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 These are 54 drivers that have been replaced by something else, and/or are 55 scheduled to be removed in a future kernel release. 56 57 Unless you intend to help test and develop a feature or driver that 58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 && 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_FREEZER 593 bool "Freezer cgroup subsystem" 594 help 595 Provides a way to freeze and unfreeze all tasks in a 596 cgroup. 597 598config CGROUP_DEVICE 599 bool "Device controller for cgroups" 600 help 601 Provides a cgroup implementing whitelists for devices which 602 a process in the cgroup can mknod or open. 603 604config CPUSETS 605 bool "Cpuset support" 606 help 607 This option will let you create and manage CPUSETs which 608 allow dynamically partitioning a system into sets of CPUs and 609 Memory Nodes and assigning tasks to run only within those sets. 610 This is primarily useful on large SMP or NUMA systems. 611 612 Say N if unsure. 613 614config PROC_PID_CPUSET 615 bool "Include legacy /proc/<pid>/cpuset file" 616 depends on CPUSETS 617 default y 618 619config CGROUP_CPUACCT 620 bool "Simple CPU accounting cgroup subsystem" 621 help 622 Provides a simple Resource Controller for monitoring the 623 total CPU consumed by the tasks in a cgroup. 624 625config RESOURCE_COUNTERS 626 bool "Resource counters" 627 help 628 This option enables controller independent resource accounting 629 infrastructure that works with cgroups. 630 631config CGROUP_MEM_RES_CTLR 632 bool "Memory Resource Controller for Control Groups" 633 depends on RESOURCE_COUNTERS 634 select MM_OWNER 635 help 636 Provides a memory resource controller that manages both anonymous 637 memory and page cache. (See Documentation/cgroups/memory.txt) 638 639 Note that setting this option increases fixed memory overhead 640 associated with each page of memory in the system. By this, 641 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 642 usage tracking struct at boot. Total amount of this is printed out 643 at boot. 644 645 Only enable when you're ok with these trade offs and really 646 sure you need the memory resource controller. Even when you enable 647 this, you can set "cgroup_disable=memory" at your boot option to 648 disable memory resource controller and you can avoid overheads. 649 (and lose benefits of memory resource controller) 650 651 This config option also selects MM_OWNER config option, which 652 could in turn add some fork/exit overhead. 653 654config CGROUP_MEM_RES_CTLR_SWAP 655 bool "Memory Resource Controller Swap Extension" 656 depends on CGROUP_MEM_RES_CTLR && SWAP 657 help 658 Add swap management feature to memory resource controller. When you 659 enable this, you can limit mem+swap usage per cgroup. In other words, 660 when you disable this, memory resource controller has no cares to 661 usage of swap...a process can exhaust all of the swap. This extension 662 is useful when you want to avoid exhaustion swap but this itself 663 adds more overheads and consumes memory for remembering information. 664 Especially if you use 32bit system or small memory system, please 665 be careful about enabling this. When memory resource controller 666 is disabled by boot option, this will be automatically disabled and 667 there will be no overhead from this. Even when you set this config=y, 668 if boot option "noswapaccount" is set, swap will not be accounted. 669 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 670 size is 4096bytes, 512k per 1Gbytes of swap. 671config CGROUP_MEM_RES_CTLR_SWAP_ENABLED 672 bool "Memory Resource Controller Swap Extension enabled by default" 673 depends on CGROUP_MEM_RES_CTLR_SWAP 674 default y 675 help 676 Memory Resource Controller Swap Extension comes with its price in 677 a bigger memory consumption. General purpose distribution kernels 678 which want to enable the feature but keep it disabled by default 679 and let the user enable it by swapaccount boot command line 680 parameter should have this option unselected. 681 For those who want to have the feature enabled by default should 682 select this option (if, for some reason, they need to disable it 683 then noswapaccount does the trick). 684 685config CGROUP_PERF 686 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 687 depends on PERF_EVENTS && CGROUPS 688 help 689 This option extends the per-cpu mode to restrict monitoring to 690 threads which belong to the cgroup specified and run on the 691 designated cpu. 692 693 Say N if unsure. 694 695menuconfig CGROUP_SCHED 696 bool "Group CPU scheduler" 697 depends on EXPERIMENTAL 698 default n 699 help 700 This feature lets CPU scheduler recognize task groups and control CPU 701 bandwidth allocation to such task groups. It uses cgroups to group 702 tasks. 703 704if CGROUP_SCHED 705config FAIR_GROUP_SCHED 706 bool "Group scheduling for SCHED_OTHER" 707 depends on CGROUP_SCHED 708 default CGROUP_SCHED 709 710config RT_GROUP_SCHED 711 bool "Group scheduling for SCHED_RR/FIFO" 712 depends on EXPERIMENTAL 713 depends on CGROUP_SCHED 714 default n 715 help 716 This feature lets you explicitly allocate real CPU bandwidth 717 to task groups. If enabled, it will also make it impossible to 718 schedule realtime tasks for non-root users until you allocate 719 realtime bandwidth for them. 720 See Documentation/scheduler/sched-rt-group.txt for more information. 721 722endif #CGROUP_SCHED 723 724config BLK_CGROUP 725 tristate "Block IO controller" 726 depends on BLOCK 727 default n 728 ---help--- 729 Generic block IO controller cgroup interface. This is the common 730 cgroup interface which should be used by various IO controlling 731 policies. 732 733 Currently, CFQ IO scheduler uses it to recognize task groups and 734 control disk bandwidth allocation (proportional time slice allocation) 735 to such task groups. It is also used by bio throttling logic in 736 block layer to implement upper limit in IO rates on a device. 737 738 This option only enables generic Block IO controller infrastructure. 739 One needs to also enable actual IO controlling logic/policy. For 740 enabling proportional weight division of disk bandwidth in CFQ, set 741 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 742 CONFIG_BLK_DEV_THROTTLING=y. 743 744 See Documentation/cgroups/blkio-controller.txt for more information. 745 746config DEBUG_BLK_CGROUP 747 bool "Enable Block IO controller debugging" 748 depends on BLK_CGROUP 749 default n 750 ---help--- 751 Enable some debugging help. Currently it exports additional stat 752 files in a cgroup which can be useful for debugging. 753 754endif # CGROUPS 755 756menuconfig NAMESPACES 757 bool "Namespaces support" if EXPERT 758 default !EXPERT 759 help 760 Provides the way to make tasks work with different objects using 761 the same id. For example same IPC id may refer to different objects 762 or same user id or pid may refer to different tasks when used in 763 different namespaces. 764 765if NAMESPACES 766 767config UTS_NS 768 bool "UTS namespace" 769 default y 770 help 771 In this namespace tasks see different info provided with the 772 uname() system call 773 774config IPC_NS 775 bool "IPC namespace" 776 depends on (SYSVIPC || POSIX_MQUEUE) 777 default y 778 help 779 In this namespace tasks work with IPC ids which correspond to 780 different IPC objects in different namespaces. 781 782config USER_NS 783 bool "User namespace (EXPERIMENTAL)" 784 depends on EXPERIMENTAL 785 default y 786 help 787 This allows containers, i.e. vservers, to use user namespaces 788 to provide different user info for different servers. 789 If unsure, say N. 790 791config PID_NS 792 bool "PID Namespaces" 793 default y 794 help 795 Support process id namespaces. This allows having multiple 796 processes with the same pid as long as they are in different 797 pid namespaces. This is a building block of containers. 798 799config NET_NS 800 bool "Network namespace" 801 depends on NET 802 default y 803 help 804 Allow user space to create what appear to be multiple instances 805 of the network stack. 806 807endif # NAMESPACES 808 809config SCHED_AUTOGROUP 810 bool "Automatic process group scheduling" 811 select EVENTFD 812 select CGROUPS 813 select CGROUP_SCHED 814 select FAIR_GROUP_SCHED 815 help 816 This option optimizes the scheduler for common desktop workloads by 817 automatically creating and populating task groups. This separation 818 of workloads isolates aggressive CPU burners (like build jobs) from 819 desktop applications. Task group autogeneration is currently based 820 upon task session. 821 822config MM_OWNER 823 bool 824 825config SYSFS_DEPRECATED 826 bool "Enable deprecated sysfs features to support old userspace tools" 827 depends on SYSFS 828 default n 829 help 830 This option adds code that switches the layout of the "block" class 831 devices, to not show up in /sys/class/block/, but only in 832 /sys/block/. 833 834 This switch is only active when the sysfs.deprecated=1 boot option is 835 passed or the SYSFS_DEPRECATED_V2 option is set. 836 837 This option allows new kernels to run on old distributions and tools, 838 which might get confused by /sys/class/block/. Since 2007/2008 all 839 major distributions and tools handle this just fine. 840 841 Recent distributions and userspace tools after 2009/2010 depend on 842 the existence of /sys/class/block/, and will not work with this 843 option enabled. 844 845 Only if you are using a new kernel on an old distribution, you might 846 need to say Y here. 847 848config SYSFS_DEPRECATED_V2 849 bool "Enable deprecated sysfs features by default" 850 default n 851 depends on SYSFS 852 depends on SYSFS_DEPRECATED 853 help 854 Enable deprecated sysfs by default. 855 856 See the CONFIG_SYSFS_DEPRECATED option for more details about this 857 option. 858 859 Only if you are using a new kernel on an old distribution, you might 860 need to say Y here. Even then, odds are you would not need it 861 enabled, you can always pass the boot option if absolutely necessary. 862 863config RELAY 864 bool "Kernel->user space relay support (formerly relayfs)" 865 help 866 This option enables support for relay interface support in 867 certain file systems (such as debugfs). 868 It is designed to provide an efficient mechanism for tools and 869 facilities to relay large amounts of data from kernel space to 870 user space. 871 872 If unsure, say N. 873 874config BLK_DEV_INITRD 875 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 876 depends on BROKEN || !FRV 877 help 878 The initial RAM filesystem is a ramfs which is loaded by the 879 boot loader (loadlin or lilo) and that is mounted as root 880 before the normal boot procedure. It is typically used to 881 load modules needed to mount the "real" root file system, 882 etc. See <file:Documentation/initrd.txt> for details. 883 884 If RAM disk support (BLK_DEV_RAM) is also included, this 885 also enables initial RAM disk (initrd) support and adds 886 15 Kbytes (more on some other architectures) to the kernel size. 887 888 If unsure say Y. 889 890if BLK_DEV_INITRD 891 892source "usr/Kconfig" 893 894endif 895 896config CC_OPTIMIZE_FOR_SIZE 897 bool "Optimize for size" 898 help 899 Enabling this option will pass "-Os" instead of "-O2" to gcc 900 resulting in a smaller kernel. 901 902 If unsure, say Y. 903 904config SYSCTL 905 bool 906 907config ANON_INODES 908 bool 909 910menuconfig EXPERT 911 bool "Configure standard kernel features (expert users)" 912 help 913 This option allows certain base kernel options and settings 914 to be disabled or tweaked. This is for specialized 915 environments which can tolerate a "non-standard" kernel. 916 Only use this if you really know what you are doing. 917 918config UID16 919 bool "Enable 16-bit UID system calls" if EXPERT 920 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 921 default y 922 help 923 This enables the legacy 16-bit UID syscall wrappers. 924 925config SYSCTL_SYSCALL 926 bool "Sysctl syscall support" if EXPERT 927 depends on PROC_SYSCTL 928 default y 929 select SYSCTL 930 ---help--- 931 sys_sysctl uses binary paths that have been found challenging 932 to properly maintain and use. The interface in /proc/sys 933 using paths with ascii names is now the primary path to this 934 information. 935 936 Almost nothing using the binary sysctl interface so if you are 937 trying to save some space it is probably safe to disable this, 938 making your kernel marginally smaller. 939 940 If unsure say Y here. 941 942config KALLSYMS 943 bool "Load all symbols for debugging/ksymoops" if EXPERT 944 default y 945 help 946 Say Y here to let the kernel print out symbolic crash information and 947 symbolic stack backtraces. This increases the size of the kernel 948 somewhat, as all symbols have to be loaded into the kernel image. 949 950config KALLSYMS_ALL 951 bool "Include all symbols in kallsyms" 952 depends on DEBUG_KERNEL && KALLSYMS 953 help 954 Normally kallsyms only contains the symbols of functions for nicer 955 OOPS messages and backtraces (i.e., symbols from the text and inittext 956 sections). This is sufficient for most cases. And only in very rare 957 cases (e.g., when a debugger is used) all symbols are required (e.g., 958 names of variables from the data sections, etc). 959 960 This option makes sure that all symbols are loaded into the kernel 961 image (i.e., symbols from all sections) in cost of increased kernel 962 size (depending on the kernel configuration, it may be 300KiB or 963 something like this). 964 965 Say N unless you really need all symbols. 966 967config HOTPLUG 968 bool "Support for hot-pluggable devices" if EXPERT 969 default y 970 help 971 This option is provided for the case where no hotplug or uevent 972 capabilities is wanted by the kernel. You should only consider 973 disabling this option for embedded systems that do not use modules, a 974 dynamic /dev tree, or dynamic device discovery. Just say Y. 975 976config PRINTK 977 default y 978 bool "Enable support for printk" if EXPERT 979 help 980 This option enables normal printk support. Removing it 981 eliminates most of the message strings from the kernel image 982 and makes the kernel more or less silent. As this makes it 983 very difficult to diagnose system problems, saying N here is 984 strongly discouraged. 985 986config BUG 987 bool "BUG() support" if EXPERT 988 default y 989 help 990 Disabling this option eliminates support for BUG and WARN, reducing 991 the size of your kernel image and potentially quietly ignoring 992 numerous fatal conditions. You should only consider disabling this 993 option for embedded systems with no facilities for reporting errors. 994 Just say Y. 995 996config ELF_CORE 997 default y 998 bool "Enable ELF core dumps" if EXPERT 999 help 1000 Enable support for generating core dumps. Disabling saves about 4k. 1001 1002config PCSPKR_PLATFORM 1003 bool "Enable PC-Speaker support" if EXPERT 1004 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 1005 default y 1006 help 1007 This option allows to disable the internal PC-Speaker 1008 support, saving some memory. 1009 1010config BASE_FULL 1011 default y 1012 bool "Enable full-sized data structures for core" if EXPERT 1013 help 1014 Disabling this option reduces the size of miscellaneous core 1015 kernel data structures. This saves memory on small machines, 1016 but may reduce performance. 1017 1018config FUTEX 1019 bool "Enable futex support" if EXPERT 1020 default y 1021 select RT_MUTEXES 1022 help 1023 Disabling this option will cause the kernel to be built without 1024 support for "fast userspace mutexes". The resulting kernel may not 1025 run glibc-based applications correctly. 1026 1027config EPOLL 1028 bool "Enable eventpoll support" if EXPERT 1029 default y 1030 select ANON_INODES 1031 help 1032 Disabling this option will cause the kernel to be built without 1033 support for epoll family of system calls. 1034 1035config SIGNALFD 1036 bool "Enable signalfd() system call" if EXPERT 1037 select ANON_INODES 1038 default y 1039 help 1040 Enable the signalfd() system call that allows to receive signals 1041 on a file descriptor. 1042 1043 If unsure, say Y. 1044 1045config TIMERFD 1046 bool "Enable timerfd() system call" if EXPERT 1047 select ANON_INODES 1048 default y 1049 help 1050 Enable the timerfd() system call that allows to receive timer 1051 events on a file descriptor. 1052 1053 If unsure, say Y. 1054 1055config EVENTFD 1056 bool "Enable eventfd() system call" if EXPERT 1057 select ANON_INODES 1058 default y 1059 help 1060 Enable the eventfd() system call that allows to receive both 1061 kernel notification (ie. KAIO) or userspace notifications. 1062 1063 If unsure, say Y. 1064 1065config SHMEM 1066 bool "Use full shmem filesystem" if EXPERT 1067 default y 1068 depends on MMU 1069 help 1070 The shmem is an internal filesystem used to manage shared memory. 1071 It is backed by swap and manages resource limits. It is also exported 1072 to userspace as tmpfs if TMPFS is enabled. Disabling this 1073 option replaces shmem and tmpfs with the much simpler ramfs code, 1074 which may be appropriate on small systems without swap. 1075 1076config AIO 1077 bool "Enable AIO support" if EXPERT 1078 default y 1079 help 1080 This option enables POSIX asynchronous I/O which may by used 1081 by some high performance threaded applications. Disabling 1082 this option saves about 7k. 1083 1084config EMBEDDED 1085 bool "Embedded system" 1086 select EXPERT 1087 help 1088 This option should be enabled if compiling the kernel for 1089 an embedded system so certain expert options are available 1090 for configuration. 1091 1092config HAVE_PERF_EVENTS 1093 bool 1094 help 1095 See tools/perf/design.txt for details. 1096 1097config PERF_USE_VMALLOC 1098 bool 1099 help 1100 See tools/perf/design.txt for details 1101 1102menu "Kernel Performance Events And Counters" 1103 1104config PERF_EVENTS 1105 bool "Kernel performance events and counters" 1106 default y if (PROFILING || PERF_COUNTERS) 1107 depends on HAVE_PERF_EVENTS 1108 select ANON_INODES 1109 select IRQ_WORK 1110 help 1111 Enable kernel support for various performance events provided 1112 by software and hardware. 1113 1114 Software events are supported either built-in or via the 1115 use of generic tracepoints. 1116 1117 Most modern CPUs support performance events via performance 1118 counter registers. These registers count the number of certain 1119 types of hw events: such as instructions executed, cachemisses 1120 suffered, or branches mis-predicted - without slowing down the 1121 kernel or applications. These registers can also trigger interrupts 1122 when a threshold number of events have passed - and can thus be 1123 used to profile the code that runs on that CPU. 1124 1125 The Linux Performance Event subsystem provides an abstraction of 1126 these software and hardware event capabilities, available via a 1127 system call and used by the "perf" utility in tools/perf/. It 1128 provides per task and per CPU counters, and it provides event 1129 capabilities on top of those. 1130 1131 Say Y if unsure. 1132 1133config PERF_COUNTERS 1134 bool "Kernel performance counters (old config option)" 1135 depends on HAVE_PERF_EVENTS 1136 help 1137 This config has been obsoleted by the PERF_EVENTS 1138 config option - please see that one for details. 1139 1140 It has no effect on the kernel whether you enable 1141 it or not, it is a compatibility placeholder. 1142 1143 Say N if unsure. 1144 1145config DEBUG_PERF_USE_VMALLOC 1146 default n 1147 bool "Debug: use vmalloc to back perf mmap() buffers" 1148 depends on PERF_EVENTS && DEBUG_KERNEL 1149 select PERF_USE_VMALLOC 1150 help 1151 Use vmalloc memory to back perf mmap() buffers. 1152 1153 Mostly useful for debugging the vmalloc code on platforms 1154 that don't require it. 1155 1156 Say N if unsure. 1157 1158endmenu 1159 1160config VM_EVENT_COUNTERS 1161 default y 1162 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1163 help 1164 VM event counters are needed for event counts to be shown. 1165 This option allows the disabling of the VM event counters 1166 on EXPERT systems. /proc/vmstat will only show page counts 1167 if VM event counters are disabled. 1168 1169config PCI_QUIRKS 1170 default y 1171 bool "Enable PCI quirk workarounds" if EXPERT 1172 depends on PCI 1173 help 1174 This enables workarounds for various PCI chipset 1175 bugs/quirks. Disable this only if your target machine is 1176 unaffected by PCI quirks. 1177 1178config SLUB_DEBUG 1179 default y 1180 bool "Enable SLUB debugging support" if EXPERT 1181 depends on SLUB && SYSFS 1182 help 1183 SLUB has extensive debug support features. Disabling these can 1184 result in significant savings in code size. This also disables 1185 SLUB sysfs support. /sys/slab will not exist and there will be 1186 no support for cache validation etc. 1187 1188config COMPAT_BRK 1189 bool "Disable heap randomization" 1190 default y 1191 help 1192 Randomizing heap placement makes heap exploits harder, but it 1193 also breaks ancient binaries (including anything libc5 based). 1194 This option changes the bootup default to heap randomization 1195 disabled, and can be overridden at runtime by setting 1196 /proc/sys/kernel/randomize_va_space to 2. 1197 1198 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1199 1200choice 1201 prompt "Choose SLAB allocator" 1202 default SLUB 1203 help 1204 This option allows to select a slab allocator. 1205 1206config SLAB 1207 bool "SLAB" 1208 help 1209 The regular slab allocator that is established and known to work 1210 well in all environments. It organizes cache hot objects in 1211 per cpu and per node queues. 1212 1213config SLUB 1214 bool "SLUB (Unqueued Allocator)" 1215 help 1216 SLUB is a slab allocator that minimizes cache line usage 1217 instead of managing queues of cached objects (SLAB approach). 1218 Per cpu caching is realized using slabs of objects instead 1219 of queues of objects. SLUB can use memory efficiently 1220 and has enhanced diagnostics. SLUB is the default choice for 1221 a slab allocator. 1222 1223config SLOB 1224 depends on EXPERT 1225 bool "SLOB (Simple Allocator)" 1226 help 1227 SLOB replaces the stock allocator with a drastically simpler 1228 allocator. SLOB is generally more space efficient but 1229 does not perform as well on large systems. 1230 1231endchoice 1232 1233config MMAP_ALLOW_UNINITIALIZED 1234 bool "Allow mmapped anonymous memory to be uninitialized" 1235 depends on EXPERT && !MMU 1236 default n 1237 help 1238 Normally, and according to the Linux spec, anonymous memory obtained 1239 from mmap() has it's contents cleared before it is passed to 1240 userspace. Enabling this config option allows you to request that 1241 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1242 providing a huge performance boost. If this option is not enabled, 1243 then the flag will be ignored. 1244 1245 This is taken advantage of by uClibc's malloc(), and also by 1246 ELF-FDPIC binfmt's brk and stack allocator. 1247 1248 Because of the obvious security issues, this option should only be 1249 enabled on embedded devices where you control what is run in 1250 userspace. Since that isn't generally a problem on no-MMU systems, 1251 it is normally safe to say Y here. 1252 1253 See Documentation/nommu-mmap.txt for more information. 1254 1255config PROFILING 1256 bool "Profiling support" 1257 help 1258 Say Y here to enable the extended profiling support mechanisms used 1259 by profilers such as OProfile. 1260 1261# 1262# Place an empty function call at each tracepoint site. Can be 1263# dynamically changed for a probe function. 1264# 1265config TRACEPOINTS 1266 bool 1267 1268source "arch/Kconfig" 1269 1270endmenu # General setup 1271 1272config HAVE_GENERIC_DMA_COHERENT 1273 bool 1274 default n 1275 1276config SLABINFO 1277 bool 1278 depends on PROC_FS 1279 depends on SLAB || SLUB_DEBUG 1280 default y 1281 1282config RT_MUTEXES 1283 boolean 1284 1285config BASE_SMALL 1286 int 1287 default 0 if BASE_FULL 1288 default 1 if !BASE_FULL 1289 1290menuconfig MODULES 1291 bool "Enable loadable module support" 1292 help 1293 Kernel modules are small pieces of compiled code which can 1294 be inserted in the running kernel, rather than being 1295 permanently built into the kernel. You use the "modprobe" 1296 tool to add (and sometimes remove) them. If you say Y here, 1297 many parts of the kernel can be built as modules (by 1298 answering M instead of Y where indicated): this is most 1299 useful for infrequently used options which are not required 1300 for booting. For more information, see the man pages for 1301 modprobe, lsmod, modinfo, insmod and rmmod. 1302 1303 If you say Y here, you will need to run "make 1304 modules_install" to put the modules under /lib/modules/ 1305 where modprobe can find them (you may need to be root to do 1306 this). 1307 1308 If unsure, say Y. 1309 1310if MODULES 1311 1312config MODULE_FORCE_LOAD 1313 bool "Forced module loading" 1314 default n 1315 help 1316 Allow loading of modules without version information (ie. modprobe 1317 --force). Forced module loading sets the 'F' (forced) taint flag and 1318 is usually a really bad idea. 1319 1320config MODULE_UNLOAD 1321 bool "Module unloading" 1322 help 1323 Without this option you will not be able to unload any 1324 modules (note that some modules may not be unloadable 1325 anyway), which makes your kernel smaller, faster 1326 and simpler. If unsure, say Y. 1327 1328config MODULE_FORCE_UNLOAD 1329 bool "Forced module unloading" 1330 depends on MODULE_UNLOAD && EXPERIMENTAL 1331 help 1332 This option allows you to force a module to unload, even if the 1333 kernel believes it is unsafe: the kernel will remove the module 1334 without waiting for anyone to stop using it (using the -f option to 1335 rmmod). This is mainly for kernel developers and desperate users. 1336 If unsure, say N. 1337 1338config MODVERSIONS 1339 bool "Module versioning support" 1340 help 1341 Usually, you have to use modules compiled with your kernel. 1342 Saying Y here makes it sometimes possible to use modules 1343 compiled for different kernels, by adding enough information 1344 to the modules to (hopefully) spot any changes which would 1345 make them incompatible with the kernel you are running. If 1346 unsure, say N. 1347 1348config MODULE_SRCVERSION_ALL 1349 bool "Source checksum for all modules" 1350 help 1351 Modules which contain a MODULE_VERSION get an extra "srcversion" 1352 field inserted into their modinfo section, which contains a 1353 sum of the source files which made it. This helps maintainers 1354 see exactly which source was used to build a module (since 1355 others sometimes change the module source without updating 1356 the version). With this option, such a "srcversion" field 1357 will be created for all modules. If unsure, say N. 1358 1359endif # MODULES 1360 1361config INIT_ALL_POSSIBLE 1362 bool 1363 help 1364 Back when each arch used to define their own cpu_online_map and 1365 cpu_possible_map, some of them chose to initialize cpu_possible_map 1366 with all 1s, and others with all 0s. When they were centralised, 1367 it was better to provide this option than to break all the archs 1368 and have several arch maintainers pursuing me down dark alleys. 1369 1370config STOP_MACHINE 1371 bool 1372 default y 1373 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1374 help 1375 Need stop_machine() primitive. 1376 1377source "block/Kconfig" 1378 1379config PREEMPT_NOTIFIERS 1380 bool 1381 1382config PADATA 1383 depends on SMP 1384 bool 1385 1386source "kernel/Kconfig.locks" 1387