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_KPROBE_OVERRIDE
 459         bool
 460         depends on KERNEL_KPROBES
 461         default n
 462
 463 config KERNEL_AIO
 464         bool "Compile the kernel with asynchronous IO support"
 465         default y if !SMALL_FLASH
 466
 467 config KERNEL_IO_URING
 468         bool "Compile the kernel with io_uring support"
 469         default y if !SMALL_FLASH
 470
 471 config KERNEL_FHANDLE
 472         bool "Compile the kernel with support for fhandle syscalls"
 473         default y if !SMALL_FLASH
 474
 475 config KERNEL_FANOTIFY
 476         bool "Compile the kernel with modern file notification support"
 477         default y if !SMALL_FLASH
 478
 479 config KERNEL_BLK_DEV_BSG
 480         bool "Compile the kernel with SCSI generic v4 support for any block device"
 481         default n
 482
 483 config KERNEL_TRANSPARENT_HUGEPAGE
 484         bool
 485
 486 choice
 487         prompt "Transparent Hugepage Support sysfs defaults"
 488         depends on KERNEL_TRANSPARENT_HUGEPAGE
 489         default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
 490
 491         config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
 492                 bool "always"
 493
 494         config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
 495                 bool "madvise"
 496 endchoice
 497
 498 config KERNEL_HUGETLBFS
 499         bool
 500
 501 config KERNEL_HUGETLB_PAGE
 502         bool "Compile the kernel with HugeTLB support"
 503         select KERNEL_TRANSPARENT_HUGEPAGE
 504         select KERNEL_HUGETLBFS
 505         default n
 506
 507 config KERNEL_MAGIC_SYSRQ
 508         bool "Compile the kernel with SysRq support"
 509         default y
 510
 511 config KERNEL_DEBUG_PINCTRL
 512         bool "Compile the kernel with pinctrl debugging"
 513         select KERNEL_DEBUG_KERNEL
 514
 515 config KERNEL_DEBUG_GPIO
 516         bool "Compile the kernel with gpio debugging"
 517         select KERNEL_DEBUG_KERNEL
 518
 519 config KERNEL_COREDUMP
 520         bool
 521
 522 config KERNEL_ELF_CORE
 523         bool "Enable process core dump support"
 524         select KERNEL_COREDUMP
 525         default y if !SMALL_FLASH
 526
 527 config KERNEL_PROVE_LOCKING
 528         bool "Enable kernel lock checking"
 529         select KERNEL_DEBUG_KERNEL
 530         default n
 531
 532 config KERNEL_SOFTLOCKUP_DETECTOR
 533         bool "Compile the kernel with detect Soft Lockups"
 534         depends on KERNEL_DEBUG_KERNEL
 535         help
 536           Say Y here to enable the kernel to act as a watchdog to detect
 537           soft lockups.
 538
 539           Softlockups are bugs that cause the kernel to loop in kernel
 540           mode for more than 20 seconds, without giving other tasks a
 541           chance to run.  The current stack trace is displayed upon
 542           detection and the system will stay locked up.
 543
 544 config KERNEL_DETECT_HUNG_TASK
 545         bool "Compile the kernel with detect Hung Tasks"
 546         depends on KERNEL_DEBUG_KERNEL
 547         default KERNEL_SOFTLOCKUP_DETECTOR
 548         help
 549           Say Y here to enable the kernel to detect "hung tasks",
 550           which are bugs that cause the task to be stuck in
 551           uninterruptible "D" state indefinitely.
 552
 553           When a hung task is detected, the kernel will print the
 554           current stack trace (which you should report), but the
 555           task will stay in uninterruptible state. If lockdep is
 556           enabled then all held locks will also be reported. This
 557           feature has negligible overhead.
 558
 559 config KERNEL_WQ_WATCHDOG
 560         bool "Compile the kernel with detect Workqueue Stalls"
 561         depends on KERNEL_DEBUG_KERNEL
 562         help
 563           Say Y here to enable stall detection on workqueues.  If a
 564           worker pool doesn't make forward progress on a pending work
 565           item for over a given amount of time, 30s by default, a
 566           warning message is printed along with dump of workqueue
 567           state.  This can be configured through kernel parameter
 568           "workqueue.watchdog_thresh" and its sysfs counterpart.
 569
 570 config KERNEL_DEBUG_ATOMIC_SLEEP
 571         bool "Compile the kernel with sleep inside atomic section checking"
 572         depends on KERNEL_DEBUG_KERNEL
 573         help
 574           If you say Y here, various routines which may sleep will become very
 575           noisy if they are called inside atomic sections: when a spinlock is
 576           held, inside an rcu read side critical section, inside preempt disabled
 577           sections, inside an interrupt, etc...
 578
 579 config KERNEL_DEBUG_VM
 580         bool "Compile the kernel with debug VM"
 581         depends on KERNEL_DEBUG_KERNEL
 582         help
 583           Enable this to turn on extended checks in the virtual-memory system
 584           that may impact performance.
 585
 586           If unsure, say N.
 587
 588 config KERNEL_PRINTK_TIME
 589         bool "Enable printk timestamps"
 590         default y
 591
 592 config KERNEL_SLUB_DEBUG
 593         bool
 594
 595 config KERNEL_SLUB_DEBUG_ON
 596         bool
 597
 598 config KERNEL_SLABINFO
 599         select KERNEL_SLUB_DEBUG
 600         select KERNEL_SLUB_DEBUG_ON
 601         bool "Enable /proc slab debug info"
 602
 603 config KERNEL_PROC_PAGE_MONITOR
 604         bool "Enable /proc page monitoring"
 605
 606 config KERNEL_RELAY
 607         bool
 608
 609 config KERNEL_KEXEC
 610         bool "Enable kexec support"
 611
 612 config KERNEL_PROC_VMCORE
 613         bool
 614
 615 config KERNEL_PROC_KCORE
 616         bool
 617
 618 config KERNEL_CRASH_DUMP
 619         depends on i386 || x86_64 || arm || armeb
 620         select KERNEL_KEXEC
 621         select KERNEL_PROC_VMCORE
 622         select KERNEL_PROC_KCORE
 623         bool "Enable support for kexec crashdump"
 624         default y
 625
 626 config USE_RFKILL
 627         bool "Enable rfkill support"
 628         default RFKILL_SUPPORT
 629
 630 config USE_SPARSE
 631         bool "Enable sparse check during kernel build"
 632         default n
 633
 634 config KERNEL_DEVTMPFS
 635         bool "Compile the kernel with device tmpfs enabled"
 636         default n
 637         help
 638           devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
 639           devices nodes for all registered devices to simplify boot, but leaves more
 640           complex tasks to userspace (e.g. udev).
 641
 642 if KERNEL_DEVTMPFS
 643
 644         config KERNEL_DEVTMPFS_MOUNT
 645                 bool "Automatically mount devtmpfs after root filesystem is mounted"
 646                 default n
 647
 648 endif
 649
 650 config KERNEL_KEYS
 651         bool "Enable kernel access key retention support"
 652         default !SMALL_FLASH
 653
 654 config KERNEL_PERSISTENT_KEYRINGS
 655         bool "Enable kernel persistent keyrings"
 656         depends on KERNEL_KEYS
 657         default n
 658
 659 config KERNEL_KEYS_REQUEST_CACHE
 660         bool "Enable temporary caching of the last request_key() result"
 661         depends on KERNEL_KEYS
 662         default n
 663
 664 config KERNEL_BIG_KEYS
 665         bool "Enable large payload keys on kernel keyrings"
 666         depends on KERNEL_KEYS
 667         default n
 668
 669 #
 670 # CGROUP support symbols
 671 #
 672
 673 config KERNEL_CGROUPS
 674         bool "Enable kernel cgroups"
 675         default y if !SMALL_FLASH
 676
 677 if KERNEL_CGROUPS
 678
 679         config KERNEL_CGROUP_DEBUG
 680                 bool "Example debug cgroup subsystem"
 681                 default n
 682                 help
 683                   This option enables a simple cgroup subsystem that
 684                   exports useful debugging information about the cgroups
 685                   framework.
 686
 687         config KERNEL_FREEZER
 688                 bool
 689
 690         config KERNEL_CGROUP_FREEZER
 691                 bool "legacy Freezer cgroup subsystem"
 692                 default n
 693                 select KERNEL_FREEZER
 694                 help
 695                   Provides a way to freeze and unfreeze all tasks in a
 696                   cgroup.
 697                   (legacy cgroup1-only controller, in cgroup2 freezer
 698                   is integrated in the Memory controller)
 699
 700         config KERNEL_CGROUP_DEVICE
 701                 bool "legacy Device controller for cgroups"
 702                 default n
 703                 help
 704                   Provides a cgroup implementing whitelists for devices which
 705                   a process in the cgroup can mknod or open.
 706                   (legacy cgroup1-only controller)
 707
 708         config KERNEL_CGROUP_HUGETLB
 709                 bool "HugeTLB controller"
 710                 default n
 711                 select KERNEL_HUGETLB_PAGE
 712
 713         config KERNEL_CGROUP_PIDS
 714                 bool "PIDs cgroup subsystem"
 715                 default y
 716                 help
 717                   Provides enforcement of process number limits in the scope of a
 718                   cgroup.
 719
 720         config KERNEL_CGROUP_RDMA
 721                 bool "RDMA controller for cgroups"
 722                 default y
 723
 724         config KERNEL_CGROUP_BPF
 725                 bool "Support for eBPF programs attached to cgroups"
 726                 default y
 727
 728         config KERNEL_CPUSETS
 729                 bool "Cpuset support"
 730                 default y
 731                 help
 732                   This option will let you create and manage CPUSETs which
 733                   allow dynamically partitioning a system into sets of CPUs and
 734                   Memory Nodes and assigning tasks to run only within those sets.
 735                   This is primarily useful on large SMP or NUMA systems.
 736
 737         config KERNEL_PROC_PID_CPUSET
 738                 bool "Include legacy /proc/<pid>/cpuset file"
 739                 default n
 740                 depends on KERNEL_CPUSETS
 741
 742         config KERNEL_CGROUP_CPUACCT
 743                 bool "Simple CPU accounting cgroup subsystem"
 744                 default y
 745                 help
 746                   Provides a simple Resource Controller for monitoring the
 747                   total CPU consumed by the tasks in a cgroup.
 748
 749         config KERNEL_RESOURCE_COUNTERS
 750                 bool "Resource counters"
 751                 default y
 752                 help
 753                   This option enables controller independent resource accounting
 754                   infrastructure that works with cgroups.
 755
 756         config KERNEL_MM_OWNER
 757                 bool
 758                 default y if KERNEL_MEMCG
 759
 760         config KERNEL_MEMCG
 761                 bool "Memory Resource Controller for Control Groups"
 762                 default y
 763                 select KERNEL_FREEZER
 764                 depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
 765                 help
 766                   Provides a memory resource controller that manages both anonymous
 767                   memory and page cache. (See Documentation/cgroups/memory.txt)
 768
 769                   Note that setting this option increases fixed memory overhead
 770                   associated with each page of memory in the system. By this,
 771                   20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 772                   usage tracking struct at boot. Total amount of this is printed out
 773                   at boot.
 774
 775                   Only enable when you're ok with these tradeoffs and really
 776                   sure you need the memory resource controller. Even when you enable
 777                   this, you can set "cgroup_disable=memory" at your boot option to
 778                   disable memory resource controller and you can avoid overheads
 779                   (but lose benefits of memory resource controller).
 780
 781                   This config option also selects MM_OWNER config option, which
 782                   could in turn add some fork/exit overhead.
 783
 784         config KERNEL_MEMCG_SWAP
 785                 bool "Memory Resource Controller Swap Extension"
 786                 default y
 787                 depends on KERNEL_MEMCG
 788                 help
 789                   Add swap management feature to memory resource controller. When you
 790                   enable this, you can limit mem+swap usage per cgroup. In other words,
 791                   when you disable this, memory resource controller has no cares to
 792                   usage of swap...a process can exhaust all of the swap. This extension
 793                   is useful when you want to avoid exhaustion swap but this itself
 794                   adds more overheads and consumes memory for remembering information.
 795                   Especially if you use 32bit system or small memory system, please
 796                   be careful about enabling this. When memory resource controller
 797                   is disabled by boot option, this will be automatically disabled and
 798                   there will be no overhead from this. Even when you set this config=y,
 799                   if boot option "swapaccount=0" is set, swap will not be accounted.
 800                   Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 801                   size is 4096bytes, 512k per 1Gbytes of swap.
 802
 803         config KERNEL_MEMCG_SWAP_ENABLED
 804                 bool "Memory Resource Controller Swap Extension enabled by default"
 805                 default n
 806                 depends on KERNEL_MEMCG_SWAP
 807                 help
 808                   Memory Resource Controller Swap Extension comes with its price in
 809                   a bigger memory consumption. General purpose distribution kernels
 810                   which want to enable the feature but keep it disabled by default
 811                   and let the user enable it by swapaccount boot command line
 812                   parameter should have this option unselected.
 813
 814                   Those who want to have the feature enabled by default should
 815                   select this option (if, for some reason, they need to disable it,
 816                   then swapaccount=0 does the trick).
 817
 818
 819         config KERNEL_MEMCG_KMEM
 820                 bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
 821                 default y
 822                 depends on KERNEL_MEMCG
 823                 help
 824                   The Kernel Memory extension for Memory Resource Controller can limit
 825                   the amount of memory used by kernel objects in the system. Those are
 826                   fundamentally different from the entities handled by the standard
 827                   Memory Controller, which are page-based, and can be swapped. Users of
 828                   the kmem extension can use it to guarantee that no group of processes
 829                   will ever exhaust kernel resources alone.
 830
 831         config KERNEL_CGROUP_PERF
 832                 bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
 833                 select KERNEL_PERF_EVENTS
 834                 default n
 835                 help
 836                   This option extends the per-cpu mode to restrict monitoring to
 837                   threads which belong to the cgroup specified and run on the
 838                   designated cpu.
 839
 840         menuconfig KERNEL_CGROUP_SCHED
 841                 bool "Group CPU scheduler"
 842                 default y
 843                 help
 844                   This feature lets CPU scheduler recognize task groups and control CPU
 845                   bandwidth allocation to such task groups. It uses cgroups to group
 846                   tasks.
 847
 848         if KERNEL_CGROUP_SCHED
 849
 850                 config KERNEL_FAIR_GROUP_SCHED
 851                         bool "Group scheduling for SCHED_OTHER"
 852                         default y
 853
 854                 config KERNEL_CFS_BANDWIDTH
 855                         bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
 856                         default y
 857                         depends on KERNEL_FAIR_GROUP_SCHED
 858                         help
 859                           This option allows users to define CPU bandwidth rates (limits) for
 860                           tasks running within the fair group scheduler.  Groups with no limit
 861                           set are considered to be unconstrained and will run with no
 862                           restriction.
 863                           See tip/Documentation/scheduler/sched-bwc.txt for more information.
 864
 865                 config KERNEL_RT_GROUP_SCHED
 866                         bool "Group scheduling for SCHED_RR/FIFO"
 867                         default y
 868                         help
 869                           This feature lets you explicitly allocate real CPU bandwidth
 870                           to task groups. If enabled, it will also make it impossible to
 871                           schedule realtime tasks for non-root users until you allocate
 872                           realtime bandwidth for them.
 873
 874         endif
 875
 876         config KERNEL_BLK_CGROUP
 877                 bool "Block IO controller"
 878                 default y
 879                 help
 880                   Generic block IO controller cgroup interface. This is the common
 881                   cgroup interface which should be used by various IO controlling
 882                   policies.
 883
 884                   Currently, CFQ IO scheduler uses it to recognize task groups and
 885                   control disk bandwidth allocation (proportional time slice allocation)
 886                   to such task groups. It is also used by bio throttling logic in
 887                   block layer to implement upper limit in IO rates on a device.
 888
 889                   This option only enables generic Block IO controller infrastructure.
 890                   One needs to also enable actual IO controlling logic/policy. For
 891                   enabling proportional weight division of disk bandwidth in CFQ, set
 892                   CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 893                   CONFIG_BLK_DEV_THROTTLING=y.
 894
 895         if KERNEL_BLK_CGROUP
 896
 897                 config KERNEL_CFQ_GROUP_IOSCHED
 898                         bool "Proportional weight of disk bandwidth in CFQ"
 899
 900                 config KERNEL_BLK_DEV_THROTTLING
 901                         bool "Enable throttling policy"
 902                         default y
 903
 904                 config KERNEL_BLK_DEV_THROTTLING_LOW
 905                         bool "Block throttling .low limit interface support (EXPERIMENTAL)"
 906                         depends on KERNEL_BLK_DEV_THROTTLING
 907         endif
 908
 909         config KERNEL_DEBUG_BLK_CGROUP
 910                 bool "Enable Block IO controller debugging"
 911                 default n
 912                 depends on KERNEL_BLK_CGROUP
 913                 help
 914                   Enable some debugging help. Currently it exports additional stat
 915                   files in a cgroup which can be useful for debugging.
 916
 917         config KERNEL_NET_CLS_CGROUP
 918                 bool "legacy Control Group Classifier"
 919                 default n
 920
 921         config KERNEL_CGROUP_NET_CLASSID
 922                 bool "legacy Network classid cgroup"
 923                 default n
 924
 925         config KERNEL_CGROUP_NET_PRIO
 926                 bool "legacy Network priority cgroup"
 927                 default n
 928
 929 endif
 930
 931 #
 932 # Namespace support symbols
 933 #
 934
 935 config KERNEL_NAMESPACES
 936         bool "Enable kernel namespaces"
 937         default y if !SMALL_FLASH
 938
 939 if KERNEL_NAMESPACES
 940
 941         config KERNEL_UTS_NS
 942                 bool "UTS namespace"
 943                 default y
 944                 help
 945                   In this namespace, tasks see different info provided
 946                   with the uname() system call.
 947
 948         config KERNEL_IPC_NS
 949                 bool "IPC namespace"
 950                 default y
 951                 help
 952                   In this namespace, tasks work with IPC ids which correspond to
 953                   different IPC objects in different namespaces.
 954
 955         config KERNEL_USER_NS
 956                 bool "User namespace (EXPERIMENTAL)"
 957                 default y
 958                 help
 959                   This allows containers, i.e. vservers, to use user namespaces
 960                   to provide different user info for different servers.
 961
 962         config KERNEL_PID_NS
 963                 bool "PID Namespaces"
 964                 default y
 965                 help
 966                   Support process id namespaces. This allows having multiple
 967                   processes with the same pid as long as they are in different
 968                   pid namespaces. This is a building block of containers.
 969
 970         config KERNEL_NET_NS
 971                 bool "Network namespace"
 972                 default y
 973                 help
 974                   Allow user space to create what appear to be multiple instances
 975                   of the network stack.
 976
 977 endif
 978
 979 config KERNEL_DEVPTS_MULTIPLE_INSTANCES
 980         bool "Support multiple instances of devpts"
 981         default y if !SMALL_FLASH
 982         help
 983           Enable support for multiple instances of devpts filesystem.
 984           If you want to have isolated PTY namespaces (eg: in containers),
 985           say Y here. Otherwise, say N. If enabled, each mount of devpts
 986           filesystem with the '-o newinstance' option will create an
 987           independent PTY namespace.
 988
 989 config KERNEL_POSIX_MQUEUE
 990         bool "POSIX Message Queues"
 991         default y if !SMALL_FLASH
 992         help
 993           POSIX variant of message queues is a part of IPC. In POSIX message
 994           queues every message has a priority which decides about succession
 995           of receiving it by a process. If you want to compile and run
 996           programs written e.g. for Solaris with use of its POSIX message
 997           queues (functions mq_*) say Y here.
 998
 999           POSIX message queues are visible as a filesystem called 'mqueue'
1000           and can be mounted somewhere if you want to do filesystem
1001           operations on message queues.
1002
1003
1004 config KERNEL_SECCOMP_FILTER
1005         bool
1006         default y if !SMALL_FLASH
1007
1008 config KERNEL_SECCOMP
1009         bool "Enable seccomp support"
1010                 depends on !(TARGET_uml)
1011                 select KERNEL_SECCOMP_FILTER
1012                 default y if !SMALL_FLASH
1013                 help
1014                   Build kernel with support for seccomp.
1015
1016 #
1017 # IPv4 configuration
1018 #
1019
1020 config KERNEL_IP_MROUTE
1021         bool "Enable IPv4 multicast routing"
1022         default y
1023         help
1024           Multicast routing requires a multicast routing daemon in
1025           addition to kernel support.
1026
1027 if KERNEL_IP_MROUTE
1028
1029         config KERNEL_IP_MROUTE_MULTIPLE_TABLES
1030                 def_bool y
1031
1032         config KERNEL_IP_PIMSM_V1
1033                 def_bool y
1034
1035         config KERNEL_IP_PIMSM_V2
1036                 def_bool y
1037
1038 endif
1039
1040 #
1041 # IPv6 configuration
1042 #
1043
1044 config KERNEL_IPV6
1045         def_bool IPV6
1046
1047 if KERNEL_IPV6
1048
1049         config KERNEL_IPV6_MULTIPLE_TABLES
1050                 def_bool y
1051
1052         config KERNEL_IPV6_SUBTREES
1053                 def_bool y
1054
1055         config KERNEL_IPV6_MROUTE
1056                 bool "Enable IPv6 multicast routing"
1057                 default y
1058                 help
1059                   Multicast routing requires a multicast routing daemon in
1060                   addition to kernel support.
1061
1062         if KERNEL_IPV6_MROUTE
1063
1064                 config KERNEL_IPV6_MROUTE_MULTIPLE_TABLES
1065                         def_bool y
1066
1067                 config KERNEL_IPV6_PIMSM_V2
1068                         def_bool y
1069
1070         endif
1071
1072         config KERNEL_IPV6_SEG6_LWTUNNEL
1073                 bool "Enable support for lightweight tunnels"
1074                 default y if !SMALL_FLASH
1075                 help
1076                   Using lwtunnel (needed for IPv6 segment routing) requires ip-full package.
1077
1078         config KERNEL_LWTUNNEL_BPF
1079                 def_bool n
1080
1081 endif
1082
1083 #
1084 # Miscellaneous network configuration
1085 #
1086
1087 config KERNEL_NET_L3_MASTER_DEV
1088         bool "L3 Master device support"
1089         help
1090           This module provides glue between core networking code and device
1091           drivers to support L3 master devices like VRF.
1092
1093 #
1094 # NFS related symbols
1095 #
1096 config KERNEL_IP_PNP
1097         bool "Compile the kernel with rootfs on NFS"
1098         help
1099            If you want to make your kernel boot off a NFS server as root
1100            filesystem, select Y here.
1101
1102 if KERNEL_IP_PNP
1103
1104         config KERNEL_IP_PNP_DHCP
1105                 def_bool y
1106
1107         config KERNEL_IP_PNP_BOOTP
1108                 def_bool n
1109
1110         config KERNEL_IP_PNP_RARP
1111                 def_bool n
1112
1113         config KERNEL_NFS_FS
1114                 def_bool y
1115
1116         config KERNEL_NFS_V2
1117                 def_bool y
1118
1119         config KERNEL_NFS_V3
1120                 def_bool y
1121
1122         config KERNEL_ROOT_NFS
1123                 def_bool y
1124
1125 endif
1126
1127 menu "Filesystem ACL and attr support options"
1128         config USE_FS_ACL_ATTR
1129                 bool "Use filesystem ACL and attr support by default"
1130                 default n
1131                 help
1132                   Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
1133                   for kernel and packages, except tmpfs, flash filesystems,
1134                   and old NFS.  Also enable userspace extended attribute support
1135                   by default.  (OpenWrt already has an expection it will be
1136                   present in the kernel).
1137
1138         config KERNEL_FS_POSIX_ACL
1139                 bool "Enable POSIX ACL support"
1140                 default y if USE_FS_ACL_ATTR
1141
1142         config KERNEL_BTRFS_FS_POSIX_ACL
1143                 bool "Enable POSIX ACL for BtrFS Filesystems"
1144                 select KERNEL_FS_POSIX_ACL
1145                 default y if USE_FS_ACL_ATTR
1146
1147         config KERNEL_EXT4_FS_POSIX_ACL
1148                 bool "Enable POSIX ACL for Ext4 Filesystems"
1149                 select KERNEL_FS_POSIX_ACL
1150                 default y if USE_FS_ACL_ATTR
1151
1152         config KERNEL_F2FS_FS_POSIX_ACL
1153                 bool "Enable POSIX ACL for F2FS Filesystems"
1154                 select KERNEL_FS_POSIX_ACL
1155                 default n
1156
1157         config KERNEL_JFFS2_FS_POSIX_ACL
1158                 bool "Enable POSIX ACL for JFFS2 Filesystems"
1159                 select KERNEL_FS_POSIX_ACL
1160                 default n
1161
1162         config KERNEL_TMPFS_POSIX_ACL
1163                 bool "Enable POSIX ACL for TMPFS Filesystems"
1164                 select KERNEL_FS_POSIX_ACL
1165                 default n
1166
1167         config KERNEL_CIFS_ACL
1168                 bool "Enable CIFS ACLs"
1169                 select KERNEL_FS_POSIX_ACL
1170                 default y if USE_FS_ACL_ATTR
1171
1172         config KERNEL_HFS_FS_POSIX_ACL
1173                 bool "Enable POSIX ACL for HFS Filesystems"
1174                 select KERNEL_FS_POSIX_ACL
1175                 default y if USE_FS_ACL_ATTR
1176
1177         config KERNEL_HFSPLUS_FS_POSIX_ACL
1178                 bool "Enable POSIX ACL for HFS+ Filesystems"
1179                 select KERNEL_FS_POSIX_ACL
1180                 default y if USE_FS_ACL_ATTR
1181
1182         config KERNEL_NFS_ACL_SUPPORT
1183                 bool "Enable ACLs for NFS"
1184                 default y if USE_FS_ACL_ATTR
1185
1186         config KERNEL_NFS_V3_ACL_SUPPORT
1187                 bool "Enable ACLs for NFSv3"
1188                 default n
1189
1190         config KERNEL_NFSD_V2_ACL_SUPPORT
1191                 bool "Enable ACLs for NFSDv2"
1192                 default n
1193
1194         config KERNEL_NFSD_V3_ACL_SUPPORT
1195                 bool "Enable ACLs for NFSDv3"
1196                 default n
1197
1198         config KERNEL_REISER_FS_POSIX_ACL
1199                 bool "Enable POSIX ACLs for ReiserFS"
1200                 select KERNEL_FS_POSIX_ACL
1201                 default y if USE_FS_ACL_ATTR
1202
1203         config KERNEL_XFS_POSIX_ACL
1204                 bool "Enable POSIX ACLs for XFS"
1205                 select KERNEL_FS_POSIX_ACL
1206                 default y if USE_FS_ACL_ATTR
1207
1208         config KERNEL_JFS_POSIX_ACL
1209                 bool "Enable POSIX ACLs for JFS"
1210                 select KERNEL_FS_POSIX_ACL
1211                 default y if USE_FS_ACL_ATTR
1212
1213 endmenu
1214
1215 config KERNEL_DEVMEM
1216         bool "/dev/mem virtual device support"
1217         help
1218           Say Y here if you want to support the /dev/mem device.
1219           The /dev/mem device is used to access areas of physical
1220           memory.
1221
1222 config KERNEL_DEVKMEM
1223         bool "/dev/kmem virtual device support"
1224         help
1225           Say Y here if you want to support the /dev/kmem device. The
1226           /dev/kmem device is rarely used, but can be used for certain
1227           kind of kernel debugging operations.
1228
1229 config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
1230         int "Number of squashfs fragments cached"
1231         default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
1232         default 3
1233
1234 config KERNEL_SQUASHFS_XATTR
1235         bool "Squashfs XATTR support"
1236
1237 #
1238 # compile optimization setting
1239 #
1240 choice
1241         prompt "Compiler optimization level"
1242         default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH
1243
1244 config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
1245         bool "Optimize for performance"
1246         help
1247           This is the default optimization level for the kernel, building
1248           with the "-O2" compiler flag for best performance and most
1249           helpful compile-time warnings.
1250
1251 config KERNEL_CC_OPTIMIZE_FOR_SIZE
1252         bool "Optimize for size"
1253         help
1254           Enabling this option will pass "-Os" instead of "-O2" to
1255           your compiler resulting in a smaller kernel.
1256
1257 endchoice
1258
1259 config KERNEL_AUDIT
1260         bool "Auditing support"
1261
1262 config KERNEL_SECURITY
1263         bool "Enable different security models"
1264
1265 config KERNEL_SECURITY_NETWORK
1266         bool "Socket and Networking Security Hooks"
1267         select KERNEL_SECURITY
1268
1269 config KERNEL_SECURITY_SELINUX
1270         bool "NSA SELinux Support"
1271         select KERNEL_SECURITY_NETWORK
1272         select KERNEL_AUDIT
1273
1274 config KERNEL_SECURITY_SELINUX_BOOTPARAM
1275         bool "NSA SELinux boot parameter"
1276         depends on KERNEL_SECURITY_SELINUX
1277         default y
1278
1279 config KERNEL_SECURITY_SELINUX_DISABLE
1280         bool "NSA SELinux runtime disable"
1281         depends on KERNEL_SECURITY_SELINUX
1282
1283 config KERNEL_SECURITY_SELINUX_DEVELOP
1284         bool "NSA SELinux Development Support"
1285         depends on KERNEL_SECURITY_SELINUX
1286         default y
1287
1288 config KERNEL_SECURITY_SELINUX_SIDTAB_HASH_BITS
1289         int
1290         depends on KERNEL_SECURITY_SELINUX
1291         default 9
1292
1293 config KERNEL_SECURITY_SELINUX_SID2STR_CACHE_SIZE
1294         int
1295         depends on KERNEL_SECURITY_SELINUX
1296         default 256
1297
1298 config KERNEL_LSM
1299         string
1300         default "lockdown,yama,loadpin,safesetid,integrity,selinux"
1301         depends on KERNEL_SECURITY_SELINUX
1302
1303 config KERNEL_EXT4_FS_SECURITY
1304         bool "Ext4 Security Labels"
1305
1306 config KERNEL_F2FS_FS_SECURITY
1307         bool "F2FS Security Labels"
1308
1309 config KERNEL_UBIFS_FS_SECURITY
1310         bool "UBIFS Security Labels"
1311
1312 config KERNEL_JFFS2_FS_SECURITY
1313         bool "JFFS2 Security Labels"