1config ARCH 2 string 3 option env="ARCH" 4 5config KERNELVERSION 6 string 7 option env="KERNELVERSION" 8 9config DEFCONFIG_LIST 10 string 11 depends on !UML 12 option defconfig_list 13 default "/lib/modules/$UNAME_RELEASE/.config" 14 default "/etc/kernel-config" 15 default "/boot/config-$UNAME_RELEASE" 16 default "$ARCH_DEFCONFIG" 17 default "arch/$ARCH/defconfig" 18 19config CONSTRUCTORS 20 bool 21 depends on !UML 22 23config HAVE_IRQ_WORK 24 bool 25 26config IRQ_WORK 27 bool 28 depends on HAVE_IRQ_WORK 29 30config BUILDTIME_EXTABLE_SORT 31 bool 32 33menu "General setup" 34 35config EXPERIMENTAL 36 bool "Prompt for development and/or incomplete code/drivers" 37 ---help--- 38 Some of the various things that Linux supports (such as network 39 drivers, file systems, network protocols, etc.) can be in a state 40 of development where the functionality, stability, or the level of 41 testing is not yet high enough for general use. This is usually 42 known as the "alpha-test" phase among developers. If a feature is 43 currently in alpha-test, then the developers usually discourage 44 uninformed widespread use of this feature by the general public to 45 avoid "Why doesn't this work?" type mail messages. However, active 46 testing and use of these systems is welcomed. Just be aware that it 47 may not meet the normal level of reliability or it may fail to work 48 in some special cases. Detailed bug reports from people familiar 49 with the kernel internals are usually welcomed by the developers 50 (before submitting bug reports, please read the documents 51 <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>, 52 <file:Documentation/BUG-HUNTING>, and 53 <file:Documentation/oops-tracing.txt> in the kernel source). 54 55 This option will also make obsoleted drivers available. These are 56 drivers that have been replaced by something else, and/or are 57 scheduled to be removed in a future kernel release. 58 59 Unless you intend to help test and develop a feature or driver that 60 falls into this category, or you have a situation that requires 61 using these features, you should probably say N here, which will 62 cause the configurator to present you with fewer choices. If 63 you say Y here, you will be offered the choice of using features or 64 drivers that are currently considered to be in the alpha-test phase. 65 66config BROKEN 67 bool 68 69config BROKEN_ON_SMP 70 bool 71 depends on BROKEN || !SMP 72 default y 73 74config INIT_ENV_ARG_LIMIT 75 int 76 default 32 if !UML 77 default 128 if UML 78 help 79 Maximum of each of the number of arguments and environment 80 variables passed to init from the kernel command line. 81 82 83config CROSS_COMPILE 84 string "Cross-compiler tool prefix" 85 help 86 Same as running 'make CROSS_COMPILE=prefix-' but stored for 87 default make runs in this kernel build directory. You don't 88 need to set this unless you want the configured kernel build 89 directory to select the cross-compiler automatically. 90 91config LOCALVERSION 92 string "Local version - append to kernel release" 93 help 94 Append an extra string to the end of your kernel version. 95 This will show up when you type uname, for example. 96 The string you set here will be appended after the contents of 97 any files with a filename matching localversion* in your 98 object and source tree, in that order. Your total string can 99 be a maximum of 64 characters. 100 101config LOCALVERSION_AUTO 102 bool "Automatically append version information to the version string" 103 default y 104 help 105 This will try to automatically determine if the current tree is a 106 release tree by looking for git tags that belong to the current 107 top of tree revision. 108 109 A string of the format -gxxxxxxxx will be added to the localversion 110 if a git-based tree is found. The string generated by this will be 111 appended after any matching localversion* files, and after the value 112 set in CONFIG_LOCALVERSION. 113 114 (The actual string used here is the first eight characters produced 115 by running the command: 116 117 $ git rev-parse --verify HEAD 118 119 which is done within the script "scripts/setlocalversion".) 120 121config HAVE_KERNEL_GZIP 122 bool 123 124config HAVE_KERNEL_BZIP2 125 bool 126 127config HAVE_KERNEL_LZMA 128 bool 129 130config HAVE_KERNEL_XZ 131 bool 132 133config HAVE_KERNEL_LZO 134 bool 135 136choice 137 prompt "Kernel compression mode" 138 default KERNEL_GZIP 139 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 140 help 141 The linux kernel is a kind of self-extracting executable. 142 Several compression algorithms are available, which differ 143 in efficiency, compression and decompression speed. 144 Compression speed is only relevant when building a kernel. 145 Decompression speed is relevant at each boot. 146 147 If you have any problems with bzip2 or lzma compressed 148 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 149 version of this functionality (bzip2 only), for 2.4, was 150 supplied by Christian Ludwig) 151 152 High compression options are mostly useful for users, who 153 are low on disk space (embedded systems), but for whom ram 154 size matters less. 155 156 If in doubt, select 'gzip' 157 158config KERNEL_GZIP 159 bool "Gzip" 160 depends on HAVE_KERNEL_GZIP 161 help 162 The old and tried gzip compression. It provides a good balance 163 between compression ratio and decompression speed. 164 165config KERNEL_BZIP2 166 bool "Bzip2" 167 depends on HAVE_KERNEL_BZIP2 168 help 169 Its compression ratio and speed is intermediate. 170 Decompression speed is slowest among the choices. The kernel 171 size is about 10% smaller with bzip2, in comparison to gzip. 172 Bzip2 uses a large amount of memory. For modern kernels you 173 will need at least 8MB RAM or more for booting. 174 175config KERNEL_LZMA 176 bool "LZMA" 177 depends on HAVE_KERNEL_LZMA 178 help 179 This compression algorithm's ratio is best. Decompression speed 180 is between gzip and bzip2. Compression is slowest. 181 The kernel size is about 33% smaller with LZMA in comparison to gzip. 182 183config KERNEL_XZ 184 bool "XZ" 185 depends on HAVE_KERNEL_XZ 186 help 187 XZ uses the LZMA2 algorithm and instruction set specific 188 BCJ filters which can improve compression ratio of executable 189 code. The size of the kernel is about 30% smaller with XZ in 190 comparison to gzip. On architectures for which there is a BCJ 191 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 192 will create a few percent smaller kernel than plain LZMA. 193 194 The speed is about the same as with LZMA: The decompression 195 speed of XZ is better than that of bzip2 but worse than gzip 196 and LZO. Compression is slow. 197 198config KERNEL_LZO 199 bool "LZO" 200 depends on HAVE_KERNEL_LZO 201 help 202 Its compression ratio is the poorest among the choices. The kernel 203 size is about 10% bigger than gzip; however its speed 204 (both compression and decompression) is the fastest. 205 206endchoice 207 208config DEFAULT_HOSTNAME 209 string "Default hostname" 210 default "(none)" 211 help 212 This option determines the default system hostname before userspace 213 calls sethostname(2). The kernel traditionally uses "(none)" here, 214 but you may wish to use a different default here to make a minimal 215 system more usable with less configuration. 216 217config SWAP 218 bool "Support for paging of anonymous memory (swap)" 219 depends on MMU && BLOCK 220 default y 221 help 222 This option allows you to choose whether you want to have support 223 for so called swap devices or swap files in your kernel that are 224 used to provide more virtual memory than the actual RAM present 225 in your computer. If unsure say Y. 226 227config SYSVIPC 228 bool "System V IPC" 229 ---help--- 230 Inter Process Communication is a suite of library functions and 231 system calls which let processes (running programs) synchronize and 232 exchange information. It is generally considered to be a good thing, 233 and some programs won't run unless you say Y here. In particular, if 234 you want to run the DOS emulator dosemu under Linux (read the 235 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 236 you'll need to say Y here. 237 238 You can find documentation about IPC with "info ipc" and also in 239 section 6.4 of the Linux Programmer's Guide, available from 240 <http://www.tldp.org/guides.html>. 241 242config SYSVIPC_SYSCTL 243 bool 244 depends on SYSVIPC 245 depends on SYSCTL 246 default y 247 248config POSIX_MQUEUE 249 bool "POSIX Message Queues" 250 depends on NET && EXPERIMENTAL 251 ---help--- 252 POSIX variant of message queues is a part of IPC. In POSIX message 253 queues every message has a priority which decides about succession 254 of receiving it by a process. If you want to compile and run 255 programs written e.g. for Solaris with use of its POSIX message 256 queues (functions mq_*) say Y here. 257 258 POSIX message queues are visible as a filesystem called 'mqueue' 259 and can be mounted somewhere if you want to do filesystem 260 operations on message queues. 261 262 If unsure, say Y. 263 264config POSIX_MQUEUE_SYSCTL 265 bool 266 depends on POSIX_MQUEUE 267 depends on SYSCTL 268 default y 269 270config BSD_PROCESS_ACCT 271 bool "BSD Process Accounting" 272 help 273 If you say Y here, a user level program will be able to instruct the 274 kernel (via a special system call) to write process accounting 275 information to a file: whenever a process exits, information about 276 that process will be appended to the file by the kernel. The 277 information includes things such as creation time, owning user, 278 command name, memory usage, controlling terminal etc. (the complete 279 list is in the struct acct in <file:include/linux/acct.h>). It is 280 up to the user level program to do useful things with this 281 information. This is generally a good idea, so say Y. 282 283config BSD_PROCESS_ACCT_V3 284 bool "BSD Process Accounting version 3 file format" 285 depends on BSD_PROCESS_ACCT 286 default n 287 help 288 If you say Y here, the process accounting information is written 289 in a new file format that also logs the process IDs of each 290 process and it's parent. Note that this file format is incompatible 291 with previous v0/v1/v2 file formats, so you will need updated tools 292 for processing it. A preliminary version of these tools is available 293 at <http://www.gnu.org/software/acct/>. 294 295config FHANDLE 296 bool "open by fhandle syscalls" 297 select EXPORTFS 298 help 299 If you say Y here, a user level program will be able to map 300 file names to handle and then later use the handle for 301 different file system operations. This is useful in implementing 302 userspace file servers, which now track files using handles instead 303 of names. The handle would remain the same even if file names 304 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 305 syscalls. 306 307config TASKSTATS 308 bool "Export task/process statistics through netlink (EXPERIMENTAL)" 309 depends on NET 310 default n 311 help 312 Export selected statistics for tasks/processes through the 313 generic netlink interface. Unlike BSD process accounting, the 314 statistics are available during the lifetime of tasks/processes as 315 responses to commands. Like BSD accounting, they are sent to user 316 space on task exit. 317 318 Say N if unsure. 319 320config TASK_DELAY_ACCT 321 bool "Enable per-task delay accounting (EXPERIMENTAL)" 322 depends on TASKSTATS 323 help 324 Collect information on time spent by a task waiting for system 325 resources like cpu, synchronous block I/O completion and swapping 326 in pages. Such statistics can help in setting a task's priorities 327 relative to other tasks for cpu, io, rss limits etc. 328 329 Say N if unsure. 330 331config TASK_XACCT 332 bool "Enable extended accounting over taskstats (EXPERIMENTAL)" 333 depends on TASKSTATS 334 help 335 Collect extended task accounting data and send the data 336 to userland for processing over the taskstats interface. 337 338 Say N if unsure. 339 340config TASK_IO_ACCOUNTING 341 bool "Enable per-task storage I/O accounting (EXPERIMENTAL)" 342 depends on TASK_XACCT 343 help 344 Collect information on the number of bytes of storage I/O which this 345 task has caused. 346 347 Say N if unsure. 348 349config AUDIT 350 bool "Auditing support" 351 depends on NET 352 help 353 Enable auditing infrastructure that can be used with another 354 kernel subsystem, such as SELinux (which requires this for 355 logging of avc messages output). Does not do system-call 356 auditing without CONFIG_AUDITSYSCALL. 357 358config AUDITSYSCALL 359 bool "Enable system-call auditing support" 360 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT)) 361 default y if SECURITY_SELINUX 362 help 363 Enable low-overhead system-call auditing infrastructure that 364 can be used independently or with another kernel subsystem, 365 such as SELinux. 366 367config AUDIT_WATCH 368 def_bool y 369 depends on AUDITSYSCALL 370 select FSNOTIFY 371 372config AUDIT_TREE 373 def_bool y 374 depends on AUDITSYSCALL 375 select FSNOTIFY 376 377config AUDIT_LOGINUID_IMMUTABLE 378 bool "Make audit loginuid immutable" 379 depends on AUDIT 380 help 381 The config option toggles if a task setting its loginuid requires 382 CAP_SYS_AUDITCONTROL or if that task should require no special permissions 383 but should instead only allow setting its loginuid if it was never 384 previously set. On systems which use systemd or a similar central 385 process to restart login services this should be set to true. On older 386 systems in which an admin would typically have to directly stop and 387 start processes this should be set to false. Setting this to true allows 388 one to drop potentially dangerous capabilites from the login tasks, 389 but may not be backwards compatible with older init systems. 390 391source "kernel/irq/Kconfig" 392source "kernel/time/Kconfig" 393 394menu "RCU Subsystem" 395 396choice 397 prompt "RCU Implementation" 398 default TREE_RCU 399 400config TREE_RCU 401 bool "Tree-based hierarchical RCU" 402 depends on !PREEMPT && SMP 403 help 404 This option selects the RCU implementation that is 405 designed for very large SMP system with hundreds or 406 thousands of CPUs. It also scales down nicely to 407 smaller systems. 408 409config TREE_PREEMPT_RCU 410 bool "Preemptible tree-based hierarchical RCU" 411 depends on PREEMPT && SMP 412 help 413 This option selects the RCU implementation that is 414 designed for very large SMP systems with hundreds or 415 thousands of CPUs, but for which real-time response 416 is also required. It also scales down nicely to 417 smaller systems. 418 419config TINY_RCU 420 bool "UP-only small-memory-footprint RCU" 421 depends on !PREEMPT && !SMP 422 help 423 This option selects the RCU implementation that is 424 designed for UP systems from which real-time response 425 is not required. This option greatly reduces the 426 memory footprint of RCU. 427 428config TINY_PREEMPT_RCU 429 bool "Preemptible UP-only small-memory-footprint RCU" 430 depends on PREEMPT && !SMP 431 help 432 This option selects the RCU implementation that is designed 433 for real-time UP systems. This option greatly reduces the 434 memory footprint of RCU. 435 436endchoice 437 438config PREEMPT_RCU 439 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 440 help 441 This option enables preemptible-RCU code that is common between 442 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 443 444config RCU_FANOUT 445 int "Tree-based hierarchical RCU fanout value" 446 range 2 64 if 64BIT 447 range 2 32 if !64BIT 448 depends on TREE_RCU || TREE_PREEMPT_RCU 449 default 64 if 64BIT 450 default 32 if !64BIT 451 help 452 This option controls the fanout of hierarchical implementations 453 of RCU, allowing RCU to work efficiently on machines with 454 large numbers of CPUs. This value must be at least the fourth 455 root of NR_CPUS, which allows NR_CPUS to be insanely large. 456 The default value of RCU_FANOUT should be used for production 457 systems, but if you are stress-testing the RCU implementation 458 itself, small RCU_FANOUT values allow you to test large-system 459 code paths on small(er) systems. 460 461 Select a specific number if testing RCU itself. 462 Take the default if unsure. 463 464config RCU_FANOUT_LEAF 465 int "Tree-based hierarchical RCU leaf-level fanout value" 466 range 2 RCU_FANOUT if 64BIT 467 range 2 RCU_FANOUT if !64BIT 468 depends on TREE_RCU || TREE_PREEMPT_RCU 469 default 16 470 help 471 This option controls the leaf-level fanout of hierarchical 472 implementations of RCU, and allows trading off cache misses 473 against lock contention. Systems that synchronize their 474 scheduling-clock interrupts for energy-efficiency reasons will 475 want the default because the smaller leaf-level fanout keeps 476 lock contention levels acceptably low. Very large systems 477 (hundreds or thousands of CPUs) will instead want to set this 478 value to the maximum value possible in order to reduce the 479 number of cache misses incurred during RCU's grace-period 480 initialization. These systems tend to run CPU-bound, and thus 481 are not helped by synchronized interrupts, and thus tend to 482 skew them, which reduces lock contention enough that large 483 leaf-level fanouts work well. 484 485 Select a specific number if testing RCU itself. 486 487 Select the maximum permissible value for large systems. 488 489 Take the default if unsure. 490 491config RCU_FANOUT_EXACT 492 bool "Disable tree-based hierarchical RCU auto-balancing" 493 depends on TREE_RCU || TREE_PREEMPT_RCU 494 default n 495 help 496 This option forces use of the exact RCU_FANOUT value specified, 497 regardless of imbalances in the hierarchy. This is useful for 498 testing RCU itself, and might one day be useful on systems with 499 strong NUMA behavior. 500 501 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 502 503 Say N if unsure. 504 505config RCU_FAST_NO_HZ 506 bool "Accelerate last non-dyntick-idle CPU's grace periods" 507 depends on NO_HZ && SMP 508 default n 509 help 510 This option causes RCU to attempt to accelerate grace periods 511 in order to allow CPUs to enter dynticks-idle state more 512 quickly. On the other hand, this option increases the overhead 513 of the dynticks-idle checking, particularly on systems with 514 large numbers of CPUs. 515 516 Say Y if energy efficiency is critically important, particularly 517 if you have relatively few CPUs. 518 519 Say N if you are unsure. 520 521config TREE_RCU_TRACE 522 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 523 select DEBUG_FS 524 help 525 This option provides tracing for the TREE_RCU and 526 TREE_PREEMPT_RCU implementations, permitting Makefile to 527 trivially select kernel/rcutree_trace.c. 528 529config RCU_BOOST 530 bool "Enable RCU priority boosting" 531 depends on RT_MUTEXES && PREEMPT_RCU 532 default n 533 help 534 This option boosts the priority of preempted RCU readers that 535 block the current preemptible RCU grace period for too long. 536 This option also prevents heavy loads from blocking RCU 537 callback invocation for all flavors of RCU. 538 539 Say Y here if you are working with real-time apps or heavy loads 540 Say N here if you are unsure. 541 542config RCU_BOOST_PRIO 543 int "Real-time priority to boost RCU readers to" 544 range 1 99 545 depends on RCU_BOOST 546 default 1 547 help 548 This option specifies the real-time priority to which long-term 549 preempted RCU readers are to be boosted. If you are working 550 with a real-time application that has one or more CPU-bound 551 threads running at a real-time priority level, you should set 552 RCU_BOOST_PRIO to a priority higher then the highest-priority 553 real-time CPU-bound thread. The default RCU_BOOST_PRIO value 554 of 1 is appropriate in the common case, which is real-time 555 applications that do not have any CPU-bound threads. 556 557 Some real-time applications might not have a single real-time 558 thread that saturates a given CPU, but instead might have 559 multiple real-time threads that, taken together, fully utilize 560 that CPU. In this case, you should set RCU_BOOST_PRIO to 561 a priority higher than the lowest-priority thread that is 562 conspiring to prevent the CPU from running any non-real-time 563 tasks. For example, if one thread at priority 10 and another 564 thread at priority 5 are between themselves fully consuming 565 the CPU time on a given CPU, then RCU_BOOST_PRIO should be 566 set to priority 6 or higher. 567 568 Specify the real-time priority, or take the default if unsure. 569 570config RCU_BOOST_DELAY 571 int "Milliseconds to delay boosting after RCU grace-period start" 572 range 0 3000 573 depends on RCU_BOOST 574 default 500 575 help 576 This option specifies the time to wait after the beginning of 577 a given grace period before priority-boosting preempted RCU 578 readers blocking that grace period. Note that any RCU reader 579 blocking an expedited RCU grace period is boosted immediately. 580 581 Accept the default if unsure. 582 583endmenu # "RCU Subsystem" 584 585config IKCONFIG 586 tristate "Kernel .config support" 587 ---help--- 588 This option enables the complete Linux kernel ".config" file 589 contents to be saved in the kernel. It provides documentation 590 of which kernel options are used in a running kernel or in an 591 on-disk kernel. This information can be extracted from the kernel 592 image file with the script scripts/extract-ikconfig and used as 593 input to rebuild the current kernel or to build another kernel. 594 It can also be extracted from a running kernel by reading 595 /proc/config.gz if enabled (below). 596 597config IKCONFIG_PROC 598 bool "Enable access to .config through /proc/config.gz" 599 depends on IKCONFIG && PROC_FS 600 ---help--- 601 This option enables access to the kernel configuration file 602 through /proc/config.gz. 603 604config LOG_BUF_SHIFT 605 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 606 range 12 21 607 default 17 608 help 609 Select kernel log buffer size as a power of 2. 610 Examples: 611 17 => 128 KB 612 16 => 64 KB 613 15 => 32 KB 614 14 => 16 KB 615 13 => 8 KB 616 12 => 4 KB 617 618# 619# Architectures with an unreliable sched_clock() should select this: 620# 621config HAVE_UNSTABLE_SCHED_CLOCK 622 bool 623 624menuconfig CGROUPS 625 boolean "Control Group support" 626 depends on EVENTFD 627 help 628 This option adds support for grouping sets of processes together, for 629 use with process control subsystems such as Cpusets, CFS, memory 630 controls or device isolation. 631 See 632 - Documentation/scheduler/sched-design-CFS.txt (CFS) 633 - Documentation/cgroups/ (features for grouping, isolation 634 and resource control) 635 636 Say N if unsure. 637 638if CGROUPS 639 640config CGROUP_DEBUG 641 bool "Example debug cgroup subsystem" 642 default n 643 help 644 This option enables a simple cgroup subsystem that 645 exports useful debugging information about the cgroups 646 framework. 647 648 Say N if unsure. 649 650config CGROUP_FREEZER 651 bool "Freezer cgroup subsystem" 652 help 653 Provides a way to freeze and unfreeze all tasks in a 654 cgroup. 655 656config CGROUP_DEVICE 657 bool "Device controller for cgroups" 658 help 659 Provides a cgroup implementing whitelists for devices which 660 a process in the cgroup can mknod or open. 661 662config CPUSETS 663 bool "Cpuset support" 664 help 665 This option will let you create and manage CPUSETs which 666 allow dynamically partitioning a system into sets of CPUs and 667 Memory Nodes and assigning tasks to run only within those sets. 668 This is primarily useful on large SMP or NUMA systems. 669 670 Say N if unsure. 671 672config PROC_PID_CPUSET 673 bool "Include legacy /proc/<pid>/cpuset file" 674 depends on CPUSETS 675 default y 676 677config CGROUP_CPUACCT 678 bool "Simple CPU accounting cgroup subsystem" 679 help 680 Provides a simple Resource Controller for monitoring the 681 total CPU consumed by the tasks in a cgroup. 682 683config RESOURCE_COUNTERS 684 bool "Resource counters" 685 help 686 This option enables controller independent resource accounting 687 infrastructure that works with cgroups. 688 689config MEMCG 690 bool "Memory Resource Controller for Control Groups" 691 depends on RESOURCE_COUNTERS 692 select MM_OWNER 693 help 694 Provides a memory resource controller that manages both anonymous 695 memory and page cache. (See Documentation/cgroups/memory.txt) 696 697 Note that setting this option increases fixed memory overhead 698 associated with each page of memory in the system. By this, 699 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 700 usage tracking struct at boot. Total amount of this is printed out 701 at boot. 702 703 Only enable when you're ok with these trade offs and really 704 sure you need the memory resource controller. Even when you enable 705 this, you can set "cgroup_disable=memory" at your boot option to 706 disable memory resource controller and you can avoid overheads. 707 (and lose benefits of memory resource controller) 708 709 This config option also selects MM_OWNER config option, which 710 could in turn add some fork/exit overhead. 711 712config MEMCG_SWAP 713 bool "Memory Resource Controller Swap Extension" 714 depends on MEMCG && SWAP 715 help 716 Add swap management feature to memory resource controller. When you 717 enable this, you can limit mem+swap usage per cgroup. In other words, 718 when you disable this, memory resource controller has no cares to 719 usage of swap...a process can exhaust all of the swap. This extension 720 is useful when you want to avoid exhaustion swap but this itself 721 adds more overheads and consumes memory for remembering information. 722 Especially if you use 32bit system or small memory system, please 723 be careful about enabling this. When memory resource controller 724 is disabled by boot option, this will be automatically disabled and 725 there will be no overhead from this. Even when you set this config=y, 726 if boot option "swapaccount=0" is set, swap will not be accounted. 727 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 728 size is 4096bytes, 512k per 1Gbytes of swap. 729config MEMCG_SWAP_ENABLED 730 bool "Memory Resource Controller Swap Extension enabled by default" 731 depends on MEMCG_SWAP 732 default y 733 help 734 Memory Resource Controller Swap Extension comes with its price in 735 a bigger memory consumption. General purpose distribution kernels 736 which want to enable the feature but keep it disabled by default 737 and let the user enable it by swapaccount boot command line 738 parameter should have this option unselected. 739 For those who want to have the feature enabled by default should 740 select this option (if, for some reason, they need to disable it 741 then swapaccount=0 does the trick). 742config MEMCG_KMEM 743 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)" 744 depends on MEMCG && EXPERIMENTAL 745 default n 746 help 747 The Kernel Memory extension for Memory Resource Controller can limit 748 the amount of memory used by kernel objects in the system. Those are 749 fundamentally different from the entities handled by the standard 750 Memory Controller, which are page-based, and can be swapped. Users of 751 the kmem extension can use it to guarantee that no group of processes 752 will ever exhaust kernel resources alone. 753 754config CGROUP_HUGETLB 755 bool "HugeTLB Resource Controller for Control Groups" 756 depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL 757 default n 758 help 759 Provides a cgroup Resource Controller for HugeTLB pages. 760 When you enable this, you can put a per cgroup limit on HugeTLB usage. 761 The limit is enforced during page fault. Since HugeTLB doesn't 762 support page reclaim, enforcing the limit at page fault time implies 763 that, the application will get SIGBUS signal if it tries to access 764 HugeTLB pages beyond its limit. This requires the application to know 765 beforehand how much HugeTLB pages it would require for its use. The 766 control group is tracked in the third page lru pointer. This means 767 that we cannot use the controller with huge page less than 3 pages. 768 769config CGROUP_PERF 770 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 771 depends on PERF_EVENTS && CGROUPS 772 help 773 This option extends the per-cpu mode to restrict monitoring to 774 threads which belong to the cgroup specified and run on the 775 designated cpu. 776 777 Say N if unsure. 778 779menuconfig CGROUP_SCHED 780 bool "Group CPU scheduler" 781 default n 782 help 783 This feature lets CPU scheduler recognize task groups and control CPU 784 bandwidth allocation to such task groups. It uses cgroups to group 785 tasks. 786 787if CGROUP_SCHED 788config FAIR_GROUP_SCHED 789 bool "Group scheduling for SCHED_OTHER" 790 depends on CGROUP_SCHED 791 default CGROUP_SCHED 792 793config CFS_BANDWIDTH 794 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 795 depends on EXPERIMENTAL 796 depends on FAIR_GROUP_SCHED 797 default n 798 help 799 This option allows users to define CPU bandwidth rates (limits) for 800 tasks running within the fair group scheduler. Groups with no limit 801 set are considered to be unconstrained and will run with no 802 restriction. 803 See tip/Documentation/scheduler/sched-bwc.txt for more information. 804 805config RT_GROUP_SCHED 806 bool "Group scheduling for SCHED_RR/FIFO" 807 depends on EXPERIMENTAL 808 depends on CGROUP_SCHED 809 default n 810 help 811 This feature lets you explicitly allocate real CPU bandwidth 812 to task groups. If enabled, it will also make it impossible to 813 schedule realtime tasks for non-root users until you allocate 814 realtime bandwidth for them. 815 See Documentation/scheduler/sched-rt-group.txt for more information. 816 817endif #CGROUP_SCHED 818 819config BLK_CGROUP 820 bool "Block IO controller" 821 depends on BLOCK 822 default n 823 ---help--- 824 Generic block IO controller cgroup interface. This is the common 825 cgroup interface which should be used by various IO controlling 826 policies. 827 828 Currently, CFQ IO scheduler uses it to recognize task groups and 829 control disk bandwidth allocation (proportional time slice allocation) 830 to such task groups. It is also used by bio throttling logic in 831 block layer to implement upper limit in IO rates on a device. 832 833 This option only enables generic Block IO controller infrastructure. 834 One needs to also enable actual IO controlling logic/policy. For 835 enabling proportional weight division of disk bandwidth in CFQ, set 836 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 837 CONFIG_BLK_DEV_THROTTLING=y. 838 839 See Documentation/cgroups/blkio-controller.txt for more information. 840 841config DEBUG_BLK_CGROUP 842 bool "Enable Block IO controller debugging" 843 depends on BLK_CGROUP 844 default n 845 ---help--- 846 Enable some debugging help. Currently it exports additional stat 847 files in a cgroup which can be useful for debugging. 848 849endif # CGROUPS 850 851config CHECKPOINT_RESTORE 852 bool "Checkpoint/restore support" if EXPERT 853 default n 854 help 855 Enables additional kernel features in a sake of checkpoint/restore. 856 In particular it adds auxiliary prctl codes to setup process text, 857 data and heap segment sizes, and a few additional /proc filesystem 858 entries. 859 860 If unsure, say N here. 861 862menuconfig NAMESPACES 863 bool "Namespaces support" if EXPERT 864 default !EXPERT 865 help 866 Provides the way to make tasks work with different objects using 867 the same id. For example same IPC id may refer to different objects 868 or same user id or pid may refer to different tasks when used in 869 different namespaces. 870 871if NAMESPACES 872 873config UTS_NS 874 bool "UTS namespace" 875 default y 876 help 877 In this namespace tasks see different info provided with the 878 uname() system call 879 880config IPC_NS 881 bool "IPC namespace" 882 depends on (SYSVIPC || POSIX_MQUEUE) 883 default y 884 help 885 In this namespace tasks work with IPC ids which correspond to 886 different IPC objects in different namespaces. 887 888config USER_NS 889 bool "User namespace (EXPERIMENTAL)" 890 depends on EXPERIMENTAL 891 depends on UIDGID_CONVERTED 892 select UIDGID_STRICT_TYPE_CHECKS 893 894 default n 895 help 896 This allows containers, i.e. vservers, to use user namespaces 897 to provide different user info for different servers. 898 If unsure, say N. 899 900config PID_NS 901 bool "PID Namespaces" 902 default y 903 help 904 Support process id namespaces. This allows having multiple 905 processes with the same pid as long as they are in different 906 pid namespaces. This is a building block of containers. 907 908config NET_NS 909 bool "Network namespace" 910 depends on NET 911 default y 912 help 913 Allow user space to create what appear to be multiple instances 914 of the network stack. 915 916endif # NAMESPACES 917 918config UIDGID_CONVERTED 919 # True if all of the selected software conmponents are known 920 # to have uid_t and gid_t converted to kuid_t and kgid_t 921 # where appropriate and are otherwise safe to use with 922 # the user namespace. 923 bool 924 default y 925 926 # List of kernel pieces that need user namespace work 927 # Features 928 depends on SYSVIPC = n 929 depends on IMA = n 930 depends on EVM = n 931 depends on KEYS = n 932 depends on AUDIT = n 933 depends on AUDITSYSCALL = n 934 depends on TASKSTATS = n 935 depends on TRACING = n 936 depends on FS_POSIX_ACL = n 937 depends on QUOTA = n 938 depends on QUOTACTL = n 939 depends on DEBUG_CREDENTIALS = n 940 depends on BSD_PROCESS_ACCT = n 941 depends on DRM = n 942 depends on PROC_EVENTS = n 943 944 # Networking 945 depends on NET_9P = n 946 depends on AF_RXRPC = n 947 depends on NET_KEY = n 948 depends on DNS_RESOLVER = n 949 950 # Filesystems 951 depends on USB_GADGETFS = n 952 depends on USB_FUNCTIONFS = n 953 depends on DEVTMPFS = n 954 depends on XENFS = n 955 956 depends on 9P_FS = n 957 depends on ADFS_FS = n 958 depends on AFFS_FS = n 959 depends on AFS_FS = n 960 depends on AUTOFS4_FS = n 961 depends on BEFS_FS = n 962 depends on BFS_FS = n 963 depends on BTRFS_FS = n 964 depends on CEPH_FS = n 965 depends on CIFS = n 966 depends on CODA_FS = n 967 depends on CONFIGFS_FS = n 968 depends on CRAMFS = n 969 depends on DEBUG_FS = n 970 depends on ECRYPT_FS = n 971 depends on EFS_FS = n 972 depends on EXOFS_FS = n 973 depends on FAT_FS = n 974 depends on FUSE_FS = n 975 depends on GFS2_FS = n 976 depends on HFS_FS = n 977 depends on HFSPLUS_FS = n 978 depends on HPFS_FS = n 979 depends on HUGETLBFS = n 980 depends on ISO9660_FS = n 981 depends on JFFS2_FS = n 982 depends on JFS_FS = n 983 depends on LOGFS = n 984 depends on MINIX_FS = n 985 depends on NCP_FS = n 986 depends on NFSD = n 987 depends on NFS_FS = n 988 depends on NILFS2_FS = n 989 depends on NTFS_FS = n 990 depends on OCFS2_FS = n 991 depends on OMFS_FS = n 992 depends on QNX4FS_FS = n 993 depends on QNX6FS_FS = n 994 depends on REISERFS_FS = n 995 depends on SQUASHFS = n 996 depends on SYSV_FS = n 997 depends on UBIFS_FS = n 998 depends on UDF_FS = n 999 depends on UFS_FS = n 1000 depends on VXFS_FS = n 1001 depends on XFS_FS = n 1002 1003 depends on !UML || HOSTFS = n 1004 1005 # The rare drivers that won't build 1006 depends on INFINIBAND_QIB = n 1007 depends on BLK_DEV_LOOP = n 1008 depends on ANDROID_BINDER_IPC = n 1009 1010 # Security modules 1011 depends on SECURITY_TOMOYO = n 1012 depends on SECURITY_APPARMOR = n 1013 1014config UIDGID_STRICT_TYPE_CHECKS 1015 bool "Require conversions between uid/gids and their internal representation" 1016 depends on UIDGID_CONVERTED 1017 default n 1018 help 1019 While the nececessary conversions are being added to all subsystems this option allows 1020 the code to continue to build for unconverted subsystems. 1021 1022 Say Y here if you want the strict type checking enabled 1023 1024config SCHED_AUTOGROUP 1025 bool "Automatic process group scheduling" 1026 select EVENTFD 1027 select CGROUPS 1028 select CGROUP_SCHED 1029 select FAIR_GROUP_SCHED 1030 help 1031 This option optimizes the scheduler for common desktop workloads by 1032 automatically creating and populating task groups. This separation 1033 of workloads isolates aggressive CPU burners (like build jobs) from 1034 desktop applications. Task group autogeneration is currently based 1035 upon task session. 1036 1037config MM_OWNER 1038 bool 1039 1040config SYSFS_DEPRECATED 1041 bool "Enable deprecated sysfs features to support old userspace tools" 1042 depends on SYSFS 1043 default n 1044 help 1045 This option adds code that switches the layout of the "block" class 1046 devices, to not show up in /sys/class/block/, but only in 1047 /sys/block/. 1048 1049 This switch is only active when the sysfs.deprecated=1 boot option is 1050 passed or the SYSFS_DEPRECATED_V2 option is set. 1051 1052 This option allows new kernels to run on old distributions and tools, 1053 which might get confused by /sys/class/block/. Since 2007/2008 all 1054 major distributions and tools handle this just fine. 1055 1056 Recent distributions and userspace tools after 2009/2010 depend on 1057 the existence of /sys/class/block/, and will not work with this 1058 option enabled. 1059 1060 Only if you are using a new kernel on an old distribution, you might 1061 need to say Y here. 1062 1063config SYSFS_DEPRECATED_V2 1064 bool "Enable deprecated sysfs features by default" 1065 default n 1066 depends on SYSFS 1067 depends on SYSFS_DEPRECATED 1068 help 1069 Enable deprecated sysfs by default. 1070 1071 See the CONFIG_SYSFS_DEPRECATED option for more details about this 1072 option. 1073 1074 Only if you are using a new kernel on an old distribution, you might 1075 need to say Y here. Even then, odds are you would not need it 1076 enabled, you can always pass the boot option if absolutely necessary. 1077 1078config RELAY 1079 bool "Kernel->user space relay support (formerly relayfs)" 1080 help 1081 This option enables support for relay interface support in 1082 certain file systems (such as debugfs). 1083 It is designed to provide an efficient mechanism for tools and 1084 facilities to relay large amounts of data from kernel space to 1085 user space. 1086 1087 If unsure, say N. 1088 1089config BLK_DEV_INITRD 1090 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1091 depends on BROKEN || !FRV 1092 help 1093 The initial RAM filesystem is a ramfs which is loaded by the 1094 boot loader (loadlin or lilo) and that is mounted as root 1095 before the normal boot procedure. It is typically used to 1096 load modules needed to mount the "real" root file system, 1097 etc. See <file:Documentation/initrd.txt> for details. 1098 1099 If RAM disk support (BLK_DEV_RAM) is also included, this 1100 also enables initial RAM disk (initrd) support and adds 1101 15 Kbytes (more on some other architectures) to the kernel size. 1102 1103 If unsure say Y. 1104 1105if BLK_DEV_INITRD 1106 1107source "usr/Kconfig" 1108 1109endif 1110 1111config CC_OPTIMIZE_FOR_SIZE 1112 bool "Optimize for size" 1113 help 1114 Enabling this option will pass "-Os" instead of "-O2" to gcc 1115 resulting in a smaller kernel. 1116 1117 If unsure, say Y. 1118 1119config SYSCTL 1120 bool 1121 1122config ANON_INODES 1123 bool 1124 1125menuconfig EXPERT 1126 bool "Configure standard kernel features (expert users)" 1127 # Unhide debug options, to make the on-by-default options visible 1128 select DEBUG_KERNEL 1129 help 1130 This option allows certain base kernel options and settings 1131 to be disabled or tweaked. This is for specialized 1132 environments which can tolerate a "non-standard" kernel. 1133 Only use this if you really know what you are doing. 1134 1135config UID16 1136 bool "Enable 16-bit UID system calls" if EXPERT 1137 depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION) 1138 default y 1139 help 1140 This enables the legacy 16-bit UID syscall wrappers. 1141 1142config SYSCTL_SYSCALL 1143 bool "Sysctl syscall support" if EXPERT 1144 depends on PROC_SYSCTL 1145 default n 1146 select SYSCTL 1147 ---help--- 1148 sys_sysctl uses binary paths that have been found challenging 1149 to properly maintain and use. The interface in /proc/sys 1150 using paths with ascii names is now the primary path to this 1151 information. 1152 1153 Almost nothing using the binary sysctl interface so if you are 1154 trying to save some space it is probably safe to disable this, 1155 making your kernel marginally smaller. 1156 1157 If unsure say N here. 1158 1159config KALLSYMS 1160 bool "Load all symbols for debugging/ksymoops" if EXPERT 1161 default y 1162 help 1163 Say Y here to let the kernel print out symbolic crash information and 1164 symbolic stack backtraces. This increases the size of the kernel 1165 somewhat, as all symbols have to be loaded into the kernel image. 1166 1167config KALLSYMS_ALL 1168 bool "Include all symbols in kallsyms" 1169 depends on DEBUG_KERNEL && KALLSYMS 1170 help 1171 Normally kallsyms only contains the symbols of functions for nicer 1172 OOPS messages and backtraces (i.e., symbols from the text and inittext 1173 sections). This is sufficient for most cases. And only in very rare 1174 cases (e.g., when a debugger is used) all symbols are required (e.g., 1175 names of variables from the data sections, etc). 1176 1177 This option makes sure that all symbols are loaded into the kernel 1178 image (i.e., symbols from all sections) in cost of increased kernel 1179 size (depending on the kernel configuration, it may be 300KiB or 1180 something like this). 1181 1182 Say N unless you really need all symbols. 1183 1184config HOTPLUG 1185 bool "Support for hot-pluggable devices" if EXPERT 1186 default y 1187 help 1188 This option is provided for the case where no hotplug or uevent 1189 capabilities is wanted by the kernel. You should only consider 1190 disabling this option for embedded systems that do not use modules, a 1191 dynamic /dev tree, or dynamic device discovery. Just say Y. 1192 1193config PRINTK 1194 default y 1195 bool "Enable support for printk" if EXPERT 1196 help 1197 This option enables normal printk support. Removing it 1198 eliminates most of the message strings from the kernel image 1199 and makes the kernel more or less silent. As this makes it 1200 very difficult to diagnose system problems, saying N here is 1201 strongly discouraged. 1202 1203config BUG 1204 bool "BUG() support" if EXPERT 1205 default y 1206 help 1207 Disabling this option eliminates support for BUG and WARN, reducing 1208 the size of your kernel image and potentially quietly ignoring 1209 numerous fatal conditions. You should only consider disabling this 1210 option for embedded systems with no facilities for reporting errors. 1211 Just say Y. 1212 1213config ELF_CORE 1214 default y 1215 bool "Enable ELF core dumps" if EXPERT 1216 help 1217 Enable support for generating core dumps. Disabling saves about 4k. 1218 1219 1220config PCSPKR_PLATFORM 1221 bool "Enable PC-Speaker support" if EXPERT 1222 depends on HAVE_PCSPKR_PLATFORM 1223 select I8253_LOCK 1224 default y 1225 help 1226 This option allows to disable the internal PC-Speaker 1227 support, saving some memory. 1228 1229config HAVE_PCSPKR_PLATFORM 1230 bool 1231 1232config BASE_FULL 1233 default y 1234 bool "Enable full-sized data structures for core" if EXPERT 1235 help 1236 Disabling this option reduces the size of miscellaneous core 1237 kernel data structures. This saves memory on small machines, 1238 but may reduce performance. 1239 1240config FUTEX 1241 bool "Enable futex support" if EXPERT 1242 default y 1243 select RT_MUTEXES 1244 help 1245 Disabling this option will cause the kernel to be built without 1246 support for "fast userspace mutexes". The resulting kernel may not 1247 run glibc-based applications correctly. 1248 1249config EPOLL 1250 bool "Enable eventpoll support" if EXPERT 1251 default y 1252 select ANON_INODES 1253 help 1254 Disabling this option will cause the kernel to be built without 1255 support for epoll family of system calls. 1256 1257config SIGNALFD 1258 bool "Enable signalfd() system call" if EXPERT 1259 select ANON_INODES 1260 default y 1261 help 1262 Enable the signalfd() system call that allows to receive signals 1263 on a file descriptor. 1264 1265 If unsure, say Y. 1266 1267config TIMERFD 1268 bool "Enable timerfd() system call" if EXPERT 1269 select ANON_INODES 1270 default y 1271 help 1272 Enable the timerfd() system call that allows to receive timer 1273 events on a file descriptor. 1274 1275 If unsure, say Y. 1276 1277config EVENTFD 1278 bool "Enable eventfd() system call" if EXPERT 1279 select ANON_INODES 1280 default y 1281 help 1282 Enable the eventfd() system call that allows to receive both 1283 kernel notification (ie. KAIO) or userspace notifications. 1284 1285 If unsure, say Y. 1286 1287config SHMEM 1288 bool "Use full shmem filesystem" if EXPERT 1289 default y 1290 depends on MMU 1291 help 1292 The shmem is an internal filesystem used to manage shared memory. 1293 It is backed by swap and manages resource limits. It is also exported 1294 to userspace as tmpfs if TMPFS is enabled. Disabling this 1295 option replaces shmem and tmpfs with the much simpler ramfs code, 1296 which may be appropriate on small systems without swap. 1297 1298config AIO 1299 bool "Enable AIO support" if EXPERT 1300 default y 1301 help 1302 This option enables POSIX asynchronous I/O which may by used 1303 by some high performance threaded applications. Disabling 1304 this option saves about 7k. 1305 1306config EMBEDDED 1307 bool "Embedded system" 1308 select EXPERT 1309 help 1310 This option should be enabled if compiling the kernel for 1311 an embedded system so certain expert options are available 1312 for configuration. 1313 1314config HAVE_PERF_EVENTS 1315 bool 1316 help 1317 See tools/perf/design.txt for details. 1318 1319config PERF_USE_VMALLOC 1320 bool 1321 help 1322 See tools/perf/design.txt for details 1323 1324menu "Kernel Performance Events And Counters" 1325 1326config PERF_EVENTS 1327 bool "Kernel performance events and counters" 1328 default y if PROFILING 1329 depends on HAVE_PERF_EVENTS 1330 select ANON_INODES 1331 select IRQ_WORK 1332 help 1333 Enable kernel support for various performance events provided 1334 by software and hardware. 1335 1336 Software events are supported either built-in or via the 1337 use of generic tracepoints. 1338 1339 Most modern CPUs support performance events via performance 1340 counter registers. These registers count the number of certain 1341 types of hw events: such as instructions executed, cachemisses 1342 suffered, or branches mis-predicted - without slowing down the 1343 kernel or applications. These registers can also trigger interrupts 1344 when a threshold number of events have passed - and can thus be 1345 used to profile the code that runs on that CPU. 1346 1347 The Linux Performance Event subsystem provides an abstraction of 1348 these software and hardware event capabilities, available via a 1349 system call and used by the "perf" utility in tools/perf/. It 1350 provides per task and per CPU counters, and it provides event 1351 capabilities on top of those. 1352 1353 Say Y if unsure. 1354 1355config DEBUG_PERF_USE_VMALLOC 1356 default n 1357 bool "Debug: use vmalloc to back perf mmap() buffers" 1358 depends on PERF_EVENTS && DEBUG_KERNEL 1359 select PERF_USE_VMALLOC 1360 help 1361 Use vmalloc memory to back perf mmap() buffers. 1362 1363 Mostly useful for debugging the vmalloc code on platforms 1364 that don't require it. 1365 1366 Say N if unsure. 1367 1368endmenu 1369 1370config VM_EVENT_COUNTERS 1371 default y 1372 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1373 help 1374 VM event counters are needed for event counts to be shown. 1375 This option allows the disabling of the VM event counters 1376 on EXPERT systems. /proc/vmstat will only show page counts 1377 if VM event counters are disabled. 1378 1379config PCI_QUIRKS 1380 default y 1381 bool "Enable PCI quirk workarounds" if EXPERT 1382 depends on PCI 1383 help 1384 This enables workarounds for various PCI chipset 1385 bugs/quirks. Disable this only if your target machine is 1386 unaffected by PCI quirks. 1387 1388config SLUB_DEBUG 1389 default y 1390 bool "Enable SLUB debugging support" if EXPERT 1391 depends on SLUB && SYSFS 1392 help 1393 SLUB has extensive debug support features. Disabling these can 1394 result in significant savings in code size. This also disables 1395 SLUB sysfs support. /sys/slab will not exist and there will be 1396 no support for cache validation etc. 1397 1398config COMPAT_BRK 1399 bool "Disable heap randomization" 1400 default y 1401 help 1402 Randomizing heap placement makes heap exploits harder, but it 1403 also breaks ancient binaries (including anything libc5 based). 1404 This option changes the bootup default to heap randomization 1405 disabled, and can be overridden at runtime by setting 1406 /proc/sys/kernel/randomize_va_space to 2. 1407 1408 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1409 1410choice 1411 prompt "Choose SLAB allocator" 1412 default SLUB 1413 help 1414 This option allows to select a slab allocator. 1415 1416config SLAB 1417 bool "SLAB" 1418 help 1419 The regular slab allocator that is established and known to work 1420 well in all environments. It organizes cache hot objects in 1421 per cpu and per node queues. 1422 1423config SLUB 1424 bool "SLUB (Unqueued Allocator)" 1425 help 1426 SLUB is a slab allocator that minimizes cache line usage 1427 instead of managing queues of cached objects (SLAB approach). 1428 Per cpu caching is realized using slabs of objects instead 1429 of queues of objects. SLUB can use memory efficiently 1430 and has enhanced diagnostics. SLUB is the default choice for 1431 a slab allocator. 1432 1433config SLOB 1434 depends on EXPERT 1435 bool "SLOB (Simple Allocator)" 1436 help 1437 SLOB replaces the stock allocator with a drastically simpler 1438 allocator. SLOB is generally more space efficient but 1439 does not perform as well on large systems. 1440 1441endchoice 1442 1443config MMAP_ALLOW_UNINITIALIZED 1444 bool "Allow mmapped anonymous memory to be uninitialized" 1445 depends on EXPERT && !MMU 1446 default n 1447 help 1448 Normally, and according to the Linux spec, anonymous memory obtained 1449 from mmap() has it's contents cleared before it is passed to 1450 userspace. Enabling this config option allows you to request that 1451 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1452 providing a huge performance boost. If this option is not enabled, 1453 then the flag will be ignored. 1454 1455 This is taken advantage of by uClibc's malloc(), and also by 1456 ELF-FDPIC binfmt's brk and stack allocator. 1457 1458 Because of the obvious security issues, this option should only be 1459 enabled on embedded devices where you control what is run in 1460 userspace. Since that isn't generally a problem on no-MMU systems, 1461 it is normally safe to say Y here. 1462 1463 See Documentation/nommu-mmap.txt for more information. 1464 1465config PROFILING 1466 bool "Profiling support" 1467 help 1468 Say Y here to enable the extended profiling support mechanisms used 1469 by profilers such as OProfile. 1470 1471# 1472# Place an empty function call at each tracepoint site. Can be 1473# dynamically changed for a probe function. 1474# 1475config TRACEPOINTS 1476 bool 1477 1478source "arch/Kconfig" 1479 1480endmenu # General setup 1481 1482config HAVE_GENERIC_DMA_COHERENT 1483 bool 1484 default n 1485 1486config SLABINFO 1487 bool 1488 depends on PROC_FS 1489 depends on SLAB || SLUB_DEBUG 1490 default y 1491 1492config RT_MUTEXES 1493 boolean 1494 1495config BASE_SMALL 1496 int 1497 default 0 if BASE_FULL 1498 default 1 if !BASE_FULL 1499 1500menuconfig MODULES 1501 bool "Enable loadable module support" 1502 help 1503 Kernel modules are small pieces of compiled code which can 1504 be inserted in the running kernel, rather than being 1505 permanently built into the kernel. You use the "modprobe" 1506 tool to add (and sometimes remove) them. If you say Y here, 1507 many parts of the kernel can be built as modules (by 1508 answering M instead of Y where indicated): this is most 1509 useful for infrequently used options which are not required 1510 for booting. For more information, see the man pages for 1511 modprobe, lsmod, modinfo, insmod and rmmod. 1512 1513 If you say Y here, you will need to run "make 1514 modules_install" to put the modules under /lib/modules/ 1515 where modprobe can find them (you may need to be root to do 1516 this). 1517 1518 If unsure, say Y. 1519 1520if MODULES 1521 1522config MODULE_FORCE_LOAD 1523 bool "Forced module loading" 1524 default n 1525 help 1526 Allow loading of modules without version information (ie. modprobe 1527 --force). Forced module loading sets the 'F' (forced) taint flag and 1528 is usually a really bad idea. 1529 1530config MODULE_UNLOAD 1531 bool "Module unloading" 1532 help 1533 Without this option you will not be able to unload any 1534 modules (note that some modules may not be unloadable 1535 anyway), which makes your kernel smaller, faster 1536 and simpler. If unsure, say Y. 1537 1538config MODULE_FORCE_UNLOAD 1539 bool "Forced module unloading" 1540 depends on MODULE_UNLOAD && EXPERIMENTAL 1541 help 1542 This option allows you to force a module to unload, even if the 1543 kernel believes it is unsafe: the kernel will remove the module 1544 without waiting for anyone to stop using it (using the -f option to 1545 rmmod). This is mainly for kernel developers and desperate users. 1546 If unsure, say N. 1547 1548config MODVERSIONS 1549 bool "Module versioning support" 1550 help 1551 Usually, you have to use modules compiled with your kernel. 1552 Saying Y here makes it sometimes possible to use modules 1553 compiled for different kernels, by adding enough information 1554 to the modules to (hopefully) spot any changes which would 1555 make them incompatible with the kernel you are running. If 1556 unsure, say N. 1557 1558config MODULE_SRCVERSION_ALL 1559 bool "Source checksum for all modules" 1560 help 1561 Modules which contain a MODULE_VERSION get an extra "srcversion" 1562 field inserted into their modinfo section, which contains a 1563 sum of the source files which made it. This helps maintainers 1564 see exactly which source was used to build a module (since 1565 others sometimes change the module source without updating 1566 the version). With this option, such a "srcversion" field 1567 will be created for all modules. If unsure, say N. 1568 1569endif # MODULES 1570 1571config INIT_ALL_POSSIBLE 1572 bool 1573 help 1574 Back when each arch used to define their own cpu_online_mask and 1575 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 1576 with all 1s, and others with all 0s. When they were centralised, 1577 it was better to provide this option than to break all the archs 1578 and have several arch maintainers pursuing me down dark alleys. 1579 1580config STOP_MACHINE 1581 bool 1582 default y 1583 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1584 help 1585 Need stop_machine() primitive. 1586 1587source "block/Kconfig" 1588 1589config PREEMPT_NOTIFIERS 1590 bool 1591 1592config PADATA 1593 depends on SMP 1594 bool 1595 1596source "kernel/Kconfig.locks" 1597