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 These are 47 drivers that have been replaced by something else, and/or are 48 scheduled to be removed in a future kernel release. 49 50 Unless you intend to help test and develop a feature or driver that 51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 118choice 119 prompt "Kernel compression mode" 120 default KERNEL_GZIP 121 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA 122 help 123 The linux kernel is a kind of self-extracting executable. 124 Several compression algorithms are available, which differ 125 in efficiency, compression and decompression speed. 126 Compression speed is only relevant when building a kernel. 127 Decompression speed is relevant at each boot. 128 129 If you have any problems with bzip2 or lzma compressed 130 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 131 version of this functionality (bzip2 only), for 2.4, was 132 supplied by Christian Ludwig) 133 134 High compression options are mostly useful for users, who 135 are low on disk space (embedded systems), but for whom ram 136 size matters less. 137 138 If in doubt, select 'gzip' 139 140config KERNEL_GZIP 141 bool "Gzip" 142 depends on HAVE_KERNEL_GZIP 143 help 144 The old and tried gzip compression. Its compression ratio is 145 the poorest among the 3 choices; however its speed (both 146 compression and decompression) is the fastest. 147 148config KERNEL_BZIP2 149 bool "Bzip2" 150 depends on HAVE_KERNEL_BZIP2 151 help 152 Its compression ratio and speed is intermediate. 153 Decompression speed is slowest among the three. The kernel 154 size is about 10% smaller with bzip2, in comparison to gzip. 155 Bzip2 uses a large amount of memory. For modern kernels you 156 will need at least 8MB RAM or more for booting. 157 158config KERNEL_LZMA 159 bool "LZMA" 160 depends on HAVE_KERNEL_LZMA 161 help 162 The most recent compression algorithm. 163 Its ratio is best, decompression speed is between the other 164 two. Compression is slowest. The kernel size is about 33% 165 smaller with LZMA in comparison to gzip. 166 167endchoice 168 169config SWAP 170 bool "Support for paging of anonymous memory (swap)" 171 depends on MMU && BLOCK 172 default y 173 help 174 This option allows you to choose whether you want to have support 175 for so called swap devices or swap files in your kernel that are 176 used to provide more virtual memory than the actual RAM present 177 in your computer. If unsure say Y. 178 179config SYSVIPC 180 bool "System V IPC" 181 ---help--- 182 Inter Process Communication is a suite of library functions and 183 system calls which let processes (running programs) synchronize and 184 exchange information. It is generally considered to be a good thing, 185 and some programs won't run unless you say Y here. In particular, if 186 you want to run the DOS emulator dosemu under Linux (read the 187 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 188 you'll need to say Y here. 189 190 You can find documentation about IPC with "info ipc" and also in 191 section 6.4 of the Linux Programmer's Guide, available from 192 <http://www.tldp.org/guides.html>. 193 194config SYSVIPC_SYSCTL 195 bool 196 depends on SYSVIPC 197 depends on SYSCTL 198 default y 199 200config POSIX_MQUEUE 201 bool "POSIX Message Queues" 202 depends on NET && EXPERIMENTAL 203 ---help--- 204 POSIX variant of message queues is a part of IPC. In POSIX message 205 queues every message has a priority which decides about succession 206 of receiving it by a process. If you want to compile and run 207 programs written e.g. for Solaris with use of its POSIX message 208 queues (functions mq_*) say Y here. 209 210 POSIX message queues are visible as a filesystem called 'mqueue' 211 and can be mounted somewhere if you want to do filesystem 212 operations on message queues. 213 214 If unsure, say Y. 215 216config POSIX_MQUEUE_SYSCTL 217 bool 218 depends on POSIX_MQUEUE 219 depends on SYSCTL 220 default y 221 222config BSD_PROCESS_ACCT 223 bool "BSD Process Accounting" 224 help 225 If you say Y here, a user level program will be able to instruct the 226 kernel (via a special system call) to write process accounting 227 information to a file: whenever a process exits, information about 228 that process will be appended to the file by the kernel. The 229 information includes things such as creation time, owning user, 230 command name, memory usage, controlling terminal etc. (the complete 231 list is in the struct acct in <file:include/linux/acct.h>). It is 232 up to the user level program to do useful things with this 233 information. This is generally a good idea, so say Y. 234 235config BSD_PROCESS_ACCT_V3 236 bool "BSD Process Accounting version 3 file format" 237 depends on BSD_PROCESS_ACCT 238 default n 239 help 240 If you say Y here, the process accounting information is written 241 in a new file format that also logs the process IDs of each 242 process and it's parent. Note that this file format is incompatible 243 with previous v0/v1/v2 file formats, so you will need updated tools 244 for processing it. A preliminary version of these tools is available 245 at <http://www.gnu.org/software/acct/>. 246 247config TASKSTATS 248 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 249 depends on NET 250 default n 251 help 252 Export selected statistics for tasks/processes through the 253 generic netlink interface. Unlike BSD process accounting, the 254 statistics are available during the lifetime of tasks/processes as 255 responses to commands. Like BSD accounting, they are sent to user 256 space on task exit. 257 258 Say N if unsure. 259 260config TASK_DELAY_ACCT 261 bool "Enable per-task delay accounting (EXPERIMENTAL)" 262 depends on TASKSTATS 263 help 264 Collect information on time spent by a task waiting for system 265 resources like cpu, synchronous block I/O completion and swapping 266 in pages. Such statistics can help in setting a task's priorities 267 relative to other tasks for cpu, io, rss limits etc. 268 269 Say N if unsure. 270 271config TASK_XACCT 272 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 273 depends on TASKSTATS 274 help 275 Collect extended task accounting data and send the data 276 to userland for processing over the taskstats interface. 277 278 Say N if unsure. 279 280config TASK_IO_ACCOUNTING 281 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 282 depends on TASK_XACCT 283 help 284 Collect information on the number of bytes of storage I/O which this 285 task has caused. 286 287 Say N if unsure. 288 289config AUDIT 290 bool "Auditing support" 291 depends on NET 292 help 293 Enable auditing infrastructure that can be used with another 294 kernel subsystem, such as SELinux (which requires this for 295 logging of avc messages output). Does not do system-call 296 auditing without CONFIG_AUDITSYSCALL. 297 298config AUDITSYSCALL 299 bool "Enable system-call auditing support" 300 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH) 301 default y if SECURITY_SELINUX 302 help 303 Enable low-overhead system-call auditing infrastructure that 304 can be used independently or with another kernel subsystem, 305 such as SELinux. To use audit's filesystem watch feature, please 306 ensure that INOTIFY is configured. 307 308config AUDIT_TREE 309 def_bool y 310 depends on AUDITSYSCALL 311 select INOTIFY 312 313menu "RCU Subsystem" 314 315choice 316 prompt "RCU Implementation" 317 default TREE_RCU 318 319config CLASSIC_RCU 320 bool "Classic RCU" 321 help 322 This option selects the classic RCU implementation that is 323 designed for best read-side performance on non-realtime 324 systems. 325 326 Select this option if you are unsure. 327 328config TREE_RCU 329 bool "Tree-based hierarchical RCU" 330 help 331 This option selects the RCU implementation that is 332 designed for very large SMP system with hundreds or 333 thousands of CPUs. 334 335config PREEMPT_RCU 336 bool "Preemptible RCU" 337 depends on PREEMPT 338 help 339 This option reduces the latency of the kernel by making certain 340 RCU sections preemptible. Normally RCU code is non-preemptible, if 341 this option is selected then read-only RCU sections become 342 preemptible. This helps latency, but may expose bugs due to 343 now-naive assumptions about each RCU read-side critical section 344 remaining on a given CPU through its execution. 345 346endchoice 347 348config RCU_TRACE 349 bool "Enable tracing for RCU" 350 depends on TREE_RCU || PREEMPT_RCU 351 help 352 This option provides tracing in RCU which presents stats 353 in debugfs for debugging RCU implementation. 354 355 Say Y here if you want to enable RCU tracing 356 Say N if you are unsure. 357 358config RCU_FANOUT 359 int "Tree-based hierarchical RCU fanout value" 360 range 2 64 if 64BIT 361 range 2 32 if !64BIT 362 depends on TREE_RCU 363 default 64 if 64BIT 364 default 32 if !64BIT 365 help 366 This option controls the fanout of hierarchical implementations 367 of RCU, allowing RCU to work efficiently on machines with 368 large numbers of CPUs. This value must be at least the cube 369 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit 370 systems and up to 262,144 for 64-bit systems. 371 372 Select a specific number if testing RCU itself. 373 Take the default if unsure. 374 375config RCU_FANOUT_EXACT 376 bool "Disable tree-based hierarchical RCU auto-balancing" 377 depends on TREE_RCU 378 default n 379 help 380 This option forces use of the exact RCU_FANOUT value specified, 381 regardless of imbalances in the hierarchy. This is useful for 382 testing RCU itself, and might one day be useful on systems with 383 strong NUMA behavior. 384 385 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 386 387 Say N if unsure. 388 389config TREE_RCU_TRACE 390 def_bool RCU_TRACE && TREE_RCU 391 select DEBUG_FS 392 help 393 This option provides tracing for the TREE_RCU implementation, 394 permitting Makefile to trivially select kernel/rcutree_trace.c. 395 396config PREEMPT_RCU_TRACE 397 def_bool RCU_TRACE && PREEMPT_RCU 398 select DEBUG_FS 399 help 400 This option provides tracing for the PREEMPT_RCU implementation, 401 permitting Makefile to trivially select kernel/rcupreempt_trace.c. 402 403endmenu # "RCU Subsystem" 404 405config IKCONFIG 406 tristate "Kernel .config support" 407 ---help--- 408 This option enables the complete Linux kernel ".config" file 409 contents to be saved in the kernel. It provides documentation 410 of which kernel options are used in a running kernel or in an 411 on-disk kernel. This information can be extracted from the kernel 412 image file with the script scripts/extract-ikconfig and used as 413 input to rebuild the current kernel or to build another kernel. 414 It can also be extracted from a running kernel by reading 415 /proc/config.gz if enabled (below). 416 417config IKCONFIG_PROC 418 bool "Enable access to .config through /proc/config.gz" 419 depends on IKCONFIG && PROC_FS 420 ---help--- 421 This option enables access to the kernel configuration file 422 through /proc/config.gz. 423 424config LOG_BUF_SHIFT 425 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 426 range 12 21 427 default 17 428 help 429 Select kernel log buffer size as a power of 2. 430 Examples: 431 17 => 128 KB 432 16 => 64 KB 433 15 => 32 KB 434 14 => 16 KB 435 13 => 8 KB 436 12 => 4 KB 437 438# 439# Architectures with an unreliable sched_clock() should select this: 440# 441config HAVE_UNSTABLE_SCHED_CLOCK 442 bool 443 444config GROUP_SCHED 445 bool "Group CPU scheduler" 446 depends on EXPERIMENTAL 447 default n 448 help 449 This feature lets CPU scheduler recognize task groups and control CPU 450 bandwidth allocation to such task groups. 451 In order to create a group from arbitrary set of processes, use 452 CONFIG_CGROUPS. (See Control Group support.) 453 454config FAIR_GROUP_SCHED 455 bool "Group scheduling for SCHED_OTHER" 456 depends on GROUP_SCHED 457 default GROUP_SCHED 458 459config RT_GROUP_SCHED 460 bool "Group scheduling for SCHED_RR/FIFO" 461 depends on EXPERIMENTAL 462 depends on GROUP_SCHED 463 default n 464 help 465 This feature lets you explicitly allocate real CPU bandwidth 466 to users or control groups (depending on the "Basis for grouping tasks" 467 setting below. If enabled, it will also make it impossible to 468 schedule realtime tasks for non-root users until you allocate 469 realtime bandwidth for them. 470 See Documentation/scheduler/sched-rt-group.txt for more information. 471 472choice 473 depends on GROUP_SCHED 474 prompt "Basis for grouping tasks" 475 default USER_SCHED 476 477config USER_SCHED 478 bool "user id" 479 help 480 This option will choose userid as the basis for grouping 481 tasks, thus providing equal CPU bandwidth to each user. 482 483config CGROUP_SCHED 484 bool "Control groups" 485 depends on CGROUPS 486 help 487 This option allows you to create arbitrary task groups 488 using the "cgroup" pseudo filesystem and control 489 the cpu bandwidth allocated to each such task group. 490 Refer to Documentation/cgroups/cgroups.txt for more 491 information on "cgroup" pseudo filesystem. 492 493endchoice 494 495menuconfig CGROUPS 496 boolean "Control Group support" 497 help 498 This option adds support for grouping sets of processes together, for 499 use with process control subsystems such as Cpusets, CFS, memory 500 controls or device isolation. 501 See 502 - Documentation/scheduler/sched-design-CFS.txt (CFS) 503 - Documentation/cgroups/ (features for grouping, isolation 504 and resource control) 505 506 Say N if unsure. 507 508if CGROUPS 509 510config CGROUP_DEBUG 511 bool "Example debug cgroup subsystem" 512 depends on CGROUPS 513 default n 514 help 515 This option enables a simple cgroup subsystem that 516 exports useful debugging information about the cgroups 517 framework. 518 519 Say N if unsure. 520 521config CGROUP_NS 522 bool "Namespace cgroup subsystem" 523 depends on CGROUPS 524 help 525 Provides a simple namespace cgroup subsystem to 526 provide hierarchical naming of sets of namespaces, 527 for instance virtual servers and checkpoint/restart 528 jobs. 529 530config CGROUP_FREEZER 531 bool "Freezer cgroup subsystem" 532 depends on CGROUPS 533 help 534 Provides a way to freeze and unfreeze all tasks in a 535 cgroup. 536 537config CGROUP_DEVICE 538 bool "Device controller for cgroups" 539 depends on CGROUPS && EXPERIMENTAL 540 help 541 Provides a cgroup implementing whitelists for devices which 542 a process in the cgroup can mknod or open. 543 544config CPUSETS 545 bool "Cpuset support" 546 depends on CGROUPS 547 help 548 This option will let you create and manage CPUSETs which 549 allow dynamically partitioning a system into sets of CPUs and 550 Memory Nodes and assigning tasks to run only within those sets. 551 This is primarily useful on large SMP or NUMA systems. 552 553 Say N if unsure. 554 555config PROC_PID_CPUSET 556 bool "Include legacy /proc/<pid>/cpuset file" 557 depends on CPUSETS 558 default y 559 560config CGROUP_CPUACCT 561 bool "Simple CPU accounting cgroup subsystem" 562 depends on CGROUPS 563 help 564 Provides a simple Resource Controller for monitoring the 565 total CPU consumed by the tasks in a cgroup. 566 567config RESOURCE_COUNTERS 568 bool "Resource counters" 569 help 570 This option enables controller independent resource accounting 571 infrastructure that works with cgroups. 572 depends on CGROUPS 573 574config CGROUP_MEM_RES_CTLR 575 bool "Memory Resource Controller for Control Groups" 576 depends on CGROUPS && RESOURCE_COUNTERS 577 select MM_OWNER 578 help 579 Provides a memory resource controller that manages both anonymous 580 memory and page cache. (See Documentation/cgroups/memory.txt) 581 582 Note that setting this option increases fixed memory overhead 583 associated with each page of memory in the system. By this, 584 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 585 usage tracking struct at boot. Total amount of this is printed out 586 at boot. 587 588 Only enable when you're ok with these trade offs and really 589 sure you need the memory resource controller. Even when you enable 590 this, you can set "cgroup_disable=memory" at your boot option to 591 disable memory resource controller and you can avoid overheads. 592 (and lose benefits of memory resource controller) 593 594 This config option also selects MM_OWNER config option, which 595 could in turn add some fork/exit overhead. 596 597config CGROUP_MEM_RES_CTLR_SWAP 598 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)" 599 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL 600 help 601 Add swap management feature to memory resource controller. When you 602 enable this, you can limit mem+swap usage per cgroup. In other words, 603 when you disable this, memory resource controller has no cares to 604 usage of swap...a process can exhaust all of the swap. This extension 605 is useful when you want to avoid exhaustion swap but this itself 606 adds more overheads and consumes memory for remembering information. 607 Especially if you use 32bit system or small memory system, please 608 be careful about enabling this. When memory resource controller 609 is disabled by boot option, this will be automatically disabled and 610 there will be no overhead from this. Even when you set this config=y, 611 if boot option "noswapaccount" is set, swap will not be accounted. 612 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 613 size is 4096bytes, 512k per 1Gbytes of swap. 614 615endif # CGROUPS 616 617config MM_OWNER 618 bool 619 620config SYSFS_DEPRECATED 621 bool 622 623config SYSFS_DEPRECATED_V2 624 bool "remove sysfs features which may confuse 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 default y 773 select SYSCTL 774 ---help--- 775 sys_sysctl uses binary paths that have been found challenging 776 to properly maintain and use. The interface in /proc/sys 777 using paths with ascii names is now the primary path to this 778 information. 779 780 Almost nothing using the binary sysctl interface so if you are 781 trying to save some space it is probably safe to disable this, 782 making your kernel marginally smaller. 783 784 If unsure say Y here. 785 786config KALLSYMS 787 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 788 default y 789 help 790 Say Y here to let the kernel print out symbolic crash information and 791 symbolic stack backtraces. This increases the size of the kernel 792 somewhat, as all symbols have to be loaded into the kernel image. 793 794config KALLSYMS_ALL 795 bool "Include all symbols in kallsyms" 796 depends on DEBUG_KERNEL && KALLSYMS 797 help 798 Normally kallsyms only contains the symbols of functions, for nicer 799 OOPS messages. Some debuggers can use kallsyms for other 800 symbols too: say Y here to include all symbols, if you need them 801 and you don't care about adding 300k to the size of your kernel. 802 803 Say N. 804 805config KALLSYMS_EXTRA_PASS 806 bool "Do an extra kallsyms pass" 807 depends on KALLSYMS 808 help 809 If kallsyms is not working correctly, the build will fail with 810 inconsistent kallsyms data. If that occurs, log a bug report and 811 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 812 Always say N here unless you find a bug in kallsyms, which must be 813 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 814 you wait for kallsyms to be fixed. 815 816 817config HOTPLUG 818 bool "Support for hot-pluggable devices" if EMBEDDED 819 default y 820 help 821 This option is provided for the case where no hotplug or uevent 822 capabilities is wanted by the kernel. You should only consider 823 disabling this option for embedded systems that do not use modules, a 824 dynamic /dev tree, or dynamic device discovery. Just say Y. 825 826config PRINTK 827 default y 828 bool "Enable support for printk" if EMBEDDED 829 help 830 This option enables normal printk support. Removing it 831 eliminates most of the message strings from the kernel image 832 and makes the kernel more or less silent. As this makes it 833 very difficult to diagnose system problems, saying N here is 834 strongly discouraged. 835 836config BUG 837 bool "BUG() support" if EMBEDDED 838 default y 839 help 840 Disabling this option eliminates support for BUG and WARN, reducing 841 the size of your kernel image and potentially quietly ignoring 842 numerous fatal conditions. You should only consider disabling this 843 option for embedded systems with no facilities for reporting errors. 844 Just say Y. 845 846config ELF_CORE 847 default y 848 bool "Enable ELF core dumps" if EMBEDDED 849 help 850 Enable support for generating core dumps. Disabling saves about 4k. 851 852config PCSPKR_PLATFORM 853 bool "Enable PC-Speaker support" if EMBEDDED 854 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 855 default y 856 help 857 This option allows to disable the internal PC-Speaker 858 support, saving some memory. 859 860config BASE_FULL 861 default y 862 bool "Enable full-sized data structures for core" if EMBEDDED 863 help 864 Disabling this option reduces the size of miscellaneous core 865 kernel data structures. This saves memory on small machines, 866 but may reduce performance. 867 868config FUTEX 869 bool "Enable futex support" if EMBEDDED 870 default y 871 select RT_MUTEXES 872 help 873 Disabling this option will cause the kernel to be built without 874 support for "fast userspace mutexes". The resulting kernel may not 875 run glibc-based applications correctly. 876 877config EPOLL 878 bool "Enable eventpoll support" if EMBEDDED 879 default y 880 select ANON_INODES 881 help 882 Disabling this option will cause the kernel to be built without 883 support for epoll family of system calls. 884 885config SIGNALFD 886 bool "Enable signalfd() system call" if EMBEDDED 887 select ANON_INODES 888 default y 889 help 890 Enable the signalfd() system call that allows to receive signals 891 on a file descriptor. 892 893 If unsure, say Y. 894 895config TIMERFD 896 bool "Enable timerfd() system call" if EMBEDDED 897 select ANON_INODES 898 default y 899 help 900 Enable the timerfd() system call that allows to receive timer 901 events on a file descriptor. 902 903 If unsure, say Y. 904 905config EVENTFD 906 bool "Enable eventfd() system call" if EMBEDDED 907 select ANON_INODES 908 default y 909 help 910 Enable the eventfd() system call that allows to receive both 911 kernel notification (ie. KAIO) or userspace notifications. 912 913 If unsure, say Y. 914 915config SHMEM 916 bool "Use full shmem filesystem" if EMBEDDED 917 default y 918 depends on MMU 919 help 920 The shmem is an internal filesystem used to manage shared memory. 921 It is backed by swap and manages resource limits. It is also exported 922 to userspace as tmpfs if TMPFS is enabled. Disabling this 923 option replaces shmem and tmpfs with the much simpler ramfs code, 924 which may be appropriate on small systems without swap. 925 926config AIO 927 bool "Enable AIO support" if EMBEDDED 928 default y 929 help 930 This option enables POSIX asynchronous I/O which may by used 931 by some high performance threaded applications. Disabling 932 this option saves about 7k. 933 934config HAVE_PERF_COUNTERS 935 bool 936 help 937 See tools/perf/design.txt for details. 938 939menu "Performance Counters" 940 941config PERF_COUNTERS 942 bool "Kernel Performance Counters" 943 default y if PROFILING 944 depends on HAVE_PERF_COUNTERS 945 select ANON_INODES 946 help 947 Enable kernel support for performance counter hardware. 948 949 Performance counters are special hardware registers available 950 on most modern CPUs. These registers count the number of certain 951 types of hw events: such as instructions executed, cachemisses 952 suffered, or branches mis-predicted - without slowing down the 953 kernel or applications. These registers can also trigger interrupts 954 when a threshold number of events have passed - and can thus be 955 used to profile the code that runs on that CPU. 956 957 The Linux Performance Counter subsystem provides an abstraction of 958 these hardware capabilities, available via a system call. It 959 provides per task and per CPU counters, and it provides event 960 capabilities on top of those. 961 962 Say Y if unsure. 963 964config EVENT_PROFILE 965 bool "Tracepoint profiling sources" 966 depends on PERF_COUNTERS && EVENT_TRACING 967 default y 968 help 969 Allow the use of tracepoints as software performance counters. 970 971 When this is enabled, you can create perf counters based on 972 tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID 973 found in debugfs://tracing/events/*/*/id. (The -e/--events 974 option to the perf tool can parse and interpret symbolic 975 tracepoints, in the subsystem:tracepoint_name format.) 976 977endmenu 978 979config VM_EVENT_COUNTERS 980 default y 981 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 982 help 983 VM event counters are needed for event counts to be shown. 984 This option allows the disabling of the VM event counters 985 on EMBEDDED systems. /proc/vmstat will only show page counts 986 if VM event counters are disabled. 987 988config PCI_QUIRKS 989 default y 990 bool "Enable PCI quirk workarounds" if EMBEDDED 991 depends on PCI 992 help 993 This enables workarounds for various PCI chipset 994 bugs/quirks. Disable this only if your target machine is 995 unaffected by PCI quirks. 996 997config SLUB_DEBUG 998 default y 999 bool "Enable SLUB debugging support" if EMBEDDED 1000 depends on SLUB && SYSFS 1001 help 1002 SLUB has extensive debug support features. Disabling these can 1003 result in significant savings in code size. This also disables 1004 SLUB sysfs support. /sys/slab will not exist and there will be 1005 no support for cache validation etc. 1006 1007config STRIP_ASM_SYMS 1008 bool "Strip assembler-generated symbols during link" 1009 default n 1010 help 1011 Strip internal assembler-generated symbols during a link (symbols 1012 that look like '.Lxxx') so they don't pollute the output of 1013 get_wchan() and suchlike. 1014 1015config COMPAT_BRK 1016 bool "Disable heap randomization" 1017 default y 1018 help 1019 Randomizing heap placement makes heap exploits harder, but it 1020 also breaks ancient binaries (including anything libc5 based). 1021 This option changes the bootup default to heap randomization 1022 disabled, and can be overridden at runtime by setting 1023 /proc/sys/kernel/randomize_va_space to 2. 1024 1025 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1026 1027choice 1028 prompt "Choose SLAB allocator" 1029 default SLUB 1030 help 1031 This option allows to select a slab allocator. 1032 1033config SLAB 1034 bool "SLAB" 1035 help 1036 The regular slab allocator that is established and known to work 1037 well in all environments. It organizes cache hot objects in 1038 per cpu and per node queues. 1039 1040config SLUB 1041 bool "SLUB (Unqueued Allocator)" 1042 help 1043 SLUB is a slab allocator that minimizes cache line usage 1044 instead of managing queues of cached objects (SLAB approach). 1045 Per cpu caching is realized using slabs of objects instead 1046 of queues of objects. SLUB can use memory efficiently 1047 and has enhanced diagnostics. SLUB is the default choice for 1048 a slab allocator. 1049 1050config SLOB 1051 depends on EMBEDDED 1052 bool "SLOB (Simple Allocator)" 1053 help 1054 SLOB replaces the stock allocator with a drastically simpler 1055 allocator. SLOB is generally more space efficient but 1056 does not perform as well on large systems. 1057 1058endchoice 1059 1060config PROFILING 1061 bool "Profiling support (EXPERIMENTAL)" 1062 help 1063 Say Y here to enable the extended profiling support mechanisms used 1064 by profilers such as OProfile. 1065 1066# 1067# Place an empty function call at each tracepoint site. Can be 1068# dynamically changed for a probe function. 1069# 1070config TRACEPOINTS 1071 bool 1072 1073config MARKERS 1074 bool "Activate markers" 1075 select TRACEPOINTS 1076 help 1077 Place an empty function call at each marker site. Can be 1078 dynamically changed for a probe function. 1079 1080source "arch/Kconfig" 1081 1082config SLOW_WORK 1083 default n 1084 bool 1085 help 1086 The slow work thread pool provides a number of dynamically allocated 1087 threads that can be used by the kernel to perform operations that 1088 take a relatively long time. 1089 1090 An example of this would be CacheFiles doing a path lookup followed 1091 by a series of mkdirs and a create call, all of which have to touch 1092 disk. 1093 1094 See Documentation/slow-work.txt. 1095 1096endmenu # General setup 1097 1098config HAVE_GENERIC_DMA_COHERENT 1099 bool 1100 default n 1101 1102config SLABINFO 1103 bool 1104 depends on PROC_FS 1105 depends on SLAB || SLUB_DEBUG 1106 default y 1107 1108config RT_MUTEXES 1109 boolean 1110 1111config BASE_SMALL 1112 int 1113 default 0 if BASE_FULL 1114 default 1 if !BASE_FULL 1115 1116menuconfig MODULES 1117 bool "Enable loadable module support" 1118 help 1119 Kernel modules are small pieces of compiled code which can 1120 be inserted in the running kernel, rather than being 1121 permanently built into the kernel. You use the "modprobe" 1122 tool to add (and sometimes remove) them. If you say Y here, 1123 many parts of the kernel can be built as modules (by 1124 answering M instead of Y where indicated): this is most 1125 useful for infrequently used options which are not required 1126 for booting. For more information, see the man pages for 1127 modprobe, lsmod, modinfo, insmod and rmmod. 1128 1129 If you say Y here, you will need to run "make 1130 modules_install" to put the modules under /lib/modules/ 1131 where modprobe can find them (you may need to be root to do 1132 this). 1133 1134 If unsure, say Y. 1135 1136if MODULES 1137 1138config MODULE_FORCE_LOAD 1139 bool "Forced module loading" 1140 default n 1141 help 1142 Allow loading of modules without version information (ie. modprobe 1143 --force). Forced module loading sets the 'F' (forced) taint flag and 1144 is usually a really bad idea. 1145 1146config MODULE_UNLOAD 1147 bool "Module unloading" 1148 help 1149 Without this option you will not be able to unload any 1150 modules (note that some modules may not be unloadable 1151 anyway), which makes your kernel smaller, faster 1152 and simpler. If unsure, say Y. 1153 1154config MODULE_FORCE_UNLOAD 1155 bool "Forced module unloading" 1156 depends on MODULE_UNLOAD && EXPERIMENTAL 1157 help 1158 This option allows you to force a module to unload, even if the 1159 kernel believes it is unsafe: the kernel will remove the module 1160 without waiting for anyone to stop using it (using the -f option to 1161 rmmod). This is mainly for kernel developers and desperate users. 1162 If unsure, say N. 1163 1164config MODVERSIONS 1165 bool "Module versioning support" 1166 help 1167 Usually, you have to use modules compiled with your kernel. 1168 Saying Y here makes it sometimes possible to use modules 1169 compiled for different kernels, by adding enough information 1170 to the modules to (hopefully) spot any changes which would 1171 make them incompatible with the kernel you are running. If 1172 unsure, say N. 1173 1174config MODULE_SRCVERSION_ALL 1175 bool "Source checksum for all modules" 1176 help 1177 Modules which contain a MODULE_VERSION get an extra "srcversion" 1178 field inserted into their modinfo section, which contains a 1179 sum of the source files which made it. This helps maintainers 1180 see exactly which source was used to build a module (since 1181 others sometimes change the module source without updating 1182 the version). With this option, such a "srcversion" field 1183 will be created for all modules. If unsure, say N. 1184 1185endif # MODULES 1186 1187config INIT_ALL_POSSIBLE 1188 bool 1189 help 1190 Back when each arch used to define their own cpu_online_map and 1191 cpu_possible_map, some of them chose to initialize cpu_possible_map 1192 with all 1s, and others with all 0s. When they were centralised, 1193 it was better to provide this option than to break all the archs 1194 and have several arch maintainers pursuing me down dark alleys. 1195 1196config STOP_MACHINE 1197 bool 1198 default y 1199 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1200 help 1201 Need stop_machine() primitive. 1202 1203source "block/Kconfig" 1204 1205config PREEMPT_NOTIFIERS 1206 bool 1207 1208