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 These are 54 drivers that have been replaced by something else, and/or are 55 scheduled to be removed in a future kernel release. 56 57 Unless you intend to help test and develop a feature or driver that 58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