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 EXPERIMENTAL 32 bool 33 default y 34 35config BROKEN 36 bool 37 38config BROKEN_ON_SMP 39 bool 40 depends on BROKEN || !SMP 41 default y 42 43config INIT_ENV_ARG_LIMIT 44 int 45 default 32 if !UML 46 default 128 if UML 47 help 48 Maximum of each of the number of arguments and environment 49 variables passed to init from the kernel command line. 50 51 52config CROSS_COMPILE 53 string "Cross-compiler tool prefix" 54 help 55 Same as running 'make CROSS_COMPILE=prefix-' but stored for 56 default make runs in this kernel build directory. You don't 57 need to set this unless you want the configured kernel build 58 directory to select the cross-compiler automatically. 59 60config LOCALVERSION 61 string "Local version - append to kernel release" 62 help 63 Append an extra string to the end of your kernel version. 64 This will show up when you type uname, for example. 65 The string you set here will be appended after the contents of 66 any files with a filename matching localversion* in your 67 object and source tree, in that order. Your total string can 68 be a maximum of 64 characters. 69 70config LOCALVERSION_AUTO 71 bool "Automatically append version information to the version string" 72 default y 73 help 74 This will try to automatically determine if the current tree is a 75 release tree by looking for git tags that belong to the current 76 top of tree revision. 77 78 A string of the format -gxxxxxxxx will be added to the localversion 79 if a git-based tree is found. The string generated by this will be 80 appended after any matching localversion* files, and after the value 81 set in CONFIG_LOCALVERSION. 82 83 (The actual string used here is the first eight characters produced 84 by running the command: 85 86 $ git rev-parse --verify HEAD 87 88 which is done within the script "scripts/setlocalversion".) 89 90config HAVE_KERNEL_GZIP 91 bool 92 93config HAVE_KERNEL_BZIP2 94 bool 95 96config HAVE_KERNEL_LZMA 97 bool 98 99config HAVE_KERNEL_XZ 100 bool 101 102config HAVE_KERNEL_LZO 103 bool 104 105choice 106 prompt "Kernel compression mode" 107 default KERNEL_GZIP 108 depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO 109 help 110 The linux kernel is a kind of self-extracting executable. 111 Several compression algorithms are available, which differ 112 in efficiency, compression and decompression speed. 113 Compression speed is only relevant when building a kernel. 114 Decompression speed is relevant at each boot. 115 116 If you have any problems with bzip2 or lzma compressed 117 kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older 118 version of this functionality (bzip2 only), for 2.4, was 119 supplied by Christian Ludwig) 120 121 High compression options are mostly useful for users, who 122 are low on disk space (embedded systems), but for whom ram 123 size matters less. 124 125 If in doubt, select 'gzip' 126 127config KERNEL_GZIP 128 bool "Gzip" 129 depends on HAVE_KERNEL_GZIP 130 help 131 The old and tried gzip compression. It provides a good balance 132 between compression ratio and decompression speed. 133 134config KERNEL_BZIP2 135 bool "Bzip2" 136 depends on HAVE_KERNEL_BZIP2 137 help 138 Its compression ratio and speed is intermediate. 139 Decompression speed is slowest among the choices. The kernel 140 size is about 10% smaller with bzip2, in comparison to gzip. 141 Bzip2 uses a large amount of memory. For modern kernels you 142 will need at least 8MB RAM or more for booting. 143 144config KERNEL_LZMA 145 bool "LZMA" 146 depends on HAVE_KERNEL_LZMA 147 help 148 This compression algorithm's ratio is best. Decompression speed 149 is between gzip and bzip2. Compression is slowest. 150 The kernel size is about 33% smaller with LZMA in comparison to gzip. 151 152config KERNEL_XZ 153 bool "XZ" 154 depends on HAVE_KERNEL_XZ 155 help 156 XZ uses the LZMA2 algorithm and instruction set specific 157 BCJ filters which can improve compression ratio of executable 158 code. The size of the kernel is about 30% smaller with XZ in 159 comparison to gzip. On architectures for which there is a BCJ 160 filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ 161 will create a few percent smaller kernel than plain LZMA. 162 163 The speed is about the same as with LZMA: The decompression 164 speed of XZ is better than that of bzip2 but worse than gzip 165 and LZO. Compression is slow. 166 167config KERNEL_LZO 168 bool "LZO" 169 depends on HAVE_KERNEL_LZO 170 help 171 Its compression ratio is the poorest among the choices. The kernel 172 size is about 10% bigger than gzip; however its speed 173 (both compression and decompression) is the fastest. 174 175endchoice 176 177config DEFAULT_HOSTNAME 178 string "Default hostname" 179 default "(none)" 180 help 181 This option determines the default system hostname before userspace 182 calls sethostname(2). The kernel traditionally uses "(none)" here, 183 but you may wish to use a different default here to make a minimal 184 system more usable with less configuration. 185 186config SWAP 187 bool "Support for paging of anonymous memory (swap)" 188 depends on MMU && BLOCK 189 default y 190 help 191 This option allows you to choose whether you want to have support 192 for so called swap devices or swap files in your kernel that are 193 used to provide more virtual memory than the actual RAM present 194 in your computer. If unsure say Y. 195 196config SYSVIPC 197 bool "System V IPC" 198 ---help--- 199 Inter Process Communication is a suite of library functions and 200 system calls which let processes (running programs) synchronize and 201 exchange information. It is generally considered to be a good thing, 202 and some programs won't run unless you say Y here. In particular, if 203 you want to run the DOS emulator dosemu under Linux (read the 204 DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>), 205 you'll need to say Y here. 206 207 You can find documentation about IPC with "info ipc" and also in 208 section 6.4 of the Linux Programmer's Guide, available from 209 <http://www.tldp.org/guides.html>. 210 211config SYSVIPC_SYSCTL 212 bool 213 depends on SYSVIPC 214 depends on SYSCTL 215 default y 216 217config POSIX_MQUEUE 218 bool "POSIX Message Queues" 219 depends on NET 220 ---help--- 221 POSIX variant of message queues is a part of IPC. In POSIX message 222 queues every message has a priority which decides about succession 223 of receiving it by a process. If you want to compile and run 224 programs written e.g. for Solaris with use of its POSIX message 225 queues (functions mq_*) say Y here. 226 227 POSIX message queues are visible as a filesystem called 'mqueue' 228 and can be mounted somewhere if you want to do filesystem 229 operations on message queues. 230 231 If unsure, say Y. 232 233config POSIX_MQUEUE_SYSCTL 234 bool 235 depends on POSIX_MQUEUE 236 depends on SYSCTL 237 default y 238 239config FHANDLE 240 bool "open by fhandle syscalls" 241 select EXPORTFS 242 help 243 If you say Y here, a user level program will be able to map 244 file names to handle and then later use the handle for 245 different file system operations. This is useful in implementing 246 userspace file servers, which now track files using handles instead 247 of names. The handle would remain the same even if file names 248 get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2) 249 syscalls. 250 251config AUDIT 252 bool "Auditing support" 253 depends on NET 254 help 255 Enable auditing infrastructure that can be used with another 256 kernel subsystem, such as SELinux (which requires this for 257 logging of avc messages output). Does not do system-call 258 auditing without CONFIG_AUDITSYSCALL. 259 260config AUDITSYSCALL 261 bool "Enable system-call auditing support" 262 depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH || (ARM && AEABI && !OABI_COMPAT)) 263 default y if SECURITY_SELINUX 264 help 265 Enable low-overhead system-call auditing infrastructure that 266 can be used independently or with another kernel subsystem, 267 such as SELinux. 268 269config AUDIT_WATCH 270 def_bool y 271 depends on AUDITSYSCALL 272 select FSNOTIFY 273 274config AUDIT_TREE 275 def_bool y 276 depends on AUDITSYSCALL 277 select FSNOTIFY 278 279config AUDIT_LOGINUID_IMMUTABLE 280 bool "Make audit loginuid immutable" 281 depends on AUDIT 282 help 283 The config option toggles if a task setting its loginuid requires 284 CAP_SYS_AUDITCONTROL or if that task should require no special permissions 285 but should instead only allow setting its loginuid if it was never 286 previously set. On systems which use systemd or a similar central 287 process to restart login services this should be set to true. On older 288 systems in which an admin would typically have to directly stop and 289 start processes this should be set to false. Setting this to true allows 290 one to drop potentially dangerous capabilites from the login tasks, 291 but may not be backwards compatible with older init systems. 292 293source "kernel/irq/Kconfig" 294source "kernel/time/Kconfig" 295 296menu "CPU/Task time and stats accounting" 297 298config VIRT_CPU_ACCOUNTING 299 bool 300 301choice 302 prompt "Cputime accounting" 303 default TICK_CPU_ACCOUNTING if !PPC64 304 default VIRT_CPU_ACCOUNTING_NATIVE if PPC64 305 306# Kind of a stub config for the pure tick based cputime accounting 307config TICK_CPU_ACCOUNTING 308 bool "Simple tick based cputime accounting" 309 depends on !S390 310 help 311 This is the basic tick based cputime accounting that maintains 312 statistics about user, system and idle time spent on per jiffies 313 granularity. 314 315 If unsure, say Y. 316 317config VIRT_CPU_ACCOUNTING_NATIVE 318 bool "Deterministic task and CPU time accounting" 319 depends on HAVE_VIRT_CPU_ACCOUNTING 320 select VIRT_CPU_ACCOUNTING 321 help 322 Select this option to enable more accurate task and CPU time 323 accounting. This is done by reading a CPU counter on each 324 kernel entry and exit and on transitions within the kernel 325 between system, softirq and hardirq state, so there is a 326 small performance impact. In the case of s390 or IBM POWER > 5, 327 this also enables accounting of stolen time on logically-partitioned 328 systems. 329 330config VIRT_CPU_ACCOUNTING_GEN 331 bool "Full dynticks CPU time accounting" 332 depends on HAVE_CONTEXT_TRACKING && 64BIT 333 select VIRT_CPU_ACCOUNTING 334 select CONTEXT_TRACKING 335 help 336 Select this option to enable task and CPU time accounting on full 337 dynticks systems. This accounting is implemented by watching every 338 kernel-user boundaries using the context tracking subsystem. 339 The accounting is thus performed at the expense of some significant 340 overhead. 341 342 For now this is only useful if you are working on the full 343 dynticks subsystem development. 344 345 If unsure, say N. 346 347config IRQ_TIME_ACCOUNTING 348 bool "Fine granularity task level IRQ time accounting" 349 depends on HAVE_IRQ_TIME_ACCOUNTING 350 help 351 Select this option to enable fine granularity task irq time 352 accounting. This is done by reading a timestamp on each 353 transitions between softirq and hardirq state, so there can be a 354 small performance impact. 355 356 If in doubt, say N here. 357 358endchoice 359 360config BSD_PROCESS_ACCT 361 bool "BSD Process Accounting" 362 help 363 If you say Y here, a user level program will be able to instruct the 364 kernel (via a special system call) to write process accounting 365 information to a file: whenever a process exits, information about 366 that process will be appended to the file by the kernel. The 367 information includes things such as creation time, owning user, 368 command name, memory usage, controlling terminal etc. (the complete 369 list is in the struct acct in <file:include/linux/acct.h>). It is 370 up to the user level program to do useful things with this 371 information. This is generally a good idea, so say Y. 372 373config BSD_PROCESS_ACCT_V3 374 bool "BSD Process Accounting version 3 file format" 375 depends on BSD_PROCESS_ACCT 376 default n 377 help 378 If you say Y here, the process accounting information is written 379 in a new file format that also logs the process IDs of each 380 process and it's parent. Note that this file format is incompatible 381 with previous v0/v1/v2 file formats, so you will need updated tools 382 for processing it. A preliminary version of these tools is available 383 at <http://www.gnu.org/software/acct/>. 384 385config TASKSTATS 386 bool "Export task/process statistics through netlink" 387 depends on NET 388 default n 389 help 390 Export selected statistics for tasks/processes through the 391 generic netlink interface. Unlike BSD process accounting, the 392 statistics are available during the lifetime of tasks/processes as 393 responses to commands. Like BSD accounting, they are sent to user 394 space on task exit. 395 396 Say N if unsure. 397 398config TASK_DELAY_ACCT 399 bool "Enable per-task delay accounting" 400 depends on TASKSTATS 401 help 402 Collect information on time spent by a task waiting for system 403 resources like cpu, synchronous block I/O completion and swapping 404 in pages. Such statistics can help in setting a task's priorities 405 relative to other tasks for cpu, io, rss limits etc. 406 407 Say N if unsure. 408 409config TASK_XACCT 410 bool "Enable extended accounting over taskstats" 411 depends on TASKSTATS 412 help 413 Collect extended task accounting data and send the data 414 to userland for processing over the taskstats interface. 415 416 Say N if unsure. 417 418config TASK_IO_ACCOUNTING 419 bool "Enable per-task storage I/O accounting" 420 depends on TASK_XACCT 421 help 422 Collect information on the number of bytes of storage I/O which this 423 task has caused. 424 425 Say N if unsure. 426 427endmenu # "CPU/Task time and stats accounting" 428 429menu "RCU Subsystem" 430 431choice 432 prompt "RCU Implementation" 433 default TREE_RCU 434 435config TREE_RCU 436 bool "Tree-based hierarchical RCU" 437 depends on !PREEMPT && SMP 438 help 439 This option selects the RCU implementation that is 440 designed for very large SMP system with hundreds or 441 thousands of CPUs. It also scales down nicely to 442 smaller systems. 443 444config TREE_PREEMPT_RCU 445 bool "Preemptible tree-based hierarchical RCU" 446 depends on PREEMPT 447 help 448 This option selects the RCU implementation that is 449 designed for very large SMP systems with hundreds or 450 thousands of CPUs, but for which real-time response 451 is also required. It also scales down nicely to 452 smaller systems. 453 454 Select this option if you are unsure. 455 456config TINY_RCU 457 bool "UP-only small-memory-footprint RCU" 458 depends on !PREEMPT && !SMP 459 help 460 This option selects the RCU implementation that is 461 designed for UP systems from which real-time response 462 is not required. This option greatly reduces the 463 memory footprint of RCU. 464 465config TINY_PREEMPT_RCU 466 bool "Preemptible UP-only small-memory-footprint RCU" 467 depends on PREEMPT && !SMP 468 help 469 This option selects the RCU implementation that is designed 470 for real-time UP systems. This option greatly reduces the 471 memory footprint of RCU. 472 473endchoice 474 475config PREEMPT_RCU 476 def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU ) 477 help 478 This option enables preemptible-RCU code that is common between 479 the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. 480 481config RCU_STALL_COMMON 482 def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE ) 483 help 484 This option enables RCU CPU stall code that is common between 485 the TINY and TREE variants of RCU. The purpose is to allow 486 the tiny variants to disable RCU CPU stall warnings, while 487 making these warnings mandatory for the tree variants. 488 489config CONTEXT_TRACKING 490 bool 491 492config RCU_USER_QS 493 bool "Consider userspace as in RCU extended quiescent state" 494 depends on HAVE_CONTEXT_TRACKING && SMP 495 select CONTEXT_TRACKING 496 help 497 This option sets hooks on kernel / userspace boundaries and 498 puts RCU in extended quiescent state when the CPU runs in 499 userspace. It means that when a CPU runs in userspace, it is 500 excluded from the global RCU state machine and thus doesn't 501 try to keep the timer tick on for RCU. 502 503 Unless you want to hack and help the development of the full 504 dynticks mode, you shouldn't enable this option. It also 505 adds unnecessary overhead. 506 507 If unsure say N 508 509config CONTEXT_TRACKING_FORCE 510 bool "Force context tracking" 511 depends on CONTEXT_TRACKING 512 help 513 Probe on user/kernel boundaries by default in order to 514 test the features that rely on it such as userspace RCU extended 515 quiescent states. 516 This test is there for debugging until we have a real user like the 517 full dynticks mode. 518 519config RCU_FANOUT 520 int "Tree-based hierarchical RCU fanout value" 521 range 2 64 if 64BIT 522 range 2 32 if !64BIT 523 depends on TREE_RCU || TREE_PREEMPT_RCU 524 default 64 if 64BIT 525 default 32 if !64BIT 526 help 527 This option controls the fanout of hierarchical implementations 528 of RCU, allowing RCU to work efficiently on machines with 529 large numbers of CPUs. This value must be at least the fourth 530 root of NR_CPUS, which allows NR_CPUS to be insanely large. 531 The default value of RCU_FANOUT should be used for production 532 systems, but if you are stress-testing the RCU implementation 533 itself, small RCU_FANOUT values allow you to test large-system 534 code paths on small(er) systems. 535 536 Select a specific number if testing RCU itself. 537 Take the default if unsure. 538 539config RCU_FANOUT_LEAF 540 int "Tree-based hierarchical RCU leaf-level fanout value" 541 range 2 RCU_FANOUT if 64BIT 542 range 2 RCU_FANOUT if !64BIT 543 depends on TREE_RCU || TREE_PREEMPT_RCU 544 default 16 545 help 546 This option controls the leaf-level fanout of hierarchical 547 implementations of RCU, and allows trading off cache misses 548 against lock contention. Systems that synchronize their 549 scheduling-clock interrupts for energy-efficiency reasons will 550 want the default because the smaller leaf-level fanout keeps 551 lock contention levels acceptably low. Very large systems 552 (hundreds or thousands of CPUs) will instead want to set this 553 value to the maximum value possible in order to reduce the 554 number of cache misses incurred during RCU's grace-period 555 initialization. These systems tend to run CPU-bound, and thus 556 are not helped by synchronized interrupts, and thus tend to 557 skew them, which reduces lock contention enough that large 558 leaf-level fanouts work well. 559 560 Select a specific number if testing RCU itself. 561 562 Select the maximum permissible value for large systems. 563 564 Take the default if unsure. 565 566config RCU_FANOUT_EXACT 567 bool "Disable tree-based hierarchical RCU auto-balancing" 568 depends on TREE_RCU || TREE_PREEMPT_RCU 569 default n 570 help 571 This option forces use of the exact RCU_FANOUT value specified, 572 regardless of imbalances in the hierarchy. This is useful for 573 testing RCU itself, and might one day be useful on systems with 574 strong NUMA behavior. 575 576 Without RCU_FANOUT_EXACT, the code will balance the hierarchy. 577 578 Say N if unsure. 579 580config RCU_FAST_NO_HZ 581 bool "Accelerate last non-dyntick-idle CPU's grace periods" 582 depends on NO_HZ && SMP 583 default n 584 help 585 This option causes RCU to attempt to accelerate grace periods in 586 order to allow CPUs to enter dynticks-idle state more quickly. 587 On the other hand, this option increases the overhead of the 588 dynticks-idle checking, thus degrading scheduling latency. 589 590 Say Y if energy efficiency is critically important, and you don't 591 care about real-time response. 592 593 Say N if you are unsure. 594 595config TREE_RCU_TRACE 596 def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) 597 select DEBUG_FS 598 help 599 This option provides tracing for the TREE_RCU and 600 TREE_PREEMPT_RCU implementations, permitting Makefile to 601 trivially select kernel/rcutree_trace.c. 602 603config RCU_BOOST 604 bool "Enable RCU priority boosting" 605 depends on RT_MUTEXES && PREEMPT_RCU 606 default n 607 help 608 This option boosts the priority of preempted RCU readers that 609 block the current preemptible RCU grace period for too long. 610 This option also prevents heavy loads from blocking RCU 611 callback invocation for all flavors of RCU. 612 613 Say Y here if you are working with real-time apps or heavy loads 614 Say N here if you are unsure. 615 616config RCU_BOOST_PRIO 617 int "Real-time priority to boost RCU readers to" 618 range 1 99 619 depends on RCU_BOOST 620 default 1 621 help 622 This option specifies the real-time priority to which long-term 623 preempted RCU readers are to be boosted. If you are working 624 with a real-time application that has one or more CPU-bound 625 threads running at a real-time priority level, you should set 626 RCU_BOOST_PRIO to a priority higher then the highest-priority 627 real-time CPU-bound thread. The default RCU_BOOST_PRIO value 628 of 1 is appropriate in the common case, which is real-time 629 applications that do not have any CPU-bound threads. 630 631 Some real-time applications might not have a single real-time 632 thread that saturates a given CPU, but instead might have 633 multiple real-time threads that, taken together, fully utilize 634 that CPU. In this case, you should set RCU_BOOST_PRIO to 635 a priority higher than the lowest-priority thread that is 636 conspiring to prevent the CPU from running any non-real-time 637 tasks. For example, if one thread at priority 10 and another 638 thread at priority 5 are between themselves fully consuming 639 the CPU time on a given CPU, then RCU_BOOST_PRIO should be 640 set to priority 6 or higher. 641 642 Specify the real-time priority, or take the default if unsure. 643 644config RCU_BOOST_DELAY 645 int "Milliseconds to delay boosting after RCU grace-period start" 646 range 0 3000 647 depends on RCU_BOOST 648 default 500 649 help 650 This option specifies the time to wait after the beginning of 651 a given grace period before priority-boosting preempted RCU 652 readers blocking that grace period. Note that any RCU reader 653 blocking an expedited RCU grace period is boosted immediately. 654 655 Accept the default if unsure. 656 657config RCU_NOCB_CPU 658 bool "Offload RCU callback processing from boot-selected CPUs" 659 depends on TREE_RCU || TREE_PREEMPT_RCU 660 default n 661 help 662 Use this option to reduce OS jitter for aggressive HPC or 663 real-time workloads. It can also be used to offload RCU 664 callback invocation to energy-efficient CPUs in battery-powered 665 asymmetric multiprocessors. 666 667 This option offloads callback invocation from the set of 668 CPUs specified at boot time by the rcu_nocbs parameter. 669 For each such CPU, a kthread ("rcuoN") will be created to 670 invoke callbacks, where the "N" is the CPU being offloaded. 671 Nothing prevents this kthread from running on the specified 672 CPUs, but (1) the kthreads may be preempted between each 673 callback, and (2) affinity or cgroups can be used to force 674 the kthreads to run on whatever set of CPUs is desired. 675 676 Say Y here if you want reduced OS jitter on selected CPUs. 677 Say N here if you are unsure. 678 679endmenu # "RCU Subsystem" 680 681config IKCONFIG 682 tristate "Kernel .config support" 683 ---help--- 684 This option enables the complete Linux kernel ".config" file 685 contents to be saved in the kernel. It provides documentation 686 of which kernel options are used in a running kernel or in an 687 on-disk kernel. This information can be extracted from the kernel 688 image file with the script scripts/extract-ikconfig and used as 689 input to rebuild the current kernel or to build another kernel. 690 It can also be extracted from a running kernel by reading 691 /proc/config.gz if enabled (below). 692 693config IKCONFIG_PROC 694 bool "Enable access to .config through /proc/config.gz" 695 depends on IKCONFIG && PROC_FS 696 ---help--- 697 This option enables access to the kernel configuration file 698 through /proc/config.gz. 699 700config LOG_BUF_SHIFT 701 int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" 702 range 12 21 703 default 17 704 help 705 Select kernel log buffer size as a power of 2. 706 Examples: 707 17 => 128 KB 708 16 => 64 KB 709 15 => 32 KB 710 14 => 16 KB 711 13 => 8 KB 712 12 => 4 KB 713 714# 715# Architectures with an unreliable sched_clock() should select this: 716# 717config HAVE_UNSTABLE_SCHED_CLOCK 718 bool 719 720# 721# For architectures that want to enable the support for NUMA-affine scheduler 722# balancing logic: 723# 724config ARCH_SUPPORTS_NUMA_BALANCING 725 bool 726 727# For architectures that (ab)use NUMA to represent different memory regions 728# all cpu-local but of different latencies, such as SuperH. 729# 730config ARCH_WANT_NUMA_VARIABLE_LOCALITY 731 bool 732 733# 734# For architectures that are willing to define _PAGE_NUMA as _PAGE_PROTNONE 735config ARCH_WANTS_PROT_NUMA_PROT_NONE 736 bool 737 738config ARCH_USES_NUMA_PROT_NONE 739 bool 740 default y 741 depends on ARCH_WANTS_PROT_NUMA_PROT_NONE 742 depends on NUMA_BALANCING 743 744config NUMA_BALANCING_DEFAULT_ENABLED 745 bool "Automatically enable NUMA aware memory/task placement" 746 default y 747 depends on NUMA_BALANCING 748 help 749 If set, autonumic NUMA balancing will be enabled if running on a NUMA 750 machine. 751 752config NUMA_BALANCING 753 bool "Memory placement aware NUMA scheduler" 754 depends on ARCH_SUPPORTS_NUMA_BALANCING 755 depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY 756 depends on SMP && NUMA && MIGRATION 757 help 758 This option adds support for automatic NUMA aware memory/task placement. 759 The mechanism is quite primitive and is based on migrating memory when 760 it is references to the node the task is running on. 761 762 This system will be inactive on UMA systems. 763 764menuconfig CGROUPS 765 boolean "Control Group support" 766 depends on EVENTFD 767 help 768 This option adds support for grouping sets of processes together, for 769 use with process control subsystems such as Cpusets, CFS, memory 770 controls or device isolation. 771 See 772 - Documentation/scheduler/sched-design-CFS.txt (CFS) 773 - Documentation/cgroups/ (features for grouping, isolation 774 and resource control) 775 776 Say N if unsure. 777 778if CGROUPS 779 780config CGROUP_DEBUG 781 bool "Example debug cgroup subsystem" 782 default n 783 help 784 This option enables a simple cgroup subsystem that 785 exports useful debugging information about the cgroups 786 framework. 787 788 Say N if unsure. 789 790config CGROUP_FREEZER 791 bool "Freezer cgroup subsystem" 792 help 793 Provides a way to freeze and unfreeze all tasks in a 794 cgroup. 795 796config CGROUP_DEVICE 797 bool "Device controller for cgroups" 798 help 799 Provides a cgroup implementing whitelists for devices which 800 a process in the cgroup can mknod or open. 801 802config CPUSETS 803 bool "Cpuset support" 804 help 805 This option will let you create and manage CPUSETs which 806 allow dynamically partitioning a system into sets of CPUs and 807 Memory Nodes and assigning tasks to run only within those sets. 808 This is primarily useful on large SMP or NUMA systems. 809 810 Say N if unsure. 811 812config PROC_PID_CPUSET 813 bool "Include legacy /proc/<pid>/cpuset file" 814 depends on CPUSETS 815 default y 816 817config CGROUP_CPUACCT 818 bool "Simple CPU accounting cgroup subsystem" 819 help 820 Provides a simple Resource Controller for monitoring the 821 total CPU consumed by the tasks in a cgroup. 822 823config RESOURCE_COUNTERS 824 bool "Resource counters" 825 help 826 This option enables controller independent resource accounting 827 infrastructure that works with cgroups. 828 829config MEMCG 830 bool "Memory Resource Controller for Control Groups" 831 depends on RESOURCE_COUNTERS 832 select MM_OWNER 833 help 834 Provides a memory resource controller that manages both anonymous 835 memory and page cache. (See Documentation/cgroups/memory.txt) 836 837 Note that setting this option increases fixed memory overhead 838 associated with each page of memory in the system. By this, 839 20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory 840 usage tracking struct at boot. Total amount of this is printed out 841 at boot. 842 843 Only enable when you're ok with these trade offs and really 844 sure you need the memory resource controller. Even when you enable 845 this, you can set "cgroup_disable=memory" at your boot option to 846 disable memory resource controller and you can avoid overheads. 847 (and lose benefits of memory resource controller) 848 849 This config option also selects MM_OWNER config option, which 850 could in turn add some fork/exit overhead. 851 852config MEMCG_SWAP 853 bool "Memory Resource Controller Swap Extension" 854 depends on MEMCG && SWAP 855 help 856 Add swap management feature to memory resource controller. When you 857 enable this, you can limit mem+swap usage per cgroup. In other words, 858 when you disable this, memory resource controller has no cares to 859 usage of swap...a process can exhaust all of the swap. This extension 860 is useful when you want to avoid exhaustion swap but this itself 861 adds more overheads and consumes memory for remembering information. 862 Especially if you use 32bit system or small memory system, please 863 be careful about enabling this. When memory resource controller 864 is disabled by boot option, this will be automatically disabled and 865 there will be no overhead from this. Even when you set this config=y, 866 if boot option "swapaccount=0" is set, swap will not be accounted. 867 Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page 868 size is 4096bytes, 512k per 1Gbytes of swap. 869config MEMCG_SWAP_ENABLED 870 bool "Memory Resource Controller Swap Extension enabled by default" 871 depends on MEMCG_SWAP 872 default y 873 help 874 Memory Resource Controller Swap Extension comes with its price in 875 a bigger memory consumption. General purpose distribution kernels 876 which want to enable the feature but keep it disabled by default 877 and let the user enable it by swapaccount boot command line 878 parameter should have this option unselected. 879 For those who want to have the feature enabled by default should 880 select this option (if, for some reason, they need to disable it 881 then swapaccount=0 does the trick). 882config MEMCG_KMEM 883 bool "Memory Resource Controller Kernel Memory accounting" 884 depends on MEMCG 885 depends on SLUB || SLAB 886 help 887 The Kernel Memory extension for Memory Resource Controller can limit 888 the amount of memory used by kernel objects in the system. Those are 889 fundamentally different from the entities handled by the standard 890 Memory Controller, which are page-based, and can be swapped. Users of 891 the kmem extension can use it to guarantee that no group of processes 892 will ever exhaust kernel resources alone. 893 894config CGROUP_HUGETLB 895 bool "HugeTLB Resource Controller for Control Groups" 896 depends on RESOURCE_COUNTERS && HUGETLB_PAGE 897 default n 898 help 899 Provides a cgroup Resource Controller for HugeTLB pages. 900 When you enable this, you can put a per cgroup limit on HugeTLB usage. 901 The limit is enforced during page fault. Since HugeTLB doesn't 902 support page reclaim, enforcing the limit at page fault time implies 903 that, the application will get SIGBUS signal if it tries to access 904 HugeTLB pages beyond its limit. This requires the application to know 905 beforehand how much HugeTLB pages it would require for its use. The 906 control group is tracked in the third page lru pointer. This means 907 that we cannot use the controller with huge page less than 3 pages. 908 909config CGROUP_PERF 910 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring" 911 depends on PERF_EVENTS && CGROUPS 912 help 913 This option extends the per-cpu mode to restrict monitoring to 914 threads which belong to the cgroup specified and run on the 915 designated cpu. 916 917 Say N if unsure. 918 919menuconfig CGROUP_SCHED 920 bool "Group CPU scheduler" 921 default n 922 help 923 This feature lets CPU scheduler recognize task groups and control CPU 924 bandwidth allocation to such task groups. It uses cgroups to group 925 tasks. 926 927if CGROUP_SCHED 928config FAIR_GROUP_SCHED 929 bool "Group scheduling for SCHED_OTHER" 930 depends on CGROUP_SCHED 931 default CGROUP_SCHED 932 933config CFS_BANDWIDTH 934 bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED" 935 depends on FAIR_GROUP_SCHED 936 default n 937 help 938 This option allows users to define CPU bandwidth rates (limits) for 939 tasks running within the fair group scheduler. Groups with no limit 940 set are considered to be unconstrained and will run with no 941 restriction. 942 See tip/Documentation/scheduler/sched-bwc.txt for more information. 943 944config RT_GROUP_SCHED 945 bool "Group scheduling for SCHED_RR/FIFO" 946 depends on CGROUP_SCHED 947 default n 948 help 949 This feature lets you explicitly allocate real CPU bandwidth 950 to task groups. If enabled, it will also make it impossible to 951 schedule realtime tasks for non-root users until you allocate 952 realtime bandwidth for them. 953 See Documentation/scheduler/sched-rt-group.txt for more information. 954 955endif #CGROUP_SCHED 956 957config BLK_CGROUP 958 bool "Block IO controller" 959 depends on BLOCK 960 default n 961 ---help--- 962 Generic block IO controller cgroup interface. This is the common 963 cgroup interface which should be used by various IO controlling 964 policies. 965 966 Currently, CFQ IO scheduler uses it to recognize task groups and 967 control disk bandwidth allocation (proportional time slice allocation) 968 to such task groups. It is also used by bio throttling logic in 969 block layer to implement upper limit in IO rates on a device. 970 971 This option only enables generic Block IO controller infrastructure. 972 One needs to also enable actual IO controlling logic/policy. For 973 enabling proportional weight division of disk bandwidth in CFQ, set 974 CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set 975 CONFIG_BLK_DEV_THROTTLING=y. 976 977 See Documentation/cgroups/blkio-controller.txt for more information. 978 979config DEBUG_BLK_CGROUP 980 bool "Enable Block IO controller debugging" 981 depends on BLK_CGROUP 982 default n 983 ---help--- 984 Enable some debugging help. Currently it exports additional stat 985 files in a cgroup which can be useful for debugging. 986 987endif # CGROUPS 988 989config CHECKPOINT_RESTORE 990 bool "Checkpoint/restore support" if EXPERT 991 default n 992 help 993 Enables additional kernel features in a sake of checkpoint/restore. 994 In particular it adds auxiliary prctl codes to setup process text, 995 data and heap segment sizes, and a few additional /proc filesystem 996 entries. 997 998 If unsure, say N here. 999 1000menuconfig NAMESPACES 1001 bool "Namespaces support" if EXPERT 1002 default !EXPERT 1003 help 1004 Provides the way to make tasks work with different objects using 1005 the same id. For example same IPC id may refer to different objects 1006 or same user id or pid may refer to different tasks when used in 1007 different namespaces. 1008 1009if NAMESPACES 1010 1011config UTS_NS 1012 bool "UTS namespace" 1013 default y 1014 help 1015 In this namespace tasks see different info provided with the 1016 uname() system call 1017 1018config IPC_NS 1019 bool "IPC namespace" 1020 depends on (SYSVIPC || POSIX_MQUEUE) 1021 default y 1022 help 1023 In this namespace tasks work with IPC ids which correspond to 1024 different IPC objects in different namespaces. 1025 1026config USER_NS 1027 bool "User namespace" 1028 depends on UIDGID_CONVERTED 1029 select UIDGID_STRICT_TYPE_CHECKS 1030 1031 default n 1032 help 1033 This allows containers, i.e. vservers, to use user namespaces 1034 to provide different user info for different servers. 1035 1036 When user namespaces are enabled in the kernel it is 1037 recommended that the MEMCG and MEMCG_KMEM options also be 1038 enabled and that user-space use the memory control groups to 1039 limit the amount of memory a memory unprivileged users can 1040 use. 1041 1042 If unsure, say N. 1043 1044config PID_NS 1045 bool "PID Namespaces" 1046 default y 1047 help 1048 Support process id namespaces. This allows having multiple 1049 processes with the same pid as long as they are in different 1050 pid namespaces. This is a building block of containers. 1051 1052config NET_NS 1053 bool "Network namespace" 1054 depends on NET 1055 default y 1056 help 1057 Allow user space to create what appear to be multiple instances 1058 of the network stack. 1059 1060endif # NAMESPACES 1061 1062config UIDGID_CONVERTED 1063 # True if all of the selected software conmponents are known 1064 # to have uid_t and gid_t converted to kuid_t and kgid_t 1065 # where appropriate and are otherwise safe to use with 1066 # the user namespace. 1067 bool 1068 default y 1069 1070 # Filesystems 1071 depends on XFS_FS = n 1072 1073config UIDGID_STRICT_TYPE_CHECKS 1074 bool "Require conversions between uid/gids and their internal representation" 1075 depends on UIDGID_CONVERTED 1076 default n 1077 help 1078 While the nececessary conversions are being added to all subsystems this option allows 1079 the code to continue to build for unconverted subsystems. 1080 1081 Say Y here if you want the strict type checking enabled 1082 1083config SCHED_AUTOGROUP 1084 bool "Automatic process group scheduling" 1085 select EVENTFD 1086 select CGROUPS 1087 select CGROUP_SCHED 1088 select FAIR_GROUP_SCHED 1089 help 1090 This option optimizes the scheduler for common desktop workloads by 1091 automatically creating and populating task groups. This separation 1092 of workloads isolates aggressive CPU burners (like build jobs) from 1093 desktop applications. Task group autogeneration is currently based 1094 upon task session. 1095 1096config MM_OWNER 1097 bool 1098 1099config SYSFS_DEPRECATED 1100 bool "Enable deprecated sysfs features to support old userspace tools" 1101 depends on SYSFS 1102 default n 1103 help 1104 This option adds code that switches the layout of the "block" class 1105 devices, to not show up in /sys/class/block/, but only in 1106 /sys/block/. 1107 1108 This switch is only active when the sysfs.deprecated=1 boot option is 1109 passed or the SYSFS_DEPRECATED_V2 option is set. 1110 1111 This option allows new kernels to run on old distributions and tools, 1112 which might get confused by /sys/class/block/. Since 2007/2008 all 1113 major distributions and tools handle this just fine. 1114 1115 Recent distributions and userspace tools after 2009/2010 depend on 1116 the existence of /sys/class/block/, and will not work with this 1117 option enabled. 1118 1119 Only if you are using a new kernel on an old distribution, you might 1120 need to say Y here. 1121 1122config SYSFS_DEPRECATED_V2 1123 bool "Enable deprecated sysfs features by default" 1124 default n 1125 depends on SYSFS 1126 depends on SYSFS_DEPRECATED 1127 help 1128 Enable deprecated sysfs by default. 1129 1130 See the CONFIG_SYSFS_DEPRECATED option for more details about this 1131 option. 1132 1133 Only if you are using a new kernel on an old distribution, you might 1134 need to say Y here. Even then, odds are you would not need it 1135 enabled, you can always pass the boot option if absolutely necessary. 1136 1137config RELAY 1138 bool "Kernel->user space relay support (formerly relayfs)" 1139 help 1140 This option enables support for relay interface support in 1141 certain file systems (such as debugfs). 1142 It is designed to provide an efficient mechanism for tools and 1143 facilities to relay large amounts of data from kernel space to 1144 user space. 1145 1146 If unsure, say N. 1147 1148config BLK_DEV_INITRD 1149 bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" 1150 depends on BROKEN || !FRV 1151 help 1152 The initial RAM filesystem is a ramfs which is loaded by the 1153 boot loader (loadlin or lilo) and that is mounted as root 1154 before the normal boot procedure. It is typically used to 1155 load modules needed to mount the "real" root file system, 1156 etc. See <file:Documentation/initrd.txt> for details. 1157 1158 If RAM disk support (BLK_DEV_RAM) is also included, this 1159 also enables initial RAM disk (initrd) support and adds 1160 15 Kbytes (more on some other architectures) to the kernel size. 1161 1162 If unsure say Y. 1163 1164if BLK_DEV_INITRD 1165 1166source "usr/Kconfig" 1167 1168endif 1169 1170config CC_OPTIMIZE_FOR_SIZE 1171 bool "Optimize for size" 1172 help 1173 Enabling this option will pass "-Os" instead of "-O2" to gcc 1174 resulting in a smaller kernel. 1175 1176 If unsure, say N. 1177 1178config SYSCTL 1179 bool 1180 1181config ANON_INODES 1182 bool 1183 1184menuconfig EXPERT 1185 bool "Configure standard kernel features (expert users)" 1186 # Unhide debug options, to make the on-by-default options visible 1187 select DEBUG_KERNEL 1188 help 1189 This option allows certain base kernel options and settings 1190 to be disabled or tweaked. This is for specialized 1191 environments which can tolerate a "non-standard" kernel. 1192 Only use this if you really know what you are doing. 1193 1194config HAVE_UID16 1195 bool 1196 1197config UID16 1198 bool "Enable 16-bit UID system calls" if EXPERT 1199 depends on HAVE_UID16 1200 default y 1201 help 1202 This enables the legacy 16-bit UID syscall wrappers. 1203 1204config SYSCTL_SYSCALL 1205 bool "Sysctl syscall support" if EXPERT 1206 depends on PROC_SYSCTL 1207 default n 1208 select SYSCTL 1209 ---help--- 1210 sys_sysctl uses binary paths that have been found challenging 1211 to properly maintain and use. The interface in /proc/sys 1212 using paths with ascii names is now the primary path to this 1213 information. 1214 1215 Almost nothing using the binary sysctl interface so if you are 1216 trying to save some space it is probably safe to disable this, 1217 making your kernel marginally smaller. 1218 1219 If unsure say N here. 1220 1221config SYSCTL_EXCEPTION_TRACE 1222 bool 1223 help 1224 Enable support for /proc/sys/debug/exception-trace. 1225 1226config SYSCTL_ARCH_UNALIGN_NO_WARN 1227 bool 1228 help 1229 Enable support for /proc/sys/kernel/ignore-unaligned-usertrap 1230 Allows arch to define/use @no_unaligned_warning to possibly warn 1231 about unaligned access emulation going on under the hood. 1232 1233config SYSCTL_ARCH_UNALIGN_ALLOW 1234 bool 1235 help 1236 Enable support for /proc/sys/kernel/unaligned-trap 1237 Allows arches to define/use @unaligned_enabled to runtime toggle 1238 the unaligned access emulation. 1239 see arch/parisc/kernel/unaligned.c for reference 1240 1241config KALLSYMS 1242 bool "Load all symbols for debugging/ksymoops" if EXPERT 1243 default y 1244 help 1245 Say Y here to let the kernel print out symbolic crash information and 1246 symbolic stack backtraces. This increases the size of the kernel 1247 somewhat, as all symbols have to be loaded into the kernel image. 1248 1249config KALLSYMS_ALL 1250 bool "Include all symbols in kallsyms" 1251 depends on DEBUG_KERNEL && KALLSYMS 1252 help 1253 Normally kallsyms only contains the symbols of functions for nicer 1254 OOPS messages and backtraces (i.e., symbols from the text and inittext 1255 sections). This is sufficient for most cases. And only in very rare 1256 cases (e.g., when a debugger is used) all symbols are required (e.g., 1257 names of variables from the data sections, etc). 1258 1259 This option makes sure that all symbols are loaded into the kernel 1260 image (i.e., symbols from all sections) in cost of increased kernel 1261 size (depending on the kernel configuration, it may be 300KiB or 1262 something like this). 1263 1264 Say N unless you really need all symbols. 1265 1266config HOTPLUG 1267 def_bool y 1268 1269config PRINTK 1270 default y 1271 bool "Enable support for printk" if EXPERT 1272 select IRQ_WORK 1273 help 1274 This option enables normal printk support. Removing it 1275 eliminates most of the message strings from the kernel image 1276 and makes the kernel more or less silent. As this makes it 1277 very difficult to diagnose system problems, saying N here is 1278 strongly discouraged. 1279 1280config BUG 1281 bool "BUG() support" if EXPERT 1282 default y 1283 help 1284 Disabling this option eliminates support for BUG and WARN, reducing 1285 the size of your kernel image and potentially quietly ignoring 1286 numerous fatal conditions. You should only consider disabling this 1287 option for embedded systems with no facilities for reporting errors. 1288 Just say Y. 1289 1290config ELF_CORE 1291 depends on COREDUMP 1292 default y 1293 bool "Enable ELF core dumps" if EXPERT 1294 help 1295 Enable support for generating core dumps. Disabling saves about 4k. 1296 1297 1298config PCSPKR_PLATFORM 1299 bool "Enable PC-Speaker support" if EXPERT 1300 depends on HAVE_PCSPKR_PLATFORM 1301 select I8253_LOCK 1302 default y 1303 help 1304 This option allows to disable the internal PC-Speaker 1305 support, saving some memory. 1306 1307config HAVE_PCSPKR_PLATFORM 1308 bool 1309 1310config BASE_FULL 1311 default y 1312 bool "Enable full-sized data structures for core" if EXPERT 1313 help 1314 Disabling this option reduces the size of miscellaneous core 1315 kernel data structures. This saves memory on small machines, 1316 but may reduce performance. 1317 1318config FUTEX 1319 bool "Enable futex support" if EXPERT 1320 default y 1321 select RT_MUTEXES 1322 help 1323 Disabling this option will cause the kernel to be built without 1324 support for "fast userspace mutexes". The resulting kernel may not 1325 run glibc-based applications correctly. 1326 1327config EPOLL 1328 bool "Enable eventpoll support" if EXPERT 1329 default y 1330 select ANON_INODES 1331 help 1332 Disabling this option will cause the kernel to be built without 1333 support for epoll family of system calls. 1334 1335config SIGNALFD 1336 bool "Enable signalfd() system call" if EXPERT 1337 select ANON_INODES 1338 default y 1339 help 1340 Enable the signalfd() system call that allows to receive signals 1341 on a file descriptor. 1342 1343 If unsure, say Y. 1344 1345config TIMERFD 1346 bool "Enable timerfd() system call" if EXPERT 1347 select ANON_INODES 1348 default y 1349 help 1350 Enable the timerfd() system call that allows to receive timer 1351 events on a file descriptor. 1352 1353 If unsure, say Y. 1354 1355config EVENTFD 1356 bool "Enable eventfd() system call" if EXPERT 1357 select ANON_INODES 1358 default y 1359 help 1360 Enable the eventfd() system call that allows to receive both 1361 kernel notification (ie. KAIO) or userspace notifications. 1362 1363 If unsure, say Y. 1364 1365config SHMEM 1366 bool "Use full shmem filesystem" if EXPERT 1367 default y 1368 depends on MMU 1369 help 1370 The shmem is an internal filesystem used to manage shared memory. 1371 It is backed by swap and manages resource limits. It is also exported 1372 to userspace as tmpfs if TMPFS is enabled. Disabling this 1373 option replaces shmem and tmpfs with the much simpler ramfs code, 1374 which may be appropriate on small systems without swap. 1375 1376config AIO 1377 bool "Enable AIO support" if EXPERT 1378 default y 1379 help 1380 This option enables POSIX asynchronous I/O which may by used 1381 by some high performance threaded applications. Disabling 1382 this option saves about 7k. 1383 1384config EMBEDDED 1385 bool "Embedded system" 1386 select EXPERT 1387 help 1388 This option should be enabled if compiling the kernel for 1389 an embedded system so certain expert options are available 1390 for configuration. 1391 1392config HAVE_PERF_EVENTS 1393 bool 1394 help 1395 See tools/perf/design.txt for details. 1396 1397config PERF_USE_VMALLOC 1398 bool 1399 help 1400 See tools/perf/design.txt for details 1401 1402menu "Kernel Performance Events And Counters" 1403 1404config PERF_EVENTS 1405 bool "Kernel performance events and counters" 1406 default y if PROFILING 1407 depends on HAVE_PERF_EVENTS 1408 select ANON_INODES 1409 select IRQ_WORK 1410 help 1411 Enable kernel support for various performance events provided 1412 by software and hardware. 1413 1414 Software events are supported either built-in or via the 1415 use of generic tracepoints. 1416 1417 Most modern CPUs support performance events via performance 1418 counter registers. These registers count the number of certain 1419 types of hw events: such as instructions executed, cachemisses 1420 suffered, or branches mis-predicted - without slowing down the 1421 kernel or applications. These registers can also trigger interrupts 1422 when a threshold number of events have passed - and can thus be 1423 used to profile the code that runs on that CPU. 1424 1425 The Linux Performance Event subsystem provides an abstraction of 1426 these software and hardware event capabilities, available via a 1427 system call and used by the "perf" utility in tools/perf/. It 1428 provides per task and per CPU counters, and it provides event 1429 capabilities on top of those. 1430 1431 Say Y if unsure. 1432 1433config DEBUG_PERF_USE_VMALLOC 1434 default n 1435 bool "Debug: use vmalloc to back perf mmap() buffers" 1436 depends on PERF_EVENTS && DEBUG_KERNEL 1437 select PERF_USE_VMALLOC 1438 help 1439 Use vmalloc memory to back perf mmap() buffers. 1440 1441 Mostly useful for debugging the vmalloc code on platforms 1442 that don't require it. 1443 1444 Say N if unsure. 1445 1446endmenu 1447 1448config VM_EVENT_COUNTERS 1449 default y 1450 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1451 help 1452 VM event counters are needed for event counts to be shown. 1453 This option allows the disabling of the VM event counters 1454 on EXPERT systems. /proc/vmstat will only show page counts 1455 if VM event counters are disabled. 1456 1457config PCI_QUIRKS 1458 default y 1459 bool "Enable PCI quirk workarounds" if EXPERT 1460 depends on PCI 1461 help 1462 This enables workarounds for various PCI chipset 1463 bugs/quirks. Disable this only if your target machine is 1464 unaffected by PCI quirks. 1465 1466config SLUB_DEBUG 1467 default y 1468 bool "Enable SLUB debugging support" if EXPERT 1469 depends on SLUB && SYSFS 1470 help 1471 SLUB has extensive debug support features. Disabling these can 1472 result in significant savings in code size. This also disables 1473 SLUB sysfs support. /sys/slab will not exist and there will be 1474 no support for cache validation etc. 1475 1476config COMPAT_BRK 1477 bool "Disable heap randomization" 1478 default y 1479 help 1480 Randomizing heap placement makes heap exploits harder, but it 1481 also breaks ancient binaries (including anything libc5 based). 1482 This option changes the bootup default to heap randomization 1483 disabled, and can be overridden at runtime by setting 1484 /proc/sys/kernel/randomize_va_space to 2. 1485 1486 On non-ancient distros (post-2000 ones) N is usually a safe choice. 1487 1488choice 1489 prompt "Choose SLAB allocator" 1490 default SLUB 1491 help 1492 This option allows to select a slab allocator. 1493 1494config SLAB 1495 bool "SLAB" 1496 help 1497 The regular slab allocator that is established and known to work 1498 well in all environments. It organizes cache hot objects in 1499 per cpu and per node queues. 1500 1501config SLUB 1502 bool "SLUB (Unqueued Allocator)" 1503 help 1504 SLUB is a slab allocator that minimizes cache line usage 1505 instead of managing queues of cached objects (SLAB approach). 1506 Per cpu caching is realized using slabs of objects instead 1507 of queues of objects. SLUB can use memory efficiently 1508 and has enhanced diagnostics. SLUB is the default choice for 1509 a slab allocator. 1510 1511config SLOB 1512 depends on EXPERT 1513 bool "SLOB (Simple Allocator)" 1514 help 1515 SLOB replaces the stock allocator with a drastically simpler 1516 allocator. SLOB is generally more space efficient but 1517 does not perform as well on large systems. 1518 1519endchoice 1520 1521config MMAP_ALLOW_UNINITIALIZED 1522 bool "Allow mmapped anonymous memory to be uninitialized" 1523 depends on EXPERT && !MMU 1524 default n 1525 help 1526 Normally, and according to the Linux spec, anonymous memory obtained 1527 from mmap() has it's contents cleared before it is passed to 1528 userspace. Enabling this config option allows you to request that 1529 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 1530 providing a huge performance boost. If this option is not enabled, 1531 then the flag will be ignored. 1532 1533 This is taken advantage of by uClibc's malloc(), and also by 1534 ELF-FDPIC binfmt's brk and stack allocator. 1535 1536 Because of the obvious security issues, this option should only be 1537 enabled on embedded devices where you control what is run in 1538 userspace. Since that isn't generally a problem on no-MMU systems, 1539 it is normally safe to say Y here. 1540 1541 See Documentation/nommu-mmap.txt for more information. 1542 1543config PROFILING 1544 bool "Profiling support" 1545 help 1546 Say Y here to enable the extended profiling support mechanisms used 1547 by profilers such as OProfile. 1548 1549# 1550# Place an empty function call at each tracepoint site. Can be 1551# dynamically changed for a probe function. 1552# 1553config TRACEPOINTS 1554 bool 1555 1556source "arch/Kconfig" 1557 1558endmenu # General setup 1559 1560config HAVE_GENERIC_DMA_COHERENT 1561 bool 1562 default n 1563 1564config SLABINFO 1565 bool 1566 depends on PROC_FS 1567 depends on SLAB || SLUB_DEBUG 1568 default y 1569 1570config RT_MUTEXES 1571 boolean 1572 1573config BASE_SMALL 1574 int 1575 default 0 if BASE_FULL 1576 default 1 if !BASE_FULL 1577 1578menuconfig MODULES 1579 bool "Enable loadable module support" 1580 help 1581 Kernel modules are small pieces of compiled code which can 1582 be inserted in the running kernel, rather than being 1583 permanently built into the kernel. You use the "modprobe" 1584 tool to add (and sometimes remove) them. If you say Y here, 1585 many parts of the kernel can be built as modules (by 1586 answering M instead of Y where indicated): this is most 1587 useful for infrequently used options which are not required 1588 for booting. For more information, see the man pages for 1589 modprobe, lsmod, modinfo, insmod and rmmod. 1590 1591 If you say Y here, you will need to run "make 1592 modules_install" to put the modules under /lib/modules/ 1593 where modprobe can find them (you may need to be root to do 1594 this). 1595 1596 If unsure, say Y. 1597 1598if MODULES 1599 1600config MODULE_FORCE_LOAD 1601 bool "Forced module loading" 1602 default n 1603 help 1604 Allow loading of modules without version information (ie. modprobe 1605 --force). Forced module loading sets the 'F' (forced) taint flag and 1606 is usually a really bad idea. 1607 1608config MODULE_UNLOAD 1609 bool "Module unloading" 1610 help 1611 Without this option you will not be able to unload any 1612 modules (note that some modules may not be unloadable 1613 anyway), which makes your kernel smaller, faster 1614 and simpler. If unsure, say Y. 1615 1616config MODULE_FORCE_UNLOAD 1617 bool "Forced module unloading" 1618 depends on MODULE_UNLOAD 1619 help 1620 This option allows you to force a module to unload, even if the 1621 kernel believes it is unsafe: the kernel will remove the module 1622 without waiting for anyone to stop using it (using the -f option to 1623 rmmod). This is mainly for kernel developers and desperate users. 1624 If unsure, say N. 1625 1626config MODVERSIONS 1627 bool "Module versioning support" 1628 help 1629 Usually, you have to use modules compiled with your kernel. 1630 Saying Y here makes it sometimes possible to use modules 1631 compiled for different kernels, by adding enough information 1632 to the modules to (hopefully) spot any changes which would 1633 make them incompatible with the kernel you are running. If 1634 unsure, say N. 1635 1636config MODULE_SRCVERSION_ALL 1637 bool "Source checksum for all modules" 1638 help 1639 Modules which contain a MODULE_VERSION get an extra "srcversion" 1640 field inserted into their modinfo section, which contains a 1641 sum of the source files which made it. This helps maintainers 1642 see exactly which source was used to build a module (since 1643 others sometimes change the module source without updating 1644 the version). With this option, such a "srcversion" field 1645 will be created for all modules. If unsure, say N. 1646 1647config MODULE_SIG 1648 bool "Module signature verification" 1649 depends on MODULES 1650 select KEYS 1651 select CRYPTO 1652 select ASYMMETRIC_KEY_TYPE 1653 select ASYMMETRIC_PUBLIC_KEY_SUBTYPE 1654 select PUBLIC_KEY_ALGO_RSA 1655 select ASN1 1656 select OID_REGISTRY 1657 select X509_CERTIFICATE_PARSER 1658 help 1659 Check modules for valid signatures upon load: the signature 1660 is simply appended to the module. For more information see 1661 Documentation/module-signing.txt. 1662 1663 !!!WARNING!!! If you enable this option, you MUST make sure that the 1664 module DOES NOT get stripped after being signed. This includes the 1665 debuginfo strip done by some packagers (such as rpmbuild) and 1666 inclusion into an initramfs that wants the module size reduced. 1667 1668config MODULE_SIG_FORCE 1669 bool "Require modules to be validly signed" 1670 depends on MODULE_SIG 1671 help 1672 Reject unsigned modules or signed modules for which we don't have a 1673 key. Without this, such modules will simply taint the kernel. 1674 1675config MODULE_SIG_ALL 1676 bool "Automatically sign all modules" 1677 default y 1678 depends on MODULE_SIG 1679 help 1680 Sign all modules during make modules_install. Without this option, 1681 modules must be signed manually, using the scripts/sign-file tool. 1682 1683comment "Do not forget to sign required modules with scripts/sign-file" 1684 depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL 1685 1686choice 1687 prompt "Which hash algorithm should modules be signed with?" 1688 depends on MODULE_SIG 1689 help 1690 This determines which sort of hashing algorithm will be used during 1691 signature generation. This algorithm _must_ be built into the kernel 1692 directly so that signature verification can take place. It is not 1693 possible to load a signed module containing the algorithm to check 1694 the signature on that module. 1695 1696config MODULE_SIG_SHA1 1697 bool "Sign modules with SHA-1" 1698 select CRYPTO_SHA1 1699 1700config MODULE_SIG_SHA224 1701 bool "Sign modules with SHA-224" 1702 select CRYPTO_SHA256 1703 1704config MODULE_SIG_SHA256 1705 bool "Sign modules with SHA-256" 1706 select CRYPTO_SHA256 1707 1708config MODULE_SIG_SHA384 1709 bool "Sign modules with SHA-384" 1710 select CRYPTO_SHA512 1711 1712config MODULE_SIG_SHA512 1713 bool "Sign modules with SHA-512" 1714 select CRYPTO_SHA512 1715 1716endchoice 1717 1718config MODULE_SIG_HASH 1719 string 1720 depends on MODULE_SIG 1721 default "sha1" if MODULE_SIG_SHA1 1722 default "sha224" if MODULE_SIG_SHA224 1723 default "sha256" if MODULE_SIG_SHA256 1724 default "sha384" if MODULE_SIG_SHA384 1725 default "sha512" if MODULE_SIG_SHA512 1726 1727endif # MODULES 1728 1729config INIT_ALL_POSSIBLE 1730 bool 1731 help 1732 Back when each arch used to define their own cpu_online_mask and 1733 cpu_possible_mask, some of them chose to initialize cpu_possible_mask 1734 with all 1s, and others with all 0s. When they were centralised, 1735 it was better to provide this option than to break all the archs 1736 and have several arch maintainers pursuing me down dark alleys. 1737 1738config STOP_MACHINE 1739 bool 1740 default y 1741 depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU 1742 help 1743 Need stop_machine() primitive. 1744 1745source "block/Kconfig" 1746 1747config PREEMPT_NOTIFIERS 1748 bool 1749 1750config PADATA 1751 depends on SMP 1752 bool 1753 1754# Can be selected by architectures with broken toolchains 1755# that get confused by correct const<->read_only section 1756# mappings 1757config BROKEN_RODATA 1758 bool 1759 1760config ASN1 1761 tristate 1762 help 1763 Build a simple ASN.1 grammar compiler that produces a bytecode output 1764 that can be interpreted by the ASN.1 stream decoder and used to 1765 inform it as to what tags are to be expected in a stream and what 1766 functions to call on what tags. 1767 1768source "kernel/Kconfig.locks" 1769