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 19menu "General setup" 20 21config EXPERIMENTAL 22 bool "Prompt for development and/or incomplete code/drivers" 23 ---help--- 24 Some of the various things that Linux supports (such as network 25 drivers, file systems, network protocols, etc.) can be in a state 26 of development where the functionality, stability, or the level of 27 testing is not yet high enough for general use. This is usually 28 known as the "alpha-test" phase among developers. If a feature is 29 currently in alpha-test, then the developers usually discourage 30 uninformed widespread use of this feature by the general public to 31 avoid "Why doesn't this work?" type mail messages. However, active 32 testing and use of these systems is welcomed. Just be aware that it 33 may not meet the normal level of reliability or it may fail to work 34 in some special cases. Detailed bug reports from people familiar 35 with the kernel internals are usually welcomed by the developers 36 (before submitting bug reports, please read the documents 37 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 38 <file:Documentation/BUG-HUNTING>, and 39 <file:Documentation/oops-tracing.txt> in the kernel source). 40 41 This option will also make obsoleted drivers available. These are 42 drivers that have been replaced by something else, and/or are 43 scheduled to be removed in a future kernel release. 44 45 Unless you intend to help test and develop a feature or driver that 46 falls into this category, or you have a situation that requires 47 using these features, you should probably say N here, which will 48 cause the configurator to present you with fewer choices. If 49 you say Y here, you will be offered the choice of using features or 50 drivers that are currently considered to be in the alpha-test phase. 51 52config BROKEN 53 bool 54 55config BROKEN_ON_SMP 56 bool 57 depends on BROKEN || !SMP 58 default y 59 60config LOCK_KERNEL 61 bool 62 depends on SMP || PREEMPT 63 default y 64 65config INIT_ENV_ARG_LIMIT 66 int 67 default 32 if !UML 68 default 128 if UML 69 help 70 Maximum of each of the number of arguments and environment 71 variables passed to init from the kernel command line. 72 73 74config LOCALVERSION 75 string "Local version - append to kernel release" 76 help 77 Append an extra string to the end of your kernel version. 78 This will show up when you type uname, for example. 79 The string you set here will be appended after the contents of 80 any files with a filename matching localversion* in your 81 object and source tree, in that order. Your total string can 82 be a maximum of 64 characters. 83 84config LOCALVERSION_AUTO 85 bool "Automatically append version information to the version string" 86 default y 87 help 88 This will try to automatically determine if the current tree is a 89 release tree by looking for git tags that belong to the current 90 top of tree revision. 91 92 A string of the format -gxxxxxxxx will be added to the localversion 93 if a git-based tree is found. The string generated by this will be 94 appended after any matching localversion* files, and after the value 95 set in CONFIG_LOCALVERSION. 96 97 (The actual string used here is the first eight characters produced 98 by running the command: 99 100 $ git rev-parse --verify HEAD 101 102 which is done within the script "scripts/setlocalversion".) 103 104config HAVE_KERNEL_GZIP 105 bool 106 107config HAVE_KERNEL_BZIP2 108 bool 109 110config HAVE_KERNEL_LZMA 111 bool 112 113choice 114 prompt "Kernel compression mode" 115 default KERNEL_GZIP 116 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA 117 help 118 The linux kernel is a kind of self-extracting executable. 119 Several compression algorithms are available, which differ 120 in efficiency, compression and decompression speed. 121 Compression speed is only relevant when building a kernel. 122 Decompression speed is relevant at each boot. 123 124 If you have any problems with bzip2 or lzma compressed 125 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 126 version of this functionality (bzip2 only), for 2.4, was 127 supplied by Christian Ludwig) 128 129 High compression options are mostly useful for users, who 130 are low on disk space (embedded systems), but for whom ram 131 size matters less. 132 133 If in doubt, select 'gzip' 134 135config KERNEL_GZIP 136 bool "Gzip" 137 depends on HAVE_KERNEL_GZIP 138 help 139 The old and tried gzip compression. Its compression ratio is 140 the poorest among the 3 choices; however its speed (both 141 compression and decompression) is the fastest. 142 143config KERNEL_BZIP2 144 bool "Bzip2" 145 depends on HAVE_KERNEL_BZIP2 146 help 147 Its compression ratio and speed is intermediate. 148 Decompression speed is slowest among the three. The kernel 149 size is about 10% smaller with bzip2, in comparison to gzip. 150 Bzip2 uses a large amount of memory. For modern kernels you 151 will need at least 8MB RAM or more for booting. 152 153config KERNEL_LZMA 154 bool "LZMA" 155 depends on HAVE_KERNEL_LZMA 156 help 157 The most recent compression algorithm. 158 Its ratio is best, decompression speed is between the other 159 two. Compression is slowest. The kernel size is about 33% 160 smaller with LZMA in comparison to gzip. 161 162endchoice 163 164config SWAP 165 bool "Support for paging of anonymous memory (swap)" 166 depends on MMU && BLOCK 167 default y 168 help 169 This option allows you to choose whether you want to have support 170 for so called swap devices or swap files in your kernel that are 171 used to provide more virtual memory than the actual RAM present 172 in your computer. If unsure say Y. 173 174config SYSVIPC 175 bool "System V IPC" 176 ---help--- 177 Inter Process Communication is a suite of library functions and 178 system calls which let processes (running programs) synchronize and 179 exchange information. It is generally considered to be a good thing, 180 and some programs won't run unless you say Y here. In particular, if 181 you want to run the DOS emulator dosemu under Linux (read the 182 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 183 you'll need to say Y here. 184 185 You can find documentation about IPC with "info ipc" and also in 186 section 6.4 of the Linux Programmer's Guide, available from 187 <http://www.tldp.org/guides.html>. 188 189config SYSVIPC_SYSCTL 190 bool 191 depends on SYSVIPC 192 depends on SYSCTL 193 default y 194 195config POSIX_MQUEUE 196 bool "POSIX Message Queues" 197 depends on NET && EXPERIMENTAL 198 ---help--- 199 POSIX variant of message queues is a part of IPC. In POSIX message 200 queues every message has a priority which decides about succession 201 of receiving it by a process. If you want to compile and run 202 programs written e.g. for Solaris with use of its POSIX message 203 queues (functions mq_*) say Y here. 204 205 POSIX message queues are visible as a filesystem called 'mqueue' 206 and can be mounted somewhere if you want to do filesystem 207 operations on message queues. 208 209 If unsure, say Y. 210 211config BSD_PROCESS_ACCT 212 bool "BSD Process Accounting" 213 help 214 If you say Y here, a user level program will be able to instruct the 215 kernel (via a special system call) to write process accounting 216 information to a file: whenever a process exits, information about 217 that process will be appended to the file by the kernel. The 218 information includes things such as creation time, owning user, 219 command name, memory usage, controlling terminal etc. (the complete 220 list is in the struct acct in <file:include/linux/acct.h>). It is 221 up to the user level program to do useful things with this 222 information. This is generally a good idea, so say Y. 223 224config BSD_PROCESS_ACCT_V3 225 bool "BSD Process Accounting version 3 file format" 226 depends on BSD_PROCESS_ACCT 227 default n 228 help 229 If you say Y here, the process accounting information is written 230 in a new file format that also logs the process IDs of each 231 process and it's parent. Note that this file format is incompatible 232 with previous v0/v1/v2 file formats, so you will need updated tools 233 for processing it. A preliminary version of these tools is available 234 at <http://www.gnu.org/software/acct/>. 235 236config TASKSTATS 237 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 238 depends on NET 239 default n 240 help 241 Export selected statistics for tasks/processes through the 242 generic netlink interface. Unlike BSD process accounting, the 243 statistics are available during the lifetime of tasks/processes as 244 responses to commands. Like BSD accounting, they are sent to user 245 space on task exit. 246 247 Say N if unsure. 248 249config TASK_DELAY_ACCT 250 bool "Enable per-task delay accounting (EXPERIMENTAL)" 251 depends on TASKSTATS 252 help 253 Collect information on time spent by a task waiting for system 254 resources like cpu, synchronous block I/O completion and swapping 255 in pages. Such statistics can help in setting a task's priorities 256 relative to other tasks for cpu, io, rss limits etc. 257 258 Say N if unsure. 259 260config TASK_XACCT 261 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 262 depends on TASKSTATS 263 help 264 Collect extended task accounting data and send the data 265 to userland for processing over the taskstats interface. 266 267 Say N if unsure. 268 269config TASK_IO_ACCOUNTING 270 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 271 depends on TASK_XACCT 272 help 273 Collect information on the number of bytes of storage I/O which this 274 task has caused. 275 276 Say N if unsure. 277 278config AUDIT 279 bool "Auditing support" 280 depends on NET 281 help 282 Enable auditing infrastructure that can be used with another 283 kernel subsystem, such as SELinux (which requires this for 284 logging of avc messages output). Does not do system-call 285 auditing without CONFIG_AUDITSYSCALL. 286 287config AUDITSYSCALL 288 bool "Enable system-call auditing support" 289 depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH) 290 default y if SECURITY_SELINUX 291 help 292 Enable low-overhead system-call auditing infrastructure that 293 can be used independently or with another kernel subsystem, 294 such as SELinux. To use audit's filesystem watch feature, please 295 ensure that INOTIFY is configured. 296 297config AUDIT_TREE 298 def_bool y 299 depends on AUDITSYSCALL && INOTIFY 300 301menu "RCU Subsystem" 302 303choice 304 prompt "RCU Implementation" 305 default CLASSIC_RCU 306 307config CLASSIC_RCU 308 bool "Classic RCU" 309 help 310 This option selects the classic RCU implementation that is 311 designed for best read-side performance on non-realtime 312 systems. 313 314 Select this option if you are unsure. 315 316config TREE_RCU 317 bool "Tree-based hierarchical RCU" 318 help 319 This option selects the RCU implementation that is 320 designed for very large SMP system with hundreds or 321 thousands of CPUs. 322 323config PREEMPT_RCU 324 bool "Preemptible RCU" 325 depends on PREEMPT 326 help 327 This option reduces the latency of the kernel by making certain 328 RCU sections preemptible. Normally RCU code is non-preemptible, if 329 this option is selected then read-only RCU sections become 330 preemptible. This helps latency, but may expose bugs due to 331 now-naive assumptions about each RCU read-side critical section 332 remaining on a given CPU through its execution. 333 334endchoice 335 336config RCU_TRACE 337 bool "Enable tracing for RCU" 338 depends on TREE_RCU || PREEMPT_RCU 339 help 340 This option provides tracing in RCU which presents stats 341 in debugfs for debugging RCU implementation. 342 343 Say Y here if you want to enable RCU tracing 344 Say N if you are unsure. 345 346config RCU_FANOUT 347 int "Tree-based hierarchical RCU fanout value" 348 range 2 64 if 64BIT 349 range 2 32 if !64BIT 350 depends on TREE_RCU 351 default 64 if 64BIT 352 default 32 if !64BIT 353 help 354 This option controls the fanout of hierarchical implementations 355 of RCU, allowing RCU to work efficiently on machines with 356 large numbers of CPUs. This value must be at least the cube 357 root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit 358 systems and up to 262,144 for 64-bit systems. 359 360 Select a specific number if testing RCU itself. 361 Take the default if unsure. 362 363config RCU_FANOUT_EXACT 364 bool "Disable tree-based hierarchical RCU auto-balancing" 365 depends on TREE_RCU 366 default n 367 help 368 This option forces use of the exact RCU_FANOUT value specified, 369 regardless of imbalances in the hierarchy. This is useful for 370 testing RCU itself, and might one day be useful on systems with 371 strong NUMA behavior. 372 373 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 374 375 Say N if unsure. 376 377config TREE_RCU_TRACE 378 def_bool RCU_TRACE && TREE_RCU 379 select DEBUG_FS 380 help 381 This option provides tracing for the TREE_RCU implementation, 382 permitting Makefile to trivially select kernel/rcutree_trace.c. 383 384config PREEMPT_RCU_TRACE 385 def_bool RCU_TRACE && PREEMPT_RCU 386 select DEBUG_FS 387 help 388 This option provides tracing for the PREEMPT_RCU implementation, 389 permitting Makefile to trivially select kernel/rcupreempt_trace.c. 390 391endmenu # "RCU Subsystem" 392 393config IKCONFIG 394 tristate "Kernel .config support" 395 ---help--- 396 This option enables the complete Linux kernel ".config" file 397 contents to be saved in the kernel. It provides documentation 398 of which kernel options are used in a running kernel or in an 399 on-disk kernel. This information can be extracted from the kernel 400 image file with the script scripts/extract-ikconfig and used as 401 input to rebuild the current kernel or to build another kernel. 402 It can also be extracted from a running kernel by reading 403 /proc/config.gz if enabled (below). 404 405config IKCONFIG_PROC 406 bool "Enable access to .config through /proc/config.gz" 407 depends on IKCONFIG && PROC_FS 408 ---help--- 409 This option enables access to the kernel configuration file 410 through /proc/config.gz. 411 412config LOG_BUF_SHIFT 413 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 414 range 12 21 415 default 17 416 help 417 Select kernel log buffer size as a power of 2. 418 Examples: 419 17 => 128 KB 420 16 => 64 KB 421 15 => 32 KB 422 14 => 16 KB 423 13 => 8 KB 424 12 => 4 KB 425 426# 427# Architectures with an unreliable sched_clock() should select this: 428# 429config HAVE_UNSTABLE_SCHED_CLOCK 430 bool 431 432config GROUP_SCHED 433 bool "Group CPU scheduler" 434 depends on EXPERIMENTAL 435 default n 436 help 437 This feature lets CPU scheduler recognize task groups and control CPU 438 bandwidth allocation to such task groups. 439 In order to create a group from arbitrary set of processes, use 440 CONFIG_CGROUPS. (See Control Group support.) 441 442config FAIR_GROUP_SCHED 443 bool "Group scheduling for SCHED_OTHER" 444 depends on GROUP_SCHED 445 default GROUP_SCHED 446 447config RT_GROUP_SCHED 448 bool "Group scheduling for SCHED_RR/FIFO" 449 depends on EXPERIMENTAL 450 depends on GROUP_SCHED 451 default n 452 help 453 This feature lets you explicitly allocate real CPU bandwidth 454 to users or control groups (depending on the "Basis for grouping tasks" 455 setting below. If enabled, it will also make it impossible to 456 schedule realtime tasks for non-root users until you allocate 457 realtime bandwidth for them. 458 See Documentation/scheduler/sched-rt-group.txt for more information. 459 460choice 461 depends on GROUP_SCHED 462 prompt "Basis for grouping tasks" 463 default USER_SCHED 464 465config USER_SCHED 466 bool "user id" 467 help 468 This option will choose userid as the basis for grouping 469 tasks, thus providing equal CPU bandwidth to each user. 470 471config CGROUP_SCHED 472 bool "Control groups" 473 depends on CGROUPS 474 help 475 This option allows you to create arbitrary task groups 476 using the "cgroup" pseudo filesystem and control 477 the cpu bandwidth allocated to each such task group. 478 Refer to Documentation/cgroups/cgroups.txt for more 479 information on "cgroup" pseudo filesystem. 480 481endchoice 482 483menuconfig CGROUPS 484 boolean "Control Group support" 485 help 486 This option adds support for grouping sets of processes together, for 487 use with process control subsystems such as Cpusets, CFS, memory 488 controls or device isolation. 489 See 490 - Documentation/scheduler/sched-design-CFS.txt (CFS) 491 - Documentation/cgroups/ (features for grouping, isolation 492 and resource control) 493 494 Say N if unsure. 495 496if CGROUPS 497 498config CGROUP_DEBUG 499 bool "Example debug cgroup subsystem" 500 depends on CGROUPS 501 default n 502 help 503 This option enables a simple cgroup subsystem that 504 exports useful debugging information about the cgroups 505 framework. 506 507 Say N if unsure. 508 509config CGROUP_NS 510 bool "Namespace cgroup subsystem" 511 depends on CGROUPS 512 help 513 Provides a simple namespace cgroup subsystem to 514 provide hierarchical naming of sets of namespaces, 515 for instance virtual servers and checkpoint/restart 516 jobs. 517 518config CGROUP_FREEZER 519 bool "Freezer cgroup subsystem" 520 depends on CGROUPS 521 help 522 Provides a way to freeze and unfreeze all tasks in a 523 cgroup. 524 525config CGROUP_DEVICE 526 bool "Device controller for cgroups" 527 depends on CGROUPS && EXPERIMENTAL 528 help 529 Provides a cgroup implementing whitelists for devices which 530 a process in the cgroup can mknod or open. 531 532config CPUSETS 533 bool "Cpuset support" 534 depends on SMP && CGROUPS 535 help 536 This option will let you create and manage CPUSETs which 537 allow dynamically partitioning a system into sets of CPUs and 538 Memory Nodes and assigning tasks to run only within those sets. 539 This is primarily useful on large SMP or NUMA systems. 540 541 Say N if unsure. 542 543config PROC_PID_CPUSET 544 bool "Include legacy /proc/<pid>/cpuset file" 545 depends on CPUSETS 546 default y 547 548config CGROUP_CPUACCT 549 bool "Simple CPU accounting cgroup subsystem" 550 depends on CGROUPS 551 help 552 Provides a simple Resource Controller for monitoring the 553 total CPU consumed by the tasks in a cgroup. 554 555config RESOURCE_COUNTERS 556 bool "Resource counters" 557 help 558 This option enables controller independent resource accounting 559 infrastructure that works with cgroups. 560 depends on CGROUPS 561 562config CGROUP_MEM_RES_CTLR 563 bool "Memory Resource Controller for Control Groups" 564 depends on CGROUPS && RESOURCE_COUNTERS 565 select MM_OWNER 566 help 567 Provides a memory resource controller that manages both anonymous 568 memory and page cache. (See Documentation/controllers/memory.txt) 569 570 Note that setting this option increases fixed memory overhead 571 associated with each page of memory in the system. By this, 572 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 573 usage tracking struct at boot. Total amount of this is printed out 574 at boot. 575 576 Only enable when you're ok with these trade offs and really 577 sure you need the memory resource controller. Even when you enable 578 this, you can set "cgroup_disable=memory" at your boot option to 579 disable memory resource controller and you can avoid overheads. 580 (and lose benefits of memory resource controller) 581 582 This config option also selects MM_OWNER config option, which 583 could in turn add some fork/exit overhead. 584 585config CGROUP_MEM_RES_CTLR_SWAP 586 bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)" 587 depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL 588 help 589 Add swap management feature to memory resource controller. When you 590 enable this, you can limit mem+swap usage per cgroup. In other words, 591 when you disable this, memory resource controller has no cares to 592 usage of swap...a process can exhaust all of the swap. This extension 593 is useful when you want to avoid exhaustion swap but this itself 594 adds more overheads and consumes memory for remembering information. 595 Especially if you use 32bit system or small memory system, please 596 be careful about enabling this. When memory resource controller 597 is disabled by boot option, this will be automatically disabled and 598 there will be no overhead from this. Even when you set this config=y, 599 if boot option "noswapaccount" is set, swap will not be accounted. 600 601endif # CGROUPS 602 603config MM_OWNER 604 bool 605 606config SYSFS_DEPRECATED 607 bool 608 609config SYSFS_DEPRECATED_V2 610 bool "Create deprecated sysfs layout for older userspace tools" 611 depends on SYSFS 612 default y 613 select SYSFS_DEPRECATED 614 help 615 This option switches the layout of sysfs to the deprecated 616 version. 617 618 The current sysfs layout features a unified device tree at 619 /sys/devices/, which is able to express a hierarchy between 620 class devices. If the deprecated option is set to Y, the 621 unified device tree is split into a bus device tree at 622 /sys/devices/ and several individual class device trees at 623 /sys/class/. The class and bus devices will be connected by 624 "<subsystem>:<name>" and the "device" links. The "block" 625 class devices, will not show up in /sys/class/block/. Some 626 subsystems will suppress the creation of some devices which 627 depend on the unified device tree. 628 629 This option is not a pure compatibility option that can 630 be safely enabled on newer distributions. It will change the 631 layout of sysfs to the non-extensible deprecated version, 632 and disable some features, which can not be exported without 633 confusing older userspace tools. Since 2007/2008 all major 634 distributions do not enable this option, and ship no tools which 635 depend on the deprecated layout or this option. 636 637 If you are using a new kernel on an older distribution, or use 638 older userspace tools, you might need to say Y here. Do not say Y, 639 if the original kernel, that came with your distribution, has 640 this option set to N. 641 642config RELAY 643 bool "Kernel->user space relay support (formerly relayfs)" 644 help 645 This option enables support for relay interface support in 646 certain file systems (such as debugfs). 647 It is designed to provide an efficient mechanism for tools and 648 facilities to relay large amounts of data from kernel space to 649 user space. 650 651 If unsure, say N. 652 653config NAMESPACES 654 bool "Namespaces support" if EMBEDDED 655 default !EMBEDDED 656 help 657 Provides the way to make tasks work with different objects using 658 the same id. For example same IPC id may refer to different objects 659 or same user id or pid may refer to different tasks when used in 660 different namespaces. 661 662config UTS_NS 663 bool "UTS namespace" 664 depends on NAMESPACES 665 help 666 In this namespace tasks see different info provided with the 667 uname() system call 668 669config IPC_NS 670 bool "IPC namespace" 671 depends on NAMESPACES && SYSVIPC 672 help 673 In this namespace tasks work with IPC ids which correspond to 674 different IPC objects in different namespaces 675 676config USER_NS 677 bool "User namespace (EXPERIMENTAL)" 678 depends on NAMESPACES && EXPERIMENTAL 679 help 680 This allows containers, i.e. vservers, to use user namespaces 681 to provide different user info for different servers. 682 If unsure, say N. 683 684config PID_NS 685 bool "PID Namespaces (EXPERIMENTAL)" 686 default n 687 depends on NAMESPACES && EXPERIMENTAL 688 help 689 Support process id namespaces. This allows having multiple 690 process with the same pid as long as they are in different 691 pid namespaces. This is a building block of containers. 692 693 Unless you want to work with an experimental feature 694 say N here. 695 696config NET_NS 697 bool "Network namespace" 698 default n 699 depends on NAMESPACES && EXPERIMENTAL && NET 700 help 701 Allow user space to create what appear to be multiple instances 702 of the network stack. 703 704config BLK_DEV_INITRD 705 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 706 depends on BROKEN || !FRV 707 help 708 The initial RAM filesystem is a ramfs which is loaded by the 709 boot loader (loadlin or lilo) and that is mounted as root 710 before the normal boot procedure. It is typically used to 711 load modules needed to mount the "real" root file system, 712 etc. See <file:Documentation/initrd.txt> for details. 713 714 If RAM disk support (BLK_DEV_RAM) is also included, this 715 also enables initial RAM disk (initrd) support and adds 716 15 Kbytes (more on some other architectures) to the kernel size. 717 718 If unsure say Y. 719 720if BLK_DEV_INITRD 721 722source "usr/Kconfig" 723 724endif 725 726config CC_OPTIMIZE_FOR_SIZE 727 bool "Optimize for size" 728 default y 729 help 730 Enabling this option will pass "-Os" instead of "-O2" to gcc 731 resulting in a smaller kernel. 732 733 If unsure, say Y. 734 735config SYSCTL 736 bool 737 738config ANON_INODES 739 bool 740 741menuconfig EMBEDDED 742 bool "Configure standard kernel features (for small systems)" 743 help 744 This option allows certain base kernel options and settings 745 to be disabled or tweaked. This is for specialized 746 environments which can tolerate a "non-standard" kernel. 747 Only use this if you really know what you are doing. 748 749config UID16 750 bool "Enable 16-bit UID system calls" if EMBEDDED 751 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 752 default y 753 help 754 This enables the legacy 16-bit UID syscall wrappers. 755 756config SYSCTL_SYSCALL 757 bool "Sysctl syscall support" if EMBEDDED 758 default y 759 select SYSCTL 760 ---help--- 761 sys_sysctl uses binary paths that have been found challenging 762 to properly maintain and use. The interface in /proc/sys 763 using paths with ascii names is now the primary path to this 764 information. 765 766 Almost nothing using the binary sysctl interface so if you are 767 trying to save some space it is probably safe to disable this, 768 making your kernel marginally smaller. 769 770 If unsure say Y here. 771 772config KALLSYMS 773 bool "Load all symbols for debugging/ksymoops" if EMBEDDED 774 default y 775 help 776 Say Y here to let the kernel print out symbolic crash information and 777 symbolic stack backtraces. This increases the size of the kernel 778 somewhat, as all symbols have to be loaded into the kernel image. 779 780config KALLSYMS_ALL 781 bool "Include all symbols in kallsyms" 782 depends on DEBUG_KERNEL && KALLSYMS 783 help 784 Normally kallsyms only contains the symbols of functions, for nicer 785 OOPS messages. Some debuggers can use kallsyms for other 786 symbols too: say Y here to include all symbols, if you need them 787 and you don't care about adding 300k to the size of your kernel. 788 789 Say N. 790 791config KALLSYMS_EXTRA_PASS 792 bool "Do an extra kallsyms pass" 793 depends on KALLSYMS 794 help 795 If kallsyms is not working correctly, the build will fail with 796 inconsistent kallsyms data. If that occurs, log a bug report and 797 turn on KALLSYMS_EXTRA_PASS which should result in a stable build. 798 Always say N here unless you find a bug in kallsyms, which must be 799 reported. KALLSYMS_EXTRA_PASS is only a temporary workaround while 800 you wait for kallsyms to be fixed. 801 802 803config HOTPLUG 804 bool "Support for hot-pluggable devices" if EMBEDDED 805 default y 806 help 807 This option is provided for the case where no hotplug or uevent 808 capabilities is wanted by the kernel. You should only consider 809 disabling this option for embedded systems that do not use modules, a 810 dynamic /dev tree, or dynamic device discovery. Just say Y. 811 812config PRINTK 813 default y 814 bool "Enable support for printk" if EMBEDDED 815 help 816 This option enables normal printk support. Removing it 817 eliminates most of the message strings from the kernel image 818 and makes the kernel more or less silent. As this makes it 819 very difficult to diagnose system problems, saying N here is 820 strongly discouraged. 821 822config BUG 823 bool "BUG() support" if EMBEDDED 824 default y 825 help 826 Disabling this option eliminates support for BUG and WARN, reducing 827 the size of your kernel image and potentially quietly ignoring 828 numerous fatal conditions. You should only consider disabling this 829 option for embedded systems with no facilities for reporting errors. 830 Just say Y. 831 832config ELF_CORE 833 default y 834 bool "Enable ELF core dumps" if EMBEDDED 835 help 836 Enable support for generating core dumps. Disabling saves about 4k. 837 838config PCSPKR_PLATFORM 839 bool "Enable PC-Speaker support" if EMBEDDED 840 depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES 841 default y 842 help 843 This option allows to disable the internal PC-Speaker 844 support, saving some memory. 845 846config BASE_FULL 847 default y 848 bool "Enable full-sized data structures for core" if EMBEDDED 849 help 850 Disabling this option reduces the size of miscellaneous core 851 kernel data structures. This saves memory on small machines, 852 but may reduce performance. 853 854config FUTEX 855 bool "Enable futex support" if EMBEDDED 856 default y 857 select RT_MUTEXES 858 help 859 Disabling this option will cause the kernel to be built without 860 support for "fast userspace mutexes". The resulting kernel may not 861 run glibc-based applications correctly. 862 863config EPOLL 864 bool "Enable eventpoll support" if EMBEDDED 865 default y 866 select ANON_INODES 867 help 868 Disabling this option will cause the kernel to be built without 869 support for epoll family of system calls. 870 871config SIGNALFD 872 bool "Enable signalfd() system call" if EMBEDDED 873 select ANON_INODES 874 default y 875 help 876 Enable the signalfd() system call that allows to receive signals 877 on a file descriptor. 878 879 If unsure, say Y. 880 881config TIMERFD 882 bool "Enable timerfd() system call" if EMBEDDED 883 select ANON_INODES 884 default y 885 help 886 Enable the timerfd() system call that allows to receive timer 887 events on a file descriptor. 888 889 If unsure, say Y. 890 891config EVENTFD 892 bool "Enable eventfd() system call" if EMBEDDED 893 select ANON_INODES 894 default y 895 help 896 Enable the eventfd() system call that allows to receive both 897 kernel notification (ie. KAIO) or userspace notifications. 898 899 If unsure, say Y. 900 901config SHMEM 902 bool "Use full shmem filesystem" if EMBEDDED 903 default y 904 depends on MMU 905 help 906 The shmem is an internal filesystem used to manage shared memory. 907 It is backed by swap and manages resource limits. It is also exported 908 to userspace as tmpfs if TMPFS is enabled. Disabling this 909 option replaces shmem and tmpfs with the much simpler ramfs code, 910 which may be appropriate on small systems without swap. 911 912config AIO 913 bool "Enable AIO support" if EMBEDDED 914 default y 915 help 916 This option enables POSIX asynchronous I/O which may by used 917 by some high performance threaded applications. Disabling 918 this option saves about 7k. 919 920config VM_EVENT_COUNTERS 921 default y 922 bool "Enable VM event counters for /proc/vmstat" if EMBEDDED 923 help 924 VM event counters are needed for event counts to be shown. 925 This option allows the disabling of the VM event counters 926 on EMBEDDED systems. /proc/vmstat will only show page counts 927 if VM event counters are disabled. 928 929config PCI_QUIRKS 930 default y 931 bool "Enable PCI quirk workarounds" if EMBEDDED 932 depends on PCI 933 help 934 This enables workarounds for various PCI chipset 935 bugs/quirks. Disable this only if your target machine is 936 unaffected by PCI quirks. 937 938config SLUB_DEBUG 939 default y 940 bool "Enable SLUB debugging support" if EMBEDDED 941 depends on SLUB && SYSFS 942 help 943 SLUB has extensive debug support features. Disabling these can 944 result in significant savings in code size. This also disables 945 SLUB sysfs support. /sys/slab will not exist and there will be 946 no support for cache validation etc. 947 948config COMPAT_BRK 949 bool "Disable heap randomization" 950 default y 951 help 952 Randomizing heap placement makes heap exploits harder, but it 953 also breaks ancient binaries (including anything libc5 based). 954 This option changes the bootup default to heap randomization 955 disabled, and can be overriden runtime by setting 956 /proc/sys/kernel/randomize_va_space to 2. 957 958 On non-ancient distros (post-2000 ones) N is usually a safe choice. 959 960choice 961 prompt "Choose SLAB allocator" 962 default SLUB 963 help 964 This option allows to select a slab allocator. 965 966config SLAB 967 bool "SLAB" 968 help 969 The regular slab allocator that is established and known to work 970 well in all environments. It organizes cache hot objects in 971 per cpu and per node queues. 972 973config SLUB 974 bool "SLUB (Unqueued Allocator)" 975 help 976 SLUB is a slab allocator that minimizes cache line usage 977 instead of managing queues of cached objects (SLAB approach). 978 Per cpu caching is realized using slabs of objects instead 979 of queues of objects. SLUB can use memory efficiently 980 and has enhanced diagnostics. SLUB is the default choice for 981 a slab allocator. 982 983config SLOB 984 depends on EMBEDDED 985 bool "SLOB (Simple Allocator)" 986 help 987 SLOB replaces the stock allocator with a drastically simpler 988 allocator. SLOB is generally more space efficient but 989 does not perform as well on large systems. 990 991endchoice 992 993config PROFILING 994 bool "Profiling support (EXPERIMENTAL)" 995 help 996 Say Y here to enable the extended profiling support mechanisms used 997 by profilers such as OProfile. 998 999# 1000# Place an empty function call at each tracepoint site. Can be 1001# dynamically changed for a probe function. 1002# 1003config TRACEPOINTS 1004 bool 1005 1006config MARKERS 1007 bool "Activate markers" 1008 depends on TRACEPOINTS 1009 help 1010 Place an empty function call at each marker site. Can be 1011 dynamically changed for a probe function. 1012 1013source "arch/Kconfig" 1014 1015endmenu # General setup 1016 1017config HAVE_GENERIC_DMA_COHERENT 1018 bool 1019 default n 1020 1021config SLABINFO 1022 bool 1023 depends on PROC_FS 1024 depends on SLAB || SLUB_DEBUG 1025 default y 1026 1027config RT_MUTEXES 1028 boolean 1029 1030config BASE_SMALL 1031 int 1032 default 0 if BASE_FULL 1033 default 1 if !BASE_FULL 1034 1035menuconfig MODULES 1036 bool "Enable loadable module support" 1037 help 1038 Kernel modules are small pieces of compiled code which can 1039 be inserted in the running kernel, rather than being 1040 permanently built into the kernel. You use the "modprobe" 1041 tool to add (and sometimes remove) them. If you say Y here, 1042 many parts of the kernel can be built as modules (by 1043 answering M instead of Y where indicated): this is most 1044 useful for infrequently used options which are not required 1045 for booting. For more information, see the man pages for 1046 modprobe, lsmod, modinfo, insmod and rmmod. 1047 1048 If you say Y here, you will need to run "make 1049 modules_install" to put the modules under /lib/modules/ 1050 where modprobe can find them (you may need to be root to do 1051 this). 1052 1053 If unsure, say Y. 1054 1055if MODULES 1056 1057config MODULE_FORCE_LOAD 1058 bool "Forced module loading" 1059 default n 1060 help 1061 Allow loading of modules without version information (ie. modprobe 1062 --force). Forced module loading sets the 'F' (forced) taint flag and 1063 is usually a really bad idea. 1064 1065config MODULE_UNLOAD 1066 bool "Module unloading" 1067 help 1068 Without this option you will not be able to unload any 1069 modules (note that some modules may not be unloadable 1070 anyway), which makes your kernel smaller, faster 1071 and simpler. If unsure, say Y. 1072 1073config MODULE_FORCE_UNLOAD 1074 bool "Forced module unloading" 1075 depends on MODULE_UNLOAD && EXPERIMENTAL 1076 help 1077 This option allows you to force a module to unload, even if the 1078 kernel believes it is unsafe: the kernel will remove the module 1079 without waiting for anyone to stop using it (using the -f option to 1080 rmmod). This is mainly for kernel developers and desperate users. 1081 If unsure, say N. 1082 1083config MODVERSIONS 1084 bool "Module versioning support" 1085 help 1086 Usually, you have to use modules compiled with your kernel. 1087 Saying Y here makes it sometimes possible to use modules 1088 compiled for different kernels, by adding enough information 1089 to the modules to (hopefully) spot any changes which would 1090 make them incompatible with the kernel you are running. If 1091 unsure, say N. 1092 1093config MODULE_SRCVERSION_ALL 1094 bool "Source checksum for all modules" 1095 help 1096 Modules which contain a MODULE_VERSION get an extra "srcversion" 1097 field inserted into their modinfo section, which contains a 1098 sum of the source files which made it. This helps maintainers 1099 see exactly which source was used to build a module (since 1100 others sometimes change the module source without updating 1101 the version). With this option, such a "srcversion" field 1102 will be created for all modules. If unsure, say N. 1103 1104endif # MODULES 1105 1106config INIT_ALL_POSSIBLE 1107 bool 1108 help 1109 Back when each arch used to define their own cpu_online_map and 1110 cpu_possible_map, some of them chose to initialize cpu_possible_map 1111 with all 1s, and others with all 0s. When they were centralised, 1112 it was better to provide this option than to break all the archs 1113 and have several arch maintainers persuing me down dark alleys. 1114 1115config STOP_MACHINE 1116 bool 1117 default y 1118 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1119 help 1120 Need stop_machine() primitive. 1121 1122source "block/Kconfig" 1123 1124config PREEMPT_NOTIFIERS 1125 bool 1126 1127