config/Config-kernel.in

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 #
   3 # Copyright (C) 2006-2014 OpenWrt.org
   4
   5 config KERNEL_BUILD_USER
   6         string "Custom Kernel Build User Name"
   7         default "builder" if BUILDBOT
   8         default ""
   9         help
  10           Sets the Kernel build user string, which for example will be returned
  11           by 'uname -a' on running systems.
  12           If not set, uses system user at build time.
  13
  14 config KERNEL_BUILD_DOMAIN
  15         string "Custom Kernel Build Domain Name"
  16         default "buildhost" if BUILDBOT
  17         default ""
  18         help
  19           Sets the Kernel build domain string, which for example will be
  20           returned by 'uname -a' on running systems.
  21           If not set, uses system hostname at build time.
  22
  23 config KERNEL_PRINTK
  24         bool "Enable support for printk"
  25         default y
  26
  27 config KERNEL_SWAP
  28         bool "Support for paging of anonymous memory (swap)"
  29         default y if !SMALL_FLASH
  30
  31 config KERNEL_PROC_STRIPPED
  32         bool "Strip non-essential /proc functionality to reduce code size"
  33         default y if SMALL_FLASH
  34
  35 config KERNEL_DEBUG_FS
  36         bool "Compile the kernel with debug filesystem enabled"
  37         default y
  38         help
  39           debugfs is a virtual file system that kernel developers use to put
  40           debugging files into. Enable this option to be able to read and
  41           write to these files. Many common debugging facilities, such as
  42           ftrace, require the existence of debugfs.
  43
  44 config KERNEL_MIPS_FP_SUPPORT
  45         bool
  46         default y if TARGET_pistachio
  47
  48 config KERNEL_ARM_PMU
  49         bool
  50         default n
  51         depends on (arm || aarch64)
  52
  53 config KERNEL_X86_VSYSCALL_EMULATION
  54         bool "Enable vsyscall emulation"
  55         default n
  56         depends on x86_64
  57         help
  58           This enables emulation of the legacy vsyscall page.  Disabling
  59           it is roughly equivalent to booting with vsyscall=none, except
  60           that it will also disable the helpful warning if a program
  61           tries to use a vsyscall.  With this option set to N, offending
  62           programs will just segfault, citing addresses of the form
  63           0xffffffffff600?00.
  64
  65           This option is required by many programs built before 2013, and
  66           care should be used even with newer programs if set to N.
  67
  68           Disabling this option saves about 7K of kernel size and
  69           possibly 4K of additional runtime pagetable memory.
  70
  71 config KERNEL_PERF_EVENTS
  72         bool "Compile the kernel with performance events and counters"
  73         default n
  74         select KERNEL_ARM_PMU if (arm || aarch64)
  75
  76 config KERNEL_PROFILING
  77         bool "Compile the kernel with profiling enabled"
  78         default n
  79         select KERNEL_PERF_EVENTS
  80         help
  81           Enable the extended profiling support mechanisms used by profilers such
  82           as OProfile.
  83
  84 config KERNEL_UBSAN
  85         bool "Compile the kernel with undefined behaviour sanity checker"
  86         help
  87           This option enables undefined behaviour sanity checker
  88           Compile-time instrumentation is used to detect various undefined
  89           behaviours in runtime. Various types of checks may be enabled
  90           via boot parameter ubsan_handle
  91           (see: Documentation/dev-tools/ubsan.rst).
  92
  93 config KERNEL_UBSAN_SANITIZE_ALL
  94         bool "Enable instrumentation for the entire kernel"
  95         depends on KERNEL_UBSAN
  96         default y
  97         help
  98           This option activates instrumentation for the entire kernel.
  99           If you don't enable this option, you have to explicitly specify
 100           UBSAN_SANITIZE := y for the files/directories you want to check for UB.
 101           Enabling this option will get kernel image size increased
 102           significantly.
 103
 104 config KERNEL_UBSAN_ALIGNMENT
 105         bool "Enable checking of pointers alignment"
 106         depends on KERNEL_UBSAN
 107         help
 108           This option enables detection of unaligned memory accesses.
 109           Enabling this option on architectures that support unaligned
 110           accesses may produce a lot of false positives.
 111
 112 config KERNEL_UBSAN_BOUNDS
 113         bool "Perform array index bounds checking"
 114         depends on KERNEL_UBSAN
 115         help
 116           This option enables detection of directly indexed out of bounds array
 117           accesses, where the array size is known at compile time. Note that
 118           this does not protect array overflows via bad calls to the
 119           {str,mem}*cpy() family of functions (that is addressed by
 120           FORTIFY_SOURCE).
 121
 122 config KERNEL_UBSAN_NULL
 123         bool "Enable checking of null pointers"
 124         depends on KERNEL_UBSAN
 125         help
 126           This option enables detection of memory accesses via a
 127           null pointer.
 128
 129 config KERNEL_UBSAN_TRAP
 130         bool "On Sanitizer warnings, abort the running kernel code"
 131         depends on KERNEL_UBSAN
 132         help
 133           Building kernels with Sanitizer features enabled tends to grow the
 134           kernel size by around 5%, due to adding all the debugging text on
 135           failure paths. To avoid this, Sanitizer instrumentation can just
 136           issue a trap. This reduces the kernel size overhead but turns all
 137           warnings (including potentially harmless conditions) into full
 138           exceptions that abort the running kernel code (regardless of context,
 139           locks held, etc), which may destabilize the system. For some system
 140           builders this is an acceptable trade-off.
 141
 142 config KERNEL_KASAN
 143         bool "Compile the kernel with KASan: runtime memory debugger"
 144         select KERNEL_SLUB_DEBUG
 145         depends on (x86_64 || aarch64)
 146         help
 147           Enables kernel address sanitizer - runtime memory debugger,
 148           designed to find out-of-bounds accesses and use-after-free bugs.
 149           This is strictly a debugging feature and it requires a gcc version
 150           of 4.9.2 or later. Detection of out of bounds accesses to stack or
 151           global variables requires gcc 5.0 or later.
 152           This feature consumes about 1/8 of available memory and brings about
 153           ~x3 performance slowdown.
 154           For better error detection enable CONFIG_STACKTRACE.
 155           Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
 156           (the resulting kernel does not boot).
 157
 158 config KERNEL_KASAN_EXTRA
 159         bool "KAsan: extra checks"
 160         depends on KERNEL_KASAN && KERNEL_DEBUG_KERNEL
 161         help
 162           This enables further checks in the kernel address sanitizer, for now
 163           it only includes the address-use-after-scope check that can lead
 164           to excessive kernel stack usage, frame size warnings and longer
 165           compile time.
 166           https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
 167
 168 config KERNEL_KASAN_VMALLOC
 169         bool "Back mappings in vmalloc space with real shadow memory"
 170         depends on KERNEL_KASAN
 171         help
 172           By default, the shadow region for vmalloc space is the read-only
 173           zero page. This means that KASAN cannot detect errors involving
 174           vmalloc space.
 175
 176           Enabling this option will hook in to vmap/vmalloc and back those
 177           mappings with real shadow memory allocated on demand. This allows
 178           for KASAN to detect more sorts of errors (and to support vmapped
 179           stacks), but at the cost of higher memory usage.
 180
 181           This option depends on HAVE_ARCH_KASAN_VMALLOC, but we can't
 182           depend on that in here, so it is possible that enabling this
 183           will have no effect.
 184
 185 if KERNEL_KASAN
 186         config KERNEL_KASAN_GENERIC
 187         def_bool y
 188
 189         config KERNEL_KASAN_SW_TAGS
 190         def_bool n
 191 endif
 192
 193 choice
 194         prompt "Instrumentation type"
 195         depends on KERNEL_KASAN
 196         default KERNEL_KASAN_OUTLINE
 197
 198 config KERNEL_KASAN_OUTLINE
 199         bool "Outline instrumentation"
 200         help
 201           Before every memory access compiler insert function call
 202           __asan_load*/__asan_store*. These functions performs check
 203           of shadow memory. This is slower than inline instrumentation,
 204           however it doesn't bloat size of kernel's .text section so
 205           much as inline does.
 206
 207 config KERNEL_KASAN_INLINE
 208         bool "Inline instrumentation"
 209         help
 210           Compiler directly inserts code checking shadow memory before
 211           memory accesses. This is faster than outline (in some workloads
 212           it gives about x2 boost over outline instrumentation), but
 213           make kernel's .text size much bigger.
 214           This requires a gcc version of 5.0 or later.
 215
 216 endchoice
 217
 218 config KERNEL_KCOV
 219         bool "Compile the kernel with code coverage for fuzzing"
 220         select KERNEL_DEBUG_FS
 221         help
 222           KCOV exposes kernel code coverage information in a form suitable
 223           for coverage-guided fuzzing (randomized testing).
 224
 225           If RANDOMIZE_BASE is enabled, PC values will not be stable across
 226           different machines and across reboots. If you need stable PC values,
 227           disable RANDOMIZE_BASE.
 228
 229           For more details, see Documentation/kcov.txt.
 230
 231 config KERNEL_KCOV_ENABLE_COMPARISONS
 232         bool "Enable comparison operands collection by KCOV"
 233         depends on KERNEL_KCOV
 234         help
 235           KCOV also exposes operands of every comparison in the instrumented
 236           code along with operand sizes and PCs of the comparison instructions.
 237           These operands can be used by fuzzing engines to improve the quality
 238           of fuzzing coverage.
 239
 240 config KERNEL_KCOV_INSTRUMENT_ALL
 241         bool "Instrument all code by default"
 242         depends on KERNEL_KCOV
 243         default y if KERNEL_KCOV
 244         help
 245           If you are doing generic system call fuzzing (like e.g. syzkaller),
 246           then you will want to instrument the whole kernel and you should
 247           say y here. If you are doing more targeted fuzzing (like e.g.
 248           filesystem fuzzing with AFL) then you will want to enable coverage
 249           for more specific subsets of files, and should say n here.
 250
 251 config KERNEL_TASKSTATS
 252         bool "Compile the kernel with task resource/io statistics and accounting"
 253         default n
 254         help
 255           Enable the collection and publishing of task/io statistics and
 256           accounting.  Enable this option to enable i/o monitoring in system
 257           monitors.
 258
 259 if KERNEL_TASKSTATS
 260
 261         config KERNEL_TASK_DELAY_ACCT
 262                 def_bool y
 263
 264         config KERNEL_TASK_IO_ACCOUNTING
 265                 def_bool y
 266
 267         config KERNEL_TASK_XACCT
 268                 def_bool y
 269
 270 endif
 271
 272 config KERNEL_KALLSYMS
 273         bool "Compile the kernel with symbol table information"
 274         default y if !SMALL_FLASH
 275         help
 276           This will give you more information in stack traces from kernel oopses.
 277
 278 config KERNEL_FTRACE
 279         bool "Compile the kernel with tracing support"
 280         depends on !TARGET_uml
 281         default n
 282
 283 config KERNEL_FTRACE_SYSCALLS
 284         bool "Trace system calls"
 285         depends on KERNEL_FTRACE
 286         default n
 287
 288 config KERNEL_ENABLE_DEFAULT_TRACERS
 289         bool "Trace process context switches and events"
 290         depends on KERNEL_FTRACE
 291         default n
 292
 293 config KERNEL_FUNCTION_TRACER
 294         bool "Function tracer"
 295         depends on KERNEL_FTRACE
 296         default n
 297
 298 config KERNEL_FUNCTION_GRAPH_TRACER
 299         bool "Function graph tracer"
 300         depends on KERNEL_FUNCTION_TRACER
 301         default n
 302
 303 config KERNEL_DYNAMIC_FTRACE
 304         bool "Enable/disable function tracing dynamically"
 305         depends on KERNEL_FUNCTION_TRACER
 306         default n
 307
 308 config KERNEL_FUNCTION_PROFILER
 309         bool "Function profiler"
 310         depends on KERNEL_FUNCTION_TRACER
 311         default n
 312
 313 config KERNEL_IRQSOFF_TRACER
 314         bool "Interrupts-off Latency Tracer"
 315         depends on KERNEL_FTRACE
 316         help
 317           This option measures the time spent in irqs-off critical
 318           sections, with microsecond accuracy.
 319
 320           The default measurement method is a maximum search, which is
 321           disabled by default and can be runtime (re-)started
 322           via:
 323
 324               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 325
 326           (Note that kernel size and overhead increase with this option
 327           enabled. This option and the preempt-off timing option can be
 328           used together or separately.)
 329
 330 config KERNEL_PREEMPT_TRACER
 331         bool "Preemption-off Latency Tracer"
 332         depends on KERNEL_FTRACE
 333         help
 334           This option measures the time spent in preemption-off critical
 335           sections, with microsecond accuracy.
 336
 337           The default measurement method is a maximum search, which is
 338           disabled by default and can be runtime (re-)started
 339           via:
 340
 341               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 342
 343           (Note that kernel size and overhead increase with this option
 344           enabled. This option and the irqs-off timing option can be
 345           used together or separately.)
 346
 347 config KERNEL_HIST_TRIGGERS
 348         bool "Histogram triggers"
 349         depends on KERNEL_FTRACE
 350         help
 351           Hist triggers allow one or more arbitrary trace event fields to be
 352           aggregated into hash tables and dumped to stdout by reading a
 353           debugfs/tracefs file. They're useful for gathering quick and dirty
 354           (though precise) summaries of event activity as an initial guide for
 355           further investigation using more advanced tools.
 356
 357           Inter-event tracing of quantities such as latencies is also
 358           supported using hist triggers under this option.
 359
 360 config KERNEL_DEBUG_KERNEL
 361         bool
 362         default n
 363
 364 config KERNEL_DEBUG_INFO
 365         bool "Compile the kernel with debug information"
 366         default y if !SMALL_FLASH
 367         select KERNEL_DEBUG_KERNEL
 368         help
 369           This will compile your kernel and modules with debug information.
 370
 371 config KERNEL_DEBUG_LL_UART_NONE
 372         bool
 373         default n
 374         depends on arm
 375
 376 config KERNEL_DEBUG_LL
 377         bool
 378         default n
 379         depends on arm
 380         select KERNEL_DEBUG_LL_UART_NONE
 381         help
 382           ARM low level debugging.
 383
 384 config KERNEL_DYNAMIC_DEBUG
 385         bool "Compile the kernel with dynamic printk"
 386         select KERNEL_DEBUG_FS
 387         default n
 388         help
 389           Compiles debug level messages into the kernel, which would not
 390           otherwise be available at runtime. These messages can then be
 391           enabled/disabled based on various levels of scope - per source file,
 392           function, module, format string, and line number. This mechanism
 393           implicitly compiles in all pr_debug() and dev_dbg() calls, which
 394           enlarges the kernel text size by about 2%.
 395
 396 config KERNEL_EARLY_PRINTK
 397         bool "Compile the kernel with early printk"
 398         default y if TARGET_bcm53xx
 399         default n
 400         depends on arm
 401         select KERNEL_DEBUG_KERNEL
 402         select KERNEL_DEBUG_LL if arm
 403         help
 404           Compile the kernel with early printk support.  This is only useful for
 405           debugging purposes to send messages over the serial console in early boot.
 406           Enable this to debug early boot problems.
 407
 408 config KERNEL_KPROBES
 409         bool "Compile the kernel with kprobes support"
 410         default n
 411         select KERNEL_FTRACE
 412         select KERNEL_PERF_EVENTS
 413         help
 414           Compiles the kernel with KPROBES support, which allows you to trap
 415           at almost any kernel address and execute a callback function.
 416           register_kprobe() establishes a probepoint and specifies the
 417           callback. Kprobes is useful for kernel debugging, non-intrusive
 418           instrumentation and testing.
 419           If in doubt, say "N".
 420
 421 config KERNEL_KPROBE_EVENTS
 422         bool
 423         default y if KERNEL_KPROBES
 424
 425 config KERNEL_BPF_KPROBE_OVERRIDE
 426         bool
 427         depends on KERNEL_KPROBES
 428         default n
 429
 430 config KERNEL_AIO
 431         bool "Compile the kernel with asynchronous IO support"
 432         default y if !SMALL_FLASH
 433
 434 config KERNEL_IO_URING
 435         bool "Compile the kernel with io_uring support"
 436         default y if !SMALL_FLASH
 437
 438 config KERNEL_FHANDLE
 439         bool "Compile the kernel with support for fhandle syscalls"
 440         default y if !SMALL_FLASH
 441
 442 config KERNEL_FANOTIFY
 443         bool "Compile the kernel with modern file notification support"
 444         default y if !SMALL_FLASH
 445
 446 config KERNEL_BLK_DEV_BSG
 447         bool "Compile the kernel with SCSI generic v4 support for any block device"
 448         default n
 449
 450 config KERNEL_TRANSPARENT_HUGEPAGE
 451         bool
 452
 453 choice
 454         prompt "Transparent Hugepage Support sysfs defaults"
 455         depends on KERNEL_TRANSPARENT_HUGEPAGE
 456         default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
 457
 458         config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
 459                 bool "always"
 460
 461         config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
 462                 bool "madvise"
 463 endchoice
 464
 465 config KERNEL_HUGETLBFS
 466         bool
 467
 468 config KERNEL_HUGETLB_PAGE
 469         bool "Compile the kernel with HugeTLB support"
 470         select KERNEL_TRANSPARENT_HUGEPAGE
 471         select KERNEL_HUGETLBFS
 472         default n
 473
 474 config KERNEL_MAGIC_SYSRQ
 475         bool "Compile the kernel with SysRq support"
 476         default y
 477
 478 config KERNEL_DEBUG_PINCTRL
 479         bool "Compile the kernel with pinctrl debugging"
 480         select KERNEL_DEBUG_KERNEL
 481
 482 config KERNEL_DEBUG_GPIO
 483         bool "Compile the kernel with gpio debugging"
 484         select KERNEL_DEBUG_KERNEL
 485
 486 config KERNEL_COREDUMP
 487         bool
 488
 489 config KERNEL_ELF_CORE
 490         bool "Enable process core dump support"
 491         select KERNEL_COREDUMP
 492         default y if !SMALL_FLASH
 493
 494 config KERNEL_PROVE_LOCKING
 495         bool "Enable kernel lock checking"
 496         select KERNEL_DEBUG_KERNEL
 497         default n
 498
 499 config KERNEL_SOFTLOCKUP_DETECTOR
 500         bool "Compile the kernel with detect Soft Lockups"
 501         depends on KERNEL_DEBUG_KERNEL
 502         help
 503           Say Y here to enable the kernel to act as a watchdog to detect
 504           soft lockups.
 505
 506           Softlockups are bugs that cause the kernel to loop in kernel
 507           mode for more than 20 seconds, without giving other tasks a
 508           chance to run.  The current stack trace is displayed upon
 509           detection and the system will stay locked up.
 510
 511 config KERNEL_DETECT_HUNG_TASK
 512         bool "Compile the kernel with detect Hung Tasks"
 513         depends on KERNEL_DEBUG_KERNEL
 514         default KERNEL_SOFTLOCKUP_DETECTOR
 515         help
 516           Say Y here to enable the kernel to detect "hung tasks",
 517           which are bugs that cause the task to be stuck in
 518           uninterruptible "D" state indefinitely.
 519
 520           When a hung task is detected, the kernel will print the
 521           current stack trace (which you should report), but the
 522           task will stay in uninterruptible state. If lockdep is
 523           enabled then all held locks will also be reported. This
 524           feature has negligible overhead.
 525
 526 config KERNEL_WQ_WATCHDOG
 527         bool "Compile the kernel with detect Workqueue Stalls"
 528         depends on KERNEL_DEBUG_KERNEL
 529         help
 530           Say Y here to enable stall detection on workqueues.  If a
 531           worker pool doesn't make forward progress on a pending work
 532           item for over a given amount of time, 30s by default, a
 533           warning message is printed along with dump of workqueue
 534           state.  This can be configured through kernel parameter
 535           "workqueue.watchdog_thresh" and its sysfs counterpart.
 536
 537 config KERNEL_DEBUG_ATOMIC_SLEEP
 538         bool "Compile the kernel with sleep inside atomic section checking"
 539         depends on KERNEL_DEBUG_KERNEL
 540         help
 541           If you say Y here, various routines which may sleep will become very
 542           noisy if they are called inside atomic sections: when a spinlock is
 543           held, inside an rcu read side critical section, inside preempt disabled
 544           sections, inside an interrupt, etc...
 545
 546 config KERNEL_DEBUG_VM
 547         bool "Compile the kernel with debug VM"
 548         depends on KERNEL_DEBUG_KERNEL
 549         help
 550           Enable this to turn on extended checks in the virtual-memory system
 551           that may impact performance.
 552
 553           If unsure, say N.
 554
 555 config KERNEL_PRINTK_TIME
 556         bool "Enable printk timestamps"
 557         default y
 558
 559 config KERNEL_SLUB_DEBUG
 560         bool
 561
 562 config KERNEL_SLUB_DEBUG_ON
 563         bool
 564
 565 config KERNEL_SLABINFO
 566         select KERNEL_SLUB_DEBUG
 567         select KERNEL_SLUB_DEBUG_ON
 568         bool "Enable /proc slab debug info"
 569
 570 config KERNEL_PROC_PAGE_MONITOR
 571         bool "Enable /proc page monitoring"
 572
 573 config KERNEL_RELAY
 574         bool
 575
 576 config KERNEL_KEXEC
 577         bool "Enable kexec support"
 578
 579 config KERNEL_PROC_VMCORE
 580         bool
 581
 582 config KERNEL_PROC_KCORE
 583         bool
 584
 585 config KERNEL_CRASH_DUMP
 586         depends on i386 || x86_64 || arm || armeb
 587         select KERNEL_KEXEC
 588         select KERNEL_PROC_VMCORE
 589         select KERNEL_PROC_KCORE
 590         bool "Enable support for kexec crashdump"
 591         default y
 592
 593 config USE_RFKILL
 594         bool "Enable rfkill support"
 595         default RFKILL_SUPPORT
 596
 597 config USE_SPARSE
 598         bool "Enable sparse check during kernel build"
 599         default n
 600
 601 config KERNEL_DEVTMPFS
 602         bool "Compile the kernel with device tmpfs enabled"
 603         default n
 604         help
 605           devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
 606           devices nodes for all registered devices to simplify boot, but leaves more
 607           complex tasks to userspace (e.g. udev).
 608
 609 if KERNEL_DEVTMPFS
 610
 611         config KERNEL_DEVTMPFS_MOUNT
 612                 bool "Automatically mount devtmpfs after root filesystem is mounted"
 613                 default n
 614
 615 endif
 616
 617 config KERNEL_KEYS
 618         bool "Enable kernel access key retention support"
 619         default !SMALL_FLASH
 620
 621 config KERNEL_PERSISTENT_KEYRINGS
 622         bool "Enable kernel persistent keyrings"
 623         depends on KERNEL_KEYS
 624         default n
 625
 626 config KERNEL_KEYS_REQUEST_CACHE
 627         bool "Enable temporary caching of the last request_key() result"
 628         depends on KERNEL_KEYS
 629         default n
 630
 631 config KERNEL_BIG_KEYS
 632         bool "Enable large payload keys on kernel keyrings"
 633         depends on KERNEL_KEYS
 634         default n
 635
 636 #
 637 # CGROUP support symbols
 638 #
 639
 640 config KERNEL_CGROUPS
 641         bool "Enable kernel cgroups"
 642         default y if !SMALL_FLASH
 643
 644 if KERNEL_CGROUPS
 645
 646         config KERNEL_CGROUP_DEBUG
 647                 bool "Example debug cgroup subsystem"
 648                 default n
 649                 help
 650                   This option enables a simple cgroup subsystem that
 651                   exports useful debugging information about the cgroups
 652                   framework.
 653
 654         config KERNEL_FREEZER
 655                 bool
 656
 657         config KERNEL_CGROUP_FREEZER
 658                 bool "legacy Freezer cgroup subsystem"
 659                 default n
 660                 select KERNEL_FREEZER
 661                 help
 662                   Provides a way to freeze and unfreeze all tasks in a
 663                   cgroup.
 664                   (legacy cgroup1-only controller, in cgroup2 freezer
 665                   is integrated in the Memory controller)
 666
 667         config KERNEL_CGROUP_DEVICE
 668                 bool "legacy Device controller for cgroups"
 669                 default n
 670                 help
 671                   Provides a cgroup implementing whitelists for devices which
 672                   a process in the cgroup can mknod or open.
 673                   (legacy cgroup1-only controller)
 674
 675         config KERNEL_CGROUP_HUGETLB
 676                 bool "HugeTLB controller"
 677                 default n
 678                 select KERNEL_HUGETLB_PAGE
 679
 680         config KERNEL_CGROUP_PIDS
 681                 bool "PIDs cgroup subsystem"
 682                 default y
 683                 help
 684                   Provides enforcement of process number limits in the scope of a
 685                   cgroup.
 686
 687         config KERNEL_CGROUP_RDMA
 688                 bool "RDMA controller for cgroups"
 689                 default y
 690
 691         config KERNEL_CGROUP_BPF
 692                 bool "Support for eBPF programs attached to cgroups"
 693                 default y
 694
 695         config KERNEL_CPUSETS
 696                 bool "Cpuset support"
 697                 default y
 698                 help
 699                   This option will let you create and manage CPUSETs which
 700                   allow dynamically partitioning a system into sets of CPUs and
 701                   Memory Nodes and assigning tasks to run only within those sets.
 702                   This is primarily useful on large SMP or NUMA systems.
 703
 704         config KERNEL_PROC_PID_CPUSET
 705                 bool "Include legacy /proc/<pid>/cpuset file"
 706                 default n
 707                 depends on KERNEL_CPUSETS
 708
 709         config KERNEL_CGROUP_CPUACCT
 710                 bool "Simple CPU accounting cgroup subsystem"
 711                 default y
 712                 help
 713                   Provides a simple Resource Controller for monitoring the
 714                   total CPU consumed by the tasks in a cgroup.
 715
 716         config KERNEL_RESOURCE_COUNTERS
 717                 bool "Resource counters"
 718                 default y
 719                 help
 720                   This option enables controller independent resource accounting
 721                   infrastructure that works with cgroups.
 722
 723         config KERNEL_MM_OWNER
 724                 bool
 725                 default y if KERNEL_MEMCG
 726
 727         config KERNEL_MEMCG
 728                 bool "Memory Resource Controller for Control Groups"
 729                 default y
 730                 select KERNEL_FREEZER
 731                 depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
 732                 help
 733                   Provides a memory resource controller that manages both anonymous
 734                   memory and page cache. (See Documentation/cgroups/memory.txt)
 735
 736                   Note that setting this option increases fixed memory overhead
 737                   associated with each page of memory in the system. By this,
 738                   20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 739                   usage tracking struct at boot. Total amount of this is printed out
 740                   at boot.
 741
 742                   Only enable when you're ok with these tradeoffs and really
 743                   sure you need the memory resource controller. Even when you enable
 744                   this, you can set "cgroup_disable=memory" at your boot option to
 745                   disable memory resource controller and you can avoid overheads
 746                   (but lose benefits of memory resource controller).
 747
 748                   This config option also selects MM_OWNER config option, which
 749                   could in turn add some fork/exit overhead.
 750
 751         config KERNEL_MEMCG_SWAP
 752                 bool "Memory Resource Controller Swap Extension"
 753                 default y
 754                 depends on KERNEL_MEMCG
 755                 help
 756                   Add swap management feature to memory resource controller. When you
 757                   enable this, you can limit mem+swap usage per cgroup. In other words,
 758                   when you disable this, memory resource controller has no cares to
 759                   usage of swap...a process can exhaust all of the swap. This extension
 760                   is useful when you want to avoid exhaustion swap but this itself
 761                   adds more overheads and consumes memory for remembering information.
 762                   Especially if you use 32bit system or small memory system, please
 763                   be careful about enabling this. When memory resource controller
 764                   is disabled by boot option, this will be automatically disabled and
 765                   there will be no overhead from this. Even when you set this config=y,
 766                   if boot option "swapaccount=0" is set, swap will not be accounted.
 767                   Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 768                   size is 4096bytes, 512k per 1Gbytes of swap.
 769
 770         config KERNEL_MEMCG_SWAP_ENABLED
 771                 bool "Memory Resource Controller Swap Extension enabled by default"
 772                 default n
 773                 depends on KERNEL_MEMCG_SWAP
 774                 help
 775                   Memory Resource Controller Swap Extension comes with its price in
 776                   a bigger memory consumption. General purpose distribution kernels
 777                   which want to enable the feature but keep it disabled by default
 778                   and let the user enable it by swapaccount boot command line
 779                   parameter should have this option unselected.
 780
 781                   Those who want to have the feature enabled by default should
 782                   select this option (if, for some reason, they need to disable it,
 783                   then swapaccount=0 does the trick).
 784
 785
 786         config KERNEL_MEMCG_KMEM
 787                 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
 788                 default y
 789                 depends on KERNEL_MEMCG
 790                 help
 791                   The Kernel Memory extension for Memory Resource Controller can limit
 792                   the amount of memory used by kernel objects in the system. Those are
 793                   fundamentally different from the entities handled by the standard
 794                   Memory Controller, which are page-based, and can be swapped. Users of
 795                   the kmem extension can use it to guarantee that no group of processes
 796                   will ever exhaust kernel resources alone.
 797
 798         config KERNEL_CGROUP_PERF
 799                 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
 800                 select KERNEL_PERF_EVENTS
 801                 default n
 802                 help
 803                   This option extends the per-cpu mode to restrict monitoring to
 804                   threads which belong to the cgroup specified and run on the
 805                   designated cpu.
 806
 807         menuconfig KERNEL_CGROUP_SCHED
 808                 bool "Group CPU scheduler"
 809                 default y
 810                 help
 811                   This feature lets CPU scheduler recognize task groups and control CPU
 812                   bandwidth allocation to such task groups. It uses cgroups to group
 813                   tasks.
 814
 815         if KERNEL_CGROUP_SCHED
 816
 817                 config KERNEL_FAIR_GROUP_SCHED
 818                         bool "Group scheduling for SCHED_OTHER"
 819                         default y
 820
 821                 config KERNEL_CFS_BANDWIDTH
 822                         bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
 823                         default y
 824                         depends on KERNEL_FAIR_GROUP_SCHED
 825                         help
 826                           This option allows users to define CPU bandwidth rates (limits) for
 827                           tasks running within the fair group scheduler.  Groups with no limit
 828                           set are considered to be unconstrained and will run with no
 829                           restriction.
 830                           See tip/Documentation/scheduler/sched-bwc.txt for more information.
 831
 832                 config KERNEL_RT_GROUP_SCHED
 833                         bool "Group scheduling for SCHED_RR/FIFO"
 834                         default y
 835                         help
 836                           This feature lets you explicitly allocate real CPU bandwidth
 837                           to task groups. If enabled, it will also make it impossible to
 838                           schedule realtime tasks for non-root users until you allocate
 839                           realtime bandwidth for them.
 840
 841         endif
 842
 843         config KERNEL_BLK_CGROUP
 844                 bool "Block IO controller"
 845                 default y
 846                 help
 847                   Generic block IO controller cgroup interface. This is the common
 848                   cgroup interface which should be used by various IO controlling
 849                   policies.
 850
 851                   Currently, CFQ IO scheduler uses it to recognize task groups and
 852                   control disk bandwidth allocation (proportional time slice allocation)
 853                   to such task groups. It is also used by bio throttling logic in
 854                   block layer to implement upper limit in IO rates on a device.
 855
 856                   This option only enables generic Block IO controller infrastructure.
 857                   One needs to also enable actual IO controlling logic/policy. For
 858                   enabling proportional weight division of disk bandwidth in CFQ, set
 859                   CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 860                   CONFIG_BLK_DEV_THROTTLING=y.
 861
 862         if KERNEL_BLK_CGROUP
 863
 864                 config KERNEL_CFQ_GROUP_IOSCHED
 865                         bool "Proportional weight of disk bandwidth in CFQ"
 866
 867                 config KERNEL_BLK_DEV_THROTTLING
 868                         bool "Enable throttling policy"
 869                         default y
 870
 871                 config KERNEL_BLK_DEV_THROTTLING_LOW
 872                         bool "Block throttling .low limit interface support (EXPERIMENTAL)"
 873                         depends on KERNEL_BLK_DEV_THROTTLING
 874         endif
 875
 876         config KERNEL_DEBUG_BLK_CGROUP
 877                 bool "Enable Block IO controller debugging"
 878                 default n
 879                 depends on KERNEL_BLK_CGROUP
 880                 help
 881                   Enable some debugging help. Currently it exports additional stat
 882                   files in a cgroup which can be useful for debugging.
 883
 884         config KERNEL_NET_CLS_CGROUP
 885                 bool "legacy Control Group Classifier"
 886                 default n
 887
 888         config KERNEL_CGROUP_NET_CLASSID
 889                 bool "legacy Network classid cgroup"
 890                 default n
 891
 892         config KERNEL_CGROUP_NET_PRIO
 893                 bool "legacy Network priority cgroup"
 894                 default n
 895
 896 endif
 897
 898 #
 899 # Namespace support symbols
 900 #
 901
 902 config KERNEL_NAMESPACES
 903         bool "Enable kernel namespaces"
 904         default y if !SMALL_FLASH
 905
 906 if KERNEL_NAMESPACES
 907
 908         config KERNEL_UTS_NS
 909                 bool "UTS namespace"
 910                 default y
 911                 help
 912                   In this namespace, tasks see different info provided
 913                   with the uname() system call.
 914
 915         config KERNEL_IPC_NS
 916                 bool "IPC namespace"
 917                 default y
 918                 help
 919                   In this namespace, tasks work with IPC ids which correspond to
 920                   different IPC objects in different namespaces.
 921
 922         config KERNEL_USER_NS
 923                 bool "User namespace (EXPERIMENTAL)"
 924                 default y
 925                 help
 926                   This allows containers, i.e. vservers, to use user namespaces
 927                   to provide different user info for different servers.
 928
 929         config KERNEL_PID_NS
 930                 bool "PID Namespaces"
 931                 default y
 932                 help
 933                   Support process id namespaces. This allows having multiple
 934                   processes with the same pid as long as they are in different
 935                   pid namespaces. This is a building block of containers.
 936
 937         config KERNEL_NET_NS
 938                 bool "Network namespace"
 939                 default y
 940                 help
 941                   Allow user space to create what appear to be multiple instances
 942                   of the network stack.
 943
 944 endif
 945
 946 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
 947         bool "Support multiple instances of devpts"
 948         default y if !SMALL_FLASH
 949         help
 950           Enable support for multiple instances of devpts filesystem.
 951           If you want to have isolated PTY namespaces (eg: in containers),
 952           say Y here. Otherwise, say N. If enabled, each mount of devpts
 953           filesystem with the '-o newinstance' option will create an
 954           independent PTY namespace.
 955
 956 config KERNEL_POSIX_MQUEUE
 957         bool "POSIX Message Queues"
 958         default y if !SMALL_FLASH
 959         help
 960           POSIX variant of message queues is a part of IPC. In POSIX message
 961           queues every message has a priority which decides about succession
 962           of receiving it by a process. If you want to compile and run
 963           programs written e.g. for Solaris with use of its POSIX message
 964           queues (functions mq_*) say Y here.
 965
 966           POSIX message queues are visible as a filesystem called 'mqueue'
 967           and can be mounted somewhere if you want to do filesystem
 968           operations on message queues.
 969
 970
 971 config KERNEL_SECCOMP_FILTER
 972         bool
 973         default y if !SMALL_FLASH
 974
 975 config KERNEL_SECCOMP
 976         bool "Enable seccomp support"
 977                 depends on !(TARGET_uml)
 978                 select KERNEL_SECCOMP_FILTER
 979                 default y if !SMALL_FLASH
 980                 help
 981                   Build kernel with support for seccomp.
 982
 983 #
 984 # IPv4 configuration
 985 #
 986
 987 config KERNEL_IP_MROUTE
 988         bool "Enable IPv4 multicast routing"
 989         default y
 990         help
 991           Multicast routing requires a multicast routing daemon in
 992           addition to kernel support.
 993
 994 if KERNEL_IP_MROUTE
 995
 996         config KERNEL_IP_MROUTE_MULTIPLE_TABLES
 997                 def_bool y
 998
 999         config KERNEL_IP_PIMSM_V1
1000                 def_bool y
1001
1002         config KERNEL_IP_PIMSM_V2
1003                 def_bool y
1004
1005 endif
1006
1007 #
1008 # IPv6 configuration
1009 #
1010
1011 config KERNEL_IPV6
1012         def_bool IPV6
1013
1014 if KERNEL_IPV6
1015
1016         config KERNEL_IPV6_MULTIPLE_TABLES
1017                 def_bool y
1018
1019         config KERNEL_IPV6_SUBTREES
1020                 def_bool y
1021
1022         config KERNEL_IPV6_MROUTE
1023                 bool "Enable IPv6 multicast routing"
1024                 default y
1025                 help
1026                   Multicast routing requires a multicast routing daemon in
1027                   addition to kernel support.
1028
1029         if KERNEL_IPV6_MROUTE
1030
1031                 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1032                         def_bool y
1033
1034                 config KERNEL_IPV6_PIMSM_V2
1035                         def_bool y
1036
1037         endif
1038
1039         config KERNEL_IPV6_SEG6_LWTUNNEL
1040                 bool "Enable support for lightweight tunnels"
1041                 default y if !SMALL_FLASH
1042                 help
1043                   Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1044
1045         config KERNEL_LWTUNNEL_BPF
1046                 def_bool n
1047
1048 endif
1049
1050 #
1051 # Miscellaneous network configuration
1052 #
1053
1054 config KERNEL_NET_L3_MASTER_DEV
1055         bool "L3 Master device support"
1056         help
1057           This module provides glue between core networking code and device
1058           drivers to support L3 master devices like VRF.
1059
1060 #
1061 # NFS related symbols
1062 #
1063 config KERNEL_IP_PNP
1064         bool "Compile the kernel with rootfs on NFS"
1065         help
1066            If you want to make your kernel boot off a NFS server as root
1067            filesystem, select Y here.
1068
1069 if KERNEL_IP_PNP
1070
1071         config KERNEL_IP_PNP_DHCP
1072                 def_bool y
1073
1074         config KERNEL_IP_PNP_BOOTP
1075                 def_bool n
1076
1077         config KERNEL_IP_PNP_RARP
1078                 def_bool n
1079
1080         config KERNEL_NFS_FS
1081                 def_bool y
1082
1083         config KERNEL_NFS_V2
1084                 def_bool y
1085
1086         config KERNEL_NFS_V3
1087                 def_bool y
1088
1089         config KERNEL_ROOT_NFS
1090                 def_bool y
1091
1092 endif
1093
1094 menu "Filesystem ACL and attr support options"
1095         config USE_FS_ACL_ATTR
1096                 bool "Use filesystem ACL and attr support by default"
1097                 default n
1098                 help
1099                   Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1100                   for kernel and packages, except tmpfs, flash filesystems,
1101                   and old NFS.  Also enable userspace extended attribute support
1102                   by default.  (OpenWrt already has an expection it will be
1103                   present in the kernel).
1104
1105         config KERNEL_FS_POSIX_ACL
1106                 bool "Enable POSIX ACL support"
1107                 default y if USE_FS_ACL_ATTR
1108
1109         config KERNEL_BTRFS_FS_POSIX_ACL
1110                 bool "Enable POSIX ACL for BtrFS Filesystems"
1111                 select KERNEL_FS_POSIX_ACL
1112                 default y if USE_FS_ACL_ATTR
1113
1114         config KERNEL_EXT4_FS_POSIX_ACL
1115                 bool "Enable POSIX ACL for Ext4 Filesystems"
1116                 select KERNEL_FS_POSIX_ACL
1117                 default y if USE_FS_ACL_ATTR
1118
1119         config KERNEL_F2FS_FS_POSIX_ACL
1120                 bool "Enable POSIX ACL for F2FS Filesystems"
1121                 select KERNEL_FS_POSIX_ACL
1122                 default n
1123
1124         config KERNEL_JFFS2_FS_POSIX_ACL
1125                 bool "Enable POSIX ACL for JFFS2 Filesystems"
1126                 select KERNEL_FS_POSIX_ACL
1127                 default n
1128
1129         config KERNEL_TMPFS_POSIX_ACL
1130                 bool "Enable POSIX ACL for TMPFS Filesystems"
1131                 select KERNEL_FS_POSIX_ACL
1132                 default n
1133
1134         config KERNEL_CIFS_ACL
1135                 bool "Enable CIFS ACLs"
1136                 select KERNEL_FS_POSIX_ACL
1137                 default y if USE_FS_ACL_ATTR
1138
1139         config KERNEL_HFS_FS_POSIX_ACL
1140                 bool "Enable POSIX ACL for HFS Filesystems"
1141                 select KERNEL_FS_POSIX_ACL
1142                 default y if USE_FS_ACL_ATTR
1143
1144         config KERNEL_HFSPLUS_FS_POSIX_ACL
1145                 bool "Enable POSIX ACL for HFS+ Filesystems"
1146                 select KERNEL_FS_POSIX_ACL
1147                 default y if USE_FS_ACL_ATTR
1148
1149         config KERNEL_NFS_ACL_SUPPORT
1150                 bool "Enable ACLs for NFS"
1151                 default y if USE_FS_ACL_ATTR
1152
1153         config KERNEL_NFS_V3_ACL_SUPPORT
1154                 bool "Enable ACLs for NFSv3"
1155                 default n
1156
1157         config KERNEL_NFSD_V2_ACL_SUPPORT
1158                 bool "Enable ACLs for NFSDv2"
1159                 default n
1160
1161         config KERNEL_NFSD_V3_ACL_SUPPORT
1162                 bool "Enable ACLs for NFSDv3"
1163                 default n
1164
1165         config KERNEL_REISER_FS_POSIX_ACL
1166                 bool "Enable POSIX ACLs for ReiserFS"
1167                 select KERNEL_FS_POSIX_ACL
1168                 default y if USE_FS_ACL_ATTR
1169
1170         config KERNEL_XFS_POSIX_ACL
1171                 bool "Enable POSIX ACLs for XFS"
1172                 select KERNEL_FS_POSIX_ACL
1173                 default y if USE_FS_ACL_ATTR
1174
1175         config KERNEL_JFS_POSIX_ACL
1176                 bool "Enable POSIX ACLs for JFS"
1177                 select KERNEL_FS_POSIX_ACL
1178                 default y if USE_FS_ACL_ATTR
1179
1180 endmenu
1181
1182 config KERNEL_DEVMEM
1183         bool "/dev/mem virtual device support"
1184         help
1185           Say Y here if you want to support the /dev/mem device.
1186           The /dev/mem device is used to access areas of physical
1187           memory.
1188
1189 config KERNEL_DEVKMEM
1190         bool "/dev/kmem virtual device support"
1191         help
1192           Say Y here if you want to support the /dev/kmem device. The
1193           /dev/kmem device is rarely used, but can be used for certain
1194           kind of kernel debugging operations.
1195
1196 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1197         int "Number of squashfs fragments cached"
1198         default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1199         default 3
1200
1201 config KERNEL_SQUASHFS_XATTR
1202         bool "Squashfs XATTR support"
1203
1204 #
1205 # compile optimization setting
1206 #
1207 choice
1208         prompt "Compiler optimization level"
1209         default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1210
1211 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1212         bool "Optimize for performance"
1213         help
1214           This is the default optimization level for the kernel, building
1215           with the "-O2" compiler flag for best performance and most
1216           helpful compile-time warnings.
1217
1218 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1219         bool "Optimize for size"
1220         help
1221           Enabling this option will pass "-Os" instead of "-O2" to
1222           your compiler resulting in a smaller kernel.
1223
1224 endchoice
1225
1226 config KERNEL_AUDIT
1227         bool "Auditing support"
1228
1229 config KERNEL_SECURITY
1230         bool "Enable different security models"
1231
1232 config KERNEL_SECURITY_NETWORK
1233         bool "Socket and Networking Security Hooks"
1234         select KERNEL_SECURITY
1235
1236 config KERNEL_SECURITY_SELINUX
1237         bool "NSA SELinux Support"
1238         select KERNEL_SECURITY_NETWORK
1239         select KERNEL_AUDIT
1240
1241 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1242         bool "NSA SELinux boot parameter"
1243         depends on KERNEL_SECURITY_SELINUX
1244         default y
1245
1246 config KERNEL_SECURITY_SELINUX_DISABLE
1247         bool "NSA SELinux runtime disable"
1248         depends on KERNEL_SECURITY_SELINUX
1249
1250 config KERNEL_SECURITY_SELINUX_DEVELOP
1251         bool "NSA SELinux Development Support"
1252         depends on KERNEL_SECURITY_SELINUX
1253         default y
1254
1255 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1256         int
1257         depends on KERNEL_SECURITY_SELINUX
1258         default 9
1259
1260 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1261         int
1262         depends on KERNEL_SECURITY_SELINUX
1263         default 256
1264
1265 config KERNEL_LSM
1266         string
1267         default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1268         depends on KERNEL_SECURITY_SELINUX
1269
1270 config KERNEL_EXT4_FS_SECURITY
1271         bool "Ext4 Security Labels"
1272
1273 config KERNEL_F2FS_FS_SECURITY
1274         bool "F2FS Security Labels"
1275
1276 config KERNEL_UBIFS_FS_SECURITY
1277         bool "UBIFS Security Labels"
1278
1279 config KERNEL_JFFS2_FS_SECURITY
1280         bool "JFFS2 Security Labels"