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_RPI_AXIPERF
  85         bool "Compile the kernel with RaspberryPi AXI Performance monitors"
  86         default y
  87         depends on KERNEL_PERF_EVENTS && TARGET_bcm27xx
  88
  89 config KERNEL_UBSAN
  90         bool "Compile the kernel with undefined behaviour sanity checker"
  91         help
  92           This option enables undefined behaviour sanity checker
  93           Compile-time instrumentation is used to detect various undefined
  94           behaviours in runtime. Various types of checks may be enabled
  95           via boot parameter ubsan_handle
  96           (see: Documentation/dev-tools/ubsan.rst).
  97
  98 config KERNEL_UBSAN_SANITIZE_ALL
  99         bool "Enable instrumentation for the entire kernel"
 100         depends on KERNEL_UBSAN
 101         default y
 102         help
 103           This option activates instrumentation for the entire kernel.
 104           If you don't enable this option, you have to explicitly specify
 105           UBSAN_SANITIZE := y for the files/directories you want to check for UB.
 106           Enabling this option will get kernel image size increased
 107           significantly.
 108
 109 config KERNEL_UBSAN_ALIGNMENT
 110         bool "Enable checking of pointers alignment"
 111         depends on KERNEL_UBSAN
 112         help
 113           This option enables detection of unaligned memory accesses.
 114           Enabling this option on architectures that support unaligned
 115           accesses may produce a lot of false positives.
 116
 117 config KERNEL_UBSAN_BOUNDS
 118         bool "Perform array index bounds checking"
 119         depends on KERNEL_UBSAN
 120         help
 121           This option enables detection of directly indexed out of bounds array
 122           accesses, where the array size is known at compile time. Note that
 123           this does not protect array overflows via bad calls to the
 124           {str,mem}*cpy() family of functions (that is addressed by
 125           FORTIFY_SOURCE).
 126
 127 config KERNEL_UBSAN_NULL
 128         bool "Enable checking of null pointers"
 129         depends on KERNEL_UBSAN
 130         help
 131           This option enables detection of memory accesses via a
 132           null pointer.
 133
 134 config KERNEL_UBSAN_TRAP
 135         bool "On Sanitizer warnings, abort the running kernel code"
 136         depends on KERNEL_UBSAN
 137         help
 138           Building kernels with Sanitizer features enabled tends to grow the
 139           kernel size by around 5%, due to adding all the debugging text on
 140           failure paths. To avoid this, Sanitizer instrumentation can just
 141           issue a trap. This reduces the kernel size overhead but turns all
 142           warnings (including potentially harmless conditions) into full
 143           exceptions that abort the running kernel code (regardless of context,
 144           locks held, etc), which may destabilize the system. For some system
 145           builders this is an acceptable trade-off.
 146
 147 config KERNEL_KASAN
 148         bool "Compile the kernel with KASan: runtime memory debugger"
 149         select KERNEL_SLUB_DEBUG
 150         depends on (x86_64 || aarch64)
 151         help
 152           Enables kernel address sanitizer - runtime memory debugger,
 153           designed to find out-of-bounds accesses and use-after-free bugs.
 154           This is strictly a debugging feature and it requires a gcc version
 155           of 4.9.2 or later. Detection of out of bounds accesses to stack or
 156           global variables requires gcc 5.0 or later.
 157           This feature consumes about 1/8 of available memory and brings about
 158           ~x3 performance slowdown.
 159           For better error detection enable CONFIG_STACKTRACE.
 160           Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
 161           (the resulting kernel does not boot).
 162
 163 config KERNEL_KASAN_EXTRA
 164         bool "KAsan: extra checks"
 165         depends on KERNEL_KASAN && KERNEL_DEBUG_KERNEL
 166         help
 167           This enables further checks in the kernel address sanitizer, for now
 168           it only includes the address-use-after-scope check that can lead
 169           to excessive kernel stack usage, frame size warnings and longer
 170           compile time.
 171           https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
 172
 173 config KERNEL_KASAN_VMALLOC
 174         bool "Back mappings in vmalloc space with real shadow memory"
 175         depends on KERNEL_KASAN
 176         help
 177           By default, the shadow region for vmalloc space is the read-only
 178           zero page. This means that KASAN cannot detect errors involving
 179           vmalloc space.
 180
 181           Enabling this option will hook in to vmap/vmalloc and back those
 182           mappings with real shadow memory allocated on demand. This allows
 183           for KASAN to detect more sorts of errors (and to support vmapped
 184           stacks), but at the cost of higher memory usage.
 185
 186           This option depends on HAVE_ARCH_KASAN_VMALLOC, but we can't
 187           depend on that in here, so it is possible that enabling this
 188           will have no effect.
 189
 190 if KERNEL_KASAN
 191         config KERNEL_KASAN_GENERIC
 192         def_bool y
 193
 194         config KERNEL_KASAN_SW_TAGS
 195         def_bool n
 196 endif
 197
 198 choice
 199         prompt "Instrumentation type"
 200         depends on KERNEL_KASAN
 201         default KERNEL_KASAN_OUTLINE
 202
 203 config KERNEL_KASAN_OUTLINE
 204         bool "Outline instrumentation"
 205         help
 206           Before every memory access compiler insert function call
 207           __asan_load*/__asan_store*. These functions performs check
 208           of shadow memory. This is slower than inline instrumentation,
 209           however it doesn't bloat size of kernel's .text section so
 210           much as inline does.
 211
 212 config KERNEL_KASAN_INLINE
 213         bool "Inline instrumentation"
 214         help
 215           Compiler directly inserts code checking shadow memory before
 216           memory accesses. This is faster than outline (in some workloads
 217           it gives about x2 boost over outline instrumentation), but
 218           make kernel's .text size much bigger.
 219           This requires a gcc version of 5.0 or later.
 220
 221 endchoice
 222
 223 config KERNEL_KCOV
 224         bool "Compile the kernel with code coverage for fuzzing"
 225         select KERNEL_DEBUG_FS
 226         help
 227           KCOV exposes kernel code coverage information in a form suitable
 228           for coverage-guided fuzzing (randomized testing).
 229
 230           If RANDOMIZE_BASE is enabled, PC values will not be stable across
 231           different machines and across reboots. If you need stable PC values,
 232           disable RANDOMIZE_BASE.
 233
 234           For more details, see Documentation/kcov.txt.
 235
 236 config KERNEL_KCOV_ENABLE_COMPARISONS
 237         bool "Enable comparison operands collection by KCOV"
 238         depends on KERNEL_KCOV
 239         help
 240           KCOV also exposes operands of every comparison in the instrumented
 241           code along with operand sizes and PCs of the comparison instructions.
 242           These operands can be used by fuzzing engines to improve the quality
 243           of fuzzing coverage.
 244
 245 config KERNEL_KCOV_INSTRUMENT_ALL
 246         bool "Instrument all code by default"
 247         depends on KERNEL_KCOV
 248         default y if KERNEL_KCOV
 249         help
 250           If you are doing generic system call fuzzing (like e.g. syzkaller),
 251           then you will want to instrument the whole kernel and you should
 252           say y here. If you are doing more targeted fuzzing (like e.g.
 253           filesystem fuzzing with AFL) then you will want to enable coverage
 254           for more specific subsets of files, and should say n here.
 255
 256 config KERNEL_TASKSTATS
 257         bool "Compile the kernel with task resource/io statistics and accounting"
 258         default n
 259         help
 260           Enable the collection and publishing of task/io statistics and
 261           accounting.  Enable this option to enable i/o monitoring in system
 262           monitors.
 263
 264 if KERNEL_TASKSTATS
 265
 266         config KERNEL_TASK_DELAY_ACCT
 267                 def_bool y
 268
 269         config KERNEL_TASK_IO_ACCOUNTING
 270                 def_bool y
 271
 272         config KERNEL_TASK_XACCT
 273                 def_bool y
 274
 275 endif
 276
 277 config KERNEL_KALLSYMS
 278         bool "Compile the kernel with symbol table information"
 279         default y if !SMALL_FLASH
 280         help
 281           This will give you more information in stack traces from kernel oopses.
 282
 283 config KERNEL_FTRACE
 284         bool "Compile the kernel with tracing support"
 285         depends on !TARGET_uml
 286         default n
 287
 288 config KERNEL_FTRACE_SYSCALLS
 289         bool "Trace system calls"
 290         depends on KERNEL_FTRACE
 291         default n
 292
 293 config KERNEL_ENABLE_DEFAULT_TRACERS
 294         bool "Trace process context switches and events"
 295         depends on KERNEL_FTRACE
 296         default n
 297
 298 config KERNEL_FUNCTION_TRACER
 299         bool "Function tracer"
 300         depends on KERNEL_FTRACE
 301         default n
 302
 303 config KERNEL_FUNCTION_GRAPH_TRACER
 304         bool "Function graph tracer"
 305         depends on KERNEL_FUNCTION_TRACER
 306         default n
 307
 308 config KERNEL_DYNAMIC_FTRACE
 309         bool "Enable/disable function tracing dynamically"
 310         depends on KERNEL_FUNCTION_TRACER
 311         default n
 312
 313 config KERNEL_FUNCTION_PROFILER
 314         bool "Function profiler"
 315         depends on KERNEL_FUNCTION_TRACER
 316         default n
 317
 318 config KERNEL_IRQSOFF_TRACER
 319         bool "Interrupts-off Latency Tracer"
 320         depends on KERNEL_FTRACE
 321         help
 322           This option measures the time spent in irqs-off critical
 323           sections, with microsecond accuracy.
 324
 325           The default measurement method is a maximum search, which is
 326           disabled by default and can be runtime (re-)started
 327           via:
 328
 329               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 330
 331           (Note that kernel size and overhead increase with this option
 332           enabled. This option and the preempt-off timing option can be
 333           used together or separately.)
 334
 335 config KERNEL_PREEMPT_TRACER
 336         bool "Preemption-off Latency Tracer"
 337         depends on KERNEL_FTRACE
 338         help
 339           This option measures the time spent in preemption-off critical
 340           sections, with microsecond accuracy.
 341
 342           The default measurement method is a maximum search, which is
 343           disabled by default and can be runtime (re-)started
 344           via:
 345
 346               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 347
 348           (Note that kernel size and overhead increase with this option
 349           enabled. This option and the irqs-off timing option can be
 350           used together or separately.)
 351
 352 config KERNEL_HIST_TRIGGERS
 353         bool "Histogram triggers"
 354         depends on KERNEL_FTRACE
 355         help
 356           Hist triggers allow one or more arbitrary trace event fields to be
 357           aggregated into hash tables and dumped to stdout by reading a
 358           debugfs/tracefs file. They're useful for gathering quick and dirty
 359           (though precise) summaries of event activity as an initial guide for
 360           further investigation using more advanced tools.
 361
 362           Inter-event tracing of quantities such as latencies is also
 363           supported using hist triggers under this option.
 364
 365 config KERNEL_DEBUG_KERNEL
 366         bool
 367         default n
 368
 369 config KERNEL_DEBUG_INFO
 370         bool "Compile the kernel with debug information"
 371         default y if !SMALL_FLASH
 372         select KERNEL_DEBUG_KERNEL
 373         help
 374           This will compile your kernel and modules with debug information.
 375
 376 config KERNEL_DEBUG_INFO_BTF
 377
 378         bool "Enable additional BTF type information"
 379         default n
 380         depends on !HOST_OS_MACOS
 381         depends on KERNEL_DEBUG_INFO && !KERNEL_DEBUG_INFO_REDUCED
 382         select DWARVES
 383         help
 384           Generate BPF Type Format (BTF) information from DWARF debug info.
 385           Turning this on expects presence of pahole tool, which will convert
 386           DWARF type info into equivalent deduplicated BTF type info.
 387
 388           Required to run BPF CO-RE applications.
 389
 390 config KERNEL_DEBUG_INFO_REDUCED
 391         bool "Reduce debugging information"
 392         default y
 393         depends on KERNEL_DEBUG_INFO
 394         help
 395           If you say Y here gcc is instructed to generate less debugging
 396           information for structure types. This means that tools that
 397           need full debugging information (like kgdb or systemtap) won't
 398           be happy. But if you merely need debugging information to
 399           resolve line numbers there is no loss. Advantage is that
 400           build directory object sizes shrink dramatically over a full
 401           DEBUG_INFO build and compile times are reduced too.
 402           Only works with newer gcc versions.
 403
 404 config KERNEL_DEBUG_LL_UART_NONE
 405         bool
 406         default n
 407         depends on arm
 408
 409 config KERNEL_DEBUG_LL
 410         bool
 411         default n
 412         depends on arm
 413         select KERNEL_DEBUG_LL_UART_NONE
 414         help
 415           ARM low level debugging.
 416
 417 config KERNEL_DYNAMIC_DEBUG
 418         bool "Compile the kernel with dynamic printk"
 419         select KERNEL_DEBUG_FS
 420         default n
 421         help
 422           Compiles debug level messages into the kernel, which would not
 423           otherwise be available at runtime. These messages can then be
 424           enabled/disabled based on various levels of scope - per source file,
 425           function, module, format string, and line number. This mechanism
 426           implicitly compiles in all pr_debug() and dev_dbg() calls, which
 427           enlarges the kernel text size by about 2%.
 428
 429 config KERNEL_EARLY_PRINTK
 430         bool "Compile the kernel with early printk"
 431         default y if TARGET_bcm53xx
 432         default n
 433         depends on arm
 434         select KERNEL_DEBUG_KERNEL
 435         select KERNEL_DEBUG_LL if arm
 436         help
 437           Compile the kernel with early printk support.  This is only useful for
 438           debugging purposes to send messages over the serial console in early boot.
 439           Enable this to debug early boot problems.
 440
 441 config KERNEL_KPROBES
 442         bool "Compile the kernel with kprobes support"
 443         default n
 444         select KERNEL_FTRACE
 445         select KERNEL_PERF_EVENTS
 446         help
 447           Compiles the kernel with KPROBES support, which allows you to trap
 448           at almost any kernel address and execute a callback function.
 449           register_kprobe() establishes a probepoint and specifies the
 450           callback. Kprobes is useful for kernel debugging, non-intrusive
 451           instrumentation and testing.
 452           If in doubt, say "N".
 453
 454 config KERNEL_KPROBE_EVENTS
 455         bool
 456         default y if KERNEL_KPROBES
 457
 458 config KERNEL_BPF_EVENTS
 459         bool "Compile the kernel with BPF event support"
 460         default n
 461         select KERNEL_KPROBES
 462         help
 463           Allows to attach BPF programs to kprobe, uprobe and tracepoint events.
 464           This is required to use BPF maps of type BPF_MAP_TYPE_PERF_EVENT_ARRAY
 465           for sending data from BPF programs to user-space for post-processing
 466           or logging.
 467
 468 config KERNEL_BPF_KPROBE_OVERRIDE
 469         bool
 470         default n
 471         depends on KERNEL_KPROBES
 472
 473 config KERNEL_AIO
 474         bool "Compile the kernel with asynchronous IO support"
 475         default y if !SMALL_FLASH
 476
 477 config KERNEL_IO_URING
 478         bool "Compile the kernel with io_uring support"
 479         default y if !SMALL_FLASH
 480
 481 config KERNEL_FHANDLE
 482         bool "Compile the kernel with support for fhandle syscalls"
 483         default y if !SMALL_FLASH
 484
 485 config KERNEL_FANOTIFY
 486         bool "Compile the kernel with modern file notification support"
 487         default y if !SMALL_FLASH
 488
 489 config KERNEL_BLK_DEV_BSG
 490         bool "Compile the kernel with SCSI generic v4 support for any block device"
 491         default n
 492
 493 config KERNEL_TRANSPARENT_HUGEPAGE
 494         bool
 495
 496 choice
 497         prompt "Transparent Hugepage Support sysfs defaults"
 498         depends on KERNEL_TRANSPARENT_HUGEPAGE
 499         default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
 500
 501         config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
 502                 bool "always"
 503
 504         config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
 505                 bool "madvise"
 506 endchoice
 507
 508 config KERNEL_HUGETLBFS
 509         bool
 510
 511 config KERNEL_HUGETLB_PAGE
 512         bool "Compile the kernel with HugeTLB support"
 513         select KERNEL_TRANSPARENT_HUGEPAGE
 514         select KERNEL_HUGETLBFS
 515         default n
 516
 517 config KERNEL_MAGIC_SYSRQ
 518         bool "Compile the kernel with SysRq support"
 519         default y
 520
 521 config KERNEL_DEBUG_PINCTRL
 522         bool "Compile the kernel with pinctrl debugging"
 523         select KERNEL_DEBUG_KERNEL
 524
 525 config KERNEL_DEBUG_GPIO
 526         bool "Compile the kernel with gpio debugging"
 527         select KERNEL_DEBUG_KERNEL
 528
 529 config KERNEL_COREDUMP
 530         bool
 531
 532 config KERNEL_ELF_CORE
 533         bool "Enable process core dump support"
 534         select KERNEL_COREDUMP
 535         default y if !SMALL_FLASH
 536
 537 config KERNEL_PROVE_LOCKING
 538         bool "Enable kernel lock checking"
 539         select KERNEL_DEBUG_KERNEL
 540         default n
 541
 542 config KERNEL_SOFTLOCKUP_DETECTOR
 543         bool "Compile the kernel with detect Soft Lockups"
 544         depends on KERNEL_DEBUG_KERNEL
 545         help
 546           Say Y here to enable the kernel to act as a watchdog to detect
 547           soft lockups.
 548
 549           Softlockups are bugs that cause the kernel to loop in kernel
 550           mode for more than 20 seconds, without giving other tasks a
 551           chance to run.  The current stack trace is displayed upon
 552           detection and the system will stay locked up.
 553
 554 config KERNEL_DETECT_HUNG_TASK
 555         bool "Compile the kernel with detect Hung Tasks"
 556         depends on KERNEL_DEBUG_KERNEL
 557         default KERNEL_SOFTLOCKUP_DETECTOR
 558         help
 559           Say Y here to enable the kernel to detect "hung tasks",
 560           which are bugs that cause the task to be stuck in
 561           uninterruptible "D" state indefinitely.
 562
 563           When a hung task is detected, the kernel will print the
 564           current stack trace (which you should report), but the
 565           task will stay in uninterruptible state. If lockdep is
 566           enabled then all held locks will also be reported. This
 567           feature has negligible overhead.
 568
 569 config KERNEL_WQ_WATCHDOG
 570         bool "Compile the kernel with detect Workqueue Stalls"
 571         depends on KERNEL_DEBUG_KERNEL
 572         help
 573           Say Y here to enable stall detection on workqueues.  If a
 574           worker pool doesn't make forward progress on a pending work
 575           item for over a given amount of time, 30s by default, a
 576           warning message is printed along with dump of workqueue
 577           state.  This can be configured through kernel parameter
 578           "workqueue.watchdog_thresh" and its sysfs counterpart.
 579
 580 config KERNEL_DEBUG_ATOMIC_SLEEP
 581         bool "Compile the kernel with sleep inside atomic section checking"
 582         depends on KERNEL_DEBUG_KERNEL
 583         help
 584           If you say Y here, various routines which may sleep will become very
 585           noisy if they are called inside atomic sections: when a spinlock is
 586           held, inside an rcu read side critical section, inside preempt disabled
 587           sections, inside an interrupt, etc...
 588
 589 config KERNEL_DEBUG_VM
 590         bool "Compile the kernel with debug VM"
 591         depends on KERNEL_DEBUG_KERNEL
 592         help
 593           Enable this to turn on extended checks in the virtual-memory system
 594           that may impact performance.
 595
 596           If unsure, say N.
 597
 598 config KERNEL_PRINTK_TIME
 599         bool "Enable printk timestamps"
 600         default y
 601
 602 config KERNEL_SLUB_DEBUG
 603         bool
 604
 605 config KERNEL_SLUB_DEBUG_ON
 606         bool
 607
 608 config KERNEL_SLABINFO
 609         select KERNEL_SLUB_DEBUG
 610         select KERNEL_SLUB_DEBUG_ON
 611         bool "Enable /proc slab debug info"
 612
 613 config KERNEL_PROC_PAGE_MONITOR
 614         bool "Enable /proc page monitoring"
 615
 616 config KERNEL_RELAY
 617         bool
 618
 619 config KERNEL_KEXEC
 620         bool "Enable kexec support"
 621
 622 config KERNEL_PROC_VMCORE
 623         bool
 624
 625 config KERNEL_PROC_KCORE
 626         bool
 627
 628 config KERNEL_CRASH_DUMP
 629         depends on i386 || x86_64 || arm || armeb
 630         select KERNEL_KEXEC
 631         select KERNEL_PROC_VMCORE
 632         select KERNEL_PROC_KCORE
 633         bool "Enable support for kexec crashdump"
 634         default y
 635
 636 config USE_RFKILL
 637         bool "Enable rfkill support"
 638         default RFKILL_SUPPORT
 639
 640 config USE_SPARSE
 641         bool "Enable sparse check during kernel build"
 642         default n
 643
 644 config KERNEL_DEVTMPFS
 645         bool "Compile the kernel with device tmpfs enabled"
 646         default n
 647         help
 648           devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
 649           devices nodes for all registered devices to simplify boot, but leaves more
 650           complex tasks to userspace (e.g. udev).
 651
 652 if KERNEL_DEVTMPFS
 653
 654         config KERNEL_DEVTMPFS_MOUNT
 655                 bool "Automatically mount devtmpfs after root filesystem is mounted"
 656                 default n
 657
 658 endif
 659
 660 config KERNEL_KEYS
 661         bool "Enable kernel access key retention support"
 662         default !SMALL_FLASH
 663
 664 config KERNEL_PERSISTENT_KEYRINGS
 665         bool "Enable kernel persistent keyrings"
 666         depends on KERNEL_KEYS
 667         default n
 668
 669 config KERNEL_KEYS_REQUEST_CACHE
 670         bool "Enable temporary caching of the last request_key() result"
 671         depends on KERNEL_KEYS
 672         default n
 673
 674 config KERNEL_BIG_KEYS
 675         bool "Enable large payload keys on kernel keyrings"
 676         depends on KERNEL_KEYS
 677         default n
 678
 679 #
 680 # CGROUP support symbols
 681 #
 682
 683 config KERNEL_CGROUPS
 684         bool "Enable kernel cgroups"
 685         default y if !SMALL_FLASH
 686
 687 if KERNEL_CGROUPS
 688
 689         config KERNEL_CGROUP_DEBUG
 690                 bool "Example debug cgroup subsystem"
 691                 default n
 692                 help
 693                   This option enables a simple cgroup subsystem that
 694                   exports useful debugging information about the cgroups
 695                   framework.
 696
 697         config KERNEL_FREEZER
 698                 bool
 699
 700         config KERNEL_CGROUP_FREEZER
 701                 bool "legacy Freezer cgroup subsystem"
 702                 default n
 703                 select KERNEL_FREEZER
 704                 help
 705                   Provides a way to freeze and unfreeze all tasks in a
 706                   cgroup.
 707                   (legacy cgroup1-only controller, in cgroup2 freezer
 708                   is integrated in the Memory controller)
 709
 710         config KERNEL_CGROUP_DEVICE
 711                 bool "legacy Device controller for cgroups"
 712                 default n
 713                 help
 714                   Provides a cgroup implementing whitelists for devices which
 715                   a process in the cgroup can mknod or open.
 716                   (legacy cgroup1-only controller)
 717
 718         config KERNEL_CGROUP_HUGETLB
 719                 bool "HugeTLB controller"
 720                 default n
 721                 select KERNEL_HUGETLB_PAGE
 722
 723         config KERNEL_CGROUP_PIDS
 724                 bool "PIDs cgroup subsystem"
 725                 default y
 726                 help
 727                   Provides enforcement of process number limits in the scope of a
 728                   cgroup.
 729
 730         config KERNEL_CGROUP_RDMA
 731                 bool "RDMA controller for cgroups"
 732                 default y
 733
 734         config KERNEL_CGROUP_BPF
 735                 bool "Support for eBPF programs attached to cgroups"
 736                 default y
 737
 738         config KERNEL_CPUSETS
 739                 bool "Cpuset support"
 740                 default y
 741                 help
 742                   This option will let you create and manage CPUSETs which
 743                   allow dynamically partitioning a system into sets of CPUs and
 744                   Memory Nodes and assigning tasks to run only within those sets.
 745                   This is primarily useful on large SMP or NUMA systems.
 746
 747         config KERNEL_PROC_PID_CPUSET
 748                 bool "Include legacy /proc/<pid>/cpuset file"
 749                 default n
 750                 depends on KERNEL_CPUSETS
 751
 752         config KERNEL_CGROUP_CPUACCT
 753                 bool "Simple CPU accounting cgroup subsystem"
 754                 default y
 755                 help
 756                   Provides a simple Resource Controller for monitoring the
 757                   total CPU consumed by the tasks in a cgroup.
 758
 759         config KERNEL_RESOURCE_COUNTERS
 760                 bool "Resource counters"
 761                 default y
 762                 help
 763                   This option enables controller independent resource accounting
 764                   infrastructure that works with cgroups.
 765
 766         config KERNEL_MM_OWNER
 767                 bool
 768                 default y if KERNEL_MEMCG
 769
 770         config KERNEL_MEMCG
 771                 bool "Memory Resource Controller for Control Groups"
 772                 default y
 773                 select KERNEL_FREEZER
 774                 depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
 775                 help
 776                   Provides a memory resource controller that manages both anonymous
 777                   memory and page cache. (See Documentation/cgroups/memory.txt)
 778
 779                   Note that setting this option increases fixed memory overhead
 780                   associated with each page of memory in the system. By this,
 781                   20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 782                   usage tracking struct at boot. Total amount of this is printed out
 783                   at boot.
 784
 785                   Only enable when you're ok with these tradeoffs and really
 786                   sure you need the memory resource controller. Even when you enable
 787                   this, you can set "cgroup_disable=memory" at your boot option to
 788                   disable memory resource controller and you can avoid overheads
 789                   (but lose benefits of memory resource controller).
 790
 791                   This config option also selects MM_OWNER config option, which
 792                   could in turn add some fork/exit overhead.
 793
 794         config KERNEL_MEMCG_SWAP
 795                 bool "Memory Resource Controller Swap Extension"
 796                 default y
 797                 depends on KERNEL_MEMCG
 798                 help
 799                   Add swap management feature to memory resource controller. When you
 800                   enable this, you can limit mem+swap usage per cgroup. In other words,
 801                   when you disable this, memory resource controller has no cares to
 802                   usage of swap...a process can exhaust all of the swap. This extension
 803                   is useful when you want to avoid exhaustion swap but this itself
 804                   adds more overheads and consumes memory for remembering information.
 805                   Especially if you use 32bit system or small memory system, please
 806                   be careful about enabling this. When memory resource controller
 807                   is disabled by boot option, this will be automatically disabled and
 808                   there will be no overhead from this. Even when you set this config=y,
 809                   if boot option "swapaccount=0" is set, swap will not be accounted.
 810                   Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 811                   size is 4096bytes, 512k per 1Gbytes of swap.
 812
 813         config KERNEL_MEMCG_SWAP_ENABLED
 814                 bool "Memory Resource Controller Swap Extension enabled by default"
 815                 default n
 816                 depends on KERNEL_MEMCG_SWAP
 817                 help
 818                   Memory Resource Controller Swap Extension comes with its price in
 819                   a bigger memory consumption. General purpose distribution kernels
 820                   which want to enable the feature but keep it disabled by default
 821                   and let the user enable it by swapaccount boot command line
 822                   parameter should have this option unselected.
 823
 824                   Those who want to have the feature enabled by default should
 825                   select this option (if, for some reason, they need to disable it,
 826                   then swapaccount=0 does the trick).
 827
 828
 829         config KERNEL_MEMCG_KMEM
 830                 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
 831                 default y
 832                 depends on KERNEL_MEMCG
 833                 help
 834                   The Kernel Memory extension for Memory Resource Controller can limit
 835                   the amount of memory used by kernel objects in the system. Those are
 836                   fundamentally different from the entities handled by the standard
 837                   Memory Controller, which are page-based, and can be swapped. Users of
 838                   the kmem extension can use it to guarantee that no group of processes
 839                   will ever exhaust kernel resources alone.
 840
 841         config KERNEL_CGROUP_PERF
 842                 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
 843                 select KERNEL_PERF_EVENTS
 844                 default n
 845                 help
 846                   This option extends the per-cpu mode to restrict monitoring to
 847                   threads which belong to the cgroup specified and run on the
 848                   designated cpu.
 849
 850         menuconfig KERNEL_CGROUP_SCHED
 851                 bool "Group CPU scheduler"
 852                 default y
 853                 help
 854                   This feature lets CPU scheduler recognize task groups and control CPU
 855                   bandwidth allocation to such task groups. It uses cgroups to group
 856                   tasks.
 857
 858         if KERNEL_CGROUP_SCHED
 859
 860                 config KERNEL_FAIR_GROUP_SCHED
 861                         bool "Group scheduling for SCHED_OTHER"
 862                         default y
 863
 864                 config KERNEL_CFS_BANDWIDTH
 865                         bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
 866                         default y
 867                         depends on KERNEL_FAIR_GROUP_SCHED
 868                         help
 869                           This option allows users to define CPU bandwidth rates (limits) for
 870                           tasks running within the fair group scheduler.  Groups with no limit
 871                           set are considered to be unconstrained and will run with no
 872                           restriction.
 873                           See tip/Documentation/scheduler/sched-bwc.txt for more information.
 874
 875                 config KERNEL_RT_GROUP_SCHED
 876                         bool "Group scheduling for SCHED_RR/FIFO"
 877                         default y
 878                         help
 879                           This feature lets you explicitly allocate real CPU bandwidth
 880                           to task groups. If enabled, it will also make it impossible to
 881                           schedule realtime tasks for non-root users until you allocate
 882                           realtime bandwidth for them.
 883
 884         endif
 885
 886         config KERNEL_BLK_CGROUP
 887                 bool "Block IO controller"
 888                 default y
 889                 help
 890                   Generic block IO controller cgroup interface. This is the common
 891                   cgroup interface which should be used by various IO controlling
 892                   policies.
 893
 894                   Currently, CFQ IO scheduler uses it to recognize task groups and
 895                   control disk bandwidth allocation (proportional time slice allocation)
 896                   to such task groups. It is also used by bio throttling logic in
 897                   block layer to implement upper limit in IO rates on a device.
 898
 899                   This option only enables generic Block IO controller infrastructure.
 900                   One needs to also enable actual IO controlling logic/policy. For
 901                   enabling proportional weight division of disk bandwidth in CFQ, set
 902                   CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 903                   CONFIG_BLK_DEV_THROTTLING=y.
 904
 905         if KERNEL_BLK_CGROUP
 906
 907                 config KERNEL_CFQ_GROUP_IOSCHED
 908                         bool "Proportional weight of disk bandwidth in CFQ"
 909
 910                 config KERNEL_BLK_DEV_THROTTLING
 911                         bool "Enable throttling policy"
 912                         default y
 913
 914                 config KERNEL_BLK_DEV_THROTTLING_LOW
 915                         bool "Block throttling .low limit interface support (EXPERIMENTAL)"
 916                         depends on KERNEL_BLK_DEV_THROTTLING
 917         endif
 918
 919         config KERNEL_DEBUG_BLK_CGROUP
 920                 bool "Enable Block IO controller debugging"
 921                 default n
 922                 depends on KERNEL_BLK_CGROUP
 923                 help
 924                   Enable some debugging help. Currently it exports additional stat
 925                   files in a cgroup which can be useful for debugging.
 926
 927         config KERNEL_NET_CLS_CGROUP
 928                 bool "legacy Control Group Classifier"
 929                 default n
 930
 931         config KERNEL_CGROUP_NET_CLASSID
 932                 bool "legacy Network classid cgroup"
 933                 default n
 934
 935         config KERNEL_CGROUP_NET_PRIO
 936                 bool "legacy Network priority cgroup"
 937                 default n
 938
 939 endif
 940
 941 #
 942 # Namespace support symbols
 943 #
 944
 945 config KERNEL_NAMESPACES
 946         bool "Enable kernel namespaces"
 947         default y if !SMALL_FLASH
 948
 949 if KERNEL_NAMESPACES
 950
 951         config KERNEL_UTS_NS
 952                 bool "UTS namespace"
 953                 default y
 954                 help
 955                   In this namespace, tasks see different info provided
 956                   with the uname() system call.
 957
 958         config KERNEL_IPC_NS
 959                 bool "IPC namespace"
 960                 default y
 961                 help
 962                   In this namespace, tasks work with IPC ids which correspond to
 963                   different IPC objects in different namespaces.
 964
 965         config KERNEL_USER_NS
 966                 bool "User namespace (EXPERIMENTAL)"
 967                 default y
 968                 help
 969                   This allows containers, i.e. vservers, to use user namespaces
 970                   to provide different user info for different servers.
 971
 972         config KERNEL_PID_NS
 973                 bool "PID Namespaces"
 974                 default y
 975                 help
 976                   Support process id namespaces. This allows having multiple
 977                   processes with the same pid as long as they are in different
 978                   pid namespaces. This is a building block of containers.
 979
 980         config KERNEL_NET_NS
 981                 bool "Network namespace"
 982                 default y
 983                 help
 984                   Allow user space to create what appear to be multiple instances
 985                   of the network stack.
 986
 987 endif
 988
 989 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
 990         bool "Support multiple instances of devpts"
 991         default y if !SMALL_FLASH
 992         help
 993           Enable support for multiple instances of devpts filesystem.
 994           If you want to have isolated PTY namespaces (eg: in containers),
 995           say Y here. Otherwise, say N. If enabled, each mount of devpts
 996           filesystem with the '-o newinstance' option will create an
 997           independent PTY namespace.
 998
 999 config KERNEL_POSIX_MQUEUE
1000         bool "POSIX Message Queues"
1001         default y if !SMALL_FLASH
1002         help
1003           POSIX variant of message queues is a part of IPC. In POSIX message
1004           queues every message has a priority which decides about succession
1005           of receiving it by a process. If you want to compile and run
1006           programs written e.g. for Solaris with use of its POSIX message
1007           queues (functions mq_*) say Y here.
1008
1009           POSIX message queues are visible as a filesystem called 'mqueue'
1010           and can be mounted somewhere if you want to do filesystem
1011           operations on message queues.
1012
1013
1014 config KERNEL_SECCOMP_FILTER
1015         bool
1016         default y if !SMALL_FLASH
1017
1018 config KERNEL_SECCOMP
1019         bool "Enable seccomp support"
1020                 depends on !(TARGET_uml)
1021                 select KERNEL_SECCOMP_FILTER
1022                 default y if !SMALL_FLASH
1023                 help
1024                   Build kernel with support for seccomp.
1025
1026 #
1027 # IPv4 configuration
1028 #
1029
1030 config KERNEL_IP_MROUTE
1031         bool "Enable IPv4 multicast routing"
1032         default y
1033         help
1034           Multicast routing requires a multicast routing daemon in
1035           addition to kernel support.
1036
1037 if KERNEL_IP_MROUTE
1038
1039         config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1040                 def_bool y
1041
1042         config KERNEL_IP_PIMSM_V1
1043                 def_bool y
1044
1045         config KERNEL_IP_PIMSM_V2
1046                 def_bool y
1047
1048 endif
1049
1050 #
1051 # IPv6 configuration
1052 #
1053
1054 config KERNEL_IPV6
1055         def_bool IPV6
1056
1057 if KERNEL_IPV6
1058
1059         config KERNEL_IPV6_MULTIPLE_TABLES
1060                 def_bool y
1061
1062         config KERNEL_IPV6_SUBTREES
1063                 def_bool y
1064
1065         config KERNEL_IPV6_MROUTE
1066                 bool "Enable IPv6 multicast routing"
1067                 default y
1068                 help
1069                   Multicast routing requires a multicast routing daemon in
1070                   addition to kernel support.
1071
1072         if KERNEL_IPV6_MROUTE
1073
1074                 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1075                         def_bool y
1076
1077                 config KERNEL_IPV6_PIMSM_V2
1078                         def_bool y
1079
1080         endif
1081
1082         config KERNEL_IPV6_SEG6_LWTUNNEL
1083                 bool "Enable support for lightweight tunnels"
1084                 default y if !SMALL_FLASH
1085                 help
1086                   Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1087
1088         config KERNEL_LWTUNNEL_BPF
1089                 def_bool n
1090
1091 endif
1092
1093 #
1094 # Miscellaneous network configuration
1095 #
1096
1097 config KERNEL_NET_L3_MASTER_DEV
1098         bool "L3 Master device support"
1099         help
1100           This module provides glue between core networking code and device
1101           drivers to support L3 master devices like VRF.
1102
1103 #
1104 # NFS related symbols
1105 #
1106 config KERNEL_IP_PNP
1107         bool "Compile the kernel with rootfs on NFS"
1108         help
1109            If you want to make your kernel boot off a NFS server as root
1110            filesystem, select Y here.
1111
1112 if KERNEL_IP_PNP
1113
1114         config KERNEL_IP_PNP_DHCP
1115                 def_bool y
1116
1117         config KERNEL_IP_PNP_BOOTP
1118                 def_bool n
1119
1120         config KERNEL_IP_PNP_RARP
1121                 def_bool n
1122
1123         config KERNEL_NFS_FS
1124                 def_bool y
1125
1126         config KERNEL_NFS_V2
1127                 def_bool y
1128
1129         config KERNEL_NFS_V3
1130                 def_bool y
1131
1132         config KERNEL_ROOT_NFS
1133                 def_bool y
1134
1135 endif
1136
1137 menu "Filesystem ACL and attr support options"
1138         config USE_FS_ACL_ATTR
1139                 bool "Use filesystem ACL and attr support by default"
1140                 default n
1141                 help
1142                   Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1143                   for kernel and packages, except tmpfs, flash filesystems,
1144                   and old NFS.  Also enable userspace extended attribute support
1145                   by default.  (OpenWrt already has an expection it will be
1146                   present in the kernel).
1147
1148         config KERNEL_FS_POSIX_ACL
1149                 bool "Enable POSIX ACL support"
1150                 default y if USE_FS_ACL_ATTR
1151
1152         config KERNEL_BTRFS_FS_POSIX_ACL
1153                 bool "Enable POSIX ACL for BtrFS Filesystems"
1154                 select KERNEL_FS_POSIX_ACL
1155                 default y if USE_FS_ACL_ATTR
1156
1157         config KERNEL_EXT4_FS_POSIX_ACL
1158                 bool "Enable POSIX ACL for Ext4 Filesystems"
1159                 select KERNEL_FS_POSIX_ACL
1160                 default y if USE_FS_ACL_ATTR
1161
1162         config KERNEL_F2FS_FS_POSIX_ACL
1163                 bool "Enable POSIX ACL for F2FS Filesystems"
1164                 select KERNEL_FS_POSIX_ACL
1165                 default n
1166
1167         config KERNEL_JFFS2_FS_POSIX_ACL
1168                 bool "Enable POSIX ACL for JFFS2 Filesystems"
1169                 select KERNEL_FS_POSIX_ACL
1170                 default n
1171
1172         config KERNEL_TMPFS_POSIX_ACL
1173                 bool "Enable POSIX ACL for TMPFS Filesystems"
1174                 select KERNEL_FS_POSIX_ACL
1175                 default n
1176
1177         config KERNEL_CIFS_ACL
1178                 bool "Enable CIFS ACLs"
1179                 select KERNEL_FS_POSIX_ACL
1180                 default y if USE_FS_ACL_ATTR
1181
1182         config KERNEL_HFS_FS_POSIX_ACL
1183                 bool "Enable POSIX ACL for HFS Filesystems"
1184                 select KERNEL_FS_POSIX_ACL
1185                 default y if USE_FS_ACL_ATTR
1186
1187         config KERNEL_HFSPLUS_FS_POSIX_ACL
1188                 bool "Enable POSIX ACL for HFS+ Filesystems"
1189                 select KERNEL_FS_POSIX_ACL
1190                 default y if USE_FS_ACL_ATTR
1191
1192         config KERNEL_NFS_ACL_SUPPORT
1193                 bool "Enable ACLs for NFS"
1194                 default y if USE_FS_ACL_ATTR
1195
1196         config KERNEL_NFS_V3_ACL_SUPPORT
1197                 bool "Enable ACLs for NFSv3"
1198                 default n
1199
1200         config KERNEL_NFSD_V2_ACL_SUPPORT
1201                 bool "Enable ACLs for NFSDv2"
1202                 default n
1203
1204         config KERNEL_NFSD_V3_ACL_SUPPORT
1205                 bool "Enable ACLs for NFSDv3"
1206                 default n
1207
1208         config KERNEL_REISER_FS_POSIX_ACL
1209                 bool "Enable POSIX ACLs for ReiserFS"
1210                 select KERNEL_FS_POSIX_ACL
1211                 default y if USE_FS_ACL_ATTR
1212
1213         config KERNEL_XFS_POSIX_ACL
1214                 bool "Enable POSIX ACLs for XFS"
1215                 select KERNEL_FS_POSIX_ACL
1216                 default y if USE_FS_ACL_ATTR
1217
1218         config KERNEL_JFS_POSIX_ACL
1219                 bool "Enable POSIX ACLs for JFS"
1220                 select KERNEL_FS_POSIX_ACL
1221                 default y if USE_FS_ACL_ATTR
1222
1223 endmenu
1224
1225 config KERNEL_DEVMEM
1226         bool "/dev/mem virtual device support"
1227         help
1228           Say Y here if you want to support the /dev/mem device.
1229           The /dev/mem device is used to access areas of physical
1230           memory.
1231
1232 config KERNEL_DEVKMEM
1233         bool "/dev/kmem virtual device support"
1234         help
1235           Say Y here if you want to support the /dev/kmem device. The
1236           /dev/kmem device is rarely used, but can be used for certain
1237           kind of kernel debugging operations.
1238
1239 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1240         int "Number of squashfs fragments cached"
1241         default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1242         default 3
1243
1244 config KERNEL_SQUASHFS_XATTR
1245         bool "Squashfs XATTR support"
1246
1247 #
1248 # compile optimization setting
1249 #
1250 choice
1251         prompt "Compiler optimization level"
1252         default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1253
1254 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1255         bool "Optimize for performance"
1256         help
1257           This is the default optimization level for the kernel, building
1258           with the "-O2" compiler flag for best performance and most
1259           helpful compile-time warnings.
1260
1261 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1262         bool "Optimize for size"
1263         help
1264           Enabling this option will pass "-Os" instead of "-O2" to
1265           your compiler resulting in a smaller kernel.
1266
1267 endchoice
1268
1269 config KERNEL_AUDIT
1270         bool "Auditing support"
1271
1272 config KERNEL_SECURITY
1273         bool "Enable different security models"
1274
1275 config KERNEL_SECURITY_NETWORK
1276         bool "Socket and Networking Security Hooks"
1277         select KERNEL_SECURITY
1278
1279 config KERNEL_SECURITY_SELINUX
1280         bool "NSA SELinux Support"
1281         select KERNEL_SECURITY_NETWORK
1282         select KERNEL_AUDIT
1283
1284 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1285         bool "NSA SELinux boot parameter"
1286         depends on KERNEL_SECURITY_SELINUX
1287         default y
1288
1289 config KERNEL_SECURITY_SELINUX_DISABLE
1290         bool "NSA SELinux runtime disable"
1291         depends on KERNEL_SECURITY_SELINUX
1292
1293 config KERNEL_SECURITY_SELINUX_DEVELOP
1294         bool "NSA SELinux Development Support"
1295         depends on KERNEL_SECURITY_SELINUX
1296         default y
1297
1298 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1299         int
1300         depends on KERNEL_SECURITY_SELINUX
1301         default 9
1302
1303 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1304         int
1305         depends on KERNEL_SECURITY_SELINUX
1306         default 256
1307
1308 config KERNEL_LSM
1309         string
1310         default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1311         depends on KERNEL_SECURITY_SELINUX
1312
1313 config KERNEL_EXT4_FS_SECURITY
1314         bool "Ext4 Security Labels"
1315
1316 config KERNEL_F2FS_FS_SECURITY
1317         bool "F2FS Security Labels"
1318
1319 config KERNEL_UBIFS_FS_SECURITY
1320         bool "UBIFS Security Labels"
1321
1322 config KERNEL_JFFS2_FS_SECURITY
1323         bool "JFFS2 Security Labels"