914 bool 915 916config ANON_INODES 917 bool 918 919menuconfig EXPERT 920 bool "Configure standard kernel features (expert users)" 921 help 922 This option allows certain base kernel options and settings 923 to be disabled or tweaked. This is for specialized 924 environments which can tolerate a "non-standard" kernel. 925 Only use this if you really know what you are doing. 926 927config UID16 928 bool "Enable 16-bit UID system calls" if EXPERT 929 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 930 default y 931 help 932 This enables the legacy 16-bit UID syscall wrappers. 933 934config SYSCTL_SYSCALL 935 bool "Sysctl syscall support" if EXPERT 936 depends on PROC_SYSCTL 937 default y 938 select SYSCTL 939 ---help--- 940 sys_sysctl uses binary paths that have been found challenging 941 to properly maintain and use. The interface in /proc/sys 942 using paths with ascii names is now the primary path to this 943 information. 944 945 Almost nothing using the binary sysctl interface so if you are 946 trying to save some space it is probably safe to disable this, 947 making your kernel marginally smaller. 948 949 If unsure say Y here. 950 951config KALLSYMS 952 bool "Load all symbols for debugging/ksymoops" if EXPERT 953 default y 954 help 955 Say Y here to let the kernel print out symbolic crash information and 956 symbolic stack backtraces. This increases the size of the kernel 957 somewhat, as all symbols have to be loaded into the kernel image. 958 959config KALLSYMS_ALL 960 bool "Include all symbols in kallsyms" 961 depends on DEBUG_KERNEL && KALLSYMS 962 help 963 Normally kallsyms only contains the symbols of functions, for nicer 964 OOPS messages. Some debuggers can use kallsyms for other 965 symbols too: say Y here to include all symbols, if you need them 966 and you don't care about adding 300k to the size of your kernel. 967 968 Say N. 969 970config KALLSYMS_EXTRA_PASS 971 bool "Do an extra kallsyms pass" 972 depends on KALLSYMS 973 help 974 If kallsyms is not working correctly, the build will fail with 975 inconsistent kallsyms data. If that occurs, log a bug report and 976 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 977 Always say N here unless you find a bug in kallsyms, which must be 978 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 979 you wait for kallsyms to be fixed. 980 981 982config HOTPLUG 983 bool "Support for hot-pluggable devices" if EXPERT 984 default y 985 help 986 This option is provided for the case where no hotplug or uevent 987 capabilities is wanted by the kernel. You should only consider 988 disabling this option for embedded systems that do not use modules, a 989 dynamic /dev tree, or dynamic device discovery. Just say Y. 990 991config PRINTK 992 default y 993 bool "Enable support for printk" if EXPERT 994 help 995 This option enables normal printk support. Removing it 996 eliminates most of the message strings from the kernel image 997 and makes the kernel more or less silent. As this makes it 998 very difficult to diagnose system problems, saying N here is 999 strongly discouraged. 1000 1001config BUG 1002 bool "BUG() support" if EXPERT 1003 default y 1004 help 1005 Disabling this option eliminates support for BUG and WARN, reducing 1006 the size of your kernel image and potentially quietly ignoring 1007 numerous fatal conditions. You should only consider disabling this 1008 option for embedded systems with no facilities for reporting errors. 1009 Just say Y. 1010 1011config ELF_CORE 1012 default y 1013 bool "Enable ELF core dumps" if EXPERT 1014 help 1015 Enable support for generating core dumps. Disabling saves about 4k. 1016 1017config PCSPKR_PLATFORM 1018 bool "Enable PC-Speaker support" if EXPERT 1019 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 1020 default y 1021 help 1022 This option allows to disable the internal PC-Speaker 1023 support, saving some memory. 1024 1025config BASE_FULL 1026 default y 1027 bool "Enable full-sized data structures for core" if EXPERT 1028 help 1029 Disabling this option reduces the size of miscellaneous core 1030 kernel data structures. This saves memory on small machines, 1031 but may reduce performance. 1032 1033config FUTEX 1034 bool "Enable futex support" if EXPERT 1035 default y 1036 select RT_MUTEXES 1037 help 1038 Disabling this option will cause the kernel to be built without 1039 support for "fast userspace mutexes". The resulting kernel may not 1040 run glibc-based applications correctly. 1041 1042config EPOLL 1043 bool "Enable eventpoll support" if EXPERT 1044 default y 1045 select ANON_INODES 1046 help 1047 Disabling this option will cause the kernel to be built without 1048 support for epoll family of system calls. 1049 1050config SIGNALFD 1051 bool "Enable signalfd() system call" if EXPERT 1052 select ANON_INODES 1053 default y 1054 help 1055 Enable the signalfd() system call that allows to receive signals 1056 on a file descriptor. 1057 1058 If unsure, say Y. 1059 1060config TIMERFD 1061 bool "Enable timerfd() system call" if EXPERT 1062 select ANON_INODES 1063 default y 1064 help 1065 Enable the timerfd() system call that allows to receive timer 1066 events on a file descriptor. 1067 1068 If unsure, say Y. 1069 1070config EVENTFD 1071 bool "Enable eventfd() system call" if EXPERT 1072 select ANON_INODES 1073 default y 1074 help 1075 Enable the eventfd() system call that allows to receive both 1076 kernel notification (ie. KAIO) or userspace notifications. 1077 1078 If unsure, say Y. 1079 1080config SHMEM 1081 bool "Use full shmem filesystem" if EXPERT 1082 default y 1083 depends on MMU 1084 help 1085 The shmem is an internal filesystem used to manage shared memory. 1086 It is backed by swap and manages resource limits. It is also exported 1087 to userspace as tmpfs if TMPFS is enabled. Disabling this 1088 option replaces shmem and tmpfs with the much simpler ramfs code, 1089 which may be appropriate on small systems without swap. 1090 1091config AIO 1092 bool "Enable AIO support" if EXPERT 1093 default y 1094 help 1095 This option enables POSIX asynchronous I/O which may by used 1096 by some high performance threaded applications. Disabling 1097 this option saves about 7k. 1098 1099config EMBEDDED 1100 bool "Embedded system" 1101 select EXPERT 1102 help 1103 This option should be enabled if compiling the kernel for 1104 an embedded system so certain expert options are available 1105 for configuration. 1106 1107config HAVE_PERF_EVENTS 1108 bool 1109 help 1110 See tools/perf/design.txt for details. 1111 1112config PERF_USE_VMALLOC 1113 bool 1114 help 1115 See tools/perf/design.txt for details 1116 1117menu "Kernel Performance Events And Counters" 1118 1119config PERF_EVENTS 1120 bool "Kernel performance events and counters" 1121 default y if (PROFILING || PERF_COUNTERS) 1122 depends on HAVE_PERF_EVENTS 1123 select ANON_INODES 1124 select IRQ_WORK 1125 help 1126 Enable kernel support for various performance events provided 1127 by software and hardware. 1128 1129 Software events are supported either built-in or via the 1130 use of generic tracepoints. 1131 1132 Most modern CPUs support performance events via performance 1133 counter registers. These registers count the number of certain 1134 types of hw events: such as instructions executed, cachemisses 1135 suffered, or branches mis-predicted - without slowing down the 1136 kernel or applications. These registers can also trigger interrupts 1137 when a threshold number of events have passed - and can thus be 1138 used to profile the code that runs on that CPU. 1139 1140 The Linux Performance Event subsystem provides an abstraction of 1141 these software and hardware event capabilities, available via a 1142 system call and used by the "perf" utility in tools/perf/. It 1143 provides per task and per CPU counters, and it provides event 1144 capabilities on top of those. 1145 1146 Say Y if unsure. 1147 1148config PERF_COUNTERS 1149 bool "Kernel performance counters (old config option)" 1150 depends on HAVE_PERF_EVENTS 1151 help 1152 This config has been obsoleted by the PERF_EVENTS 1153 config option - please see that one for details. 1154 1155 It has no effect on the kernel whether you enable 1156 it or not, it is a compatibility placeholder. 1157 1158 Say N if unsure. 1159 1160config DEBUG_PERF_USE_VMALLOC 1161 default n 1162 bool "Debug: use vmalloc to back perf mmap() buffers" 1163 depends on PERF_EVENTS && DEBUG_KERNEL 1164 select PERF_USE_VMALLOC 1165 help 1166 Use vmalloc memory to back perf mmap() buffers. 1167 1168 Mostly useful for debugging the vmalloc code on platforms 1169 that don't require it. 1170 1171 Say N if unsure. 1172 1173endmenu 1174 1175config VM_EVENT_COUNTERS 1176 default y 1177 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1178 help 1179 VM event counters are needed for event counts to be shown. 1180 This option allows the disabling of the VM event counters 1181 on EXPERT systems. /proc/vmstat will only show page counts 1182 if VM event counters are disabled. 1183 1184config PCI_QUIRKS 1185 default y 1186 bool "Enable PCI quirk workarounds" if EXPERT 1187 depends on PCI 1188 help 1189 This enables workarounds for various PCI chipset 1190 bugs/quirks. Disable this only if your target machine is 1191 unaffected by PCI quirks. 1192 1193config SLUB_DEBUG 1194 default y 1195 bool "Enable SLUB debugging support" if EXPERT 1196 depends on SLUB && SYSFS 1197 help 1198 SLUB has extensive debug support features. Disabling these can 1199 result in significant savings in code size. This also disables 1200 SLUB sysfs support. /sys/slab will not exist and there will be 1201 no support for cache validation etc. 1202 1203config COMPAT_BRK 1204 bool "Disable heap randomization" 1205 default y 1206 help 1207 Randomizing heap placement makes heap exploits harder, but it 1208 also breaks ancient binaries (including anything libc5 based). 1209 This option changes the bootup default to heap randomization 1210 disabled, and can be overridden at runtime by setting 1211 /proc/sys/kernel/randomize_va_space to 2. 1212 1213 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1214 1215choice 1216 prompt "Choose SLAB allocator" 1217 default SLUB 1218 help 1219 This option allows to select a slab allocator. 1220 1221config SLAB 1222 bool "SLAB" 1223 help 1224 The regular slab allocator that is established and known to work 1225 well in all environments. It organizes cache hot objects in 1226 per cpu and per node queues. 1227 1228config SLUB 1229 bool "SLUB (Unqueued Allocator)" 1230 help 1231 SLUB is a slab allocator that minimizes cache line usage 1232 instead of managing queues of cached objects (SLAB approach). 1233 Per cpu caching is realized using slabs of objects instead 1234 of queues of objects. SLUB can use memory efficiently 1235 and has enhanced diagnostics. SLUB is the default choice for 1236 a slab allocator. 1237 1238config SLOB 1239 depends on EXPERT 1240 bool "SLOB (Simple Allocator)" 1241 help 1242 SLOB replaces the stock allocator with a drastically simpler 1243 allocator. SLOB is generally more space efficient but 1244 does not perform as well on large systems. 1245 1246endchoice 1247 1248config MMAP_ALLOW_UNINITIALIZED 1249 bool "Allow mmapped anonymous memory to be uninitialized" 1250 depends on EXPERT && !MMU 1251 default n 1252 help 1253 Normally, and according to the Linux spec, anonymous memory obtained 1254 from mmap() has it's contents cleared before it is passed to 1255 userspace. Enabling this config option allows you to request that 1256 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1257 providing a huge performance boost. If this option is not enabled, 1258 then the flag will be ignored. 1259 1260 This is taken advantage of by uClibc's malloc(), and also by 1261 ELF-FDPIC binfmt's brk and stack allocator. 1262 1263 Because of the obvious security issues, this option should only be 1264 enabled on embedded devices where you control what is run in 1265 userspace. Since that isn't generally a problem on no-MMU systems, 1266 it is normally safe to say Y here. 1267 1268 See Documentation/nommu-mmap.txt for more information. 1269 1270config PROFILING 1271 bool "Profiling support" 1272 help 1273 Say Y here to enable the extended profiling support mechanisms used 1274 by profilers such as OProfile. 1275 1276# 1277# Place an empty function call at each tracepoint site. Can be 1278# dynamically changed for a probe function. 1279# 1280config TRACEPOINTS 1281 bool 1282 1283source "arch/Kconfig" 1284 1285endmenu # General setup 1286 1287config HAVE_GENERIC_DMA_COHERENT 1288 bool 1289 default n 1290 1291config SLABINFO 1292 bool 1293 depends on PROC_FS 1294 depends on SLAB || SLUB_DEBUG 1295 default y 1296 1297config RT_MUTEXES 1298 boolean 1299 1300config BASE_SMALL 1301 int 1302 default 0 if BASE_FULL 1303 default 1 if !BASE_FULL 1304 1305menuconfig MODULES 1306 bool "Enable loadable module support" 1307 help 1308 Kernel modules are small pieces of compiled code which can 1309 be inserted in the running kernel, rather than being 1310 permanently built into the kernel. You use the "modprobe" 1311 tool to add (and sometimes remove) them. If you say Y here, 1312 many parts of the kernel can be built as modules (by 1313 answering M instead of Y where indicated): this is most 1314 useful for infrequently used options which are not required 1315 for booting. For more information, see the man pages for 1316 modprobe, lsmod, modinfo, insmod and rmmod. 1317 1318 If you say Y here, you will need to run "make 1319 modules_install" to put the modules under /lib/modules/ 1320 where modprobe can find them (you may need to be root to do 1321 this). 1322 1323 If unsure, say Y. 1324 1325if MODULES 1326 1327config MODULE_FORCE_LOAD 1328 bool "Forced module loading" 1329 default n 1330 help 1331 Allow loading of modules without version information (ie. modprobe 1332 --force). Forced module loading sets the 'F' (forced) taint flag and 1333 is usually a really bad idea. 1334 1335config MODULE_UNLOAD 1336 bool "Module unloading" 1337 help 1338 Without this option you will not be able to unload any 1339 modules (note that some modules may not be unloadable 1340 anyway), which makes your kernel smaller, faster 1341 and simpler. If unsure, say Y. 1342 1343config MODULE_FORCE_UNLOAD 1344 bool "Forced module unloading" 1345 depends on MODULE_UNLOAD && EXPERIMENTAL 1346 help 1347 This option allows you to force a module to unload, even if the 1348 kernel believes it is unsafe: the kernel will remove the module 1349 without waiting for anyone to stop using it (using the -f option to 1350 rmmod). This is mainly for kernel developers and desperate users. 1351 If unsure, say N. 1352 1353config MODVERSIONS 1354 bool "Module versioning support" 1355 help 1356 Usually, you have to use modules compiled with your kernel. 1357 Saying Y here makes it sometimes possible to use modules 1358 compiled for different kernels, by adding enough information 1359 to the modules to (hopefully) spot any changes which would 1360 make them incompatible with the kernel you are running. If 1361 unsure, say N. 1362 1363config MODULE_SRCVERSION_ALL 1364 bool "Source checksum for all modules" 1365 help 1366 Modules which contain a MODULE_VERSION get an extra "srcversion" 1367 field inserted into their modinfo section, which contains a 1368 sum of the source files which made it. This helps maintainers 1369 see exactly which source was used to build a module (since 1370 others sometimes change the module source without updating 1371 the version). With this option, such a "srcversion" field 1372 will be created for all modules. If unsure, say N. 1373 1374endif # MODULES 1375 1376config INIT_ALL_POSSIBLE 1377 bool 1378 help 1379 Back when each arch used to define their own cpu_online_map and 1380 cpu_possible_map, some of them chose to initialize cpu_possible_map 1381 with all 1s, and others with all 0s. When they were centralised, 1382 it was better to provide this option than to break all the archs 1383 and have several arch maintainers pursuing me down dark alleys. 1384 1385config STOP_MACHINE 1386 bool 1387 default y 1388 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1389 help 1390 Need stop_machine() primitive. 1391 1392source "block/Kconfig" 1393 1394config PREEMPT_NOTIFIERS 1395 bool 1396 1397config PADATA 1398 depends on SMP 1399 bool 1400 1401source "kernel/Kconfig.locks" 1402