1# SPDX-License-Identifier: GPL-2.0-only
 
 
 
 
 
 
 
   2config DEFCONFIG_LIST
   3	string
   4	depends on !UML
   5	option defconfig_list
   6	default "/lib/modules/$(shell,uname -r)/.config"
   7	default "/etc/kernel-config"
   8	default "/boot/config-$(shell,uname -r)"
   9	default ARCH_DEFCONFIG
  10	default "arch/$(ARCH)/defconfig"
  11
  12config CC_IS_GCC
  13	def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
  14
  15config GCC_VERSION
  16	int
  17	default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
  18	default 0
  19
  20config CC_IS_CLANG
  21	def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
  22
  23config CLANG_VERSION
  24	int
  25	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
  26
  27config CC_CAN_LINK
  28	def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
  29
  30config CC_HAS_ASM_GOTO
  31	def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
  32
  33config TOOLS_SUPPORT_RELR
  34	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
  35
  36config CC_HAS_ASM_INLINE
  37	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
  38
  39config CC_HAS_WARN_MAYBE_UNINITIALIZED
  40	def_bool $(cc-option,-Wmaybe-uninitialized)
  41	help
  42	  GCC >= 4.7 supports this option.
  43
  44config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
  45	bool
  46	depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
  47	default CC_IS_GCC && GCC_VERSION < 40900  # unreliable for GCC < 4.9
  48	help
  49	  GCC's -Wmaybe-uninitialized is not reliable by definition.
  50	  Lots of false positive warnings are produced in some cases.
  51
  52	  If this option is enabled, -Wno-maybe-uninitialzed is passed
  53	  to the compiler to suppress maybe-uninitialized warnings.
  54
  55config CONSTRUCTORS
  56	bool
 
  57
  58config IRQ_WORK
  59	bool
  60
  61config BUILDTIME_EXTABLE_SORT
  62	bool
  63
  64config THREAD_INFO_IN_TASK
  65	bool
  66	help
  67	  Select this to move thread_info off the stack into task_struct.  To
  68	  make this work, an arch will need to remove all thread_info fields
  69	  except flags and fix any runtime bugs.
  70
  71	  One subtle change that will be needed is to use try_get_task_stack()
  72	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
  73
  74menu "General setup"
  75
  76config BROKEN
  77	bool
  78
  79config BROKEN_ON_SMP
  80	bool
  81	depends on BROKEN || !SMP
  82	default y
  83
  84config INIT_ENV_ARG_LIMIT
  85	int
  86	default 32 if !UML
  87	default 128 if UML
  88	help
  89	  Maximum of each of the number of arguments and environment
  90	  variables passed to init from the kernel command line.
  91
 
 
 
 
 
 
 
 
 
  92config COMPILE_TEST
  93	bool "Compile also drivers which will not load"
  94	depends on !UML
  95	default n
  96	help
  97	  Some drivers can be compiled on a different platform than they are
  98	  intended to be run on. Despite they cannot be loaded there (or even
  99	  when they load they cannot be used due to missing HW support),
 100	  developers still, opposing to distributors, might want to build such
 101	  drivers to compile-test them.
 102
 103	  If you are a developer and want to build everything available, say Y
 104	  here. If you are a user/distributor, say N here to exclude useless
 105	  drivers to be distributed.
 106
 107config HEADER_TEST
 108	bool "Compile test headers that should be standalone compilable"
 109	help
 110	  Compile test headers listed in header-test-y target to ensure they are
 111	  self-contained, i.e. compilable as standalone units.
 112
 113	  If you are a developer or tester and want to ensure the requested
 114	  headers are self-contained, say Y here. Otherwise, choose N.
 115
 116config KERNEL_HEADER_TEST
 117	bool "Compile test kernel headers"
 118	depends on HEADER_TEST
 119	help
 120	  Headers in include/ are used to build external moduls.
 121	  Compile test them to ensure they are self-contained, i.e.
 122	  compilable as standalone units.
 123
 124	  If you are a developer or tester and want to ensure the headers
 125	  in include/ are self-contained, say Y here. Otherwise, choose N.
 126
 127config UAPI_HEADER_TEST
 128	bool "Compile test UAPI headers"
 129	depends on HEADER_TEST && HEADERS_INSTALL && CC_CAN_LINK
 130	help
 131	  Compile test headers exported to user-space to ensure they are
 132	  self-contained, i.e. compilable as standalone units.
 133
 134	  If you are a developer or tester and want to ensure the exported
 135	  headers are self-contained, say Y here. Otherwise, choose N.
 136
 137config LOCALVERSION
 138	string "Local version - append to kernel release"
 139	help
 140	  Append an extra string to the end of your kernel version.
 141	  This will show up when you type uname, for example.
 142	  The string you set here will be appended after the contents of
 143	  any files with a filename matching localversion* in your
 144	  object and source tree, in that order.  Your total string can
 145	  be a maximum of 64 characters.
 146
 147config LOCALVERSION_AUTO
 148	bool "Automatically append version information to the version string"
 149	default y
 150	depends on !COMPILE_TEST
 151	help
 152	  This will try to automatically determine if the current tree is a
 153	  release tree by looking for git tags that belong to the current
 154	  top of tree revision.
 155
 156	  A string of the format -gxxxxxxxx will be added to the localversion
 157	  if a git-based tree is found.  The string generated by this will be
 158	  appended after any matching localversion* files, and after the value
 159	  set in CONFIG_LOCALVERSION.
 160
 161	  (The actual string used here is the first eight characters produced
 162	  by running the command:
 163
 164	    $ git rev-parse --verify HEAD
 165
 166	  which is done within the script "scripts/setlocalversion".)
 167
 168config BUILD_SALT
 169       string "Build ID Salt"
 170       default ""
 171       help
 172          The build ID is used to link binaries and their debug info. Setting
 173          this option will use the value in the calculation of the build id.
 174          This is mostly useful for distributions which want to ensure the
 175          build is unique between builds. It's safe to leave the default.
 176
 177config HAVE_KERNEL_GZIP
 178	bool
 179
 180config HAVE_KERNEL_BZIP2
 181	bool
 182
 183config HAVE_KERNEL_LZMA
 184	bool
 185
 186config HAVE_KERNEL_XZ
 187	bool
 188
 189config HAVE_KERNEL_LZO
 190	bool
 191
 192config HAVE_KERNEL_LZ4
 193	bool
 194
 195config HAVE_KERNEL_UNCOMPRESSED
 196	bool
 197
 198choice
 199	prompt "Kernel compression mode"
 200	default KERNEL_GZIP
 201	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
 202	help
 203	  The linux kernel is a kind of self-extracting executable.
 204	  Several compression algorithms are available, which differ
 205	  in efficiency, compression and decompression speed.
 206	  Compression speed is only relevant when building a kernel.
 207	  Decompression speed is relevant at each boot.
 208
 209	  If you have any problems with bzip2 or lzma compressed
 210	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 211	  version of this functionality (bzip2 only), for 2.4, was
 212	  supplied by Christian Ludwig)
 213
 214	  High compression options are mostly useful for users, who
 215	  are low on disk space (embedded systems), but for whom ram
 216	  size matters less.
 217
 218	  If in doubt, select 'gzip'
 219
 220config KERNEL_GZIP
 221	bool "Gzip"
 222	depends on HAVE_KERNEL_GZIP
 223	help
 224	  The old and tried gzip compression. It provides a good balance
 225	  between compression ratio and decompression speed.
 226
 227config KERNEL_BZIP2
 228	bool "Bzip2"
 229	depends on HAVE_KERNEL_BZIP2
 230	help
 231	  Its compression ratio and speed is intermediate.
 232	  Decompression speed is slowest among the choices.  The kernel
 233	  size is about 10% smaller with bzip2, in comparison to gzip.
 234	  Bzip2 uses a large amount of memory. For modern kernels you
 235	  will need at least 8MB RAM or more for booting.
 236
 237config KERNEL_LZMA
 238	bool "LZMA"
 239	depends on HAVE_KERNEL_LZMA
 240	help
 241	  This compression algorithm's ratio is best.  Decompression speed
 242	  is between gzip and bzip2.  Compression is slowest.
 243	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
 244
 245config KERNEL_XZ
 246	bool "XZ"
 247	depends on HAVE_KERNEL_XZ
 248	help
 249	  XZ uses the LZMA2 algorithm and instruction set specific
 250	  BCJ filters which can improve compression ratio of executable
 251	  code. The size of the kernel is about 30% smaller with XZ in
 252	  comparison to gzip. On architectures for which there is a BCJ
 253	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
 254	  will create a few percent smaller kernel than plain LZMA.
 255
 256	  The speed is about the same as with LZMA: The decompression
 257	  speed of XZ is better than that of bzip2 but worse than gzip
 258	  and LZO. Compression is slow.
 259
 260config KERNEL_LZO
 261	bool "LZO"
 262	depends on HAVE_KERNEL_LZO
 263	help
 264	  Its compression ratio is the poorest among the choices. The kernel
 265	  size is about 10% bigger than gzip; however its speed
 266	  (both compression and decompression) is the fastest.
 267
 268config KERNEL_LZ4
 269	bool "LZ4"
 270	depends on HAVE_KERNEL_LZ4
 271	help
 272	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
 273	  A preliminary version of LZ4 de/compression tool is available at
 274	  <https://code.google.com/p/lz4/>.
 275
 276	  Its compression ratio is worse than LZO. The size of the kernel
 277	  is about 8% bigger than LZO. But the decompression speed is
 278	  faster than LZO.
 279
 280config KERNEL_UNCOMPRESSED
 281	bool "None"
 282	depends on HAVE_KERNEL_UNCOMPRESSED
 283	help
 284	  Produce uncompressed kernel image. This option is usually not what
 285	  you want. It is useful for debugging the kernel in slow simulation
 286	  environments, where decompressing and moving the kernel is awfully
 287	  slow. This option allows early boot code to skip the decompressor
 288	  and jump right at uncompressed kernel image.
 289
 290endchoice
 291
 292config DEFAULT_HOSTNAME
 293	string "Default hostname"
 294	default "(none)"
 295	help
 296	  This option determines the default system hostname before userspace
 297	  calls sethostname(2). The kernel traditionally uses "(none)" here,
 298	  but you may wish to use a different default here to make a minimal
 299	  system more usable with less configuration.
 300
 301#
 302# For some reason microblaze and nios2 hard code SWAP=n.  Hopefully we can
 303# add proper SWAP support to them, in which case this can be remove.
 304#
 305config ARCH_NO_SWAP
 306	bool
 307
 308config SWAP
 309	bool "Support for paging of anonymous memory (swap)"
 310	depends on MMU && BLOCK && !ARCH_NO_SWAP
 311	default y
 312	help
 313	  This option allows you to choose whether you want to have support
 314	  for so called swap devices or swap files in your kernel that are
 315	  used to provide more virtual memory than the actual RAM present
 316	  in your computer.  If unsure say Y.
 317
 318config SYSVIPC
 319	bool "System V IPC"
 320	---help---
 321	  Inter Process Communication is a suite of library functions and
 322	  system calls which let processes (running programs) synchronize and
 323	  exchange information. It is generally considered to be a good thing,
 324	  and some programs won't run unless you say Y here. In particular, if
 325	  you want to run the DOS emulator dosemu under Linux (read the
 326	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 327	  you'll need to say Y here.
 328
 329	  You can find documentation about IPC with "info ipc" and also in
 330	  section 6.4 of the Linux Programmer's Guide, available from
 331	  <http://www.tldp.org/guides.html>.
 332
 333config SYSVIPC_SYSCTL
 334	bool
 335	depends on SYSVIPC
 336	depends on SYSCTL
 337	default y
 338
 339config POSIX_MQUEUE
 340	bool "POSIX Message Queues"
 341	depends on NET
 342	---help---
 343	  POSIX variant of message queues is a part of IPC. In POSIX message
 344	  queues every message has a priority which decides about succession
 345	  of receiving it by a process. If you want to compile and run
 346	  programs written e.g. for Solaris with use of its POSIX message
 347	  queues (functions mq_*) say Y here.
 348
 349	  POSIX message queues are visible as a filesystem called 'mqueue'
 350	  and can be mounted somewhere if you want to do filesystem
 351	  operations on message queues.
 352
 353	  If unsure, say Y.
 354
 355config POSIX_MQUEUE_SYSCTL
 356	bool
 357	depends on POSIX_MQUEUE
 358	depends on SYSCTL
 359	default y
 360
 361config CROSS_MEMORY_ATTACH
 362	bool "Enable process_vm_readv/writev syscalls"
 363	depends on MMU
 364	default y
 365	help
 366	  Enabling this option adds the system calls process_vm_readv and
 367	  process_vm_writev which allow a process with the correct privileges
 368	  to directly read from or write to another process' address space.
 369	  See the man page for more details.
 370
 371config USELIB
 372	bool "uselib syscall"
 373	def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
 374	help
 375	  This option enables the uselib syscall, a system call used in the
 376	  dynamic linker from libc5 and earlier.  glibc does not use this
 377	  system call.  If you intend to run programs built on libc5 or
 378	  earlier, you may need to enable this syscall.  Current systems
 379	  running glibc can safely disable this.
 380
 381config AUDIT
 382	bool "Auditing support"
 383	depends on NET
 384	help
 385	  Enable auditing infrastructure that can be used with another
 386	  kernel subsystem, such as SELinux (which requires this for
 387	  logging of avc messages output).  System call auditing is included
 388	  on architectures which support it.
 389
 390config HAVE_ARCH_AUDITSYSCALL
 391	bool
 392
 393config AUDITSYSCALL
 394	def_bool y
 395	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
 
 
 
 
 
 
 
 
 
 396	select FSNOTIFY
 397
 398source "kernel/irq/Kconfig"
 399source "kernel/time/Kconfig"
 400source "kernel/Kconfig.preempt"
 401
 402menu "CPU/Task time and stats accounting"
 403
 404config VIRT_CPU_ACCOUNTING
 405	bool
 406
 407choice
 408	prompt "Cputime accounting"
 409	default TICK_CPU_ACCOUNTING if !PPC64
 410	default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
 411
 412# Kind of a stub config for the pure tick based cputime accounting
 413config TICK_CPU_ACCOUNTING
 414	bool "Simple tick based cputime accounting"
 415	depends on !S390 && !NO_HZ_FULL
 416	help
 417	  This is the basic tick based cputime accounting that maintains
 418	  statistics about user, system and idle time spent on per jiffies
 419	  granularity.
 420
 421	  If unsure, say Y.
 422
 423config VIRT_CPU_ACCOUNTING_NATIVE
 424	bool "Deterministic task and CPU time accounting"
 425	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
 426	select VIRT_CPU_ACCOUNTING
 427	help
 428	  Select this option to enable more accurate task and CPU time
 429	  accounting.  This is done by reading a CPU counter on each
 430	  kernel entry and exit and on transitions within the kernel
 431	  between system, softirq and hardirq state, so there is a
 432	  small performance impact.  In the case of s390 or IBM POWER > 5,
 433	  this also enables accounting of stolen time on logically-partitioned
 434	  systems.
 435
 436config VIRT_CPU_ACCOUNTING_GEN
 437	bool "Full dynticks CPU time accounting"
 438	depends on HAVE_CONTEXT_TRACKING
 439	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 440	depends on GENERIC_CLOCKEVENTS
 441	select VIRT_CPU_ACCOUNTING
 442	select CONTEXT_TRACKING
 443	help
 444	  Select this option to enable task and CPU time accounting on full
 445	  dynticks systems. This accounting is implemented by watching every
 446	  kernel-user boundaries using the context tracking subsystem.
 447	  The accounting is thus performed at the expense of some significant
 448	  overhead.
 449
 450	  For now this is only useful if you are working on the full
 451	  dynticks subsystem development.
 452
 453	  If unsure, say N.
 454
 455endchoice
 456
 457config IRQ_TIME_ACCOUNTING
 458	bool "Fine granularity task level IRQ time accounting"
 459	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
 460	help
 461	  Select this option to enable fine granularity task irq time
 462	  accounting. This is done by reading a timestamp on each
 463	  transitions between softirq and hardirq state, so there can be a
 464	  small performance impact.
 465
 466	  If in doubt, say N here.
 467
 468config HAVE_SCHED_AVG_IRQ
 469	def_bool y
 470	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
 471	depends on SMP
 472
 473config BSD_PROCESS_ACCT
 474	bool "BSD Process Accounting"
 475	depends on MULTIUSER
 476	help
 477	  If you say Y here, a user level program will be able to instruct the
 478	  kernel (via a special system call) to write process accounting
 479	  information to a file: whenever a process exits, information about
 480	  that process will be appended to the file by the kernel.  The
 481	  information includes things such as creation time, owning user,
 482	  command name, memory usage, controlling terminal etc. (the complete
 483	  list is in the struct acct in <file:include/linux/acct.h>).  It is
 484	  up to the user level program to do useful things with this
 485	  information.  This is generally a good idea, so say Y.
 486
 487config BSD_PROCESS_ACCT_V3
 488	bool "BSD Process Accounting version 3 file format"
 489	depends on BSD_PROCESS_ACCT
 490	default n
 491	help
 492	  If you say Y here, the process accounting information is written
 493	  in a new file format that also logs the process IDs of each
 494	  process and its parent. Note that this file format is incompatible
 495	  with previous v0/v1/v2 file formats, so you will need updated tools
 496	  for processing it. A preliminary version of these tools is available
 497	  at <http://www.gnu.org/software/acct/>.
 498
 499config TASKSTATS
 500	bool "Export task/process statistics through netlink"
 501	depends on NET
 502	depends on MULTIUSER
 503	default n
 504	help
 505	  Export selected statistics for tasks/processes through the
 506	  generic netlink interface. Unlike BSD process accounting, the
 507	  statistics are available during the lifetime of tasks/processes as
 508	  responses to commands. Like BSD accounting, they are sent to user
 509	  space on task exit.
 510
 511	  Say N if unsure.
 512
 513config TASK_DELAY_ACCT
 514	bool "Enable per-task delay accounting"
 515	depends on TASKSTATS
 516	select SCHED_INFO
 517	help
 518	  Collect information on time spent by a task waiting for system
 519	  resources like cpu, synchronous block I/O completion and swapping
 520	  in pages. Such statistics can help in setting a task's priorities
 521	  relative to other tasks for cpu, io, rss limits etc.
 522
 523	  Say N if unsure.
 524
 525config TASK_XACCT
 526	bool "Enable extended accounting over taskstats"
 527	depends on TASKSTATS
 528	help
 529	  Collect extended task accounting data and send the data
 530	  to userland for processing over the taskstats interface.
 531
 532	  Say N if unsure.
 533
 534config TASK_IO_ACCOUNTING
 535	bool "Enable per-task storage I/O accounting"
 536	depends on TASK_XACCT
 537	help
 538	  Collect information on the number of bytes of storage I/O which this
 539	  task has caused.
 540
 541	  Say N if unsure.
 542
 543config PSI
 544	bool "Pressure stall information tracking"
 545	help
 546	  Collect metrics that indicate how overcommitted the CPU, memory,
 547	  and IO capacity are in the system.
 548
 549	  If you say Y here, the kernel will create /proc/pressure/ with the
 550	  pressure statistics files cpu, memory, and io. These will indicate
 551	  the share of walltime in which some or all tasks in the system are
 552	  delayed due to contention of the respective resource.
 553
 554	  In kernels with cgroup support, cgroups (cgroup2 only) will
 555	  have cpu.pressure, memory.pressure, and io.pressure files,
 556	  which aggregate pressure stalls for the grouped tasks only.
 557
 558	  For more details see Documentation/accounting/psi.rst.
 559
 560	  Say N if unsure.
 561
 562config PSI_DEFAULT_DISABLED
 563	bool "Require boot parameter to enable pressure stall information tracking"
 564	default n
 565	depends on PSI
 566	help
 567	  If set, pressure stall information tracking will be disabled
 568	  per default but can be enabled through passing psi=1 on the
 569	  kernel commandline during boot.
 570
 571	  This feature adds some code to the task wakeup and sleep
 572	  paths of the scheduler. The overhead is too low to affect
 573	  common scheduling-intense workloads in practice (such as
 574	  webservers, memcache), but it does show up in artificial
 575	  scheduler stress tests, such as hackbench.
 576
 577	  If you are paranoid and not sure what the kernel will be
 578	  used for, say Y.
 579
 580	  Say N if unsure.
 581
 582endmenu # "CPU/Task time and stats accounting"
 583
 584config CPU_ISOLATION
 585	bool "CPU isolation"
 586	depends on SMP || COMPILE_TEST
 587	default y
 588	help
 589	  Make sure that CPUs running critical tasks are not disturbed by
 590	  any source of "noise" such as unbound workqueues, timers, kthreads...
 591	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
 592	  the "isolcpus=" boot parameter.
 593
 594	  Say Y if unsure.
 595
 596source "kernel/rcu/Kconfig"
 597
 598config BUILD_BIN2C
 599	bool
 600	default n
 601
 602config IKCONFIG
 603	tristate "Kernel .config support"
 
 604	---help---
 605	  This option enables the complete Linux kernel ".config" file
 606	  contents to be saved in the kernel. It provides documentation
 607	  of which kernel options are used in a running kernel or in an
 608	  on-disk kernel.  This information can be extracted from the kernel
 609	  image file with the script scripts/extract-ikconfig and used as
 610	  input to rebuild the current kernel or to build another kernel.
 611	  It can also be extracted from a running kernel by reading
 612	  /proc/config.gz if enabled (below).
 613
 614config IKCONFIG_PROC
 615	bool "Enable access to .config through /proc/config.gz"
 616	depends on IKCONFIG && PROC_FS
 617	---help---
 618	  This option enables access to the kernel configuration file
 619	  through /proc/config.gz.
 620
 621config IKHEADERS
 622	tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
 623	depends on SYSFS
 624	help
 625	  This option enables access to the in-kernel headers that are generated during
 626	  the build process. These can be used to build eBPF tracing programs,
 627	  or similar programs.  If you build the headers as a module, a module called
 628	  kheaders.ko is built which can be loaded on-demand to get access to headers.
 629
 630config LOG_BUF_SHIFT
 631	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 632	range 12 25
 633	default 17
 634	depends on PRINTK
 635	help
 636	  Select the minimal kernel log buffer size as a power of 2.
 637	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
 638	  parameter, see below. Any higher size also might be forced
 639	  by "log_buf_len" boot parameter.
 640
 641	  Examples:
 642		     17 => 128 KB
 643		     16 => 64 KB
 644		     15 => 32 KB
 645		     14 => 16 KB
 646		     13 =>  8 KB
 647		     12 =>  4 KB
 648
 649config LOG_CPU_MAX_BUF_SHIFT
 650	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
 651	depends on SMP
 652	range 0 21
 653	default 12 if !BASE_SMALL
 654	default 0 if BASE_SMALL
 655	depends on PRINTK
 656	help
 657	  This option allows to increase the default ring buffer size
 658	  according to the number of CPUs. The value defines the contribution
 659	  of each CPU as a power of 2. The used space is typically only few
 660	  lines however it might be much more when problems are reported,
 661	  e.g. backtraces.
 662
 663	  The increased size means that a new buffer has to be allocated and
 664	  the original static one is unused. It makes sense only on systems
 665	  with more CPUs. Therefore this value is used only when the sum of
 666	  contributions is greater than the half of the default kernel ring
 667	  buffer as defined by LOG_BUF_SHIFT. The default values are set
 668	  so that more than 64 CPUs are needed to trigger the allocation.
 669
 670	  Also this option is ignored when "log_buf_len" kernel parameter is
 671	  used as it forces an exact (power of two) size of the ring buffer.
 672
 673	  The number of possible CPUs is used for this computation ignoring
 674	  hotplugging making the computation optimal for the worst case
 675	  scenario while allowing a simple algorithm to be used from bootup.
 676
 677	  Examples shift values and their meaning:
 678		     17 => 128 KB for each CPU
 679		     16 =>  64 KB for each CPU
 680		     15 =>  32 KB for each CPU
 681		     14 =>  16 KB for each CPU
 682		     13 =>   8 KB for each CPU
 683		     12 =>   4 KB for each CPU
 684
 685config PRINTK_SAFE_LOG_BUF_SHIFT
 686	int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
 687	range 10 21
 688	default 13
 689	depends on PRINTK
 690	help
 691	  Select the size of an alternate printk per-CPU buffer where messages
 692	  printed from usafe contexts are temporary stored. One example would
 693	  be NMI messages, another one - printk recursion. The messages are
 694	  copied to the main log buffer in a safe context to avoid a deadlock.
 695	  The value defines the size as a power of 2.
 696
 697	  Those messages are rare and limited. The largest one is when
 698	  a backtrace is printed. It usually fits into 4KB. Select
 699	  8KB if you want to be on the safe side.
 700
 701	  Examples:
 702		     17 => 128 KB for each CPU
 703		     16 =>  64 KB for each CPU
 704		     15 =>  32 KB for each CPU
 705		     14 =>  16 KB for each CPU
 706		     13 =>   8 KB for each CPU
 707		     12 =>   4 KB for each CPU
 708
 709#
 710# Architectures with an unreliable sched_clock() should select this:
 711#
 712config HAVE_UNSTABLE_SCHED_CLOCK
 713	bool
 714
 715config GENERIC_SCHED_CLOCK
 716	bool
 717
 718menu "Scheduler features"
 719
 720config UCLAMP_TASK
 721	bool "Enable utilization clamping for RT/FAIR tasks"
 722	depends on CPU_FREQ_GOV_SCHEDUTIL
 723	help
 724	  This feature enables the scheduler to track the clamped utilization
 725	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
 726
 727	  With this option, the user can specify the min and max CPU
 728	  utilization allowed for RUNNABLE tasks. The max utilization defines
 729	  the maximum frequency a task should use while the min utilization
 730	  defines the minimum frequency it should use.
 731
 732	  Both min and max utilization clamp values are hints to the scheduler,
 733	  aiming at improving its frequency selection policy, but they do not
 734	  enforce or grant any specific bandwidth for tasks.
 735
 736	  If in doubt, say N.
 737
 738config UCLAMP_BUCKETS_COUNT
 739	int "Number of supported utilization clamp buckets"
 740	range 5 20
 741	default 5
 742	depends on UCLAMP_TASK
 743	help
 744	  Defines the number of clamp buckets to use. The range of each bucket
 745	  will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
 746	  number of clamp buckets the finer their granularity and the higher
 747	  the precision of clamping aggregation and tracking at run-time.
 748
 749	  For example, with the minimum configuration value we will have 5
 750	  clamp buckets tracking 20% utilization each. A 25% boosted tasks will
 751	  be refcounted in the [20..39]% bucket and will set the bucket clamp
 752	  effective value to 25%.
 753	  If a second 30% boosted task should be co-scheduled on the same CPU,
 754	  that task will be refcounted in the same bucket of the first task and
 755	  it will boost the bucket clamp effective value to 30%.
 756	  The clamp effective value of a bucket is reset to its nominal value
 757	  (20% in the example above) when there are no more tasks refcounted in
 758	  that bucket.
 759
 760	  An additional boost/capping margin can be added to some tasks. In the
 761	  example above the 25% task will be boosted to 30% until it exits the
 762	  CPU. If that should be considered not acceptable on certain systems,
 763	  it's always possible to reduce the margin by increasing the number of
 764	  clamp buckets to trade off used memory for run-time tracking
 765	  precision.
 766
 767	  If in doubt, use the default value.
 768
 769endmenu
 770
 771#
 772# For architectures that want to enable the support for NUMA-affine scheduler
 773# balancing logic:
 774#
 775config ARCH_SUPPORTS_NUMA_BALANCING
 776	bool
 777
 778#
 779# For architectures that prefer to flush all TLBs after a number of pages
 780# are unmapped instead of sending one IPI per page to flush. The architecture
 781# must provide guarantees on what happens if a clean TLB cache entry is
 782# written after the unmap. Details are in mm/rmap.c near the check for
 783# should_defer_flush. The architecture should also consider if the full flush
 784# and the refill costs are offset by the savings of sending fewer IPIs.
 785config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 786	bool
 787
 788#
 789# For architectures that know their GCC __int128 support is sound
 790#
 791config ARCH_SUPPORTS_INT128
 792	bool
 793
 794# For architectures that (ab)use NUMA to represent different memory regions
 795# all cpu-local but of different latencies, such as SuperH.
 796#
 797config ARCH_WANT_NUMA_VARIABLE_LOCALITY
 798	bool
 799
 800config NUMA_BALANCING
 801	bool "Memory placement aware NUMA scheduler"
 802	depends on ARCH_SUPPORTS_NUMA_BALANCING
 803	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
 804	depends on SMP && NUMA && MIGRATION
 805	help
 806	  This option adds support for automatic NUMA aware memory/task placement.
 807	  The mechanism is quite primitive and is based on migrating memory when
 808	  it has references to the node the task is running on.
 809
 810	  This system will be inactive on UMA systems.
 811
 812config NUMA_BALANCING_DEFAULT_ENABLED
 813	bool "Automatically enable NUMA aware memory/task placement"
 814	default y
 815	depends on NUMA_BALANCING
 816	help
 817	  If set, automatic NUMA balancing will be enabled if running on a NUMA
 818	  machine.
 819
 820menuconfig CGROUPS
 821	bool "Control Group support"
 822	select KERNFS
 823	help
 824	  This option adds support for grouping sets of processes together, for
 825	  use with process control subsystems such as Cpusets, CFS, memory
 826	  controls or device isolation.
 827	  See
 828		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
 829		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
 830					  and resource control)
 831
 832	  Say N if unsure.
 833
 834if CGROUPS
 835
 836config PAGE_COUNTER
 837       bool
 838
 839config MEMCG
 840	bool "Memory controller"
 841	select PAGE_COUNTER
 842	select EVENTFD
 843	help
 844	  Provides control over the memory footprint of tasks in a cgroup.
 845
 846config MEMCG_SWAP
 847	bool "Swap controller"
 848	depends on MEMCG && SWAP
 849	help
 850	  Provides control over the swap space consumed by tasks in a cgroup.
 851
 852config MEMCG_SWAP_ENABLED
 853	bool "Swap controller enabled by default"
 854	depends on MEMCG_SWAP
 855	default y
 856	help
 857	  Memory Resource Controller Swap Extension comes with its price in
 858	  a bigger memory consumption. General purpose distribution kernels
 859	  which want to enable the feature but keep it disabled by default
 860	  and let the user enable it by swapaccount=1 boot command line
 861	  parameter should have this option unselected.
 862	  For those who want to have the feature enabled by default should
 863	  select this option (if, for some reason, they need to disable it
 864	  then swapaccount=0 does the trick).
 865
 866config MEMCG_KMEM
 867	bool
 868	depends on MEMCG && !SLOB
 869	default y
 870
 871config BLK_CGROUP
 872	bool "IO controller"
 873	depends on BLOCK
 874	default n
 875	---help---
 876	Generic block IO controller cgroup interface. This is the common
 877	cgroup interface which should be used by various IO controlling
 878	policies.
 879
 880	Currently, CFQ IO scheduler uses it to recognize task groups and
 881	control disk bandwidth allocation (proportional time slice allocation)
 882	to such task groups. It is also used by bio throttling logic in
 883	block layer to implement upper limit in IO rates on a device.
 884
 885	This option only enables generic Block IO controller infrastructure.
 886	One needs to also enable actual IO controlling logic/policy. For
 887	enabling proportional weight division of disk bandwidth in CFQ, set
 888	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 889	CONFIG_BLK_DEV_THROTTLING=y.
 890
 891	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
 
 
 
 
 
 
 
 
 892
 893config CGROUP_WRITEBACK
 894	bool
 895	depends on MEMCG && BLK_CGROUP
 896	default y
 897
 898menuconfig CGROUP_SCHED
 899	bool "CPU controller"
 900	default n
 901	help
 902	  This feature lets CPU scheduler recognize task groups and control CPU
 903	  bandwidth allocation to such task groups. It uses cgroups to group
 904	  tasks.
 905
 906if CGROUP_SCHED
 907config FAIR_GROUP_SCHED
 908	bool "Group scheduling for SCHED_OTHER"
 909	depends on CGROUP_SCHED
 910	default CGROUP_SCHED
 911
 912config CFS_BANDWIDTH
 913	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
 914	depends on FAIR_GROUP_SCHED
 915	default n
 916	help
 917	  This option allows users to define CPU bandwidth rates (limits) for
 918	  tasks running within the fair group scheduler.  Groups with no limit
 919	  set are considered to be unconstrained and will run with no
 920	  restriction.
 921	  See Documentation/scheduler/sched-bwc.rst for more information.
 922
 923config RT_GROUP_SCHED
 924	bool "Group scheduling for SCHED_RR/FIFO"
 925	depends on CGROUP_SCHED
 926	default n
 927	help
 928	  This feature lets you explicitly allocate real CPU bandwidth
 929	  to task groups. If enabled, it will also make it impossible to
 930	  schedule realtime tasks for non-root users until you allocate
 931	  realtime bandwidth for them.
 932	  See Documentation/scheduler/sched-rt-group.rst for more information.
 933
 934endif #CGROUP_SCHED
 935
 936config UCLAMP_TASK_GROUP
 937	bool "Utilization clamping per group of tasks"
 938	depends on CGROUP_SCHED
 939	depends on UCLAMP_TASK
 940	default n
 941	help
 942	  This feature enables the scheduler to track the clamped utilization
 943	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
 944
 945	  When this option is enabled, the user can specify a min and max
 946	  CPU bandwidth which is allowed for each single task in a group.
 947	  The max bandwidth allows to clamp the maximum frequency a task
 948	  can use, while the min bandwidth allows to define a minimum
 949	  frequency a task will always use.
 950
 951	  When task group based utilization clamping is enabled, an eventually
 952	  specified task-specific clamp value is constrained by the cgroup
 953	  specified clamp value. Both minimum and maximum task clamping cannot
 954	  be bigger than the corresponding clamping defined at task group level.
 955
 956	  If in doubt, say N.
 957
 958config CGROUP_PIDS
 959	bool "PIDs controller"
 960	help
 961	  Provides enforcement of process number limits in the scope of a
 962	  cgroup. Any attempt to fork more processes than is allowed in the
 963	  cgroup will fail. PIDs are fundamentally a global resource because it
 964	  is fairly trivial to reach PID exhaustion before you reach even a
 965	  conservative kmemcg limit. As a result, it is possible to grind a
 966	  system to halt without being limited by other cgroup policies. The
 967	  PIDs controller is designed to stop this from happening.
 968
 969	  It should be noted that organisational operations (such as attaching
 970	  to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
 971	  since the PIDs limit only affects a process's ability to fork, not to
 972	  attach to a cgroup.
 973
 974config CGROUP_RDMA
 975	bool "RDMA controller"
 976	help
 977	  Provides enforcement of RDMA resources defined by IB stack.
 978	  It is fairly easy for consumers to exhaust RDMA resources, which
 979	  can result into resource unavailability to other consumers.
 980	  RDMA controller is designed to stop this from happening.
 981	  Attaching processes with active RDMA resources to the cgroup
 982	  hierarchy is allowed even if can cross the hierarchy's limit.
 983
 984config CGROUP_FREEZER
 985	bool "Freezer controller"
 986	help
 987	  Provides a way to freeze and unfreeze all tasks in a
 988	  cgroup.
 989
 990	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
 991	  controller includes important in-kernel memory consumers per default.
 992
 993	  If you're using cgroup2, say N.
 994
 995config CGROUP_HUGETLB
 996	bool "HugeTLB controller"
 997	depends on HUGETLB_PAGE
 998	select PAGE_COUNTER
 999	default n
1000	help
1001	  Provides a cgroup controller for HugeTLB pages.
1002	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
1003	  The limit is enforced during page fault. Since HugeTLB doesn't
1004	  support page reclaim, enforcing the limit at page fault time implies
1005	  that, the application will get SIGBUS signal if it tries to access
1006	  HugeTLB pages beyond its limit. This requires the application to know
1007	  beforehand how much HugeTLB pages it would require for its use. The
1008	  control group is tracked in the third page lru pointer. This means
1009	  that we cannot use the controller with huge page less than 3 pages.
1010
1011config CPUSETS
1012	bool "Cpuset controller"
1013	depends on SMP
1014	help
1015	  This option will let you create and manage CPUSETs which
1016	  allow dynamically partitioning a system into sets of CPUs and
1017	  Memory Nodes and assigning tasks to run only within those sets.
1018	  This is primarily useful on large SMP or NUMA systems.
1019
1020	  Say N if unsure.
1021
1022config PROC_PID_CPUSET
1023	bool "Include legacy /proc/<pid>/cpuset file"
1024	depends on CPUSETS
1025	default y
1026
1027config CGROUP_DEVICE
1028	bool "Device controller"
1029	help
1030	  Provides a cgroup controller implementing whitelists for
1031	  devices which a process in the cgroup can mknod or open.
1032
1033config CGROUP_CPUACCT
1034	bool "Simple CPU accounting controller"
1035	help
1036	  Provides a simple controller for monitoring the
1037	  total CPU consumed by the tasks in a cgroup.
1038
1039config CGROUP_PERF
1040	bool "Perf controller"
1041	depends on PERF_EVENTS
1042	help
1043	  This option extends the perf per-cpu mode to restrict monitoring
1044	  to threads which belong to the cgroup specified and run on the
1045	  designated cpu.
1046
1047	  Say N if unsure.
1048
1049config CGROUP_BPF
1050	bool "Support for eBPF programs attached to cgroups"
1051	depends on BPF_SYSCALL
1052	select SOCK_CGROUP_DATA
1053	help
1054	  Allow attaching eBPF programs to a cgroup using the bpf(2)
1055	  syscall command BPF_PROG_ATTACH.
1056
1057	  In which context these programs are accessed depends on the type
1058	  of attachment. For instance, programs that are attached using
1059	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
1060	  inet sockets.
1061
1062config CGROUP_DEBUG
1063	bool "Debug controller"
1064	default n
1065	depends on DEBUG_KERNEL
1066	help
1067	  This option enables a simple controller that exports
1068	  debugging information about the cgroups framework. This
1069	  controller is for control cgroup debugging only. Its
1070	  interfaces are not stable.
1071
1072	  Say N.
1073
1074config SOCK_CGROUP_DATA
1075	bool
1076	default n
1077
1078endif # CGROUPS
1079
1080menuconfig NAMESPACES
1081	bool "Namespaces support" if EXPERT
1082	depends on MULTIUSER
1083	default !EXPERT
1084	help
1085	  Provides the way to make tasks work with different objects using
1086	  the same id. For example same IPC id may refer to different objects
1087	  or same user id or pid may refer to different tasks when used in
1088	  different namespaces.
1089
1090if NAMESPACES
1091
1092config UTS_NS
1093	bool "UTS namespace"
1094	default y
1095	help
1096	  In this namespace tasks see different info provided with the
1097	  uname() system call
1098
1099config IPC_NS
1100	bool "IPC namespace"
1101	depends on (SYSVIPC || POSIX_MQUEUE)
1102	default y
1103	help
1104	  In this namespace tasks work with IPC ids which correspond to
1105	  different IPC objects in different namespaces.
1106
1107config USER_NS
1108	bool "User namespace"
1109	default n
1110	help
1111	  This allows containers, i.e. vservers, to use user namespaces
1112	  to provide different user info for different servers.
1113
1114	  When user namespaces are enabled in the kernel it is
1115	  recommended that the MEMCG option also be enabled and that
1116	  user-space use the memory control groups to limit the amount
1117	  of memory a memory unprivileged users can use.
1118
1119	  If unsure, say N.
1120
1121config PID_NS
1122	bool "PID Namespaces"
1123	default y
1124	help
1125	  Support process id namespaces.  This allows having multiple
1126	  processes with the same pid as long as they are in different
1127	  pid namespaces.  This is a building block of containers.
1128
1129config NET_NS
1130	bool "Network namespace"
1131	depends on NET
1132	default y
1133	help
1134	  Allow user space to create what appear to be multiple instances
1135	  of the network stack.
1136
1137endif # NAMESPACES
1138
1139config CHECKPOINT_RESTORE
1140	bool "Checkpoint/restore support"
1141	select PROC_CHILDREN
1142	default n
1143	help
1144	  Enables additional kernel features in a sake of checkpoint/restore.
1145	  In particular it adds auxiliary prctl codes to setup process text,
1146	  data and heap segment sizes, and a few additional /proc filesystem
1147	  entries.
1148
1149	  If unsure, say N here.
1150
1151config SCHED_AUTOGROUP
1152	bool "Automatic process group scheduling"
1153	select CGROUPS
1154	select CGROUP_SCHED
1155	select FAIR_GROUP_SCHED
1156	help
1157	  This option optimizes the scheduler for common desktop workloads by
1158	  automatically creating and populating task groups.  This separation
1159	  of workloads isolates aggressive CPU burners (like build jobs) from
1160	  desktop applications.  Task group autogeneration is currently based
1161	  upon task session.
1162
1163config SYSFS_DEPRECATED
1164	bool "Enable deprecated sysfs features to support old userspace tools"
1165	depends on SYSFS
1166	default n
1167	help
1168	  This option adds code that switches the layout of the "block" class
1169	  devices, to not show up in /sys/class/block/, but only in
1170	  /sys/block/.
1171
1172	  This switch is only active when the sysfs.deprecated=1 boot option is
1173	  passed or the SYSFS_DEPRECATED_V2 option is set.
1174
1175	  This option allows new kernels to run on old distributions and tools,
1176	  which might get confused by /sys/class/block/. Since 2007/2008 all
1177	  major distributions and tools handle this just fine.
1178
1179	  Recent distributions and userspace tools after 2009/2010 depend on
1180	  the existence of /sys/class/block/, and will not work with this
1181	  option enabled.
1182
1183	  Only if you are using a new kernel on an old distribution, you might
1184	  need to say Y here.
1185
1186config SYSFS_DEPRECATED_V2
1187	bool "Enable deprecated sysfs features by default"
1188	default n
1189	depends on SYSFS
1190	depends on SYSFS_DEPRECATED
1191	help
1192	  Enable deprecated sysfs by default.
1193
1194	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
1195	  option.
1196
1197	  Only if you are using a new kernel on an old distribution, you might
1198	  need to say Y here. Even then, odds are you would not need it
1199	  enabled, you can always pass the boot option if absolutely necessary.
1200
1201config RELAY
1202	bool "Kernel->user space relay support (formerly relayfs)"
1203	select IRQ_WORK
1204	help
1205	  This option enables support for relay interface support in
1206	  certain file systems (such as debugfs).
1207	  It is designed to provide an efficient mechanism for tools and
1208	  facilities to relay large amounts of data from kernel space to
1209	  user space.
1210
1211	  If unsure, say N.
1212
1213config BLK_DEV_INITRD
1214	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
1215	help
1216	  The initial RAM filesystem is a ramfs which is loaded by the
1217	  boot loader (loadlin or lilo) and that is mounted as root
1218	  before the normal boot procedure. It is typically used to
1219	  load modules needed to mount the "real" root file system,
1220	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1221
1222	  If RAM disk support (BLK_DEV_RAM) is also included, this
1223	  also enables initial RAM disk (initrd) support and adds
1224	  15 Kbytes (more on some other architectures) to the kernel size.
1225
1226	  If unsure say Y.
1227
1228if BLK_DEV_INITRD
1229
1230source "usr/Kconfig"
1231
1232endif
1233
1234choice
1235	prompt "Compiler optimization level"
1236	default CC_OPTIMIZE_FOR_PERFORMANCE
1237
1238config CC_OPTIMIZE_FOR_PERFORMANCE
1239	bool "Optimize for performance (-O2)"
1240	help
1241	  This is the default optimization level for the kernel, building
1242	  with the "-O2" compiler flag for best performance and most
1243	  helpful compile-time warnings.
1244
1245config CC_OPTIMIZE_FOR_PERFORMANCE_O3
1246	bool "Optimize more for performance (-O3)"
1247	depends on ARC
1248	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
1249	help
1250	  Choosing this option will pass "-O3" to your compiler to optimize
1251	  the kernel yet more for performance.
1252
1253config CC_OPTIMIZE_FOR_SIZE
1254	bool "Optimize for size (-Os)"
1255	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
1256	help
1257	  Choosing this option will pass "-Os" to your compiler resulting
1258	  in a smaller kernel.
 
 
1259
1260endchoice
1261
1262config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1263	bool
1264	help
1265	  This requires that the arch annotates or otherwise protects
1266	  its external entry points from being discarded. Linker scripts
1267	  must also merge .text.*, .data.*, and .bss.* correctly into
1268	  output sections. Care must be taken not to pull in unrelated
1269	  sections (e.g., '.text.init'). Typically '.' in section names
1270	  is used to distinguish them from label names / C identifiers.
1271
1272config LD_DEAD_CODE_DATA_ELIMINATION
1273	bool "Dead code and data elimination (EXPERIMENTAL)"
1274	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
1275	depends on EXPERT
1276	depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
1277	depends on $(cc-option,-ffunction-sections -fdata-sections)
1278	depends on $(ld-option,--gc-sections)
1279	help
1280	  Enable this if you want to do dead code and data elimination with
1281	  the linker by compiling with -ffunction-sections -fdata-sections,
1282	  and linking with --gc-sections.
1283
1284	  This can reduce on disk and in-memory size of the kernel
1285	  code and static data, particularly for small configs and
1286	  on small systems. This has the possibility of introducing
1287	  silently broken kernel if the required annotations are not
1288	  present. This option is not well tested yet, so use at your
1289	  own risk.
1290
1291config SYSCTL
1292	bool
1293
1294config HAVE_UID16
1295	bool
1296
1297config SYSCTL_EXCEPTION_TRACE
1298	bool
1299	help
1300	  Enable support for /proc/sys/debug/exception-trace.
1301
1302config SYSCTL_ARCH_UNALIGN_NO_WARN
1303	bool
1304	help
1305	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1306	  Allows arch to define/use @no_unaligned_warning to possibly warn
1307	  about unaligned access emulation going on under the hood.
1308
1309config SYSCTL_ARCH_UNALIGN_ALLOW
1310	bool
1311	help
1312	  Enable support for /proc/sys/kernel/unaligned-trap
1313	  Allows arches to define/use @unaligned_enabled to runtime toggle
1314	  the unaligned access emulation.
1315	  see arch/parisc/kernel/unaligned.c for reference
1316
1317config HAVE_PCSPKR_PLATFORM
1318	bool
1319
1320# interpreter that classic socket filters depend on
1321config BPF
1322	bool
1323
1324menuconfig EXPERT
1325	bool "Configure standard kernel features (expert users)"
1326	# Unhide debug options, to make the on-by-default options visible
1327	select DEBUG_KERNEL
1328	help
1329	  This option allows certain base kernel options and settings
1330          to be disabled or tweaked. This is for specialized
1331          environments which can tolerate a "non-standard" kernel.
1332          Only use this if you really know what you are doing.
1333
1334config UID16
1335	bool "Enable 16-bit UID system calls" if EXPERT
1336	depends on HAVE_UID16 && MULTIUSER
1337	default y
1338	help
1339	  This enables the legacy 16-bit UID syscall wrappers.
1340
1341config MULTIUSER
1342	bool "Multiple users, groups and capabilities support" if EXPERT
1343	default y
1344	help
1345	  This option enables support for non-root users, groups and
1346	  capabilities.
1347
1348	  If you say N here, all processes will run with UID 0, GID 0, and all
1349	  possible capabilities.  Saying N here also compiles out support for
1350	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
1351	  setgid, and capset.
1352
1353	  If unsure, say Y here.
1354
1355config SGETMASK_SYSCALL
1356	bool "sgetmask/ssetmask syscalls support" if EXPERT
1357	def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1358	---help---
1359	  sys_sgetmask and sys_ssetmask are obsolete system calls
1360	  no longer supported in libc but still enabled by default in some
1361	  architectures.
1362
1363	  If unsure, leave the default option here.
1364
1365config SYSFS_SYSCALL
1366	bool "Sysfs syscall support" if EXPERT
1367	default y
1368	---help---
1369	  sys_sysfs is an obsolete system call no longer supported in libc.
1370	  Note that disabling this option is more secure but might break
1371	  compatibility with some systems.
1372
1373	  If unsure say Y here.
1374
1375config SYSCTL_SYSCALL
1376	bool "Sysctl syscall support" if EXPERT
1377	depends on PROC_SYSCTL
1378	default n
1379	select SYSCTL
1380	---help---
1381	  sys_sysctl uses binary paths that have been found challenging
1382	  to properly maintain and use.  The interface in /proc/sys
1383	  using paths with ascii names is now the primary path to this
1384	  information.
1385
1386	  Almost nothing using the binary sysctl interface so if you are
1387	  trying to save some space it is probably safe to disable this,
1388	  making your kernel marginally smaller.
1389
1390	  If unsure say N here.
1391
1392config FHANDLE
1393	bool "open by fhandle syscalls" if EXPERT
1394	select EXPORTFS
1395	default y
1396	help
1397	  If you say Y here, a user level program will be able to map
1398	  file names to handle and then later use the handle for
1399	  different file system operations. This is useful in implementing
1400	  userspace file servers, which now track files using handles instead
1401	  of names. The handle would remain the same even if file names
1402	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1403	  syscalls.
1404
1405config POSIX_TIMERS
1406	bool "Posix Clocks & timers" if EXPERT
1407	default y
1408	help
1409	  This includes native support for POSIX timers to the kernel.
1410	  Some embedded systems have no use for them and therefore they
1411	  can be configured out to reduce the size of the kernel image.
1412
1413	  When this option is disabled, the following syscalls won't be
1414	  available: timer_create, timer_gettime: timer_getoverrun,
1415	  timer_settime, timer_delete, clock_adjtime, getitimer,
1416	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1417	  clock_getres and clock_nanosleep syscalls will be limited to
1418	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1419
1420	  If unsure say y.
1421
1422config PRINTK
1423	default y
1424	bool "Enable support for printk" if EXPERT
1425	select IRQ_WORK
1426	help
1427	  This option enables normal printk support. Removing it
1428	  eliminates most of the message strings from the kernel image
1429	  and makes the kernel more or less silent. As this makes it
1430	  very difficult to diagnose system problems, saying N here is
1431	  strongly discouraged.
1432
1433config PRINTK_NMI
1434	def_bool y
1435	depends on PRINTK
1436	depends on HAVE_NMI
1437
1438config BUG
1439	bool "BUG() support" if EXPERT
1440	default y
1441	help
1442          Disabling this option eliminates support for BUG and WARN, reducing
1443          the size of your kernel image and potentially quietly ignoring
1444          numerous fatal conditions. You should only consider disabling this
1445          option for embedded systems with no facilities for reporting errors.
1446          Just say Y.
1447
1448config ELF_CORE
1449	depends on COREDUMP
1450	default y
1451	bool "Enable ELF core dumps" if EXPERT
1452	help
1453	  Enable support for generating core dumps. Disabling saves about 4k.
1454
1455
1456config PCSPKR_PLATFORM
1457	bool "Enable PC-Speaker support" if EXPERT
1458	depends on HAVE_PCSPKR_PLATFORM
1459	select I8253_LOCK
1460	default y
1461	help
1462          This option allows to disable the internal PC-Speaker
1463          support, saving some memory.
1464
1465config BASE_FULL
1466	default y
1467	bool "Enable full-sized data structures for core" if EXPERT
1468	help
1469	  Disabling this option reduces the size of miscellaneous core
1470	  kernel data structures. This saves memory on small machines,
1471	  but may reduce performance.
1472
1473config FUTEX
1474	bool "Enable futex support" if EXPERT
1475	default y
1476	imply RT_MUTEXES
1477	help
1478	  Disabling this option will cause the kernel to be built without
1479	  support for "fast userspace mutexes".  The resulting kernel may not
1480	  run glibc-based applications correctly.
1481
1482config FUTEX_PI
1483	bool
1484	depends on FUTEX && RT_MUTEXES
1485	default y
1486
1487config HAVE_FUTEX_CMPXCHG
1488	bool
1489	depends on FUTEX
1490	help
1491	  Architectures should select this if futex_atomic_cmpxchg_inatomic()
1492	  is implemented and always working. This removes a couple of runtime
1493	  checks.
1494
1495config EPOLL
1496	bool "Enable eventpoll support" if EXPERT
1497	default y
 
1498	help
1499	  Disabling this option will cause the kernel to be built without
1500	  support for epoll family of system calls.
1501
1502config SIGNALFD
1503	bool "Enable signalfd() system call" if EXPERT
 
1504	default y
1505	help
1506	  Enable the signalfd() system call that allows to receive signals
1507	  on a file descriptor.
1508
1509	  If unsure, say Y.
1510
1511config TIMERFD
1512	bool "Enable timerfd() system call" if EXPERT
 
1513	default y
1514	help
1515	  Enable the timerfd() system call that allows to receive timer
1516	  events on a file descriptor.
1517
1518	  If unsure, say Y.
1519
1520config EVENTFD
1521	bool "Enable eventfd() system call" if EXPERT
 
1522	default y
1523	help
1524	  Enable the eventfd() system call that allows to receive both
1525	  kernel notification (ie. KAIO) or userspace notifications.
1526
1527	  If unsure, say Y.
1528
1529config SHMEM
1530	bool "Use full shmem filesystem" if EXPERT
1531	default y
1532	depends on MMU
1533	help
1534	  The shmem is an internal filesystem used to manage shared memory.
1535	  It is backed by swap and manages resource limits. It is also exported
1536	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1537	  option replaces shmem and tmpfs with the much simpler ramfs code,
1538	  which may be appropriate on small systems without swap.
1539
1540config AIO
1541	bool "Enable AIO support" if EXPERT
1542	default y
1543	help
1544	  This option enables POSIX asynchronous I/O which may by used
1545	  by some high performance threaded applications. Disabling
1546	  this option saves about 7k.
1547
1548config IO_URING
1549	bool "Enable IO uring support" if EXPERT
1550	select ANON_INODES
1551	default y
1552	help
1553	  This option enables support for the io_uring interface, enabling
1554	  applications to submit and complete IO through submission and
1555	  completion rings that are shared between the kernel and application.
1556
1557config ADVISE_SYSCALLS
1558	bool "Enable madvise/fadvise syscalls" if EXPERT
1559	default y
1560	help
1561	  This option enables the madvise and fadvise syscalls, used by
1562	  applications to advise the kernel about their future memory or file
1563	  usage, improving performance. If building an embedded system where no
1564	  applications use these syscalls, you can disable this option to save
1565	  space.
1566
1567config MEMBARRIER
1568	bool "Enable membarrier() system call" if EXPERT
1569	default y
1570	help
1571	  Enable the membarrier() system call that allows issuing memory
1572	  barriers across all running threads, which can be used to distribute
1573	  the cost of user-space memory barriers asymmetrically by transforming
1574	  pairs of memory barriers into pairs consisting of membarrier() and a
1575	  compiler barrier.
1576
1577	  If unsure, say Y.
1578
 
 
 
 
 
 
 
 
 
 
 
 
1579config KALLSYMS
1580	 bool "Load all symbols for debugging/ksymoops" if EXPERT
1581	 default y
1582	 help
1583	   Say Y here to let the kernel print out symbolic crash information and
1584	   symbolic stack backtraces. This increases the size of the kernel
1585	   somewhat, as all symbols have to be loaded into the kernel image.
1586
1587config KALLSYMS_ALL
1588	bool "Include all symbols in kallsyms"
1589	depends on DEBUG_KERNEL && KALLSYMS
1590	help
1591	   Normally kallsyms only contains the symbols of functions for nicer
1592	   OOPS messages and backtraces (i.e., symbols from the text and inittext
1593	   sections). This is sufficient for most cases. And only in very rare
1594	   cases (e.g., when a debugger is used) all symbols are required (e.g.,
1595	   names of variables from the data sections, etc).
1596
1597	   This option makes sure that all symbols are loaded into the kernel
1598	   image (i.e., symbols from all sections) in cost of increased kernel
1599	   size (depending on the kernel configuration, it may be 300KiB or
1600	   something like this).
1601
1602	   Say N unless you really need all symbols.
1603
1604config KALLSYMS_ABSOLUTE_PERCPU
1605	bool
1606	depends on KALLSYMS
1607	default X86_64 && SMP
1608
1609config KALLSYMS_BASE_RELATIVE
1610	bool
1611	depends on KALLSYMS
1612	default !IA64
1613	help
1614	  Instead of emitting them as absolute values in the native word size,
1615	  emit the symbol references in the kallsyms table as 32-bit entries,
1616	  each containing a relative value in the range [base, base + U32_MAX]
1617	  or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1618	  an absolute value in the range [0, S32_MAX] or a relative value in the
1619	  range [base, base + S32_MAX], where base is the lowest relative symbol
1620	  address encountered in the image.
1621
1622	  On 64-bit builds, this reduces the size of the address table by 50%,
1623	  but more importantly, it results in entries whose values are build
1624	  time constants, and no relocation pass is required at runtime to fix
1625	  up the entries based on the runtime load address of the kernel.
1626
1627# end of the "standard kernel features (expert users)" menu
1628
1629# syscall, maps, verifier
1630config BPF_SYSCALL
1631	bool "Enable bpf() system call"
 
1632	select BPF
1633	select IRQ_WORK
1634	default n
1635	help
1636	  Enable the bpf() system call that allows to manipulate eBPF
1637	  programs and maps via file descriptors.
1638
1639config BPF_JIT_ALWAYS_ON
1640	bool "Permanently enable BPF JIT and remove BPF interpreter"
1641	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1642	help
1643	  Enables BPF JIT and removes BPF interpreter to avoid
1644	  speculative execution of BPF instructions by the interpreter
1645
1646config USERFAULTFD
1647	bool "Enable userfaultfd() system call"
 
1648	depends on MMU
1649	help
1650	  Enable the userfaultfd() system call that allows to intercept and
1651	  handle page faults in userland.
1652
1653config ARCH_HAS_MEMBARRIER_CALLBACKS
1654	bool
1655
1656config ARCH_HAS_MEMBARRIER_SYNC_CORE
1657	bool
1658
1659config RSEQ
1660	bool "Enable rseq() system call" if EXPERT
1661	default y
1662	depends on HAVE_RSEQ
1663	select MEMBARRIER
1664	help
1665	  Enable the restartable sequences system call. It provides a
1666	  user-space cache for the current CPU number value, which
1667	  speeds up getting the current CPU number from user-space,
1668	  as well as an ABI to speed up user-space operations on
1669	  per-CPU data.
1670
1671	  If unsure, say Y.
1672
1673config DEBUG_RSEQ
1674	default n
1675	bool "Enabled debugging of rseq() system call" if EXPERT
1676	depends on RSEQ && DEBUG_KERNEL
1677	help
1678	  Enable extra debugging checks for the rseq system call.
1679
1680	  If unsure, say N.
1681
1682config EMBEDDED
1683	bool "Embedded system"
1684	option allnoconfig_y
1685	select EXPERT
1686	help
1687	  This option should be enabled if compiling the kernel for
1688	  an embedded system so certain expert options are available
1689	  for configuration.
1690
1691config HAVE_PERF_EVENTS
1692	bool
1693	help
1694	  See tools/perf/design.txt for details.
1695
1696config PERF_USE_VMALLOC
1697	bool
1698	help
1699	  See tools/perf/design.txt for details
1700
1701config PC104
1702	bool "PC/104 support" if EXPERT
1703	help
1704	  Expose PC/104 form factor device drivers and options available for
1705	  selection and configuration. Enable this option if your target
1706	  machine has a PC/104 bus.
1707
1708menu "Kernel Performance Events And Counters"
1709
1710config PERF_EVENTS
1711	bool "Kernel performance events and counters"
1712	default y if PROFILING
1713	depends on HAVE_PERF_EVENTS
 
1714	select IRQ_WORK
1715	select SRCU
1716	help
1717	  Enable kernel support for various performance events provided
1718	  by software and hardware.
1719
1720	  Software events are supported either built-in or via the
1721	  use of generic tracepoints.
1722
1723	  Most modern CPUs support performance events via performance
1724	  counter registers. These registers count the number of certain
1725	  types of hw events: such as instructions executed, cachemisses
1726	  suffered, or branches mis-predicted - without slowing down the
1727	  kernel or applications. These registers can also trigger interrupts
1728	  when a threshold number of events have passed - and can thus be
1729	  used to profile the code that runs on that CPU.
1730
1731	  The Linux Performance Event subsystem provides an abstraction of
1732	  these software and hardware event capabilities, available via a
1733	  system call and used by the "perf" utility in tools/perf/. It
1734	  provides per task and per CPU counters, and it provides event
1735	  capabilities on top of those.
1736
1737	  Say Y if unsure.
1738
1739config DEBUG_PERF_USE_VMALLOC
1740	default n
1741	bool "Debug: use vmalloc to back perf mmap() buffers"
1742	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1743	select PERF_USE_VMALLOC
1744	help
1745	 Use vmalloc memory to back perf mmap() buffers.
1746
1747	 Mostly useful for debugging the vmalloc code on platforms
1748	 that don't require it.
1749
1750	 Say N if unsure.
1751
1752endmenu
1753
1754config VM_EVENT_COUNTERS
1755	default y
1756	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1757	help
1758	  VM event counters are needed for event counts to be shown.
1759	  This option allows the disabling of the VM event counters
1760	  on EXPERT systems.  /proc/vmstat will only show page counts
1761	  if VM event counters are disabled.
1762
1763config SLUB_DEBUG
1764	default y
1765	bool "Enable SLUB debugging support" if EXPERT
1766	depends on SLUB && SYSFS
1767	help
1768	  SLUB has extensive debug support features. Disabling these can
1769	  result in significant savings in code size. This also disables
1770	  SLUB sysfs support. /sys/slab will not exist and there will be
1771	  no support for cache validation etc.
1772
1773config SLUB_MEMCG_SYSFS_ON
1774	default n
1775	bool "Enable memcg SLUB sysfs support by default" if EXPERT
1776	depends on SLUB && SYSFS && MEMCG
1777	help
1778	  SLUB creates a directory under /sys/kernel/slab for each
1779	  allocation cache to host info and debug files. If memory
1780	  cgroup is enabled, each cache can have per memory cgroup
1781	  caches. SLUB can create the same sysfs directories for these
1782	  caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1783	  to a very high number of debug files being created. This is
1784	  controlled by slub_memcg_sysfs boot parameter and this
1785	  config option determines the parameter's default value.
1786
1787config COMPAT_BRK
1788	bool "Disable heap randomization"
1789	default y
1790	help
1791	  Randomizing heap placement makes heap exploits harder, but it
1792	  also breaks ancient binaries (including anything libc5 based).
1793	  This option changes the bootup default to heap randomization
1794	  disabled, and can be overridden at runtime by setting
1795	  /proc/sys/kernel/randomize_va_space to 2.
1796
1797	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
1798
1799choice
1800	prompt "Choose SLAB allocator"
1801	default SLUB
1802	help
1803	   This option allows to select a slab allocator.
1804
1805config SLAB
1806	bool "SLAB"
1807	select HAVE_HARDENED_USERCOPY_ALLOCATOR
1808	help
1809	  The regular slab allocator that is established and known to work
1810	  well in all environments. It organizes cache hot objects in
1811	  per cpu and per node queues.
1812
1813config SLUB
1814	bool "SLUB (Unqueued Allocator)"
1815	select HAVE_HARDENED_USERCOPY_ALLOCATOR
1816	help
1817	   SLUB is a slab allocator that minimizes cache line usage
1818	   instead of managing queues of cached objects (SLAB approach).
1819	   Per cpu caching is realized using slabs of objects instead
1820	   of queues of objects. SLUB can use memory efficiently
1821	   and has enhanced diagnostics. SLUB is the default choice for
1822	   a slab allocator.
1823
1824config SLOB
1825	depends on EXPERT
1826	bool "SLOB (Simple Allocator)"
1827	help
1828	   SLOB replaces the stock allocator with a drastically simpler
1829	   allocator. SLOB is generally more space efficient but
1830	   does not perform as well on large systems.
1831
1832endchoice
1833
1834config SLAB_MERGE_DEFAULT
1835	bool "Allow slab caches to be merged"
1836	default y
1837	help
1838	  For reduced kernel memory fragmentation, slab caches can be
1839	  merged when they share the same size and other characteristics.
1840	  This carries a risk of kernel heap overflows being able to
1841	  overwrite objects from merged caches (and more easily control
1842	  cache layout), which makes such heap attacks easier to exploit
1843	  by attackers. By keeping caches unmerged, these kinds of exploits
1844	  can usually only damage objects in the same cache. To disable
1845	  merging at runtime, "slab_nomerge" can be passed on the kernel
1846	  command line.
1847
1848config SLAB_FREELIST_RANDOM
1849	default n
1850	depends on SLAB || SLUB
1851	bool "SLAB freelist randomization"
1852	help
1853	  Randomizes the freelist order used on creating new pages. This
1854	  security feature reduces the predictability of the kernel slab
1855	  allocator against heap overflows.
1856
1857config SLAB_FREELIST_HARDENED
1858	bool "Harden slab freelist metadata"
1859	depends on SLUB
1860	help
1861	  Many kernel heap attacks try to target slab cache metadata and
1862	  other infrastructure. This options makes minor performance
1863	  sacrifices to harden the kernel slab allocator against common
1864	  freelist exploit methods.
1865
1866config SHUFFLE_PAGE_ALLOCATOR
1867	bool "Page allocator randomization"
1868	default SLAB_FREELIST_RANDOM && ACPI_NUMA
1869	help
1870	  Randomization of the page allocator improves the average
1871	  utilization of a direct-mapped memory-side-cache. See section
1872	  5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
1873	  6.2a specification for an example of how a platform advertises
1874	  the presence of a memory-side-cache. There are also incidental
1875	  security benefits as it reduces the predictability of page
1876	  allocations to compliment SLAB_FREELIST_RANDOM, but the
1877	  default granularity of shuffling on the "MAX_ORDER - 1" i.e,
1878	  10th order of pages is selected based on cache utilization
1879	  benefits on x86.
1880
1881	  While the randomization improves cache utilization it may
1882	  negatively impact workloads on platforms without a cache. For
1883	  this reason, by default, the randomization is enabled only
1884	  after runtime detection of a direct-mapped memory-side-cache.
1885	  Otherwise, the randomization may be force enabled with the
1886	  'page_alloc.shuffle' kernel command line parameter.
1887
1888	  Say Y if unsure.
1889
1890config SLUB_CPU_PARTIAL
1891	default y
1892	depends on SLUB && SMP
1893	bool "SLUB per cpu partial cache"
1894	help
1895	  Per cpu partial caches accelerate objects allocation and freeing
1896	  that is local to a processor at the price of more indeterminism
1897	  in the latency of the free. On overflow these caches will be cleared
1898	  which requires the taking of locks that may cause latency spikes.
1899	  Typically one would choose no for a realtime system.
1900
1901config MMAP_ALLOW_UNINITIALIZED
1902	bool "Allow mmapped anonymous memory to be uninitialized"
1903	depends on EXPERT && !MMU
1904	default n
1905	help
1906	  Normally, and according to the Linux spec, anonymous memory obtained
1907	  from mmap() has its contents cleared before it is passed to
1908	  userspace.  Enabling this config option allows you to request that
1909	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1910	  providing a huge performance boost.  If this option is not enabled,
1911	  then the flag will be ignored.
1912
1913	  This is taken advantage of by uClibc's malloc(), and also by
1914	  ELF-FDPIC binfmt's brk and stack allocator.
1915
1916	  Because of the obvious security issues, this option should only be
1917	  enabled on embedded devices where you control what is run in
1918	  userspace.  Since that isn't generally a problem on no-MMU systems,
1919	  it is normally safe to say Y here.
1920
1921	  See Documentation/nommu-mmap.txt for more information.
1922
1923config SYSTEM_DATA_VERIFICATION
1924	def_bool n
1925	select SYSTEM_TRUSTED_KEYRING
1926	select KEYS
1927	select CRYPTO
1928	select CRYPTO_RSA
1929	select ASYMMETRIC_KEY_TYPE
1930	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1931	select ASN1
1932	select OID_REGISTRY
1933	select X509_CERTIFICATE_PARSER
1934	select PKCS7_MESSAGE_PARSER
1935	help
1936	  Provide PKCS#7 message verification using the contents of the system
1937	  trusted keyring to provide public keys.  This then can be used for
1938	  module verification, kexec image verification and firmware blob
1939	  verification.
1940
1941config PROFILING
1942	bool "Profiling support"
1943	help
1944	  Say Y here to enable the extended profiling support mechanisms used
1945	  by profilers such as OProfile.
1946
1947#
1948# Place an empty function call at each tracepoint site. Can be
1949# dynamically changed for a probe function.
1950#
1951config TRACEPOINTS
1952	bool
1953
 
 
1954endmenu		# General setup
1955
1956source "arch/Kconfig"
 
 
1957
1958config RT_MUTEXES
1959	bool
1960
1961config BASE_SMALL
1962	int
1963	default 0 if BASE_FULL
1964	default 1 if !BASE_FULL
1965
1966config MODULE_SIG_FORMAT
1967	def_bool n
1968	select SYSTEM_DATA_VERIFICATION
1969
1970menuconfig MODULES
1971	bool "Enable loadable module support"
1972	option modules
1973	help
1974	  Kernel modules are small pieces of compiled code which can
1975	  be inserted in the running kernel, rather than being
1976	  permanently built into the kernel.  You use the "modprobe"
1977	  tool to add (and sometimes remove) them.  If you say Y here,
1978	  many parts of the kernel can be built as modules (by
1979	  answering M instead of Y where indicated): this is most
1980	  useful for infrequently used options which are not required
1981	  for booting.  For more information, see the man pages for
1982	  modprobe, lsmod, modinfo, insmod and rmmod.
1983
1984	  If you say Y here, you will need to run "make
1985	  modules_install" to put the modules under /lib/modules/
1986	  where modprobe can find them (you may need to be root to do
1987	  this).
1988
1989	  If unsure, say Y.
1990
1991if MODULES
1992
1993config MODULE_FORCE_LOAD
1994	bool "Forced module loading"
1995	default n
1996	help
1997	  Allow loading of modules without version information (ie. modprobe
1998	  --force).  Forced module loading sets the 'F' (forced) taint flag and
1999	  is usually a really bad idea.
2000
2001config MODULE_UNLOAD
2002	bool "Module unloading"
2003	help
2004	  Without this option you will not be able to unload any
2005	  modules (note that some modules may not be unloadable
2006	  anyway), which makes your kernel smaller, faster
2007	  and simpler.  If unsure, say Y.
2008
2009config MODULE_FORCE_UNLOAD
2010	bool "Forced module unloading"
2011	depends on MODULE_UNLOAD
2012	help
2013	  This option allows you to force a module to unload, even if the
2014	  kernel believes it is unsafe: the kernel will remove the module
2015	  without waiting for anyone to stop using it (using the -f option to
2016	  rmmod).  This is mainly for kernel developers and desperate users.
2017	  If unsure, say N.
2018
2019config MODVERSIONS
2020	bool "Module versioning support"
2021	help
2022	  Usually, you have to use modules compiled with your kernel.
2023	  Saying Y here makes it sometimes possible to use modules
2024	  compiled for different kernels, by adding enough information
2025	  to the modules to (hopefully) spot any changes which would
2026	  make them incompatible with the kernel you are running.  If
2027	  unsure, say N.
2028
2029config ASM_MODVERSIONS
2030	bool
2031	default HAVE_ASM_MODVERSIONS && MODVERSIONS
2032	help
2033	  This enables module versioning for exported symbols also from
2034	  assembly. This can be enabled only when the target architecture
2035	  supports it.
2036
2037config MODULE_REL_CRCS
2038	bool
2039	depends on MODVERSIONS
2040
2041config MODULE_SRCVERSION_ALL
2042	bool "Source checksum for all modules"
2043	help
2044	  Modules which contain a MODULE_VERSION get an extra "srcversion"
2045	  field inserted into their modinfo section, which contains a
2046    	  sum of the source files which made it.  This helps maintainers
2047	  see exactly which source was used to build a module (since
2048	  others sometimes change the module source without updating
2049	  the version).  With this option, such a "srcversion" field
2050	  will be created for all modules.  If unsure, say N.
2051
2052config MODULE_SIG
2053	bool "Module signature verification"
2054	select MODULE_SIG_FORMAT
 
2055	help
2056	  Check modules for valid signatures upon load: the signature
2057	  is simply appended to the module. For more information see
2058	  <file:Documentation/admin-guide/module-signing.rst>.
2059
2060	  Note that this option adds the OpenSSL development packages as a
2061	  kernel build dependency so that the signing tool can use its crypto
2062	  library.
2063
2064	  You should enable this option if you wish to use either
2065	  CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
2066	  another LSM - otherwise unsigned modules will be loadable regardless
2067	  of the lockdown policy.
2068
2069	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
2070	  module DOES NOT get stripped after being signed.  This includes the
2071	  debuginfo strip done by some packagers (such as rpmbuild) and
2072	  inclusion into an initramfs that wants the module size reduced.
2073
2074config MODULE_SIG_FORCE
2075	bool "Require modules to be validly signed"
2076	depends on MODULE_SIG
2077	help
2078	  Reject unsigned modules or signed modules for which we don't have a
2079	  key.  Without this, such modules will simply taint the kernel.
2080
2081config MODULE_SIG_ALL
2082	bool "Automatically sign all modules"
2083	default y
2084	depends on MODULE_SIG
2085	help
2086	  Sign all modules during make modules_install. Without this option,
2087	  modules must be signed manually, using the scripts/sign-file tool.
2088
2089comment "Do not forget to sign required modules with scripts/sign-file"
2090	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
2091
2092choice
2093	prompt "Which hash algorithm should modules be signed with?"
2094	depends on MODULE_SIG
2095	help
2096	  This determines which sort of hashing algorithm will be used during
2097	  signature generation.  This algorithm _must_ be built into the kernel
2098	  directly so that signature verification can take place.  It is not
2099	  possible to load a signed module containing the algorithm to check
2100	  the signature on that module.
2101
2102config MODULE_SIG_SHA1
2103	bool "Sign modules with SHA-1"
2104	select CRYPTO_SHA1
2105
2106config MODULE_SIG_SHA224
2107	bool "Sign modules with SHA-224"
2108	select CRYPTO_SHA256
2109
2110config MODULE_SIG_SHA256
2111	bool "Sign modules with SHA-256"
2112	select CRYPTO_SHA256
2113
2114config MODULE_SIG_SHA384
2115	bool "Sign modules with SHA-384"
2116	select CRYPTO_SHA512
2117
2118config MODULE_SIG_SHA512
2119	bool "Sign modules with SHA-512"
2120	select CRYPTO_SHA512
2121
2122endchoice
2123
2124config MODULE_SIG_HASH
2125	string
2126	depends on MODULE_SIG
2127	default "sha1" if MODULE_SIG_SHA1
2128	default "sha224" if MODULE_SIG_SHA224
2129	default "sha256" if MODULE_SIG_SHA256
2130	default "sha384" if MODULE_SIG_SHA384
2131	default "sha512" if MODULE_SIG_SHA512
2132
2133config MODULE_COMPRESS
2134	bool "Compress modules on installation"
 
2135	help
2136
2137	  Compresses kernel modules when 'make modules_install' is run; gzip or
2138	  xz depending on "Compression algorithm" below.
2139
2140	  module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
2141
2142	  Out-of-tree kernel modules installed using Kbuild will also be
2143	  compressed upon installation.
2144
2145	  Note: for modules inside an initrd or initramfs, it's more efficient
2146	  to compress the whole initrd or initramfs instead.
2147
2148	  Note: This is fully compatible with signed modules.
2149
2150	  If in doubt, say N.
2151
2152choice
2153	prompt "Compression algorithm"
2154	depends on MODULE_COMPRESS
2155	default MODULE_COMPRESS_GZIP
2156	help
2157	  This determines which sort of compression will be used during
2158	  'make modules_install'.
2159
2160	  GZIP (default) and XZ are supported.
2161
2162config MODULE_COMPRESS_GZIP
2163	bool "GZIP"
2164
2165config MODULE_COMPRESS_XZ
2166	bool "XZ"
2167
2168endchoice
2169
2170config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
2171	bool "Allow loading of modules with missing namespace imports"
2172	help
2173	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
2174	  a namespace. A module that makes use of a symbol exported with such a
2175	  namespace is required to import the namespace via MODULE_IMPORT_NS().
2176	  There is no technical reason to enforce correct namespace imports,
2177	  but it creates consistency between symbols defining namespaces and
2178	  users importing namespaces they make use of. This option relaxes this
2179	  requirement and lifts the enforcement when loading a module.
2180
2181	  If unsure, say N.
2182
2183config UNUSED_SYMBOLS
2184	bool "Enable unused/obsolete exported symbols"
2185	default y if X86
2186	help
2187	  Unused but exported symbols make the kernel needlessly bigger.  For
2188	  that reason most of these unused exports will soon be removed.  This
2189	  option is provided temporarily to provide a transition period in case
2190	  some external kernel module needs one of these symbols anyway. If you
2191	  encounter such a case in your module, consider if you are actually
2192	  using the right API.  (rationale: since nobody in the kernel is using
2193	  this in a module, there is a pretty good chance it's actually the
2194	  wrong interface to use).  If you really need the symbol, please send a
2195	  mail to the linux kernel mailing list mentioning the symbol and why
2196	  you really need it, and what the merge plan to the mainline kernel for
2197	  your module is.
2198
2199config TRIM_UNUSED_KSYMS
2200	bool "Trim unused exported kernel symbols"
2201	depends on !UNUSED_SYMBOLS
2202	help
2203	  The kernel and some modules make many symbols available for
2204	  other modules to use via EXPORT_SYMBOL() and variants. Depending
2205	  on the set of modules being selected in your kernel configuration,
2206	  many of those exported symbols might never be used.
2207
2208	  This option allows for unused exported symbols to be dropped from
2209	  the build. In turn, this provides the compiler more opportunities
2210	  (especially when using LTO) for optimizing the code and reducing
2211	  binary size.  This might have some security advantages as well.
2212
2213	  If unsure, or if you need to build out-of-tree modules, say N.
2214
2215endif # MODULES
2216
2217config MODULES_TREE_LOOKUP
2218	def_bool y
2219	depends on PERF_EVENTS || TRACING
2220
2221config INIT_ALL_POSSIBLE
2222	bool
2223	help
2224	  Back when each arch used to define their own cpu_online_mask and
2225	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
2226	  with all 1s, and others with all 0s.  When they were centralised,
2227	  it was better to provide this option than to break all the archs
2228	  and have several arch maintainers pursuing me down dark alleys.
2229
2230source "block/Kconfig"
2231
2232config PREEMPT_NOTIFIERS
2233	bool
2234
2235config PADATA
2236	depends on SMP
2237	bool
2238
2239config ASN1
2240	tristate
2241	help
2242	  Build a simple ASN.1 grammar compiler that produces a bytecode output
2243	  that can be interpreted by the ASN.1 stream decoder and used to
2244	  inform it as to what tags are to be expected in a stream and what
2245	  functions to call on what tags.
2246
2247source "kernel/Kconfig.locks"
2248
2249config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
2250	bool
2251
2252# It may be useful for an architecture to override the definitions of the
2253# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
2254# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
2255# different calling convention for syscalls. They can also override the
2256# macros for not-implemented syscalls in kernel/sys_ni.c and
2257# kernel/time/posix-stubs.c. All these overrides need to be available in
2258# <asm/syscall_wrapper.h>.
2259config ARCH_HAS_SYSCALL_WRAPPER
2260	def_bool n