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 These are 53 drivers that have been replaced by something else, and/or are 54 scheduled to be removed in a future kernel release. 55 56 Unless you intend to help test and develop a feature or driver that 57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