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 IRQ_WORK 24 bool 25 26config BUILDTIME_EXTABLE_SORT 27 bool 28 29menu "General setup" 30 31config BROKEN 32 bool 33 34config BROKEN_ON_SMP 35 bool 36 depends on BROKEN || !SMP 37 default y 38 39config INIT_ENV_ARG_LIMIT 40 int 41 default 32 if !UML 42 default 128 if UML 43 help 44 Maximum of each of the number of arguments and environment 45 variables passed to init from the kernel command line. 46 47 48config CROSS_COMPILE 49 string "Cross-compiler tool prefix" 50 help 51 Same as running 'make CROSS_COMPILE=prefix-' but stored for 52 default make runs in this kernel build directory. You don't 53 need to set this unless you want the configured kernel build 54 directory to select the cross-compiler automatically. 55 56config LOCALVERSION 57 string "Local version - append to kernel release" 58 help 59 Append an extra string to the end of your kernel version. 60 This will show up when you type uname, for example. 61 The string you set here will be appended after the contents of 62 any files with a filename matching localversion* in your 63 object and source tree, in that order. Your total string can 64 be a maximum of 64 characters. 65 66config LOCALVERSION_AUTO 67 bool "Automatically append version information to the version string" 68 default y 69 help 70 This will try to automatically determine if the current tree is a 71 release tree by looking for git tags that belong to the current 72 top of tree revision. 73 74 A string of the format -gxxxxxxxx will be added to the localversion 75 if a git-based tree is found. The string generated by this will be 76 appended after any matching localversion* files, and after the value 77 set in CONFIG_LOCALVERSION. 78 79 (The actual string used here is the first eight characters produced 80 by running the command: 81 82 $ git rev-parse --verify HEAD 83 84 which is done within the script "scripts/setlocalversion".) 85 86config HAVE_KERNEL_GZIP 87 bool 88 89config HAVE_KERNEL_BZIP2 90 bool 91 92config HAVE_KERNEL_LZMA 93 bool 94 95config HAVE_KERNEL_XZ 96 bool 97 98config HAVE_KERNEL_LZO 99 bool 100 101choice 102 prompt "Kernel compression mode" 103 default KERNEL_GZIP 104 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 105 help 106 The linux kernel is a kind of self-extracting executable. 107 Several compression algorithms are available, which differ 108 in efficiency, compression and decompression speed. 109 Compression speed is only relevant when building a kernel. 110 Decompression speed is relevant at each boot. 111 112 If you have any problems with bzip2 or lzma compressed 113 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 114 version of this functionality (bzip2 only), for 2.4, was 115 supplied by Christian Ludwig) 116 117 High compression options are mostly useful for users, who 118 are low on disk space (embedded systems), but for whom ram 119 size matters less. 120 121 If in doubt, select 'gzip' 122 123config KERNEL_GZIP 124 bool "Gzip" 125 depends on HAVE_KERNEL_GZIP 126 help 127 The old and tried gzip compression. It provides a good balance 128 between compression ratio and decompression speed. 129 130config KERNEL_BZIP2 131 bool "Bzip2" 132 depends on HAVE_KERNEL_BZIP2 133 help 134 Its compression ratio and speed is intermediate. 135 Decompression speed is slowest among the choices. The kernel 136 size is about 10% smaller with bzip2, in comparison to gzip. 137 Bzip2 uses a large amount of memory. For modern kernels you 138 will need at least 8MB RAM or more for booting. 139 140config KERNEL_LZMA 141 bool "LZMA" 142 depends on HAVE_KERNEL_LZMA 143 help 144 This compression algorithm's ratio is best. Decompression speed 145 is between gzip and bzip2. Compression is slowest. 146 The kernel size is about 33% smaller with LZMA in comparison to gzip. 147 148config KERNEL_XZ 149 bool "XZ" 150 depends on HAVE_KERNEL_XZ 151 help 152 XZ uses the LZMA2 algorithm and instruction set specific 153 BCJ filters which can improve compression ratio of executable 154 code. The size of the kernel is about 30% smaller with XZ in 155 comparison to gzip. On architectures for which there is a BCJ 156 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 157 will create a few percent smaller kernel than plain LZMA. 158 159 The speed is about the same as with LZMA: The decompression 160 speed of XZ is better than that of bzip2 but worse than gzip 161 and LZO. Compression is slow. 162 163config KERNEL_LZO 164 bool "LZO" 165 depends on HAVE_KERNEL_LZO 166 help 167 Its compression ratio is the poorest among the choices. The kernel 168 size is about 10% bigger than gzip; however its speed 169 (both compression and decompression) is the fastest. 170 171endchoice 172 173config DEFAULT_HOSTNAME 174 string "Default hostname" 175 default "(none)" 176 help 177 This option determines the default system hostname before userspace 178 calls sethostname(2). The kernel traditionally uses "(none)" here, 179 but you may wish to use a different default here to make a minimal 180 system more usable with less configuration. 181 182config SWAP 183 bool "Support for paging of anonymous memory (swap)" 184 depends on MMU && BLOCK 185 default y 186 help 187 This option allows you to choose whether you want to have support 188 for so called swap devices or swap files in your kernel that are 189 used to provide more virtual memory than the actual RAM present 190 in your computer. If unsure say Y. 191 192config SYSVIPC 193 bool "System V IPC" 194 ---help--- 195 Inter Process Communication is a suite of library functions and 196 system calls which let processes (running programs) synchronize and 197 exchange information. It is generally considered to be a good thing, 198 and some programs won't run unless you say Y here. In particular, if 199 you want to run the DOS emulator dosemu under Linux (read the 200 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 201 you'll need to say Y here. 202 203 You can find documentation about IPC with "info ipc" and also in 204 section 6.4 of the Linux Programmer's Guide, available from 205 <http://www.tldp.org/guides.html>. 206 207config SYSVIPC_SYSCTL 208 bool 209 depends on SYSVIPC 210 depends on SYSCTL 211 default y 212 213config POSIX_MQUEUE 214 bool "POSIX Message Queues" 215 depends on NET 216 ---help--- 217 POSIX variant of message queues is a part of IPC. In POSIX message 218 queues every message has a priority which decides about succession 219 of receiving it by a process. If you want to compile and run 220 programs written e.g. for Solaris with use of its POSIX message 221 queues (functions mq_*) say Y here. 222 223 POSIX message queues are visible as a filesystem called 'mqueue' 224 and can be mounted somewhere if you want to do filesystem 225 operations on message queues. 226 227 If unsure, say Y. 228 229config POSIX_MQUEUE_SYSCTL 230 bool 231 depends on POSIX_MQUEUE 232 depends on SYSCTL 233 default y 234 235config FHANDLE 236 bool "open by fhandle syscalls" 237 select EXPORTFS 238 help 239 If you say Y here, a user level program will be able to map 240 file names to handle and then later use the handle for 241 different file system operations. This is useful in implementing 242 userspace file servers, which now track files using handles instead 243 of names. The handle would remain the same even if file names 244 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 245 syscalls. 246 247config AUDIT 248 bool "Auditing support" 249 depends on NET 250 help 251 Enable auditing infrastructure that can be used with another 252 kernel subsystem, such as SELinux (which requires this for 253 logging of avc messages output). Does not do system-call 254 auditing without CONFIG_AUDITSYSCALL. 255 256config AUDITSYSCALL 257 bool "Enable system-call auditing support" 258 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT)) 259 default y if SECURITY_SELINUX 260 help 261 Enable low-overhead system-call auditing infrastructure that 262 can be used independently or with another kernel subsystem, 263 such as SELinux. 264 265config AUDIT_WATCH 266 def_bool y 267 depends on AUDITSYSCALL 268 select FSNOTIFY 269 270config AUDIT_TREE 271 def_bool y 272 depends on AUDITSYSCALL 273 select FSNOTIFY 274 275config AUDIT_LOGINUID_IMMUTABLE 276 bool "Make audit loginuid immutable" 277 depends on AUDIT 278 help 279 The config option toggles if a task setting its loginuid requires 280 CAP_SYS_AUDITCONTROL or if that task should require no special permissions 281 but should instead only allow setting its loginuid if it was never 282 previously set. On systems which use systemd or a similar central 283 process to restart login services this should be set to true. On older 284 systems in which an admin would typically have to directly stop and 285 start processes this should be set to false. Setting this to true allows 286 one to drop potentially dangerous capabilites from the login tasks, 287 but may not be backwards compatible with older init systems. 288 289source "kernel/irq/Kconfig" 290source "kernel/time/Kconfig" 291 292menu "CPU/Task time and stats accounting" 293 294config VIRT_CPU_ACCOUNTING 295 bool 296 297choice 298 prompt "Cputime accounting" 299 default TICK_CPU_ACCOUNTING if !PPC64 300 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 301 302# Kind of a stub config for the pure tick based cputime accounting 303config TICK_CPU_ACCOUNTING 304 bool "Simple tick based cputime accounting" 305 depends on !S390 306 help 307 This is the basic tick based cputime accounting that maintains 308 statistics about user, system and idle time spent on per jiffies 309 granularity. 310 311 If unsure, say Y. 312 313config VIRT_CPU_ACCOUNTING_NATIVE 314 bool "Deterministic task and CPU time accounting" 315 depends on HAVE_VIRT_CPU_ACCOUNTING 316 select VIRT_CPU_ACCOUNTING 317 help 318 Select this option to enable more accurate task and CPU time 319 accounting. This is done by reading a CPU counter on each 320 kernel entry and exit and on transitions within the kernel 321 between system, softirq and hardirq state, so there is a 322 small performance impact. In the case of s390 or IBM POWER > 5, 323 this also enables accounting of stolen time on logically-partitioned 324 systems. 325 326config VIRT_CPU_ACCOUNTING_GEN 327 bool "Full dynticks CPU time accounting" 328 depends on HAVE_CONTEXT_TRACKING && 64BIT 329 select VIRT_CPU_ACCOUNTING 330 select CONTEXT_TRACKING 331 help 332 Select this option to enable task and CPU time accounting on full 333 dynticks systems. This accounting is implemented by watching every 334 kernel-user boundaries using the context tracking subsystem. 335 The accounting is thus performed at the expense of some significant 336 overhead. 337 338 For now this is only useful if you are working on the full 339 dynticks subsystem development. 340 341 If unsure, say N. 342 343config IRQ_TIME_ACCOUNTING 344 bool "Fine granularity task level IRQ time accounting" 345 depends on HAVE_IRQ_TIME_ACCOUNTING 346 help 347 Select this option to enable fine granularity task irq time 348 accounting. This is done by reading a timestamp on each 349 transitions between softirq and hardirq state, so there can be a 350 small performance impact. 351 352 If in doubt, say N here. 353 354endchoice 355 356config BSD_PROCESS_ACCT 357 bool "BSD Process Accounting" 358 help 359 If you say Y here, a user level program will be able to instruct the 360 kernel (via a special system call) to write process accounting 361 information to a file: whenever a process exits, information about 362 that process will be appended to the file by the kernel. The 363 information includes things such as creation time, owning user, 364 command name, memory usage, controlling terminal etc. (the complete 365 list is in the struct acct in <file:include/linux/acct.h>). It is 366 up to the user level program to do useful things with this 367 information. This is generally a good idea, so say Y. 368 369config BSD_PROCESS_ACCT_V3 370 bool "BSD Process Accounting version 3 file format" 371 depends on BSD_PROCESS_ACCT 372 default n 373 help 374 If you say Y here, the process accounting information is written 375 in a new file format that also logs the process IDs of each 376 process and it's parent. Note that this file format is incompatible 377 with previous v0/v1/v2 file formats, so you will need updated tools 378 for processing it. A preliminary version of these tools is available 379 at <http://www.gnu.org/software/acct/>. 380 381config TASKSTATS 382 bool "Export task/process statistics through netlink" 383 depends on NET 384 default n 385 help 386 Export selected statistics for tasks/processes through the 387 generic netlink interface. Unlike BSD process accounting, the 388 statistics are available during the lifetime of tasks/processes as 389 responses to commands. Like BSD accounting, they are sent to user 390 space on task exit. 391 392 Say N if unsure. 393 394config TASK_DELAY_ACCT 395 bool "Enable per-task delay accounting" 396 depends on TASKSTATS 397 help 398 Collect information on time spent by a task waiting for system 399 resources like cpu, synchronous block I/O completion and swapping 400 in pages. Such statistics can help in setting a task's priorities 401 relative to other tasks for cpu, io, rss limits etc. 402 403 Say N if unsure. 404 405config TASK_XACCT 406 bool "Enable extended accounting over taskstats" 407 depends on TASKSTATS 408 help 409 Collect extended task accounting data and send the data 410 to userland for processing over the taskstats interface. 411 412 Say N if unsure. 413 414config TASK_IO_ACCOUNTING 415 bool "Enable per-task storage I/O accounting" 416 depends on TASK_XACCT 417 help 418 Collect information on the number of bytes of storage I/O which this 419 task has caused. 420 421 Say N if unsure. 422 423endmenu # "CPU/Task time and stats accounting" 424 425menu "RCU Subsystem" 426 427choice 428 prompt "RCU Implementation" 429 default TREE_RCU 430 431config TREE_RCU 432 bool "Tree-based hierarchical RCU" 433 depends on !PREEMPT && SMP 434 help 435 This option selects the RCU implementation that is 436 designed for very large SMP system with hundreds or 437 thousands of CPUs. It also scales down nicely to 438 smaller systems. 439 440config TREE_PREEMPT_RCU 441 bool "Preemptible tree-based hierarchical RCU" 442 depends on PREEMPT 443 help 444 This option selects the RCU implementation that is 445 designed for very large SMP systems with hundreds or 446 thousands of CPUs, but for which real-time response 447 is also required. It also scales down nicely to 448 smaller systems. 449 450 Select this option if you are unsure. 451 452config TINY_RCU 453 bool "UP-only small-memory-footprint RCU" 454 depends on !PREEMPT && !SMP 455 help 456 This option selects the RCU implementation that is 457 designed for UP systems from which real-time response 458 is not required. This option greatly reduces the 459 memory footprint of RCU. 460 461config TINY_PREEMPT_RCU 462 bool "Preemptible UP-only small-memory-footprint RCU" 463 depends on PREEMPT && !SMP 464 help 465 This option selects the RCU implementation that is designed 466 for real-time UP systems. This option greatly reduces the 467 memory footprint of RCU. 468 469endchoice 470 471config PREEMPT_RCU 472 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 473 help 474 This option enables preemptible-RCU code that is common between 475 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 476 477config RCU_STALL_COMMON 478 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE ) 479 help 480 This option enables RCU CPU stall code that is common between 481 the TINY and TREE variants of RCU. The purpose is to allow 482 the tiny variants to disable RCU CPU stall warnings, while 483 making these warnings mandatory for the tree variants. 484 485config CONTEXT_TRACKING 486 bool 487 488config RCU_USER_QS 489 bool "Consider userspace as in RCU extended quiescent state" 490 depends on HAVE_CONTEXT_TRACKING && SMP 491 select CONTEXT_TRACKING 492 help 493 This option sets hooks on kernel / userspace boundaries and 494 puts RCU in extended quiescent state when the CPU runs in 495 userspace. It means that when a CPU runs in userspace, it is 496 excluded from the global RCU state machine and thus doesn't 497 try to keep the timer tick on for RCU. 498 499 Unless you want to hack and help the development of the full 500 dynticks mode, you shouldn't enable this option. It also 501 adds unnecessary overhead. 502 503 If unsure say N 504 505config CONTEXT_TRACKING_FORCE 506 bool "Force context tracking" 507 depends on CONTEXT_TRACKING 508 help 509 Probe on user/kernel boundaries by default in order to 510 test the features that rely on it such as userspace RCU extended 511 quiescent states. 512 This test is there for debugging until we have a real user like the 513 full dynticks mode. 514 515config RCU_FANOUT 516 int "Tree-based hierarchical RCU fanout value" 517 range 2 64 if 64BIT 518 range 2 32 if !64BIT 519 depends on TREE_RCU || TREE_PREEMPT_RCU 520 default 64 if 64BIT 521 default 32 if !64BIT 522 help 523 This option controls the fanout of hierarchical implementations 524 of RCU, allowing RCU to work efficiently on machines with 525 large numbers of CPUs. This value must be at least the fourth 526 root of NR_CPUS, which allows NR_CPUS to be insanely large. 527 The default value of RCU_FANOUT should be used for production 528 systems, but if you are stress-testing the RCU implementation 529 itself, small RCU_FANOUT values allow you to test large-system 530 code paths on small(er) systems. 531 532 Select a specific number if testing RCU itself. 533 Take the default if unsure. 534 535config RCU_FANOUT_LEAF 536 int "Tree-based hierarchical RCU leaf-level fanout value" 537 range 2 RCU_FANOUT if 64BIT 538 range 2 RCU_FANOUT if !64BIT 539 depends on TREE_RCU || TREE_PREEMPT_RCU 540 default 16 541 help 542 This option controls the leaf-level fanout of hierarchical 543 implementations of RCU, and allows trading off cache misses 544 against lock contention. Systems that synchronize their 545 scheduling-clock interrupts for energy-efficiency reasons will 546 want the default because the smaller leaf-level fanout keeps 547 lock contention levels acceptably low. Very large systems 548 (hundreds or thousands of CPUs) will instead want to set this 549 value to the maximum value possible in order to reduce the 550 number of cache misses incurred during RCU's grace-period 551 initialization. These systems tend to run CPU-bound, and thus 552 are not helped by synchronized interrupts, and thus tend to 553 skew them, which reduces lock contention enough that large 554 leaf-level fanouts work well. 555 556 Select a specific number if testing RCU itself. 557 558 Select the maximum permissible value for large systems. 559 560 Take the default if unsure. 561 562config RCU_FANOUT_EXACT 563 bool "Disable tree-based hierarchical RCU auto-balancing" 564 depends on TREE_RCU || TREE_PREEMPT_RCU 565 default n 566 help 567 This option forces use of the exact RCU_FANOUT value specified, 568 regardless of imbalances in the hierarchy. This is useful for 569 testing RCU itself, and might one day be useful on systems with 570 strong NUMA behavior. 571 572 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 573 574 Say N if unsure. 575 576config RCU_FAST_NO_HZ 577 bool "Accelerate last non-dyntick-idle CPU's grace periods" 578 depends on NO_HZ && SMP 579 default n 580 help 581 This option causes RCU to attempt to accelerate grace periods in 582 order to allow CPUs to enter dynticks-idle state more quickly. 583 On the other hand, this option increases the overhead of the 584 dynticks-idle checking, thus degrading scheduling latency. 585 586 Say Y if energy efficiency is critically important, and you don't 587 care about real-time response. 588 589 Say N if you are unsure. 590 591config TREE_RCU_TRACE 592 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 593 select DEBUG_FS 594 help 595 This option provides tracing for the TREE_RCU and 596 TREE_PREEMPT_RCU implementations, permitting Makefile to 597 trivially select kernel/rcutree_trace.c. 598 599config RCU_BOOST 600 bool "Enable RCU priority boosting" 601 depends on RT_MUTEXES && PREEMPT_RCU 602 default n 603 help 604 This option boosts the priority of preempted RCU readers that 605 block the current preemptible RCU grace period for too long. 606 This option also prevents heavy loads from blocking RCU 607 callback invocation for all flavors of RCU. 608 609 Say Y here if you are working with real-time apps or heavy loads 610 Say N here if you are unsure. 611 612config RCU_BOOST_PRIO 613 int "Real-time priority to boost RCU readers to" 614 range 1 99 615 depends on RCU_BOOST 616 default 1 617 help 618 This option specifies the real-time priority to which long-term 619 preempted RCU readers are to be boosted. If you are working 620 with a real-time application that has one or more CPU-bound 621 threads running at a real-time priority level, you should set 622 RCU_BOOST_PRIO to a priority higher then the highest-priority 623 real-time CPU-bound thread. The default RCU_BOOST_PRIO value 624 of 1 is appropriate in the common case, which is real-time 625 applications that do not have any CPU-bound threads. 626 627 Some real-time applications might not have a single real-time 628 thread that saturates a given CPU, but instead might have 629 multiple real-time threads that, taken together, fully utilize 630 that CPU. In this case, you should set RCU_BOOST_PRIO to 631 a priority higher than the lowest-priority thread that is 632 conspiring to prevent the CPU from running any non-real-time 633 tasks. For example, if one thread at priority 10 and another 634 thread at priority 5 are between themselves fully consuming 635 the CPU time on a given CPU, then RCU_BOOST_PRIO should be 636 set to priority 6 or higher. 637 638 Specify the real-time priority, or take the default if unsure. 639 640config RCU_BOOST_DELAY 641 int "Milliseconds to delay boosting after RCU grace-period start" 642 range 0 3000 643 depends on RCU_BOOST 644 default 500 645 help 646 This option specifies the time to wait after the beginning of 647 a given grace period before priority-boosting preempted RCU 648 readers blocking that grace period. Note that any RCU reader 649 blocking an expedited RCU grace period is boosted immediately. 650 651 Accept the default if unsure. 652 653config RCU_NOCB_CPU 654 bool "Offload RCU callback processing from boot-selected CPUs" 655 depends on TREE_RCU || TREE_PREEMPT_RCU 656 default n 657 help 658 Use this option to reduce OS jitter for aggressive HPC or 659 real-time workloads. It can also be used to offload RCU 660 callback invocation to energy-efficient CPUs in battery-powered 661 asymmetric multiprocessors. 662 663 This option offloads callback invocation from the set of 664 CPUs specified at boot time by the rcu_nocbs parameter. 665 For each such CPU, a kthread ("rcuoN") will be created to 666 invoke callbacks, where the "N" is the CPU being offloaded. 667 Nothing prevents this kthread from running on the specified 668 CPUs, but (1) the kthreads may be preempted between each 669 callback, and (2) affinity or cgroups can be used to force 670 the kthreads to run on whatever set of CPUs is desired. 671 672 Say Y here if you want reduced OS jitter on selected CPUs. 673 Say N here if you are unsure. 674 675endmenu # "RCU Subsystem" 676 677config IKCONFIG 678 tristate "Kernel .config support" 679 ---help--- 680 This option enables the complete Linux kernel ".config" file 681 contents to be saved in the kernel. It provides documentation 682 of which kernel options are used in a running kernel or in an 683 on-disk kernel. This information can be extracted from the kernel 684 image file with the script scripts/extract-ikconfig and used as 685 input to rebuild the current kernel or to build another kernel. 686 It can also be extracted from a running kernel by reading 687 /proc/config.gz if enabled (below). 688 689config IKCONFIG_PROC 690 bool "Enable access to .config through /proc/config.gz" 691 depends on IKCONFIG && PROC_FS 692 ---help--- 693 This option enables access to the kernel configuration file 694 through /proc/config.gz. 695 696config LOG_BUF_SHIFT 697 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 698 range 12 21 699 default 17 700 help 701 Select kernel log buffer size as a power of 2. 702 Examples: 703 17 => 128 KB 704 16 => 64 KB 705 15 => 32 KB 706 14 => 16 KB 707 13 => 8 KB 708 12 => 4 KB 709 710# 711# Architectures with an unreliable sched_clock() should select this: 712# 713config HAVE_UNSTABLE_SCHED_CLOCK 714 bool 715 716# 717# For architectures that want to enable the support for NUMA-affine scheduler 718# balancing logic: 719# 720config ARCH_SUPPORTS_NUMA_BALANCING 721 bool 722 723# For architectures that (ab)use NUMA to represent different memory regions 724# all cpu-local but of different latencies, such as SuperH. 725# 726config ARCH_WANT_NUMA_VARIABLE_LOCALITY 727 bool 728 729# 730# For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE 731config ARCH_WANTS_PROT_NUMA_PROT_NONE 732 bool 733 734config ARCH_USES_NUMA_PROT_NONE 735 bool 736 default y 737 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE 738 depends on NUMA_BALANCING 739 740config NUMA_BALANCING_DEFAULT_ENABLED 741 bool "Automatically enable NUMA aware memory/task placement" 742 default y 743 depends on NUMA_BALANCING 744 help 745 If set, autonumic NUMA balancing will be enabled if running on a NUMA 746 machine. 747 748config NUMA_BALANCING 749 bool "Memory placement aware NUMA scheduler" 750 depends on ARCH_SUPPORTS_NUMA_BALANCING 751 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 752 depends on SMP && NUMA && MIGRATION 753 help 754 This option adds support for automatic NUMA aware memory/task placement. 755 The mechanism is quite primitive and is based on migrating memory when 756 it is references to the node the task is running on. 757 758 This system will be inactive on UMA systems. 759 760menuconfig CGROUPS 761 boolean "Control Group support" 762 depends on EVENTFD 763 help 764 This option adds support for grouping sets of processes together, for 765 use with process control subsystems such as Cpusets, CFS, memory 766 controls or device isolation. 767 See 768 - Documentation/scheduler/sched-design-CFS.txt (CFS) 769 - Documentation/cgroups/ (features for grouping, isolation 770 and resource control) 771 772 Say N if unsure. 773 774if CGROUPS 775 776config CGROUP_DEBUG 777 bool "Example debug cgroup subsystem" 778 default n 779 help 780 This option enables a simple cgroup subsystem that 781 exports useful debugging information about the cgroups 782 framework. 783 784 Say N if unsure. 785 786config CGROUP_FREEZER 787 bool "Freezer cgroup subsystem" 788 help 789 Provides a way to freeze and unfreeze all tasks in a 790 cgroup. 791 792config CGROUP_DEVICE 793 bool "Device controller for cgroups" 794 help 795 Provides a cgroup implementing whitelists for devices which 796 a process in the cgroup can mknod or open. 797 798config CPUSETS 799 bool "Cpuset support" 800 help 801 This option will let you create and manage CPUSETs which 802 allow dynamically partitioning a system into sets of CPUs and 803 Memory Nodes and assigning tasks to run only within those sets. 804 This is primarily useful on large SMP or NUMA systems. 805 806 Say N if unsure. 807 808config PROC_PID_CPUSET 809 bool "Include legacy /proc/<pid>/cpuset file" 810 depends on CPUSETS 811 default y 812 813config CGROUP_CPUACCT 814 bool "Simple CPU accounting cgroup subsystem" 815 help 816 Provides a simple Resource Controller for monitoring the 817 total CPU consumed by the tasks in a cgroup. 818 819config RESOURCE_COUNTERS 820 bool "Resource counters" 821 help 822 This option enables controller independent resource accounting 823 infrastructure that works with cgroups. 824 825config MEMCG 826 bool "Memory Resource Controller for Control Groups" 827 depends on RESOURCE_COUNTERS 828 select MM_OWNER 829 help 830 Provides a memory resource controller that manages both anonymous 831 memory and page cache. (See Documentation/cgroups/memory.txt) 832 833 Note that setting this option increases fixed memory overhead 834 associated with each page of memory in the system. By this, 835 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 836 usage tracking struct at boot. Total amount of this is printed out 837 at boot. 838 839 Only enable when you're ok with these trade offs and really 840 sure you need the memory resource controller. Even when you enable 841 this, you can set "cgroup_disable=memory" at your boot option to 842 disable memory resource controller and you can avoid overheads. 843 (and lose benefits of memory resource controller) 844 845 This config option also selects MM_OWNER config option, which 846 could in turn add some fork/exit overhead. 847 848config MEMCG_SWAP 849 bool "Memory Resource Controller Swap Extension" 850 depends on MEMCG && SWAP 851 help 852 Add swap management feature to memory resource controller. When you 853 enable this, you can limit mem+swap usage per cgroup. In other words, 854 when you disable this, memory resource controller has no cares to 855 usage of swap...a process can exhaust all of the swap. This extension 856 is useful when you want to avoid exhaustion swap but this itself 857 adds more overheads and consumes memory for remembering information. 858 Especially if you use 32bit system or small memory system, please 859 be careful about enabling this. When memory resource controller 860 is disabled by boot option, this will be automatically disabled and 861 there will be no overhead from this. Even when you set this config=y, 862 if boot option "swapaccount=0" is set, swap will not be accounted. 863 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 864 size is 4096bytes, 512k per 1Gbytes of swap. 865config MEMCG_SWAP_ENABLED 866 bool "Memory Resource Controller Swap Extension enabled by default" 867 depends on MEMCG_SWAP 868 default y 869 help 870 Memory Resource Controller Swap Extension comes with its price in 871 a bigger memory consumption. General purpose distribution kernels 872 which want to enable the feature but keep it disabled by default 873 and let the user enable it by swapaccount boot command line 874 parameter should have this option unselected. 875 For those who want to have the feature enabled by default should 876 select this option (if, for some reason, they need to disable it 877 then swapaccount=0 does the trick). 878config MEMCG_KMEM 879 bool "Memory Resource Controller Kernel Memory accounting" 880 depends on MEMCG 881 depends on SLUB || SLAB 882 help 883 The Kernel Memory extension for Memory Resource Controller can limit 884 the amount of memory used by kernel objects in the system. Those are 885 fundamentally different from the entities handled by the standard 886 Memory Controller, which are page-based, and can be swapped. Users of 887 the kmem extension can use it to guarantee that no group of processes 888 will ever exhaust kernel resources alone. 889 890config CGROUP_HUGETLB 891 bool "HugeTLB Resource Controller for Control Groups" 892 depends on RESOURCE_COUNTERS && HUGETLB_PAGE 893 default n 894 help 895 Provides a cgroup Resource Controller for HugeTLB pages. 896 When you enable this, you can put a per cgroup limit on HugeTLB usage. 897 The limit is enforced during page fault. Since HugeTLB doesn't 898 support page reclaim, enforcing the limit at page fault time implies 899 that, the application will get SIGBUS signal if it tries to access 900 HugeTLB pages beyond its limit. This requires the application to know 901 beforehand how much HugeTLB pages it would require for its use. The 902 control group is tracked in the third page lru pointer. This means 903 that we cannot use the controller with huge page less than 3 pages. 904 905config CGROUP_PERF 906 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 907 depends on PERF_EVENTS && CGROUPS 908 help 909 This option extends the per-cpu mode to restrict monitoring to 910 threads which belong to the cgroup specified and run on the 911 designated cpu. 912 913 Say N if unsure. 914 915menuconfig CGROUP_SCHED 916 bool "Group CPU scheduler" 917 default n 918 help 919 This feature lets CPU scheduler recognize task groups and control CPU 920 bandwidth allocation to such task groups. It uses cgroups to group 921 tasks. 922 923if CGROUP_SCHED 924config FAIR_GROUP_SCHED 925 bool "Group scheduling for SCHED_OTHER" 926 depends on CGROUP_SCHED 927 default CGROUP_SCHED 928 929config CFS_BANDWIDTH 930 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 931 depends on FAIR_GROUP_SCHED 932 default n 933 help 934 This option allows users to define CPU bandwidth rates (limits) for 935 tasks running within the fair group scheduler. Groups with no limit 936 set are considered to be unconstrained and will run with no 937 restriction. 938 See tip/Documentation/scheduler/sched-bwc.txt for more information. 939 940config RT_GROUP_SCHED 941 bool "Group scheduling for SCHED_RR/FIFO" 942 depends on CGROUP_SCHED 943 default n 944 help 945 This feature lets you explicitly allocate real CPU bandwidth 946 to task groups. If enabled, it will also make it impossible to 947 schedule realtime tasks for non-root users until you allocate 948 realtime bandwidth for them. 949 See Documentation/scheduler/sched-rt-group.txt for more information. 950 951endif #CGROUP_SCHED 952 953config BLK_CGROUP 954 bool "Block IO controller" 955 depends on BLOCK 956 default n 957 ---help--- 958 Generic block IO controller cgroup interface. This is the common 959 cgroup interface which should be used by various IO controlling 960 policies. 961 962 Currently, CFQ IO scheduler uses it to recognize task groups and 963 control disk bandwidth allocation (proportional time slice allocation) 964 to such task groups. It is also used by bio throttling logic in 965 block layer to implement upper limit in IO rates on a device. 966 967 This option only enables generic Block IO controller infrastructure. 968 One needs to also enable actual IO controlling logic/policy. For 969 enabling proportional weight division of disk bandwidth in CFQ, set 970 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 971 CONFIG_BLK_DEV_THROTTLING=y. 972 973 See Documentation/cgroups/blkio-controller.txt for more information. 974 975config DEBUG_BLK_CGROUP 976 bool "Enable Block IO controller debugging" 977 depends on BLK_CGROUP 978 default n 979 ---help--- 980 Enable some debugging help. Currently it exports additional stat 981 files in a cgroup which can be useful for debugging. 982 983endif # CGROUPS 984 985config CHECKPOINT_RESTORE 986 bool "Checkpoint/restore support" if EXPERT 987 default n 988 help 989 Enables additional kernel features in a sake of checkpoint/restore. 990 In particular it adds auxiliary prctl codes to setup process text, 991 data and heap segment sizes, and a few additional /proc filesystem 992 entries. 993 994 If unsure, say N here. 995 996menuconfig NAMESPACES 997 bool "Namespaces support" if EXPERT 998 default !EXPERT 999 help 1000 Provides the way to make tasks work with different objects using 1001 the same id. For example same IPC id may refer to different objects 1002 or same user id or pid may refer to different tasks when used in 1003 different namespaces. 1004 1005if NAMESPACES 1006 1007config UTS_NS 1008 bool "UTS namespace" 1009 default y 1010 help 1011 In this namespace tasks see different info provided with the 1012 uname() system call 1013 1014config IPC_NS 1015 bool "IPC namespace" 1016 depends on (SYSVIPC || POSIX_MQUEUE) 1017 default y 1018 help 1019 In this namespace tasks work with IPC ids which correspond to 1020 different IPC objects in different namespaces. 1021 1022config USER_NS 1023 bool "User namespace" 1024 depends on UIDGID_CONVERTED 1025 select UIDGID_STRICT_TYPE_CHECKS 1026 1027 default n 1028 help 1029 This allows containers, i.e. vservers, to use user namespaces 1030 to provide different user info for different servers. 1031 1032 When user namespaces are enabled in the kernel it is 1033 recommended that the MEMCG and MEMCG_KMEM options also be 1034 enabled and that user-space use the memory control groups to 1035 limit the amount of memory a memory unprivileged users can 1036 use. 1037 1038 If unsure, say N. 1039 1040config PID_NS 1041 bool "PID Namespaces" 1042 default y 1043 help 1044 Support process id namespaces. This allows having multiple 1045 processes with the same pid as long as they are in different 1046 pid namespaces. This is a building block of containers. 1047 1048config NET_NS 1049 bool "Network namespace" 1050 depends on NET 1051 default y 1052 help 1053 Allow user space to create what appear to be multiple instances 1054 of the network stack. 1055 1056endif # NAMESPACES 1057 1058config UIDGID_CONVERTED 1059 # True if all of the selected software conmponents are known 1060 # to have uid_t and gid_t converted to kuid_t and kgid_t 1061 # where appropriate and are otherwise safe to use with 1062 # the user namespace. 1063 bool 1064 default y 1065 1066 # Filesystems 1067 depends on XFS_FS = n 1068 1069config UIDGID_STRICT_TYPE_CHECKS 1070 bool "Require conversions between uid/gids and their internal representation" 1071 depends on UIDGID_CONVERTED 1072 default n 1073 help 1074 While the nececessary conversions are being added to all subsystems this option allows 1075 the code to continue to build for unconverted subsystems. 1076 1077 Say Y here if you want the strict type checking enabled 1078 1079config SCHED_AUTOGROUP 1080 bool "Automatic process group scheduling" 1081 select EVENTFD 1082 select CGROUPS 1083 select CGROUP_SCHED 1084 select FAIR_GROUP_SCHED 1085 help 1086 This option optimizes the scheduler for common desktop workloads by 1087 automatically creating and populating task groups. This separation 1088 of workloads isolates aggressive CPU burners (like build jobs) from 1089 desktop applications. Task group autogeneration is currently based 1090 upon task session. 1091 1092config MM_OWNER 1093 bool 1094 1095config SYSFS_DEPRECATED 1096 bool "Enable deprecated sysfs features to support old userspace tools" 1097 depends on SYSFS 1098 default n 1099 help 1100 This option adds code that switches the layout of the "block" class 1101 devices, to not show up in /sys/class/block/, but only in 1102 /sys/block/. 1103 1104 This switch is only active when the sysfs.deprecated=1 boot option is 1105 passed or the SYSFS_DEPRECATED_V2 option is set. 1106 1107 This option allows new kernels to run on old distributions and tools, 1108 which might get confused by /sys/class/block/. Since 2007/2008 all 1109 major distributions and tools handle this just fine. 1110 1111 Recent distributions and userspace tools after 2009/2010 depend on 1112 the existence of /sys/class/block/, and will not work with this 1113 option enabled. 1114 1115 Only if you are using a new kernel on an old distribution, you might 1116 need to say Y here. 1117 1118config SYSFS_DEPRECATED_V2 1119 bool "Enable deprecated sysfs features by default" 1120 default n 1121 depends on SYSFS 1122 depends on SYSFS_DEPRECATED 1123 help 1124 Enable deprecated sysfs by default. 1125 1126 See the CONFIG_SYSFS_DEPRECATED option for more details about this 1127 option. 1128 1129 Only if you are using a new kernel on an old distribution, you might 1130 need to say Y here. Even then, odds are you would not need it 1131 enabled, you can always pass the boot option if absolutely necessary. 1132 1133config RELAY 1134 bool "Kernel->user space relay support (formerly relayfs)" 1135 help 1136 This option enables support for relay interface support in 1137 certain file systems (such as debugfs). 1138 It is designed to provide an efficient mechanism for tools and 1139 facilities to relay large amounts of data from kernel space to 1140 user space. 1141 1142 If unsure, say N. 1143 1144config BLK_DEV_INITRD 1145 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1146 depends on BROKEN || !FRV 1147 help 1148 The initial RAM filesystem is a ramfs which is loaded by the 1149 boot loader (loadlin or lilo) and that is mounted as root 1150 before the normal boot procedure. It is typically used to 1151 load modules needed to mount the "real" root file system, 1152 etc. See <file:Documentation/initrd.txt> for details. 1153 1154 If RAM disk support (BLK_DEV_RAM) is also included, this 1155 also enables initial RAM disk (initrd) support and adds 1156 15 Kbytes (more on some other architectures) to the kernel size. 1157 1158 If unsure say Y. 1159 1160if BLK_DEV_INITRD 1161 1162source "usr/Kconfig" 1163 1164endif 1165 1166config CC_OPTIMIZE_FOR_SIZE 1167 bool "Optimize for size" 1168 help 1169 Enabling this option will pass "-Os" instead of "-O2" to gcc 1170 resulting in a smaller kernel. 1171 1172 If unsure, say N. 1173 1174config SYSCTL 1175 bool 1176 1177config ANON_INODES 1178 bool 1179 1180menuconfig EXPERT 1181 bool "Configure standard kernel features (expert users)" 1182 # Unhide debug options, to make the on-by-default options visible 1183 select DEBUG_KERNEL 1184 help 1185 This option allows certain base kernel options and settings 1186 to be disabled or tweaked. This is for specialized 1187 environments which can tolerate a "non-standard" kernel. 1188 Only use this if you really know what you are doing. 1189 1190config HAVE_UID16 1191 bool 1192 1193config UID16 1194 bool "Enable 16-bit UID system calls" if EXPERT 1195 depends on HAVE_UID16 1196 default y 1197 help 1198 This enables the legacy 16-bit UID syscall wrappers. 1199 1200config SYSCTL_SYSCALL 1201 bool "Sysctl syscall support" if EXPERT 1202 depends on PROC_SYSCTL 1203 default n 1204 select SYSCTL 1205 ---help--- 1206 sys_sysctl uses binary paths that have been found challenging 1207 to properly maintain and use. The interface in /proc/sys 1208 using paths with ascii names is now the primary path to this 1209 information. 1210 1211 Almost nothing using the binary sysctl interface so if you are 1212 trying to save some space it is probably safe to disable this, 1213 making your kernel marginally smaller. 1214 1215 If unsure say N here. 1216 1217config SYSCTL_EXCEPTION_TRACE 1218 bool 1219 help 1220 Enable support for /proc/sys/debug/exception-trace. 1221 1222config SYSCTL_ARCH_UNALIGN_NO_WARN 1223 bool 1224 help 1225 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1226 Allows arch to define/use @no_unaligned_warning to possibly warn 1227 about unaligned access emulation going on under the hood. 1228 1229config SYSCTL_ARCH_UNALIGN_ALLOW 1230 bool 1231 help 1232 Enable support for /proc/sys/kernel/unaligned-trap 1233 Allows arches to define/use @unaligned_enabled to runtime toggle 1234 the unaligned access emulation. 1235 see arch/parisc/kernel/unaligned.c for reference 1236 1237config KALLSYMS 1238 bool "Load all symbols for debugging/ksymoops" if EXPERT 1239 default y 1240 help 1241 Say Y here to let the kernel print out symbolic crash information and 1242 symbolic stack backtraces. This increases the size of the kernel 1243 somewhat, as all symbols have to be loaded into the kernel image. 1244 1245config KALLSYMS_ALL 1246 bool "Include all symbols in kallsyms" 1247 depends on DEBUG_KERNEL && KALLSYMS 1248 help 1249 Normally kallsyms only contains the symbols of functions for nicer 1250 OOPS messages and backtraces (i.e., symbols from the text and inittext 1251 sections). This is sufficient for most cases. And only in very rare 1252 cases (e.g., when a debugger is used) all symbols are required (e.g., 1253 names of variables from the data sections, etc). 1254 1255 This option makes sure that all symbols are loaded into the kernel 1256 image (i.e., symbols from all sections) in cost of increased kernel 1257 size (depending on the kernel configuration, it may be 300KiB or 1258 something like this). 1259 1260 Say N unless you really need all symbols. 1261 1262config HOTPLUG 1263 def_bool y 1264 1265config PRINTK 1266 default y 1267 bool "Enable support for printk" if EXPERT 1268 select IRQ_WORK 1269 help 1270 This option enables normal printk support. Removing it 1271 eliminates most of the message strings from the kernel image 1272 and makes the kernel more or less silent. As this makes it 1273 very difficult to diagnose system problems, saying N here is 1274 strongly discouraged. 1275 1276config BUG 1277 bool "BUG() support" if EXPERT 1278 default y 1279 help 1280 Disabling this option eliminates support for BUG and WARN, reducing 1281 the size of your kernel image and potentially quietly ignoring 1282 numerous fatal conditions. You should only consider disabling this 1283 option for embedded systems with no facilities for reporting errors. 1284 Just say Y. 1285 1286config ELF_CORE 1287 depends on COREDUMP 1288 default y 1289 bool "Enable ELF core dumps" if EXPERT 1290 help 1291 Enable support for generating core dumps. Disabling saves about 4k. 1292 1293 1294config PCSPKR_PLATFORM 1295 bool "Enable PC-Speaker support" if EXPERT 1296 depends on HAVE_PCSPKR_PLATFORM 1297 select I8253_LOCK 1298 default y 1299 help 1300 This option allows to disable the internal PC-Speaker 1301 support, saving some memory. 1302 1303config HAVE_PCSPKR_PLATFORM 1304 bool 1305 1306config BASE_FULL 1307 default y 1308 bool "Enable full-sized data structures for core" if EXPERT 1309 help 1310 Disabling this option reduces the size of miscellaneous core 1311 kernel data structures. This saves memory on small machines, 1312 but may reduce performance. 1313 1314config FUTEX 1315 bool "Enable futex support" if EXPERT 1316 default y 1317 select RT_MUTEXES 1318 help 1319 Disabling this option will cause the kernel to be built without 1320 support for "fast userspace mutexes". The resulting kernel may not 1321 run glibc-based applications correctly. 1322 1323config EPOLL 1324 bool "Enable eventpoll support" if EXPERT 1325 default y 1326 select ANON_INODES 1327 help 1328 Disabling this option will cause the kernel to be built without 1329 support for epoll family of system calls. 1330 1331config SIGNALFD 1332 bool "Enable signalfd() system call" if EXPERT 1333 select ANON_INODES 1334 default y 1335 help 1336 Enable the signalfd() system call that allows to receive signals 1337 on a file descriptor. 1338 1339 If unsure, say Y. 1340 1341config TIMERFD 1342 bool "Enable timerfd() system call" if EXPERT 1343 select ANON_INODES 1344 default y 1345 help 1346 Enable the timerfd() system call that allows to receive timer 1347 events on a file descriptor. 1348 1349 If unsure, say Y. 1350 1351config EVENTFD 1352 bool "Enable eventfd() system call" if EXPERT 1353 select ANON_INODES 1354 default y 1355 help 1356 Enable the eventfd() system call that allows to receive both 1357 kernel notification (ie. KAIO) or userspace notifications. 1358 1359 If unsure, say Y. 1360 1361config SHMEM 1362 bool "Use full shmem filesystem" if EXPERT 1363 default y 1364 depends on MMU 1365 help 1366 The shmem is an internal filesystem used to manage shared memory. 1367 It is backed by swap and manages resource limits. It is also exported 1368 to userspace as tmpfs if TMPFS is enabled. Disabling this 1369 option replaces shmem and tmpfs with the much simpler ramfs code, 1370 which may be appropriate on small systems without swap. 1371 1372config AIO 1373 bool "Enable AIO support" if EXPERT 1374 default y 1375 help 1376 This option enables POSIX asynchronous I/O which may by used 1377 by some high performance threaded applications. Disabling 1378 this option saves about 7k. 1379 1380config EMBEDDED 1381 bool "Embedded system" 1382 select EXPERT 1383 help 1384 This option should be enabled if compiling the kernel for 1385 an embedded system so certain expert options are available 1386 for configuration. 1387 1388config HAVE_PERF_EVENTS 1389 bool 1390 help 1391 See tools/perf/design.txt for details. 1392 1393config PERF_USE_VMALLOC 1394 bool 1395 help 1396 See tools/perf/design.txt for details 1397 1398menu "Kernel Performance Events And Counters" 1399 1400config PERF_EVENTS 1401 bool "Kernel performance events and counters" 1402 default y if PROFILING 1403 depends on HAVE_PERF_EVENTS 1404 select ANON_INODES 1405 select IRQ_WORK 1406 help 1407 Enable kernel support for various performance events provided 1408 by software and hardware. 1409 1410 Software events are supported either built-in or via the 1411 use of generic tracepoints. 1412 1413 Most modern CPUs support performance events via performance 1414 counter registers. These registers count the number of certain 1415 types of hw events: such as instructions executed, cachemisses 1416 suffered, or branches mis-predicted - without slowing down the 1417 kernel or applications. These registers can also trigger interrupts 1418 when a threshold number of events have passed - and can thus be 1419 used to profile the code that runs on that CPU. 1420 1421 The Linux Performance Event subsystem provides an abstraction of 1422 these software and hardware event capabilities, available via a 1423 system call and used by the "perf" utility in tools/perf/. It 1424 provides per task and per CPU counters, and it provides event 1425 capabilities on top of those. 1426 1427 Say Y if unsure. 1428 1429config DEBUG_PERF_USE_VMALLOC 1430 default n 1431 bool "Debug: use vmalloc to back perf mmap() buffers" 1432 depends on PERF_EVENTS && DEBUG_KERNEL 1433 select PERF_USE_VMALLOC 1434 help 1435 Use vmalloc memory to back perf mmap() buffers. 1436 1437 Mostly useful for debugging the vmalloc code on platforms 1438 that don't require it. 1439 1440 Say N if unsure. 1441 1442endmenu 1443 1444config VM_EVENT_COUNTERS 1445 default y 1446 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1447 help 1448 VM event counters are needed for event counts to be shown. 1449 This option allows the disabling of the VM event counters 1450 on EXPERT systems. /proc/vmstat will only show page counts 1451 if VM event counters are disabled. 1452 1453config PCI_QUIRKS 1454 default y 1455 bool "Enable PCI quirk workarounds" if EXPERT 1456 depends on PCI 1457 help 1458 This enables workarounds for various PCI chipset 1459 bugs/quirks. Disable this only if your target machine is 1460 unaffected by PCI quirks. 1461 1462config SLUB_DEBUG 1463 default y 1464 bool "Enable SLUB debugging support" if EXPERT 1465 depends on SLUB && SYSFS 1466 help 1467 SLUB has extensive debug support features. Disabling these can 1468 result in significant savings in code size. This also disables 1469 SLUB sysfs support. /sys/slab will not exist and there will be 1470 no support for cache validation etc. 1471 1472config COMPAT_BRK 1473 bool "Disable heap randomization" 1474 default y 1475 help 1476 Randomizing heap placement makes heap exploits harder, but it 1477 also breaks ancient binaries (including anything libc5 based). 1478 This option changes the bootup default to heap randomization 1479 disabled, and can be overridden at runtime by setting 1480 /proc/sys/kernel/randomize_va_space to 2. 1481 1482 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1483 1484choice 1485 prompt "Choose SLAB allocator" 1486 default SLUB 1487 help 1488 This option allows to select a slab allocator. 1489 1490config SLAB 1491 bool "SLAB" 1492 help 1493 The regular slab allocator that is established and known to work 1494 well in all environments. It organizes cache hot objects in 1495 per cpu and per node queues. 1496 1497config SLUB 1498 bool "SLUB (Unqueued Allocator)" 1499 help 1500 SLUB is a slab allocator that minimizes cache line usage 1501 instead of managing queues of cached objects (SLAB approach). 1502 Per cpu caching is realized using slabs of objects instead 1503 of queues of objects. SLUB can use memory efficiently 1504 and has enhanced diagnostics. SLUB is the default choice for 1505 a slab allocator. 1506 1507config SLOB 1508 depends on EXPERT 1509 bool "SLOB (Simple Allocator)" 1510 help 1511 SLOB replaces the stock allocator with a drastically simpler 1512 allocator. SLOB is generally more space efficient but 1513 does not perform as well on large systems. 1514 1515endchoice 1516 1517config MMAP_ALLOW_UNINITIALIZED 1518 bool "Allow mmapped anonymous memory to be uninitialized" 1519 depends on EXPERT && !MMU 1520 default n 1521 help 1522 Normally, and according to the Linux spec, anonymous memory obtained 1523 from mmap() has it's contents cleared before it is passed to 1524 userspace. Enabling this config option allows you to request that 1525 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1526 providing a huge performance boost. If this option is not enabled, 1527 then the flag will be ignored. 1528 1529 This is taken advantage of by uClibc's malloc(), and also by 1530 ELF-FDPIC binfmt's brk and stack allocator. 1531 1532 Because of the obvious security issues, this option should only be 1533 enabled on embedded devices where you control what is run in 1534 userspace. Since that isn't generally a problem on no-MMU systems, 1535 it is normally safe to say Y here. 1536 1537 See Documentation/nommu-mmap.txt for more information. 1538 1539config PROFILING 1540 bool "Profiling support" 1541 help 1542 Say Y here to enable the extended profiling support mechanisms used 1543 by profilers such as OProfile. 1544 1545# 1546# Place an empty function call at each tracepoint site. Can be 1547# dynamically changed for a probe function. 1548# 1549config TRACEPOINTS 1550 bool 1551 1552source "arch/Kconfig" 1553 1554endmenu # General setup 1555 1556config HAVE_GENERIC_DMA_COHERENT 1557 bool 1558 default n 1559 1560config SLABINFO 1561 bool 1562 depends on PROC_FS 1563 depends on SLAB || SLUB_DEBUG 1564 default y 1565 1566config RT_MUTEXES 1567 boolean 1568 1569config BASE_SMALL 1570 int 1571 default 0 if BASE_FULL 1572 default 1 if !BASE_FULL 1573 1574menuconfig MODULES 1575 bool "Enable loadable module support" 1576 help 1577 Kernel modules are small pieces of compiled code which can 1578 be inserted in the running kernel, rather than being 1579 permanently built into the kernel. You use the "modprobe" 1580 tool to add (and sometimes remove) them. If you say Y here, 1581 many parts of the kernel can be built as modules (by 1582 answering M instead of Y where indicated): this is most 1583 useful for infrequently used options which are not required 1584 for booting. For more information, see the man pages for 1585 modprobe, lsmod, modinfo, insmod and rmmod. 1586 1587 If you say Y here, you will need to run "make 1588 modules_install" to put the modules under /lib/modules/ 1589 where modprobe can find them (you may need to be root to do 1590 this). 1591 1592 If unsure, say Y. 1593 1594if MODULES 1595 1596config MODULE_FORCE_LOAD 1597 bool "Forced module loading" 1598 default n 1599 help 1600 Allow loading of modules without version information (ie. modprobe 1601 --force). Forced module loading sets the 'F' (forced) taint flag and 1602 is usually a really bad idea. 1603 1604config MODULE_UNLOAD 1605 bool "Module unloading" 1606 help 1607 Without this option you will not be able to unload any 1608 modules (note that some modules may not be unloadable 1609 anyway), which makes your kernel smaller, faster 1610 and simpler. If unsure, say Y. 1611 1612config MODULE_FORCE_UNLOAD 1613 bool "Forced module unloading" 1614 depends on MODULE_UNLOAD 1615 help 1616 This option allows you to force a module to unload, even if the 1617 kernel believes it is unsafe: the kernel will remove the module 1618 without waiting for anyone to stop using it (using the -f option to 1619 rmmod). This is mainly for kernel developers and desperate users. 1620 If unsure, say N. 1621 1622config MODVERSIONS 1623 bool "Module versioning support" 1624 help 1625 Usually, you have to use modules compiled with your kernel. 1626 Saying Y here makes it sometimes possible to use modules 1627 compiled for different kernels, by adding enough information 1628 to the modules to (hopefully) spot any changes which would 1629 make them incompatible with the kernel you are running. If 1630 unsure, say N. 1631 1632config MODULE_SRCVERSION_ALL 1633 bool "Source checksum for all modules" 1634 help 1635 Modules which contain a MODULE_VERSION get an extra "srcversion" 1636 field inserted into their modinfo section, which contains a 1637 sum of the source files which made it. This helps maintainers 1638 see exactly which source was used to build a module (since 1639 others sometimes change the module source without updating 1640 the version). With this option, such a "srcversion" field 1641 will be created for all modules. If unsure, say N. 1642 1643config MODULE_SIG 1644 bool "Module signature verification" 1645 depends on MODULES 1646 select KEYS 1647 select CRYPTO 1648 select ASYMMETRIC_KEY_TYPE 1649 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1650 select PUBLIC_KEY_ALGO_RSA 1651 select ASN1 1652 select OID_REGISTRY 1653 select X509_CERTIFICATE_PARSER 1654 help 1655 Check modules for valid signatures upon load: the signature 1656 is simply appended to the module. For more information see 1657 Documentation/module-signing.txt. 1658 1659 !!!WARNING!!! If you enable this option, you MUST make sure that the 1660 module DOES NOT get stripped after being signed. This includes the 1661 debuginfo strip done by some packagers (such as rpmbuild) and 1662 inclusion into an initramfs that wants the module size reduced. 1663 1664config MODULE_SIG_FORCE 1665 bool "Require modules to be validly signed" 1666 depends on MODULE_SIG 1667 help 1668 Reject unsigned modules or signed modules for which we don't have a 1669 key. Without this, such modules will simply taint the kernel. 1670 1671config MODULE_SIG_ALL 1672 bool "Automatically sign all modules" 1673 default y 1674 depends on MODULE_SIG 1675 help 1676 Sign all modules during make modules_install. Without this option, 1677 modules must be signed manually, using the scripts/sign-file tool. 1678 1679comment "Do not forget to sign required modules with scripts/sign-file" 1680 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL 1681 1682choice 1683 prompt "Which hash algorithm should modules be signed with?" 1684 depends on MODULE_SIG 1685 help 1686 This determines which sort of hashing algorithm will be used during 1687 signature generation. This algorithm _must_ be built into the kernel 1688 directly so that signature verification can take place. It is not 1689 possible to load a signed module containing the algorithm to check 1690 the signature on that module. 1691 1692config MODULE_SIG_SHA1 1693 bool "Sign modules with SHA-1" 1694 select CRYPTO_SHA1 1695 1696config MODULE_SIG_SHA224 1697 bool "Sign modules with SHA-224" 1698 select CRYPTO_SHA256 1699 1700config MODULE_SIG_SHA256 1701 bool "Sign modules with SHA-256" 1702 select CRYPTO_SHA256 1703 1704config MODULE_SIG_SHA384 1705 bool "Sign modules with SHA-384" 1706 select CRYPTO_SHA512 1707 1708config MODULE_SIG_SHA512 1709 bool "Sign modules with SHA-512" 1710 select CRYPTO_SHA512 1711 1712endchoice 1713 1714config MODULE_SIG_HASH 1715 string 1716 depends on MODULE_SIG 1717 default "sha1" if MODULE_SIG_SHA1 1718 default "sha224" if MODULE_SIG_SHA224 1719 default "sha256" if MODULE_SIG_SHA256 1720 default "sha384" if MODULE_SIG_SHA384 1721 default "sha512" if MODULE_SIG_SHA512 1722 1723endif # MODULES 1724 1725config INIT_ALL_POSSIBLE 1726 bool 1727 help 1728 Back when each arch used to define their own cpu_online_mask and 1729 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 1730 with all 1s, and others with all 0s. When they were centralised, 1731 it was better to provide this option than to break all the archs 1732 and have several arch maintainers pursuing me down dark alleys. 1733 1734config STOP_MACHINE 1735 bool 1736 default y 1737 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1738 help 1739 Need stop_machine() primitive. 1740 1741source "block/Kconfig" 1742 1743config PREEMPT_NOTIFIERS 1744 bool 1745 1746config PADATA 1747 depends on SMP 1748 bool 1749 1750# Can be selected by architectures with broken toolchains 1751# that get confused by correct const<->read_only section 1752# mappings 1753config BROKEN_RODATA 1754 bool 1755 1756config ASN1 1757 tristate 1758 help 1759 Build a simple ASN.1 grammar compiler that produces a bytecode output 1760 that can be interpreted by the ASN.1 stream decoder and used to 1761 inform it as to what tags are to be expected in a stream and what 1762 functions to call on what tags. 1763 1764source "kernel/Kconfig.locks" 1765