1config ARCH 2 string 3 option env="ARCH" 4 5config KERNELVERSION 6 string 7 option env="KERNELVERSION" 8 9config DEFCONFIG_LIST 10 string 11 depends on !UML 12 option defconfig_list 13 default "/lib/modules/$UNAME_RELEASE/.config" 14 default "/etc/kernel-config" 15 default "/boot/config-$UNAME_RELEASE" 16 default "$ARCH_DEFCONFIG" 17 default "arch/$ARCH/defconfig" 18 19config CONSTRUCTORS 20 bool 21 depends on !UML 22 23config HAVE_IRQ_WORK 24 bool 25 26config IRQ_WORK 27 bool 28 depends on HAVE_IRQ_WORK 29 30menu "General setup" 31 32config EXPERIMENTAL 33 bool "Prompt for development and/or incomplete code/drivers" 34 ---help--- 35 Some of the various things that Linux supports (such as network 36 drivers, file systems, network protocols, etc.) can be in a state 37 of development where the functionality, stability, or the level of 38 testing is not yet high enough for general use. This is usually 39 known as the "alpha-test" phase among developers. If a feature is 40 currently in alpha-test, then the developers usually discourage 41 uninformed widespread use of this feature by the general public to 42 avoid "Why doesn't this work?" type mail messages. However, active 43 testing and use of these systems is welcomed. Just be aware that it 44 may not meet the normal level of reliability or it may fail to work 45 in some special cases. Detailed bug reports from people familiar 46 with the kernel internals are usually welcomed by the developers 47 (before submitting bug reports, please read the documents 48 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 49 <file:Documentation/BUG-HUNTING>, and 50 <file:Documentation/oops-tracing.txt> in the kernel source). 51 52 This option will also make obsoleted drivers available. These are 53 drivers that have been replaced by something else, and/or are 54 scheduled to be removed in a future kernel release. 55 56 Unless you intend to help test and develop a feature or driver that 57 falls into this category, or you have a situation that requires 58 using these features, you should probably say N here, which will 59 cause the configurator to present you with fewer choices. If 60 you say Y here, you will be offered the choice of using features or 61 drivers that are currently considered to be in the alpha-test phase. 62 63config BROKEN 64 bool 65 66config BROKEN_ON_SMP 67 bool 68 depends on BROKEN || !SMP 69 default y 70 71config INIT_ENV_ARG_LIMIT 72 int 73 default 32 if !UML 74 default 128 if UML 75 help 76 Maximum of each of the number of arguments and environment 77 variables passed to init from the kernel command line. 78 79 80config CROSS_COMPILE 81 string "Cross-compiler tool prefix" 82 help 83 Same as running 'make CROSS_COMPILE=prefix-' but stored for 84 default make runs in this kernel build directory. You don't 85 need to set this unless you want the configured kernel build 86 directory to select the cross-compiler automatically. 87 88config LOCALVERSION 89 string "Local version - append to kernel release" 90 help 91 Append an extra string to the end of your kernel version. 92 This will show up when you type uname, for example. 93 The string you set here will be appended after the contents of 94 any files with a filename matching localversion* in your 95 object and source tree, in that order. Your total string can 96 be a maximum of 64 characters. 97 98config LOCALVERSION_AUTO 99 bool "Automatically append version information to the version string" 100 default y 101 help 102 This will try to automatically determine if the current tree is a 103 release tree by looking for git tags that belong to the current 104 top of tree revision. 105 106 A string of the format -gxxxxxxxx will be added to the localversion 107 if a git-based tree is found. The string generated by this will be 108 appended after any matching localversion* files, and after the value 109 set in CONFIG_LOCALVERSION. 110 111 (The actual string used here is the first eight characters produced 112 by running the command: 113 114 $ git rev-parse --verify HEAD 115 116 which is done within the script "scripts/setlocalversion".) 117 118config HAVE_KERNEL_GZIP 119 bool 120 121config HAVE_KERNEL_BZIP2 122 bool 123 124config HAVE_KERNEL_LZMA 125 bool 126 127config HAVE_KERNEL_XZ 128 bool 129 130config HAVE_KERNEL_LZO 131 bool 132 133choice 134 prompt "Kernel compression mode" 135 default KERNEL_GZIP 136 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 137 help 138 The linux kernel is a kind of self-extracting executable. 139 Several compression algorithms are available, which differ 140 in efficiency, compression and decompression speed. 141 Compression speed is only relevant when building a kernel. 142 Decompression speed is relevant at each boot. 143 144 If you have any problems with bzip2 or lzma compressed 145 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 146 version of this functionality (bzip2 only), for 2.4, was 147 supplied by Christian Ludwig) 148 149 High compression options are mostly useful for users, who 150 are low on disk space (embedded systems), but for whom ram 151 size matters less. 152 153 If in doubt, select 'gzip' 154 155config KERNEL_GZIP 156 bool "Gzip" 157 depends on HAVE_KERNEL_GZIP 158 help 159 The old and tried gzip compression. It provides a good balance 160 between compression ratio and decompression speed. 161 162config KERNEL_BZIP2 163 bool "Bzip2" 164 depends on HAVE_KERNEL_BZIP2 165 help 166 Its compression ratio and speed is intermediate. 167 Decompression speed is slowest among the three. The kernel 168 size is about 10% smaller with bzip2, in comparison to gzip. 169 Bzip2 uses a large amount of memory. For modern kernels you 170 will need at least 8MB RAM or more for booting. 171 172config KERNEL_LZMA 173 bool "LZMA" 174 depends on HAVE_KERNEL_LZMA 175 help 176 The most recent compression algorithm. 177 Its ratio is best, decompression speed is between the other 178 two. Compression is slowest. The kernel size is about 33% 179 smaller with LZMA in comparison to gzip. 180 181config KERNEL_XZ 182 bool "XZ" 183 depends on HAVE_KERNEL_XZ 184 help 185 XZ uses the LZMA2 algorithm and instruction set specific 186 BCJ filters which can improve compression ratio of executable 187 code. The size of the kernel is about 30% smaller with XZ in 188 comparison to gzip. On architectures for which there is a BCJ 189 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 190 will create a few percent smaller kernel than plain LZMA. 191 192 The speed is about the same as with LZMA: The decompression 193 speed of XZ is better than that of bzip2 but worse than gzip 194 and LZO. Compression is slow. 195 196config KERNEL_LZO 197 bool "LZO" 198 depends on HAVE_KERNEL_LZO 199 help 200 Its compression ratio is the poorest among the 4. The kernel 201 size is about 10% bigger than gzip; however its speed 202 (both compression and decompression) is the fastest. 203 204endchoice 205 206config DEFAULT_HOSTNAME 207 string "Default hostname" 208 default "(none)" 209 help 210 This option determines the default system hostname before userspace 211 calls sethostname(2). The kernel traditionally uses "(none)" here, 212 but you may wish to use a different default here to make a minimal 213 system more usable with less configuration. 214 215config SWAP 216 bool "Support for paging of anonymous memory (swap)" 217 depends on MMU && BLOCK 218 default y 219 help 220 This option allows you to choose whether you want to have support 221 for so called swap devices or swap files in your kernel that are 222 used to provide more virtual memory than the actual RAM present 223 in your computer. If unsure say Y. 224 225config SYSVIPC 226 bool "System V IPC" 227 ---help--- 228 Inter Process Communication is a suite of library functions and 229 system calls which let processes (running programs) synchronize and 230 exchange information. It is generally considered to be a good thing, 231 and some programs won't run unless you say Y here. In particular, if 232 you want to run the DOS emulator dosemu under Linux (read the 233 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 234 you'll need to say Y here. 235 236 You can find documentation about IPC with "info ipc" and also in 237 section 6.4 of the Linux Programmer's Guide, available from 238 <http://www.tldp.org/guides.html>. 239 240config SYSVIPC_SYSCTL 241 bool 242 depends on SYSVIPC 243 depends on SYSCTL 244 default y 245 246config POSIX_MQUEUE 247 bool "POSIX Message Queues" 248 depends on NET && EXPERIMENTAL 249 ---help--- 250 POSIX variant of message queues is a part of IPC. In POSIX message 251 queues every message has a priority which decides about succession 252 of receiving it by a process. If you want to compile and run 253 programs written e.g. for Solaris with use of its POSIX message 254 queues (functions mq_*) say Y here. 255 256 POSIX message queues are visible as a filesystem called 'mqueue' 257 and can be mounted somewhere if you want to do filesystem 258 operations on message queues. 259 260 If unsure, say Y. 261 262config POSIX_MQUEUE_SYSCTL 263 bool 264 depends on POSIX_MQUEUE 265 depends on SYSCTL 266 default y 267 268config BSD_PROCESS_ACCT 269 bool "BSD Process Accounting" 270 help 271 If you say Y here, a user level program will be able to instruct the 272 kernel (via a special system call) to write process accounting 273 information to a file: whenever a process exits, information about 274 that process will be appended to the file by the kernel. The 275 information includes things such as creation time, owning user, 276 command name, memory usage, controlling terminal etc. (the complete 277 list is in the struct acct in <file:include/linux/acct.h>). It is 278 up to the user level program to do useful things with this 279 information. This is generally a good idea, so say Y. 280 281config BSD_PROCESS_ACCT_V3 282 bool "BSD Process Accounting version 3 file format" 283 depends on BSD_PROCESS_ACCT 284 default n 285 help 286 If you say Y here, the process accounting information is written 287 in a new file format that also logs the process IDs of each 288 process and it's parent. Note that this file format is incompatible 289 with previous v0/v1/v2 file formats, so you will need updated tools 290 for processing it. A preliminary version of these tools is available 291 at <http://www.gnu.org/software/acct/>. 292 293config FHANDLE 294 bool "open by fhandle syscalls" 295 select EXPORTFS 296 help 297 If you say Y here, a user level program will be able to map 298 file names to handle and then later use the handle for 299 different file system operations. This is useful in implementing 300 userspace file servers, which now track files using handles instead 301 of names. The handle would remain the same even if file names 302 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 303 syscalls. 304 305config TASKSTATS 306 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 307 depends on NET 308 default n 309 help 310 Export selected statistics for tasks/processes through the 311 generic netlink interface. Unlike BSD process accounting, the 312 statistics are available during the lifetime of tasks/processes as 313 responses to commands. Like BSD accounting, they are sent to user 314 space on task exit. 315 316 Say N if unsure. 317 318config TASK_DELAY_ACCT 319 bool "Enable per-task delay accounting (EXPERIMENTAL)" 320 depends on TASKSTATS 321 help 322 Collect information on time spent by a task waiting for system 323 resources like cpu, synchronous block I/O completion and swapping 324 in pages. Such statistics can help in setting a task's priorities 325 relative to other tasks for cpu, io, rss limits etc. 326 327 Say N if unsure. 328 329config TASK_XACCT 330 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 331 depends on TASKSTATS 332 help 333 Collect extended task accounting data and send the data 334 to userland for processing over the taskstats interface. 335 336 Say N if unsure. 337 338config TASK_IO_ACCOUNTING 339 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 340 depends on TASK_XACCT 341 help 342 Collect information on the number of bytes of storage I/O which this 343 task has caused. 344 345 Say N if unsure. 346 347config AUDIT 348 bool "Auditing support" 349 depends on NET 350 help 351 Enable auditing infrastructure that can be used with another 352 kernel subsystem, such as SELinux (which requires this for 353 logging of avc messages output). Does not do system-call 354 auditing without CONFIG_AUDITSYSCALL. 355 356config AUDITSYSCALL 357 bool "Enable system-call auditing support" 358 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || ARM) 359 default y if SECURITY_SELINUX 360 help 361 Enable low-overhead system-call auditing infrastructure that 362 can be used independently or with another kernel subsystem, 363 such as SELinux. 364 365config AUDIT_WATCH 366 def_bool y 367 depends on AUDITSYSCALL 368 select FSNOTIFY 369 370config AUDIT_TREE 371 def_bool y 372 depends on AUDITSYSCALL 373 select FSNOTIFY 374 375config AUDIT_LOGINUID_IMMUTABLE 376 bool "Make audit loginuid immutable" 377 depends on AUDIT 378 help 379 The config option toggles if a task setting its loginuid requires 380 CAP_SYS_AUDITCONTROL or if that task should require no special permissions 381 but should instead only allow setting its loginuid if it was never 382 previously set. On systems which use systemd or a similar central 383 process to restart login services this should be set to true. On older 384 systems in which an admin would typically have to directly stop and 385 start processes this should be set to false. Setting this to true allows 386 one to drop potentially dangerous capabilites from the login tasks, 387 but may not be backwards compatible with older init systems. 388 389source "kernel/irq/Kconfig" 390 391menu "RCU Subsystem" 392 393choice 394 prompt "RCU Implementation" 395 default TREE_RCU 396 397config TREE_RCU 398 bool "Tree-based hierarchical RCU" 399 depends on !PREEMPT && SMP 400 help 401 This option selects the RCU implementation that is 402 designed for very large SMP system with hundreds or 403 thousands of CPUs. It also scales down nicely to 404 smaller systems. 405 406config TREE_PREEMPT_RCU 407 bool "Preemptible tree-based hierarchical RCU" 408 depends on PREEMPT && SMP 409 help 410 This option selects the RCU implementation that is 411 designed for very large SMP systems with hundreds or 412 thousands of CPUs, but for which real-time response 413 is also required. It also scales down nicely to 414 smaller systems. 415 416config TINY_RCU 417 bool "UP-only small-memory-footprint RCU" 418 depends on !PREEMPT && !SMP 419 help 420 This option selects the RCU implementation that is 421 designed for UP systems from which real-time response 422 is not required. This option greatly reduces the 423 memory footprint of RCU. 424 425config TINY_PREEMPT_RCU 426 bool "Preemptible UP-only small-memory-footprint RCU" 427 depends on PREEMPT && !SMP 428 help 429 This option selects the RCU implementation that is designed 430 for real-time UP systems. This option greatly reduces the 431 memory footprint of RCU. 432 433endchoice 434 435config PREEMPT_RCU 436 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 437 help 438 This option enables preemptible-RCU code that is common between 439 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 440 441config RCU_FANOUT 442 int "Tree-based hierarchical RCU fanout value" 443 range 2 64 if 64BIT 444 range 2 32 if !64BIT 445 depends on TREE_RCU || TREE_PREEMPT_RCU 446 default 64 if 64BIT 447 default 32 if !64BIT 448 help 449 This option controls the fanout of hierarchical implementations 450 of RCU, allowing RCU to work efficiently on machines with 451 large numbers of CPUs. This value must be at least the fourth 452 root of NR_CPUS, which allows NR_CPUS to be insanely large. 453 The default value of RCU_FANOUT should be used for production 454 systems, but if you are stress-testing the RCU implementation 455 itself, small RCU_FANOUT values allow you to test large-system 456 code paths on small(er) systems. 457 458 Select a specific number if testing RCU itself. 459 Take the default if unsure. 460 461config RCU_FANOUT_EXACT 462 bool "Disable tree-based hierarchical RCU auto-balancing" 463 depends on TREE_RCU || TREE_PREEMPT_RCU 464 default n 465 help 466 This option forces use of the exact RCU_FANOUT value specified, 467 regardless of imbalances in the hierarchy. This is useful for 468 testing RCU itself, and might one day be useful on systems with 469 strong NUMA behavior. 470 471 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 472 473 Say N if unsure. 474 475config RCU_FAST_NO_HZ 476 bool "Accelerate last non-dyntick-idle CPU's grace periods" 477 depends on NO_HZ && SMP 478 default n 479 help 480 This option causes RCU to attempt to accelerate grace periods 481 in order to allow CPUs to enter dynticks-idle state more 482 quickly. On the other hand, this option increases the overhead 483 of the dynticks-idle checking, particularly on systems with 484 large numbers of CPUs. 485 486 Say Y if energy efficiency is critically important, particularly 487 if you have relatively few CPUs. 488 489 Say N if you are unsure. 490 491config TREE_RCU_TRACE 492 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 493 select DEBUG_FS 494 help 495 This option provides tracing for the TREE_RCU and 496 TREE_PREEMPT_RCU implementations, permitting Makefile to 497 trivially select kernel/rcutree_trace.c. 498 499config RCU_BOOST 500 bool "Enable RCU priority boosting" 501 depends on RT_MUTEXES && PREEMPT_RCU 502 default n 503 help 504 This option boosts the priority of preempted RCU readers that 505 block the current preemptible RCU grace period for too long. 506 This option also prevents heavy loads from blocking RCU 507 callback invocation for all flavors of RCU. 508 509 Say Y here if you are working with real-time apps or heavy loads 510 Say N here if you are unsure. 511 512config RCU_BOOST_PRIO 513 int "Real-time priority to boost RCU readers to" 514 range 1 99 515 depends on RCU_BOOST 516 default 1 517 help 518 This option specifies the real-time priority to which preempted 519 RCU readers are to be boosted. If you are working with CPU-bound 520 real-time applications, you should specify a priority higher then 521 the highest-priority CPU-bound application. 522 523 Specify the real-time priority, or take the default if unsure. 524 525config RCU_BOOST_DELAY 526 int "Milliseconds to delay boosting after RCU grace-period start" 527 range 0 3000 528 depends on RCU_BOOST 529 default 500 530 help 531 This option specifies the time to wait after the beginning of 532 a given grace period before priority-boosting preempted RCU 533 readers blocking that grace period. Note that any RCU reader 534 blocking an expedited RCU grace period is boosted immediately. 535 536 Accept the default if unsure. 537 538endmenu # "RCU Subsystem" 539 540config IKCONFIG 541 tristate "Kernel .config support" 542 ---help--- 543 This option enables the complete Linux kernel ".config" file 544 contents to be saved in the kernel. It provides documentation 545 of which kernel options are used in a running kernel or in an 546 on-disk kernel. This information can be extracted from the kernel 547 image file with the script scripts/extract-ikconfig and used as 548 input to rebuild the current kernel or to build another kernel. 549 It can also be extracted from a running kernel by reading 550 /proc/config.gz if enabled (below). 551 552config IKCONFIG_PROC 553 bool "Enable access to .config through /proc/config.gz" 554 depends on IKCONFIG && PROC_FS 555 ---help--- 556 This option enables access to the kernel configuration file 557 through /proc/config.gz. 558 559config LOG_BUF_SHIFT 560 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 561 range 12 21 562 default 17 563 help 564 Select kernel log buffer size as a power of 2. 565 Examples: 566 17 => 128 KB 567 16 => 64 KB 568 15 => 32 KB 569 14 => 16 KB 570 13 => 8 KB 571 12 => 4 KB 572 573# 574# Architectures with an unreliable sched_clock() should select this: 575# 576config HAVE_UNSTABLE_SCHED_CLOCK 577 bool 578 579menuconfig CGROUPS 580 boolean "Control Group support" 581 depends on EVENTFD 582 help 583 This option adds support for grouping sets of processes together, for 584 use with process control subsystems such as Cpusets, CFS, memory 585 controls or device isolation. 586 See 587 - Documentation/scheduler/sched-design-CFS.txt (CFS) 588 - Documentation/cgroups/ (features for grouping, isolation 589 and resource control) 590 591 Say N if unsure. 592 593if CGROUPS 594 595config CGROUP_DEBUG 596 bool "Example debug cgroup subsystem" 597 default n 598 help 599 This option enables a simple cgroup subsystem that 600 exports useful debugging information about the cgroups 601 framework. 602 603 Say N if unsure. 604 605config CGROUP_FREEZER 606 bool "Freezer cgroup subsystem" 607 help 608 Provides a way to freeze and unfreeze all tasks in a 609 cgroup. 610 611config CGROUP_DEVICE 612 bool "Device controller for cgroups" 613 help 614 Provides a cgroup implementing whitelists for devices which 615 a process in the cgroup can mknod or open. 616 617config CPUSETS 618 bool "Cpuset support" 619 help 620 This option will let you create and manage CPUSETs which 621 allow dynamically partitioning a system into sets of CPUs and 622 Memory Nodes and assigning tasks to run only within those sets. 623 This is primarily useful on large SMP or NUMA systems. 624 625 Say N if unsure. 626 627config PROC_PID_CPUSET 628 bool "Include legacy /proc/<pid>/cpuset file" 629 depends on CPUSETS 630 default y 631 632config CGROUP_CPUACCT 633 bool "Simple CPU accounting cgroup subsystem" 634 help 635 Provides a simple Resource Controller for monitoring the 636 total CPU consumed by the tasks in a cgroup. 637 638config RESOURCE_COUNTERS 639 bool "Resource counters" 640 help 641 This option enables controller independent resource accounting 642 infrastructure that works with cgroups. 643 644config CGROUP_MEM_RES_CTLR 645 bool "Memory Resource Controller for Control Groups" 646 depends on RESOURCE_COUNTERS 647 select MM_OWNER 648 help 649 Provides a memory resource controller that manages both anonymous 650 memory and page cache. (See Documentation/cgroups/memory.txt) 651 652 Note that setting this option increases fixed memory overhead 653 associated with each page of memory in the system. By this, 654 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 655 usage tracking struct at boot. Total amount of this is printed out 656 at boot. 657 658 Only enable when you're ok with these trade offs and really 659 sure you need the memory resource controller. Even when you enable 660 this, you can set "cgroup_disable=memory" at your boot option to 661 disable memory resource controller and you can avoid overheads. 662 (and lose benefits of memory resource controller) 663 664 This config option also selects MM_OWNER config option, which 665 could in turn add some fork/exit overhead. 666 667config CGROUP_MEM_RES_CTLR_SWAP 668 bool "Memory Resource Controller Swap Extension" 669 depends on CGROUP_MEM_RES_CTLR && SWAP 670 help 671 Add swap management feature to memory resource controller. When you 672 enable this, you can limit mem+swap usage per cgroup. In other words, 673 when you disable this, memory resource controller has no cares to 674 usage of swap...a process can exhaust all of the swap. This extension 675 is useful when you want to avoid exhaustion swap but this itself 676 adds more overheads and consumes memory for remembering information. 677 Especially if you use 32bit system or small memory system, please 678 be careful about enabling this. When memory resource controller 679 is disabled by boot option, this will be automatically disabled and 680 there will be no overhead from this. Even when you set this config=y, 681 if boot option "swapaccount=0" is set, swap will not be accounted. 682 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 683 size is 4096bytes, 512k per 1Gbytes of swap. 684config CGROUP_MEM_RES_CTLR_SWAP_ENABLED 685 bool "Memory Resource Controller Swap Extension enabled by default" 686 depends on CGROUP_MEM_RES_CTLR_SWAP 687 default y 688 help 689 Memory Resource Controller Swap Extension comes with its price in 690 a bigger memory consumption. General purpose distribution kernels 691 which want to enable the feature but keep it disabled by default 692 and let the user enable it by swapaccount boot command line 693 parameter should have this option unselected. 694 For those who want to have the feature enabled by default should 695 select this option (if, for some reason, they need to disable it 696 then swapaccount=0 does the trick). 697config CGROUP_MEM_RES_CTLR_KMEM 698 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)" 699 depends on CGROUP_MEM_RES_CTLR && EXPERIMENTAL 700 default n 701 help 702 The Kernel Memory extension for Memory Resource Controller can limit 703 the amount of memory used by kernel objects in the system. Those are 704 fundamentally different from the entities handled by the standard 705 Memory Controller, which are page-based, and can be swapped. Users of 706 the kmem extension can use it to guarantee that no group of processes 707 will ever exhaust kernel resources alone. 708 709config CGROUP_PERF 710 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 711 depends on PERF_EVENTS && CGROUPS 712 help 713 This option extends the per-cpu mode to restrict monitoring to 714 threads which belong to the cgroup specified and run on the 715 designated cpu. 716 717 Say N if unsure. 718 719menuconfig CGROUP_SCHED 720 bool "Group CPU scheduler" 721 default n 722 help 723 This feature lets CPU scheduler recognize task groups and control CPU 724 bandwidth allocation to such task groups. It uses cgroups to group 725 tasks. 726 727if CGROUP_SCHED 728config FAIR_GROUP_SCHED 729 bool "Group scheduling for SCHED_OTHER" 730 depends on CGROUP_SCHED 731 default CGROUP_SCHED 732 733config CFS_BANDWIDTH 734 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 735 depends on EXPERIMENTAL 736 depends on FAIR_GROUP_SCHED 737 default n 738 help 739 This option allows users to define CPU bandwidth rates (limits) for 740 tasks running within the fair group scheduler. Groups with no limit 741 set are considered to be unconstrained and will run with no 742 restriction. 743 See tip/Documentation/scheduler/sched-bwc.txt for more information. 744 745config RT_GROUP_SCHED 746 bool "Group scheduling for SCHED_RR/FIFO" 747 depends on EXPERIMENTAL 748 depends on CGROUP_SCHED 749 default n 750 help 751 This feature lets you explicitly allocate real CPU bandwidth 752 to task groups. If enabled, it will also make it impossible to 753 schedule realtime tasks for non-root users until you allocate 754 realtime bandwidth for them. 755 See Documentation/scheduler/sched-rt-group.txt for more information. 756 757endif #CGROUP_SCHED 758 759config BLK_CGROUP 760 tristate "Block IO controller" 761 depends on BLOCK 762 default n 763 ---help--- 764 Generic block IO controller cgroup interface. This is the common 765 cgroup interface which should be used by various IO controlling 766 policies. 767 768 Currently, CFQ IO scheduler uses it to recognize task groups and 769 control disk bandwidth allocation (proportional time slice allocation) 770 to such task groups. It is also used by bio throttling logic in 771 block layer to implement upper limit in IO rates on a device. 772 773 This option only enables generic Block IO controller infrastructure. 774 One needs to also enable actual IO controlling logic/policy. For 775 enabling proportional weight division of disk bandwidth in CFQ, set 776 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 777 CONFIG_BLK_DEV_THROTTLING=y. 778 779 See Documentation/cgroups/blkio-controller.txt for more information. 780 781config DEBUG_BLK_CGROUP 782 bool "Enable Block IO controller debugging" 783 depends on BLK_CGROUP 784 default n 785 ---help--- 786 Enable some debugging help. Currently it exports additional stat 787 files in a cgroup which can be useful for debugging. 788 789endif # CGROUPS 790 791config CHECKPOINT_RESTORE 792 bool "Checkpoint/restore support" if EXPERT 793 default n 794 help 795 Enables additional kernel features in a sake of checkpoint/restore. 796 In particular it adds auxiliary prctl codes to setup process text, 797 data and heap segment sizes, and a few additional /proc filesystem 798 entries. 799 800 If unsure, say N here. 801 802menuconfig NAMESPACES 803 bool "Namespaces support" if EXPERT 804 default !EXPERT 805 help 806 Provides the way to make tasks work with different objects using 807 the same id. For example same IPC id may refer to different objects 808 or same user id or pid may refer to different tasks when used in 809 different namespaces. 810 811if NAMESPACES 812 813config UTS_NS 814 bool "UTS namespace" 815 default y 816 help 817 In this namespace tasks see different info provided with the 818 uname() system call 819 820config IPC_NS 821 bool "IPC namespace" 822 depends on (SYSVIPC || POSIX_MQUEUE) 823 default y 824 help 825 In this namespace tasks work with IPC ids which correspond to 826 different IPC objects in different namespaces. 827 828config USER_NS 829 bool "User namespace (EXPERIMENTAL)" 830 depends on EXPERIMENTAL 831 default y 832 help 833 This allows containers, i.e. vservers, to use user namespaces 834 to provide different user info for different servers. 835 If unsure, say N. 836 837config PID_NS 838 bool "PID Namespaces" 839 default y 840 help 841 Support process id namespaces. This allows having multiple 842 processes with the same pid as long as they are in different 843 pid namespaces. This is a building block of containers. 844 845config NET_NS 846 bool "Network namespace" 847 depends on NET 848 default y 849 help 850 Allow user space to create what appear to be multiple instances 851 of the network stack. 852 853endif # NAMESPACES 854 855config SCHED_AUTOGROUP 856 bool "Automatic process group scheduling" 857 select EVENTFD 858 select CGROUPS 859 select CGROUP_SCHED 860 select FAIR_GROUP_SCHED 861 help 862 This option optimizes the scheduler for common desktop workloads by 863 automatically creating and populating task groups. This separation 864 of workloads isolates aggressive CPU burners (like build jobs) from 865 desktop applications. Task group autogeneration is currently based 866 upon task session. 867 868config MM_OWNER 869 bool 870 871config SYSFS_DEPRECATED 872 bool "Enable deprecated sysfs features to support old userspace tools" 873 depends on SYSFS 874 default n 875 help 876 This option adds code that switches the layout of the "block" class 877 devices, to not show up in /sys/class/block/, but only in 878 /sys/block/. 879 880 This switch is only active when the sysfs.deprecated=1 boot option is 881 passed or the SYSFS_DEPRECATED_V2 option is set. 882 883 This option allows new kernels to run on old distributions and tools, 884 which might get confused by /sys/class/block/. Since 2007/2008 all 885 major distributions and tools handle this just fine. 886 887 Recent distributions and userspace tools after 2009/2010 depend on 888 the existence of /sys/class/block/, and will not work with this 889 option enabled. 890 891 Only if you are using a new kernel on an old distribution, you might 892 need to say Y here. 893 894config SYSFS_DEPRECATED_V2 895 bool "Enable deprecated sysfs features by default" 896 default n 897 depends on SYSFS 898 depends on SYSFS_DEPRECATED 899 help 900 Enable deprecated sysfs by default. 901 902 See the CONFIG_SYSFS_DEPRECATED option for more details about this 903 option. 904 905 Only if you are using a new kernel on an old distribution, you might 906 need to say Y here. Even then, odds are you would not need it 907 enabled, you can always pass the boot option if absolutely necessary. 908 909config RELAY 910 bool "Kernel->user space relay support (formerly relayfs)" 911 help 912 This option enables support for relay interface support in 913 certain file systems (such as debugfs). 914 It is designed to provide an efficient mechanism for tools and 915 facilities to relay large amounts of data from kernel space to 916 user space. 917 918 If unsure, say N. 919 920config BLK_DEV_INITRD 921 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 922 depends on BROKEN || !FRV 923 help 924 The initial RAM filesystem is a ramfs which is loaded by the 925 boot loader (loadlin or lilo) and that is mounted as root 926 before the normal boot procedure. It is typically used to 927 load modules needed to mount the "real" root file system, 928 etc. See <file:Documentation/initrd.txt> for details. 929 930 If RAM disk support (BLK_DEV_RAM) is also included, this 931 also enables initial RAM disk (initrd) support and adds 932 15 Kbytes (more on some other architectures) to the kernel size. 933 934 If unsure say Y. 935 936if BLK_DEV_INITRD 937 938source "usr/Kconfig" 939 940endif 941 942config CC_OPTIMIZE_FOR_SIZE 943 bool "Optimize for size" 944 help 945 Enabling this option will pass "-Os" instead of "-O2" to gcc 946 resulting in a smaller kernel. 947 948 If unsure, say Y. 949 950config SYSCTL 951 bool 952 953config ANON_INODES 954 bool 955 956menuconfig EXPERT 957 bool "Configure standard kernel features (expert users)" 958 # Unhide debug options, to make the on-by-default options visible 959 select DEBUG_KERNEL 960 help 961 This option allows certain base kernel options and settings 962 to be disabled or tweaked. This is for specialized 963 environments which can tolerate a "non-standard" kernel. 964 Only use this if you really know what you are doing. 965 966config UID16 967 bool "Enable 16-bit UID system calls" if EXPERT 968 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 969 default y 970 help 971 This enables the legacy 16-bit UID syscall wrappers. 972 973config SYSCTL_SYSCALL 974 bool "Sysctl syscall support" if EXPERT 975 depends on PROC_SYSCTL 976 default n 977 select SYSCTL 978 ---help--- 979 sys_sysctl uses binary paths that have been found challenging 980 to properly maintain and use. The interface in /proc/sys 981 using paths with ascii names is now the primary path to this 982 information. 983 984 Almost nothing using the binary sysctl interface so if you are 985 trying to save some space it is probably safe to disable this, 986 making your kernel marginally smaller. 987 988 If unsure say N here. 989 990config KALLSYMS 991 bool "Load all symbols for debugging/ksymoops" if EXPERT 992 default y 993 help 994 Say Y here to let the kernel print out symbolic crash information and 995 symbolic stack backtraces. This increases the size of the kernel 996 somewhat, as all symbols have to be loaded into the kernel image. 997 998config KALLSYMS_ALL 999 bool "Include all symbols in kallsyms" 1000 depends on DEBUG_KERNEL && KALLSYMS 1001 help 1002 Normally kallsyms only contains the symbols of functions for nicer 1003 OOPS messages and backtraces (i.e., symbols from the text and inittext 1004 sections). This is sufficient for most cases. And only in very rare 1005 cases (e.g., when a debugger is used) all symbols are required (e.g., 1006 names of variables from the data sections, etc). 1007 1008 This option makes sure that all symbols are loaded into the kernel 1009 image (i.e., symbols from all sections) in cost of increased kernel 1010 size (depending on the kernel configuration, it may be 300KiB or 1011 something like this). 1012 1013 Say N unless you really need all symbols. 1014 1015config HOTPLUG 1016 bool "Support for hot-pluggable devices" if EXPERT 1017 default y 1018 help 1019 This option is provided for the case where no hotplug or uevent 1020 capabilities is wanted by the kernel. You should only consider 1021 disabling this option for embedded systems that do not use modules, a 1022 dynamic /dev tree, or dynamic device discovery. Just say Y. 1023 1024config PRINTK 1025 default y 1026 bool "Enable support for printk" if EXPERT 1027 help 1028 This option enables normal printk support. Removing it 1029 eliminates most of the message strings from the kernel image 1030 and makes the kernel more or less silent. As this makes it 1031 very difficult to diagnose system problems, saying N here is 1032 strongly discouraged. 1033 1034config BUG 1035 bool "BUG() support" if EXPERT 1036 default y 1037 help 1038 Disabling this option eliminates support for BUG and WARN, reducing 1039 the size of your kernel image and potentially quietly ignoring 1040 numerous fatal conditions. You should only consider disabling this 1041 option for embedded systems with no facilities for reporting errors. 1042 Just say Y. 1043 1044config ELF_CORE 1045 default y 1046 bool "Enable ELF core dumps" if EXPERT 1047 help 1048 Enable support for generating core dumps. Disabling saves about 4k. 1049 1050 1051config PCSPKR_PLATFORM 1052 bool "Enable PC-Speaker support" if EXPERT 1053 depends on HAVE_PCSPKR_PLATFORM 1054 select I8253_LOCK 1055 default y 1056 help 1057 This option allows to disable the internal PC-Speaker 1058 support, saving some memory. 1059 1060config HAVE_PCSPKR_PLATFORM 1061 bool 1062 1063config BASE_FULL 1064 default y 1065 bool "Enable full-sized data structures for core" if EXPERT 1066 help 1067 Disabling this option reduces the size of miscellaneous core 1068 kernel data structures. This saves memory on small machines, 1069 but may reduce performance. 1070 1071config FUTEX 1072 bool "Enable futex support" if EXPERT 1073 default y 1074 select RT_MUTEXES 1075 help 1076 Disabling this option will cause the kernel to be built without 1077 support for "fast userspace mutexes". The resulting kernel may not 1078 run glibc-based applications correctly. 1079 1080config EPOLL 1081 bool "Enable eventpoll support" if EXPERT 1082 default y 1083 select ANON_INODES 1084 help 1085 Disabling this option will cause the kernel to be built without 1086 support for epoll family of system calls. 1087 1088config SIGNALFD 1089 bool "Enable signalfd() system call" if EXPERT 1090 select ANON_INODES 1091 default y 1092 help 1093 Enable the signalfd() system call that allows to receive signals 1094 on a file descriptor. 1095 1096 If unsure, say Y. 1097 1098config TIMERFD 1099 bool "Enable timerfd() system call" if EXPERT 1100 select ANON_INODES 1101 default y 1102 help 1103 Enable the timerfd() system call that allows to receive timer 1104 events on a file descriptor. 1105 1106 If unsure, say Y. 1107 1108config EVENTFD 1109 bool "Enable eventfd() system call" if EXPERT 1110 select ANON_INODES 1111 default y 1112 help 1113 Enable the eventfd() system call that allows to receive both 1114 kernel notification (ie. KAIO) or userspace notifications. 1115 1116 If unsure, say Y. 1117 1118config SHMEM 1119 bool "Use full shmem filesystem" if EXPERT 1120 default y 1121 depends on MMU 1122 help 1123 The shmem is an internal filesystem used to manage shared memory. 1124 It is backed by swap and manages resource limits. It is also exported 1125 to userspace as tmpfs if TMPFS is enabled. Disabling this 1126 option replaces shmem and tmpfs with the much simpler ramfs code, 1127 which may be appropriate on small systems without swap. 1128 1129config AIO 1130 bool "Enable AIO support" if EXPERT 1131 default y 1132 help 1133 This option enables POSIX asynchronous I/O which may by used 1134 by some high performance threaded applications. Disabling 1135 this option saves about 7k. 1136 1137config EMBEDDED 1138 bool "Embedded system" 1139 select EXPERT 1140 help 1141 This option should be enabled if compiling the kernel for 1142 an embedded system so certain expert options are available 1143 for configuration. 1144 1145config HAVE_PERF_EVENTS 1146 bool 1147 help 1148 See tools/perf/design.txt for details. 1149 1150config PERF_USE_VMALLOC 1151 bool 1152 help 1153 See tools/perf/design.txt for details 1154 1155menu "Kernel Performance Events And Counters" 1156 1157config PERF_EVENTS 1158 bool "Kernel performance events and counters" 1159 default y if (PROFILING || PERF_COUNTERS) 1160 depends on HAVE_PERF_EVENTS 1161 select ANON_INODES 1162 select IRQ_WORK 1163 help 1164 Enable kernel support for various performance events provided 1165 by software and hardware. 1166 1167 Software events are supported either built-in or via the 1168 use of generic tracepoints. 1169 1170 Most modern CPUs support performance events via performance 1171 counter registers. These registers count the number of certain 1172 types of hw events: such as instructions executed, cachemisses 1173 suffered, or branches mis-predicted - without slowing down the 1174 kernel or applications. These registers can also trigger interrupts 1175 when a threshold number of events have passed - and can thus be 1176 used to profile the code that runs on that CPU. 1177 1178 The Linux Performance Event subsystem provides an abstraction of 1179 these software and hardware event capabilities, available via a 1180 system call and used by the "perf" utility in tools/perf/. It 1181 provides per task and per CPU counters, and it provides event 1182 capabilities on top of those. 1183 1184 Say Y if unsure. 1185 1186config PERF_COUNTERS 1187 bool "Kernel performance counters (old config option)" 1188 depends on HAVE_PERF_EVENTS 1189 help 1190 This config has been obsoleted by the PERF_EVENTS 1191 config option - please see that one for details. 1192 1193 It has no effect on the kernel whether you enable 1194 it or not, it is a compatibility placeholder. 1195 1196 Say N if unsure. 1197 1198config DEBUG_PERF_USE_VMALLOC 1199 default n 1200 bool "Debug: use vmalloc to back perf mmap() buffers" 1201 depends on PERF_EVENTS && DEBUG_KERNEL 1202 select PERF_USE_VMALLOC 1203 help 1204 Use vmalloc memory to back perf mmap() buffers. 1205 1206 Mostly useful for debugging the vmalloc code on platforms 1207 that don't require it. 1208 1209 Say N if unsure. 1210 1211endmenu 1212 1213config VM_EVENT_COUNTERS 1214 default y 1215 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1216 help 1217 VM event counters are needed for event counts to be shown. 1218 This option allows the disabling of the VM event counters 1219 on EXPERT systems. /proc/vmstat will only show page counts 1220 if VM event counters are disabled. 1221 1222config PCI_QUIRKS 1223 default y 1224 bool "Enable PCI quirk workarounds" if EXPERT 1225 depends on PCI 1226 help 1227 This enables workarounds for various PCI chipset 1228 bugs/quirks. Disable this only if your target machine is 1229 unaffected by PCI quirks. 1230 1231config SLUB_DEBUG 1232 default y 1233 bool "Enable SLUB debugging support" if EXPERT 1234 depends on SLUB && SYSFS 1235 help 1236 SLUB has extensive debug support features. Disabling these can 1237 result in significant savings in code size. This also disables 1238 SLUB sysfs support. /sys/slab will not exist and there will be 1239 no support for cache validation etc. 1240 1241config COMPAT_BRK 1242 bool "Disable heap randomization" 1243 default y 1244 help 1245 Randomizing heap placement makes heap exploits harder, but it 1246 also breaks ancient binaries (including anything libc5 based). 1247 This option changes the bootup default to heap randomization 1248 disabled, and can be overridden at runtime by setting 1249 /proc/sys/kernel/randomize_va_space to 2. 1250 1251 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1252 1253choice 1254 prompt "Choose SLAB allocator" 1255 default SLUB 1256 help 1257 This option allows to select a slab allocator. 1258 1259config SLAB 1260 bool "SLAB" 1261 help 1262 The regular slab allocator that is established and known to work 1263 well in all environments. It organizes cache hot objects in 1264 per cpu and per node queues. 1265 1266config SLUB 1267 bool "SLUB (Unqueued Allocator)" 1268 help 1269 SLUB is a slab allocator that minimizes cache line usage 1270 instead of managing queues of cached objects (SLAB approach). 1271 Per cpu caching is realized using slabs of objects instead 1272 of queues of objects. SLUB can use memory efficiently 1273 and has enhanced diagnostics. SLUB is the default choice for 1274 a slab allocator. 1275 1276config SLOB 1277 depends on EXPERT 1278 bool "SLOB (Simple Allocator)" 1279 help 1280 SLOB replaces the stock allocator with a drastically simpler 1281 allocator. SLOB is generally more space efficient but 1282 does not perform as well on large systems. 1283 1284endchoice 1285 1286config MMAP_ALLOW_UNINITIALIZED 1287 bool "Allow mmapped anonymous memory to be uninitialized" 1288 depends on EXPERT && !MMU 1289 default n 1290 help 1291 Normally, and according to the Linux spec, anonymous memory obtained 1292 from mmap() has it's contents cleared before it is passed to 1293 userspace. Enabling this config option allows you to request that 1294 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1295 providing a huge performance boost. If this option is not enabled, 1296 then the flag will be ignored. 1297 1298 This is taken advantage of by uClibc's malloc(), and also by 1299 ELF-FDPIC binfmt's brk and stack allocator. 1300 1301 Because of the obvious security issues, this option should only be 1302 enabled on embedded devices where you control what is run in 1303 userspace. Since that isn't generally a problem on no-MMU systems, 1304 it is normally safe to say Y here. 1305 1306 See Documentation/nommu-mmap.txt for more information. 1307 1308config PROFILING 1309 bool "Profiling support" 1310 help 1311 Say Y here to enable the extended profiling support mechanisms used 1312 by profilers such as OProfile. 1313 1314# 1315# Place an empty function call at each tracepoint site. Can be 1316# dynamically changed for a probe function. 1317# 1318config TRACEPOINTS 1319 bool 1320 1321source "arch/Kconfig" 1322 1323endmenu # General setup 1324 1325config HAVE_GENERIC_DMA_COHERENT 1326 bool 1327 default n 1328 1329config SLABINFO 1330 bool 1331 depends on PROC_FS 1332 depends on SLAB || SLUB_DEBUG 1333 default y 1334 1335config RT_MUTEXES 1336 boolean 1337 1338config BASE_SMALL 1339 int 1340 default 0 if BASE_FULL 1341 default 1 if !BASE_FULL 1342 1343menuconfig MODULES 1344 bool "Enable loadable module support" 1345 help 1346 Kernel modules are small pieces of compiled code which can 1347 be inserted in the running kernel, rather than being 1348 permanently built into the kernel. You use the "modprobe" 1349 tool to add (and sometimes remove) them. If you say Y here, 1350 many parts of the kernel can be built as modules (by 1351 answering M instead of Y where indicated): this is most 1352 useful for infrequently used options which are not required 1353 for booting. For more information, see the man pages for 1354 modprobe, lsmod, modinfo, insmod and rmmod. 1355 1356 If you say Y here, you will need to run "make 1357 modules_install" to put the modules under /lib/modules/ 1358 where modprobe can find them (you may need to be root to do 1359 this). 1360 1361 If unsure, say Y. 1362 1363if MODULES 1364 1365config MODULE_FORCE_LOAD 1366 bool "Forced module loading" 1367 default n 1368 help 1369 Allow loading of modules without version information (ie. modprobe 1370 --force). Forced module loading sets the 'F' (forced) taint flag and 1371 is usually a really bad idea. 1372 1373config MODULE_UNLOAD 1374 bool "Module unloading" 1375 help 1376 Without this option you will not be able to unload any 1377 modules (note that some modules may not be unloadable 1378 anyway), which makes your kernel smaller, faster 1379 and simpler. If unsure, say Y. 1380 1381config MODULE_FORCE_UNLOAD 1382 bool "Forced module unloading" 1383 depends on MODULE_UNLOAD && EXPERIMENTAL 1384 help 1385 This option allows you to force a module to unload, even if the 1386 kernel believes it is unsafe: the kernel will remove the module 1387 without waiting for anyone to stop using it (using the -f option to 1388 rmmod). This is mainly for kernel developers and desperate users. 1389 If unsure, say N. 1390 1391config MODVERSIONS 1392 bool "Module versioning support" 1393 help 1394 Usually, you have to use modules compiled with your kernel. 1395 Saying Y here makes it sometimes possible to use modules 1396 compiled for different kernels, by adding enough information 1397 to the modules to (hopefully) spot any changes which would 1398 make them incompatible with the kernel you are running. If 1399 unsure, say N. 1400 1401config MODULE_SRCVERSION_ALL 1402 bool "Source checksum for all modules" 1403 help 1404 Modules which contain a MODULE_VERSION get an extra "srcversion" 1405 field inserted into their modinfo section, which contains a 1406 sum of the source files which made it. This helps maintainers 1407 see exactly which source was used to build a module (since 1408 others sometimes change the module source without updating 1409 the version). With this option, such a "srcversion" field 1410 will be created for all modules. If unsure, say N. 1411 1412endif # MODULES 1413 1414config INIT_ALL_POSSIBLE 1415 bool 1416 help 1417 Back when each arch used to define their own cpu_online_mask and 1418 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 1419 with all 1s, and others with all 0s. When they were centralised, 1420 it was better to provide this option than to break all the archs 1421 and have several arch maintainers pursuing me down dark alleys. 1422 1423config STOP_MACHINE 1424 bool 1425 default y 1426 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1427 help 1428 Need stop_machine() primitive. 1429 1430source "block/Kconfig" 1431 1432config PREEMPT_NOTIFIERS 1433 bool 1434 1435config PADATA 1436 depends on SMP 1437 bool 1438 1439source "kernel/Kconfig.locks" 1440