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 These are 47 drivers that have been replaced by something else, and/or are 48 scheduled to be removed in a future kernel release. 49 50 Unless you intend to help test and develop a feature or driver that 51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