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   1config ARCH
   2	string
   3	option env="ARCH"
   4
   5config KERNELVERSION
   6	string
   7	option env="KERNELVERSION"
   8
   9config DEFCONFIG_LIST
  10	string
  11	depends on !UML
  12	option defconfig_list
  13	default "/lib/modules/$UNAME_RELEASE/.config"
  14	default "/etc/kernel-config"
  15	default "/boot/config-$UNAME_RELEASE"
  16	default "$ARCH_DEFCONFIG"
  17	default "arch/$ARCH/defconfig"
  18
  19config CONSTRUCTORS
  20	bool
  21	depends on !UML
  22
  23config HAVE_IRQ_WORK
  24	bool
  25
  26config IRQ_WORK
  27	bool
  28	depends on HAVE_IRQ_WORK
  29
  30menu "General setup"
 
 
 
 
 
  31
  32config EXPERIMENTAL
  33	bool "Prompt for development and/or incomplete code/drivers"
  34	---help---
  35	  Some of the various things that Linux supports (such as network
  36	  drivers, file systems, network protocols, etc.) can be in a state
  37	  of development where the functionality, stability, or the level of
  38	  testing is not yet high enough for general use. This is usually
  39	  known as the "alpha-test" phase among developers. If a feature is
  40	  currently in alpha-test, then the developers usually discourage
  41	  uninformed widespread use of this feature by the general public to
  42	  avoid "Why doesn't this work?" type mail messages. However, active
  43	  testing and use of these systems is welcomed. Just be aware that it
  44	  may not meet the normal level of reliability or it may fail to work
  45	  in some special cases. Detailed bug reports from people familiar
  46	  with the kernel internals are usually welcomed by the developers
  47	  (before submitting bug reports, please read the documents
  48	  <file:README>, <file:MAINTAINERS>, <file:REPORTING-BUGS>,
  49	  <file:Documentation/BUG-HUNTING>, and
  50	  <file:Documentation/oops-tracing.txt> in the kernel source).
  51
  52	  This option will also make obsoleted drivers available. These are
  53	  drivers that have been replaced by something else, and/or are
  54	  scheduled to be removed in a future kernel release.
  55
  56	  Unless you intend to help test and develop a feature or driver that
  57	  falls into this category, or you have a situation that requires
  58	  using these features, you should probably say N here, which will
  59	  cause the configurator to present you with fewer choices. If
  60	  you say Y here, you will be offered the choice of using features or
  61	  drivers that are currently considered to be in the alpha-test phase.
  62
  63config BROKEN
  64	bool
  65
  66config BROKEN_ON_SMP
  67	bool
  68	depends on BROKEN || !SMP
  69	default y
  70
  71config INIT_ENV_ARG_LIMIT
  72	int
  73	default 32 if !UML
  74	default 128 if UML
  75	help
  76	  Maximum of each of the number of arguments and environment
  77	  variables passed to init from the kernel command line.
  78
  79
  80config CROSS_COMPILE
  81	string "Cross-compiler tool prefix"
  82	help
  83	  Same as running 'make CROSS_COMPILE=prefix-' but stored for
  84	  default make runs in this kernel build directory.  You don't
  85	  need to set this unless you want the configured kernel build
  86	  directory to select the cross-compiler automatically.
  87
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  88config LOCALVERSION
  89	string "Local version - append to kernel release"
  90	help
  91	  Append an extra string to the end of your kernel version.
  92	  This will show up when you type uname, for example.
  93	  The string you set here will be appended after the contents of
  94	  any files with a filename matching localversion* in your
  95	  object and source tree, in that order.  Your total string can
  96	  be a maximum of 64 characters.
  97
  98config LOCALVERSION_AUTO
  99	bool "Automatically append version information to the version string"
 100	default y
 
 101	help
 102	  This will try to automatically determine if the current tree is a
 103	  release tree by looking for git tags that belong to the current
 104	  top of tree revision.
 105
 106	  A string of the format -gxxxxxxxx will be added to the localversion
 107	  if a git-based tree is found.  The string generated by this will be
 108	  appended after any matching localversion* files, and after the value
 109	  set in CONFIG_LOCALVERSION.
 110
 111	  (The actual string used here is the first eight characters produced
 112	  by running the command:
 113
 114	    $ git rev-parse --verify HEAD
 115
 116	  which is done within the script "scripts/setlocalversion".)
 117
 118config HAVE_KERNEL_GZIP
 119	bool
 120
 121config HAVE_KERNEL_BZIP2
 122	bool
 123
 124config HAVE_KERNEL_LZMA
 125	bool
 126
 127config HAVE_KERNEL_XZ
 128	bool
 129
 130config HAVE_KERNEL_LZO
 131	bool
 132
 
 
 
 133choice
 134	prompt "Kernel compression mode"
 135	default KERNEL_GZIP
 136	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
 137	help
 138	  The linux kernel is a kind of self-extracting executable.
 139	  Several compression algorithms are available, which differ
 140	  in efficiency, compression and decompression speed.
 141	  Compression speed is only relevant when building a kernel.
 142	  Decompression speed is relevant at each boot.
 143
 144	  If you have any problems with bzip2 or lzma compressed
 145	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 146	  version of this functionality (bzip2 only), for 2.4, was
 147	  supplied by Christian Ludwig)
 148
 149	  High compression options are mostly useful for users, who
 150	  are low on disk space (embedded systems), but for whom ram
 151	  size matters less.
 152
 153	  If in doubt, select 'gzip'
 154
 155config KERNEL_GZIP
 156	bool "Gzip"
 157	depends on HAVE_KERNEL_GZIP
 158	help
 159	  The old and tried gzip compression. It provides a good balance
 160	  between compression ratio and decompression speed.
 161
 162config KERNEL_BZIP2
 163	bool "Bzip2"
 164	depends on HAVE_KERNEL_BZIP2
 165	help
 166	  Its compression ratio and speed is intermediate.
 167	  Decompression speed is slowest among the three.  The kernel
 168	  size is about 10% smaller with bzip2, in comparison to gzip.
 169	  Bzip2 uses a large amount of memory. For modern kernels you
 170	  will need at least 8MB RAM or more for booting.
 171
 172config KERNEL_LZMA
 173	bool "LZMA"
 174	depends on HAVE_KERNEL_LZMA
 175	help
 176	  The most recent compression algorithm.
 177	  Its ratio is best, decompression speed is between the other
 178	  two. Compression is slowest.	The kernel size is about 33%
 179	  smaller with LZMA in comparison to gzip.
 180
 181config KERNEL_XZ
 182	bool "XZ"
 183	depends on HAVE_KERNEL_XZ
 184	help
 185	  XZ uses the LZMA2 algorithm and instruction set specific
 186	  BCJ filters which can improve compression ratio of executable
 187	  code. The size of the kernel is about 30% smaller with XZ in
 188	  comparison to gzip. On architectures for which there is a BCJ
 189	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
 190	  will create a few percent smaller kernel than plain LZMA.
 191
 192	  The speed is about the same as with LZMA: The decompression
 193	  speed of XZ is better than that of bzip2 but worse than gzip
 194	  and LZO. Compression is slow.
 195
 196config KERNEL_LZO
 197	bool "LZO"
 198	depends on HAVE_KERNEL_LZO
 199	help
 200	  Its compression ratio is the poorest among the 4. The kernel
 201	  size is about 10% bigger than gzip; however its speed
 202	  (both compression and decompression) is the fastest.
 203
 
 
 
 
 
 
 
 
 
 
 
 
 204endchoice
 205
 206config DEFAULT_HOSTNAME
 207	string "Default hostname"
 208	default "(none)"
 209	help
 210	  This option determines the default system hostname before userspace
 211	  calls sethostname(2). The kernel traditionally uses "(none)" here,
 212	  but you may wish to use a different default here to make a minimal
 213	  system more usable with less configuration.
 214
 215config SWAP
 216	bool "Support for paging of anonymous memory (swap)"
 217	depends on MMU && BLOCK
 218	default y
 219	help
 220	  This option allows you to choose whether you want to have support
 221	  for so called swap devices or swap files in your kernel that are
 222	  used to provide more virtual memory than the actual RAM present
 223	  in your computer.  If unsure say Y.
 224
 225config SYSVIPC
 226	bool "System V IPC"
 227	---help---
 228	  Inter Process Communication is a suite of library functions and
 229	  system calls which let processes (running programs) synchronize and
 230	  exchange information. It is generally considered to be a good thing,
 231	  and some programs won't run unless you say Y here. In particular, if
 232	  you want to run the DOS emulator dosemu under Linux (read the
 233	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 234	  you'll need to say Y here.
 235
 236	  You can find documentation about IPC with "info ipc" and also in
 237	  section 6.4 of the Linux Programmer's Guide, available from
 238	  <http://www.tldp.org/guides.html>.
 239
 240config SYSVIPC_SYSCTL
 241	bool
 242	depends on SYSVIPC
 243	depends on SYSCTL
 244	default y
 245
 246config POSIX_MQUEUE
 247	bool "POSIX Message Queues"
 248	depends on NET && EXPERIMENTAL
 249	---help---
 250	  POSIX variant of message queues is a part of IPC. In POSIX message
 251	  queues every message has a priority which decides about succession
 252	  of receiving it by a process. If you want to compile and run
 253	  programs written e.g. for Solaris with use of its POSIX message
 254	  queues (functions mq_*) say Y here.
 255
 256	  POSIX message queues are visible as a filesystem called 'mqueue'
 257	  and can be mounted somewhere if you want to do filesystem
 258	  operations on message queues.
 259
 260	  If unsure, say Y.
 261
 262config POSIX_MQUEUE_SYSCTL
 263	bool
 264	depends on POSIX_MQUEUE
 265	depends on SYSCTL
 266	default y
 267
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 268config BSD_PROCESS_ACCT
 269	bool "BSD Process Accounting"
 
 270	help
 271	  If you say Y here, a user level program will be able to instruct the
 272	  kernel (via a special system call) to write process accounting
 273	  information to a file: whenever a process exits, information about
 274	  that process will be appended to the file by the kernel.  The
 275	  information includes things such as creation time, owning user,
 276	  command name, memory usage, controlling terminal etc. (the complete
 277	  list is in the struct acct in <file:include/linux/acct.h>).  It is
 278	  up to the user level program to do useful things with this
 279	  information.  This is generally a good idea, so say Y.
 280
 281config BSD_PROCESS_ACCT_V3
 282	bool "BSD Process Accounting version 3 file format"
 283	depends on BSD_PROCESS_ACCT
 284	default n
 285	help
 286	  If you say Y here, the process accounting information is written
 287	  in a new file format that also logs the process IDs of each
 288	  process and it's parent. Note that this file format is incompatible
 289	  with previous v0/v1/v2 file formats, so you will need updated tools
 290	  for processing it. A preliminary version of these tools is available
 291	  at <http://www.gnu.org/software/acct/>.
 292
 293config FHANDLE
 294	bool "open by fhandle syscalls"
 295	select EXPORTFS
 296	help
 297	  If you say Y here, a user level program will be able to map
 298	  file names to handle and then later use the handle for
 299	  different file system operations. This is useful in implementing
 300	  userspace file servers, which now track files using handles instead
 301	  of names. The handle would remain the same even if file names
 302	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
 303	  syscalls.
 304
 305config TASKSTATS
 306	bool "Export task/process statistics through netlink (EXPERIMENTAL)"
 307	depends on NET
 
 308	default n
 309	help
 310	  Export selected statistics for tasks/processes through the
 311	  generic netlink interface. Unlike BSD process accounting, the
 312	  statistics are available during the lifetime of tasks/processes as
 313	  responses to commands. Like BSD accounting, they are sent to user
 314	  space on task exit.
 315
 316	  Say N if unsure.
 317
 318config TASK_DELAY_ACCT
 319	bool "Enable per-task delay accounting (EXPERIMENTAL)"
 320	depends on TASKSTATS
 
 321	help
 322	  Collect information on time spent by a task waiting for system
 323	  resources like cpu, synchronous block I/O completion and swapping
 324	  in pages. Such statistics can help in setting a task's priorities
 325	  relative to other tasks for cpu, io, rss limits etc.
 326
 327	  Say N if unsure.
 328
 329config TASK_XACCT
 330	bool "Enable extended accounting over taskstats (EXPERIMENTAL)"
 331	depends on TASKSTATS
 332	help
 333	  Collect extended task accounting data and send the data
 334	  to userland for processing over the taskstats interface.
 335
 336	  Say N if unsure.
 337
 338config TASK_IO_ACCOUNTING
 339	bool "Enable per-task storage I/O accounting (EXPERIMENTAL)"
 340	depends on TASK_XACCT
 341	help
 342	  Collect information on the number of bytes of storage I/O which this
 343	  task has caused.
 344
 345	  Say N if unsure.
 346
 347config AUDIT
 348	bool "Auditing support"
 349	depends on NET
 350	help
 351	  Enable auditing infrastructure that can be used with another
 352	  kernel subsystem, such as SELinux (which requires this for
 353	  logging of avc messages output).  Does not do system-call
 354	  auditing without CONFIG_AUDITSYSCALL.
 355
 356config AUDITSYSCALL
 357	bool "Enable system-call auditing support"
 358	depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
 359	default y if SECURITY_SELINUX
 360	help
 361	  Enable low-overhead system-call auditing infrastructure that
 362	  can be used independently or with another kernel subsystem,
 363	  such as SELinux.
 364
 365config AUDIT_WATCH
 366	def_bool y
 367	depends on AUDITSYSCALL
 368	select FSNOTIFY
 369
 370config AUDIT_TREE
 371	def_bool y
 372	depends on AUDITSYSCALL
 373	select FSNOTIFY
 374
 375source "kernel/irq/Kconfig"
 376
 377menu "RCU Subsystem"
 378
 379choice
 380	prompt "RCU Implementation"
 381	default TREE_RCU
 382
 383config TREE_RCU
 384	bool "Tree-based hierarchical RCU"
 385	depends on !PREEMPT && SMP
 386	help
 387	  This option selects the RCU implementation that is
 388	  designed for very large SMP system with hundreds or
 389	  thousands of CPUs.  It also scales down nicely to
 390	  smaller systems.
 391
 392config TREE_PREEMPT_RCU
 393	bool "Preemptible tree-based hierarchical RCU"
 394	depends on PREEMPT
 395	help
 396	  This option selects the RCU implementation that is
 397	  designed for very large SMP systems with hundreds or
 398	  thousands of CPUs, but for which real-time response
 399	  is also required.  It also scales down nicely to
 400	  smaller systems.
 401
 402config TINY_RCU
 403	bool "UP-only small-memory-footprint RCU"
 404	depends on !SMP
 405	help
 406	  This option selects the RCU implementation that is
 407	  designed for UP systems from which real-time response
 408	  is not required.  This option greatly reduces the
 409	  memory footprint of RCU.
 410
 411config TINY_PREEMPT_RCU
 412	bool "Preemptible UP-only small-memory-footprint RCU"
 413	depends on !SMP && PREEMPT
 414	help
 415	  This option selects the RCU implementation that is designed
 416	  for real-time UP systems.  This option greatly reduces the
 417	  memory footprint of RCU.
 418
 419endchoice
 420
 421config PREEMPT_RCU
 422	def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
 423	help
 424	  This option enables preemptible-RCU code that is common between
 425	  the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
 426
 427config RCU_TRACE
 428	bool "Enable tracing for RCU"
 429	help
 430	  This option provides tracing in RCU which presents stats
 431	  in debugfs for debugging RCU implementation.
 432
 433	  Say Y here if you want to enable RCU tracing
 434	  Say N if you are unsure.
 435
 436config RCU_FANOUT
 437	int "Tree-based hierarchical RCU fanout value"
 438	range 2 64 if 64BIT
 439	range 2 32 if !64BIT
 440	depends on TREE_RCU || TREE_PREEMPT_RCU
 441	default 64 if 64BIT
 442	default 32 if !64BIT
 443	help
 444	  This option controls the fanout of hierarchical implementations
 445	  of RCU, allowing RCU to work efficiently on machines with
 446	  large numbers of CPUs.  This value must be at least the fourth
 447	  root of NR_CPUS, which allows NR_CPUS to be insanely large.
 448	  The default value of RCU_FANOUT should be used for production
 449	  systems, but if you are stress-testing the RCU implementation
 450	  itself, small RCU_FANOUT values allow you to test large-system
 451	  code paths on small(er) systems.
 452
 453	  Select a specific number if testing RCU itself.
 454	  Take the default if unsure.
 455
 456config RCU_FANOUT_EXACT
 457	bool "Disable tree-based hierarchical RCU auto-balancing"
 458	depends on TREE_RCU || TREE_PREEMPT_RCU
 459	default n
 460	help
 461	  This option forces use of the exact RCU_FANOUT value specified,
 462	  regardless of imbalances in the hierarchy.  This is useful for
 463	  testing RCU itself, and might one day be useful on systems with
 464	  strong NUMA behavior.
 465
 466	  Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
 467
 468	  Say N if unsure.
 469
 470config RCU_FAST_NO_HZ
 471	bool "Accelerate last non-dyntick-idle CPU's grace periods"
 472	depends on TREE_RCU && NO_HZ && SMP
 473	default n
 474	help
 475	  This option causes RCU to attempt to accelerate grace periods
 476	  in order to allow the final CPU to enter dynticks-idle state
 477	  more quickly.  On the other hand, this option increases the
 478	  overhead of the dynticks-idle checking, particularly on systems
 479	  with large numbers of CPUs.
 480
 481	  Say Y if energy efficiency is critically important, particularly
 482	  	if you have relatively few CPUs.
 483
 484	  Say N if you are unsure.
 485
 486config TREE_RCU_TRACE
 487	def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
 488	select DEBUG_FS
 489	help
 490	  This option provides tracing for the TREE_RCU and
 491	  TREE_PREEMPT_RCU implementations, permitting Makefile to
 492	  trivially select kernel/rcutree_trace.c.
 493
 494config RCU_BOOST
 495	bool "Enable RCU priority boosting"
 496	depends on RT_MUTEXES && PREEMPT_RCU
 497	default n
 498	help
 499	  This option boosts the priority of preempted RCU readers that
 500	  block the current preemptible RCU grace period for too long.
 501	  This option also prevents heavy loads from blocking RCU
 502	  callback invocation for all flavors of RCU.
 503
 504	  Say Y here if you are working with real-time apps or heavy loads
 505	  Say N here if you are unsure.
 506
 507config RCU_BOOST_PRIO
 508	int "Real-time priority to boost RCU readers to"
 509	range 1 99
 510	depends on RCU_BOOST
 511	default 1
 512	help
 513	  This option specifies the real-time priority to which preempted
 514	  RCU readers are to be boosted.  If you are working with CPU-bound
 515	  real-time applications, you should specify a priority higher then
 516	  the highest-priority CPU-bound application.
 517
 518	  Specify the real-time priority, or take the default if unsure.
 519
 520config RCU_BOOST_DELAY
 521	int "Milliseconds to delay boosting after RCU grace-period start"
 522	range 0 3000
 523	depends on RCU_BOOST
 524	default 500
 525	help
 526	  This option specifies the time to wait after the beginning of
 527	  a given grace period before priority-boosting preempted RCU
 528	  readers blocking that grace period.  Note that any RCU reader
 529	  blocking an expedited RCU grace period is boosted immediately.
 530
 531	  Accept the default if unsure.
 532
 533endmenu # "RCU Subsystem"
 534
 535config IKCONFIG
 536	tristate "Kernel .config support"
 
 537	---help---
 538	  This option enables the complete Linux kernel ".config" file
 539	  contents to be saved in the kernel. It provides documentation
 540	  of which kernel options are used in a running kernel or in an
 541	  on-disk kernel.  This information can be extracted from the kernel
 542	  image file with the script scripts/extract-ikconfig and used as
 543	  input to rebuild the current kernel or to build another kernel.
 544	  It can also be extracted from a running kernel by reading
 545	  /proc/config.gz if enabled (below).
 546
 547config IKCONFIG_PROC
 548	bool "Enable access to .config through /proc/config.gz"
 549	depends on IKCONFIG && PROC_FS
 550	---help---
 551	  This option enables access to the kernel configuration file
 552	  through /proc/config.gz.
 553
 554config LOG_BUF_SHIFT
 555	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 556	range 12 21
 557	default 17
 
 558	help
 559	  Select kernel log buffer size as a power of 2.
 
 
 
 
 560	  Examples:
 561	  	     17 => 128 KB
 562		     16 => 64 KB
 563	             15 => 32 KB
 564	             14 => 16 KB
 565		     13 =>  8 KB
 566		     12 =>  4 KB
 567
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 568#
 569# Architectures with an unreliable sched_clock() should select this:
 570#
 571config HAVE_UNSTABLE_SCHED_CLOCK
 572	bool
 573
 574menuconfig CGROUPS
 575	boolean "Control Group support"
 576	depends on EVENTFD
 577	help
 578	  This option adds support for grouping sets of processes together, for
 579	  use with process control subsystems such as Cpusets, CFS, memory
 580	  controls or device isolation.
 581	  See
 582		- Documentation/scheduler/sched-design-CFS.txt	(CFS)
 583		- Documentation/cgroups/ (features for grouping, isolation
 584					  and resource control)
 585
 586	  Say N if unsure.
 
 
 
 
 
 587
 588if CGROUPS
 
 
 
 
 
 
 
 
 589
 590config CGROUP_DEBUG
 591	bool "Example debug cgroup subsystem"
 592	default n
 593	help
 594	  This option enables a simple cgroup subsystem that
 595	  exports useful debugging information about the cgroups
 596	  framework.
 597
 598	  Say N if unsure.
 
 
 
 
 599
 600config CGROUP_FREEZER
 601	bool "Freezer cgroup subsystem"
 
 
 
 602	help
 603	  Provides a way to freeze and unfreeze all tasks in a
 604	  cgroup.
 
 605
 606config CGROUP_DEVICE
 607	bool "Device controller for cgroups"
 
 
 
 
 608	help
 609	  Provides a cgroup implementing whitelists for devices which
 610	  a process in the cgroup can mknod or open.
 611
 612config CPUSETS
 613	bool "Cpuset support"
 
 614	help
 615	  This option will let you create and manage CPUSETs which
 616	  allow dynamically partitioning a system into sets of CPUs and
 617	  Memory Nodes and assigning tasks to run only within those sets.
 618	  This is primarily useful on large SMP or NUMA systems.
 
 
 
 619
 620	  Say N if unsure.
 621
 622config PROC_PID_CPUSET
 623	bool "Include legacy /proc/<pid>/cpuset file"
 624	depends on CPUSETS
 625	default y
 626
 627config CGROUP_CPUACCT
 628	bool "Simple CPU accounting cgroup subsystem"
 
 
 
 
 
 629	help
 630	  Provides a simple Resource Controller for monitoring the
 631	  total CPU consumed by the tasks in a cgroup.
 632
 633config RESOURCE_COUNTERS
 634	bool "Resource counters"
 
 635	help
 636	  This option enables controller independent resource accounting
 637	  infrastructure that works with cgroups.
 638
 639config CGROUP_MEM_RES_CTLR
 640	bool "Memory Resource Controller for Control Groups"
 641	depends on RESOURCE_COUNTERS
 642	select MM_OWNER
 643	help
 644	  Provides a memory resource controller that manages both anonymous
 645	  memory and page cache. (See Documentation/cgroups/memory.txt)
 646
 647	  Note that setting this option increases fixed memory overhead
 648	  associated with each page of memory in the system. By this,
 649	  20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
 650	  usage tracking struct at boot. Total amount of this is printed out
 651	  at boot.
 652
 653	  Only enable when you're ok with these trade offs and really
 654	  sure you need the memory resource controller. Even when you enable
 655	  this, you can set "cgroup_disable=memory" at your boot option to
 656	  disable memory resource controller and you can avoid overheads.
 657	  (and lose benefits of memory resource controller)
 658
 659	  This config option also selects MM_OWNER config option, which
 660	  could in turn add some fork/exit overhead.
 661
 662config CGROUP_MEM_RES_CTLR_SWAP
 663	bool "Memory Resource Controller Swap Extension"
 664	depends on CGROUP_MEM_RES_CTLR && SWAP
 665	help
 666	  Add swap management feature to memory resource controller. When you
 667	  enable this, you can limit mem+swap usage per cgroup. In other words,
 668	  when you disable this, memory resource controller has no cares to
 669	  usage of swap...a process can exhaust all of the swap. This extension
 670	  is useful when you want to avoid exhaustion swap but this itself
 671	  adds more overheads and consumes memory for remembering information.
 672	  Especially if you use 32bit system or small memory system, please
 673	  be careful about enabling this. When memory resource controller
 674	  is disabled by boot option, this will be automatically disabled and
 675	  there will be no overhead from this. Even when you set this config=y,
 676	  if boot option "swapaccount=0" is set, swap will not be accounted.
 677	  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
 678	  size is 4096bytes, 512k per 1Gbytes of swap.
 679config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
 680	bool "Memory Resource Controller Swap Extension enabled by default"
 681	depends on CGROUP_MEM_RES_CTLR_SWAP
 682	default y
 683	help
 684	  Memory Resource Controller Swap Extension comes with its price in
 685	  a bigger memory consumption. General purpose distribution kernels
 686	  which want to enable the feature but keep it disabled by default
 687	  and let the user enable it by swapaccount boot command line
 688	  parameter should have this option unselected.
 689	  For those who want to have the feature enabled by default should
 690	  select this option (if, for some reason, they need to disable it
 691	  then swapaccount=0 does the trick).
 692
 693config CGROUP_PERF
 694	bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
 695	depends on PERF_EVENTS && CGROUPS
 696	help
 697	  This option extends the per-cpu mode to restrict monitoring to
 698	  threads which belong to the cgroup specified and run on the
 699	  designated cpu.
 
 700
 701	  Say N if unsure.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 702
 703menuconfig CGROUP_SCHED
 704	bool "Group CPU scheduler"
 705	depends on EXPERIMENTAL
 706	default n
 707	help
 708	  This feature lets CPU scheduler recognize task groups and control CPU
 709	  bandwidth allocation to such task groups. It uses cgroups to group
 710	  tasks.
 711
 712if CGROUP_SCHED
 713config FAIR_GROUP_SCHED
 714	bool "Group scheduling for SCHED_OTHER"
 715	depends on CGROUP_SCHED
 716	default CGROUP_SCHED
 717
 
 
 
 
 
 
 
 
 
 
 
 718config RT_GROUP_SCHED
 719	bool "Group scheduling for SCHED_RR/FIFO"
 720	depends on EXPERIMENTAL
 721	depends on CGROUP_SCHED
 722	default n
 723	help
 724	  This feature lets you explicitly allocate real CPU bandwidth
 725	  to task groups. If enabled, it will also make it impossible to
 726	  schedule realtime tasks for non-root users until you allocate
 727	  realtime bandwidth for them.
 728	  See Documentation/scheduler/sched-rt-group.txt for more information.
 729
 730endif #CGROUP_SCHED
 731
 732config BLK_CGROUP
 733	tristate "Block IO controller"
 734	depends on BLOCK
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 735	default n
 736	---help---
 737	Generic block IO controller cgroup interface. This is the common
 738	cgroup interface which should be used by various IO controlling
 739	policies.
 
 
 
 
 
 
 740
 741	Currently, CFQ IO scheduler uses it to recognize task groups and
 742	control disk bandwidth allocation (proportional time slice allocation)
 743	to such task groups. It is also used by bio throttling logic in
 744	block layer to implement upper limit in IO rates on a device.
 
 
 
 
 745
 746	This option only enables generic Block IO controller infrastructure.
 747	One needs to also enable actual IO controlling logic/policy. For
 748	enabling proportional weight division of disk bandwidth in CFQ, set
 749	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 750	CONFIG_BLK_DEV_THROTTLING=y.
 
 751
 752	See Documentation/cgroups/blkio-controller.txt for more information.
 
 
 
 
 753
 754config DEBUG_BLK_CGROUP
 755	bool "Enable Block IO controller debugging"
 756	depends on BLK_CGROUP
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 757	default n
 758	---help---
 759	Enable some debugging help. Currently it exports additional stat
 760	files in a cgroup which can be useful for debugging.
 761
 762endif # CGROUPS
 763
 764menuconfig NAMESPACES
 765	bool "Namespaces support" if EXPERT
 
 766	default !EXPERT
 767	help
 768	  Provides the way to make tasks work with different objects using
 769	  the same id. For example same IPC id may refer to different objects
 770	  or same user id or pid may refer to different tasks when used in
 771	  different namespaces.
 772
 773if NAMESPACES
 774
 775config UTS_NS
 776	bool "UTS namespace"
 777	default y
 778	help
 779	  In this namespace tasks see different info provided with the
 780	  uname() system call
 781
 782config IPC_NS
 783	bool "IPC namespace"
 784	depends on (SYSVIPC || POSIX_MQUEUE)
 785	default y
 786	help
 787	  In this namespace tasks work with IPC ids which correspond to
 788	  different IPC objects in different namespaces.
 789
 790config USER_NS
 791	bool "User namespace (EXPERIMENTAL)"
 792	depends on EXPERIMENTAL
 793	default y
 794	help
 795	  This allows containers, i.e. vservers, to use user namespaces
 796	  to provide different user info for different servers.
 
 
 
 
 
 
 797	  If unsure, say N.
 798
 799config PID_NS
 800	bool "PID Namespaces"
 801	default y
 802	help
 803	  Support process id namespaces.  This allows having multiple
 804	  processes with the same pid as long as they are in different
 805	  pid namespaces.  This is a building block of containers.
 806
 807config NET_NS
 808	bool "Network namespace"
 809	depends on NET
 810	default y
 811	help
 812	  Allow user space to create what appear to be multiple instances
 813	  of the network stack.
 814
 815endif # NAMESPACES
 816
 817config SCHED_AUTOGROUP
 818	bool "Automatic process group scheduling"
 819	select EVENTFD
 820	select CGROUPS
 821	select CGROUP_SCHED
 822	select FAIR_GROUP_SCHED
 823	help
 824	  This option optimizes the scheduler for common desktop workloads by
 825	  automatically creating and populating task groups.  This separation
 826	  of workloads isolates aggressive CPU burners (like build jobs) from
 827	  desktop applications.  Task group autogeneration is currently based
 828	  upon task session.
 829
 830config MM_OWNER
 831	bool
 832
 833config SYSFS_DEPRECATED
 834	bool "Enable deprecated sysfs features to support old userspace tools"
 835	depends on SYSFS
 836	default n
 837	help
 838	  This option adds code that switches the layout of the "block" class
 839	  devices, to not show up in /sys/class/block/, but only in
 840	  /sys/block/.
 841
 842	  This switch is only active when the sysfs.deprecated=1 boot option is
 843	  passed or the SYSFS_DEPRECATED_V2 option is set.
 844
 845	  This option allows new kernels to run on old distributions and tools,
 846	  which might get confused by /sys/class/block/. Since 2007/2008 all
 847	  major distributions and tools handle this just fine.
 848
 849	  Recent distributions and userspace tools after 2009/2010 depend on
 850	  the existence of /sys/class/block/, and will not work with this
 851	  option enabled.
 852
 853	  Only if you are using a new kernel on an old distribution, you might
 854	  need to say Y here.
 855
 856config SYSFS_DEPRECATED_V2
 857	bool "Enable deprecated sysfs features by default"
 858	default n
 859	depends on SYSFS
 860	depends on SYSFS_DEPRECATED
 861	help
 862	  Enable deprecated sysfs by default.
 863
 864	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
 865	  option.
 866
 867	  Only if you are using a new kernel on an old distribution, you might
 868	  need to say Y here. Even then, odds are you would not need it
 869	  enabled, you can always pass the boot option if absolutely necessary.
 870
 871config RELAY
 872	bool "Kernel->user space relay support (formerly relayfs)"
 
 873	help
 874	  This option enables support for relay interface support in
 875	  certain file systems (such as debugfs).
 876	  It is designed to provide an efficient mechanism for tools and
 877	  facilities to relay large amounts of data from kernel space to
 878	  user space.
 879
 880	  If unsure, say N.
 881
 882config BLK_DEV_INITRD
 883	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 884	depends on BROKEN || !FRV
 885	help
 886	  The initial RAM filesystem is a ramfs which is loaded by the
 887	  boot loader (loadlin or lilo) and that is mounted as root
 888	  before the normal boot procedure. It is typically used to
 889	  load modules needed to mount the "real" root file system,
 890	  etc. See <file:Documentation/initrd.txt> for details.
 891
 892	  If RAM disk support (BLK_DEV_RAM) is also included, this
 893	  also enables initial RAM disk (initrd) support and adds
 894	  15 Kbytes (more on some other architectures) to the kernel size.
 895
 896	  If unsure say Y.
 897
 898if BLK_DEV_INITRD
 899
 900source "usr/Kconfig"
 901
 902endif
 903
 
 
 
 
 
 
 
 
 
 
 
 904config CC_OPTIMIZE_FOR_SIZE
 905	bool "Optimize for size"
 906	help
 907	  Enabling this option will pass "-Os" instead of "-O2" to gcc
 908	  resulting in a smaller kernel.
 909
 910	  If unsure, say Y.
 
 
 911
 912config SYSCTL
 913	bool
 914
 915config ANON_INODES
 916	bool
 917
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 918menuconfig EXPERT
 919	bool "Configure standard kernel features (expert users)"
 920	# Unhide debug options, to make the on-by-default options visible
 921	select DEBUG_KERNEL
 922	help
 923	  This option allows certain base kernel options and settings
 924          to be disabled or tweaked. This is for specialized
 925          environments which can tolerate a "non-standard" kernel.
 926          Only use this if you really know what you are doing.
 927
 928config UID16
 929	bool "Enable 16-bit UID system calls" if EXPERT
 930	depends on ARM || BLACKFIN || CRIS || FRV || H8300 || X86_32 || M68K || (S390 && !64BIT) || SUPERH || SPARC32 || (SPARC64 && COMPAT) || UML || (X86_64 && IA32_EMULATION)
 931	default y
 932	help
 933	  This enables the legacy 16-bit UID syscall wrappers.
 934
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 935config SYSCTL_SYSCALL
 936	bool "Sysctl syscall support" if EXPERT
 937	depends on PROC_SYSCTL
 938	default y
 939	select SYSCTL
 940	---help---
 941	  sys_sysctl uses binary paths that have been found challenging
 942	  to properly maintain and use.  The interface in /proc/sys
 943	  using paths with ascii names is now the primary path to this
 944	  information.
 945
 946	  Almost nothing using the binary sysctl interface so if you are
 947	  trying to save some space it is probably safe to disable this,
 948	  making your kernel marginally smaller.
 949
 950	  If unsure say Y here.
 951
 952config KALLSYMS
 953	 bool "Load all symbols for debugging/ksymoops" if EXPERT
 954	 default y
 955	 help
 956	   Say Y here to let the kernel print out symbolic crash information and
 957	   symbolic stack backtraces. This increases the size of the kernel
 958	   somewhat, as all symbols have to be loaded into the kernel image.
 959
 960config KALLSYMS_ALL
 961	bool "Include all symbols in kallsyms"
 962	depends on DEBUG_KERNEL && KALLSYMS
 963	help
 964	   Normally kallsyms only contains the symbols of functions for nicer
 965	   OOPS messages and backtraces (i.e., symbols from the text and inittext
 966	   sections). This is sufficient for most cases. And only in very rare
 967	   cases (e.g., when a debugger is used) all symbols are required (e.g.,
 968	   names of variables from the data sections, etc).
 969
 970	   This option makes sure that all symbols are loaded into the kernel
 971	   image (i.e., symbols from all sections) in cost of increased kernel
 972	   size (depending on the kernel configuration, it may be 300KiB or
 973	   something like this).
 974
 975	   Say N unless you really need all symbols.
 976
 977config HOTPLUG
 978	bool "Support for hot-pluggable devices" if EXPERT
 979	default y
 980	help
 981	  This option is provided for the case where no hotplug or uevent
 982	  capabilities is wanted by the kernel.  You should only consider
 983	  disabling this option for embedded systems that do not use modules, a
 984	  dynamic /dev tree, or dynamic device discovery.  Just say Y.
 
 
 
 
 
 
 
 
 985
 986config PRINTK
 987	default y
 988	bool "Enable support for printk" if EXPERT
 
 989	help
 990	  This option enables normal printk support. Removing it
 991	  eliminates most of the message strings from the kernel image
 992	  and makes the kernel more or less silent. As this makes it
 993	  very difficult to diagnose system problems, saying N here is
 994	  strongly discouraged.
 995
 
 
 
 
 
 996config BUG
 997	bool "BUG() support" if EXPERT
 998	default y
 999	help
1000          Disabling this option eliminates support for BUG and WARN, reducing
1001          the size of your kernel image and potentially quietly ignoring
1002          numerous fatal conditions. You should only consider disabling this
1003          option for embedded systems with no facilities for reporting errors.
1004          Just say Y.
1005
1006config ELF_CORE
 
1007	default y
1008	bool "Enable ELF core dumps" if EXPERT
1009	help
1010	  Enable support for generating core dumps. Disabling saves about 4k.
1011
1012
1013config PCSPKR_PLATFORM
1014	bool "Enable PC-Speaker support" if EXPERT
1015	depends on HAVE_PCSPKR_PLATFORM
1016	select I8253_LOCK
1017	default y
1018	help
1019          This option allows to disable the internal PC-Speaker
1020          support, saving some memory.
1021
1022config HAVE_PCSPKR_PLATFORM
1023	bool
1024
1025config BASE_FULL
1026	default y
1027	bool "Enable full-sized data structures for core" if EXPERT
1028	help
1029	  Disabling this option reduces the size of miscellaneous core
1030	  kernel data structures. This saves memory on small machines,
1031	  but may reduce performance.
1032
1033config FUTEX
1034	bool "Enable futex support" if EXPERT
1035	default y
1036	select RT_MUTEXES
1037	help
1038	  Disabling this option will cause the kernel to be built without
1039	  support for "fast userspace mutexes".  The resulting kernel may not
1040	  run glibc-based applications correctly.
1041
 
 
 
 
 
 
 
 
 
 
 
 
 
1042config EPOLL
1043	bool "Enable eventpoll support" if EXPERT
1044	default y
1045	select ANON_INODES
1046	help
1047	  Disabling this option will cause the kernel to be built without
1048	  support for epoll family of system calls.
1049
1050config SIGNALFD
1051	bool "Enable signalfd() system call" if EXPERT
1052	select ANON_INODES
1053	default y
1054	help
1055	  Enable the signalfd() system call that allows to receive signals
1056	  on a file descriptor.
1057
1058	  If unsure, say Y.
1059
1060config TIMERFD
1061	bool "Enable timerfd() system call" if EXPERT
1062	select ANON_INODES
1063	default y
1064	help
1065	  Enable the timerfd() system call that allows to receive timer
1066	  events on a file descriptor.
1067
1068	  If unsure, say Y.
1069
1070config EVENTFD
1071	bool "Enable eventfd() system call" if EXPERT
1072	select ANON_INODES
1073	default y
1074	help
1075	  Enable the eventfd() system call that allows to receive both
1076	  kernel notification (ie. KAIO) or userspace notifications.
1077
1078	  If unsure, say Y.
1079
1080config SHMEM
1081	bool "Use full shmem filesystem" if EXPERT
1082	default y
1083	depends on MMU
1084	help
1085	  The shmem is an internal filesystem used to manage shared memory.
1086	  It is backed by swap and manages resource limits. It is also exported
1087	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1088	  option replaces shmem and tmpfs with the much simpler ramfs code,
1089	  which may be appropriate on small systems without swap.
1090
1091config AIO
1092	bool "Enable AIO support" if EXPERT
1093	default y
1094	help
1095	  This option enables POSIX asynchronous I/O which may by used
1096          by some high performance threaded applications. Disabling
1097          this option saves about 7k.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1098
1099config EMBEDDED
1100	bool "Embedded system"
 
1101	select EXPERT
1102	help
1103	  This option should be enabled if compiling the kernel for
1104	  an embedded system so certain expert options are available
1105	  for configuration.
1106
1107config HAVE_PERF_EVENTS
1108	bool
1109	help
1110	  See tools/perf/design.txt for details.
1111
1112config PERF_USE_VMALLOC
1113	bool
1114	help
1115	  See tools/perf/design.txt for details
1116
 
 
 
 
 
 
 
1117menu "Kernel Performance Events And Counters"
1118
1119config PERF_EVENTS
1120	bool "Kernel performance events and counters"
1121	default y if (PROFILING || PERF_COUNTERS)
1122	depends on HAVE_PERF_EVENTS
1123	select ANON_INODES
1124	select IRQ_WORK
 
1125	help
1126	  Enable kernel support for various performance events provided
1127	  by software and hardware.
1128
1129	  Software events are supported either built-in or via the
1130	  use of generic tracepoints.
1131
1132	  Most modern CPUs support performance events via performance
1133	  counter registers. These registers count the number of certain
1134	  types of hw events: such as instructions executed, cachemisses
1135	  suffered, or branches mis-predicted - without slowing down the
1136	  kernel or applications. These registers can also trigger interrupts
1137	  when a threshold number of events have passed - and can thus be
1138	  used to profile the code that runs on that CPU.
1139
1140	  The Linux Performance Event subsystem provides an abstraction of
1141	  these software and hardware event capabilities, available via a
1142	  system call and used by the "perf" utility in tools/perf/. It
1143	  provides per task and per CPU counters, and it provides event
1144	  capabilities on top of those.
1145
1146	  Say Y if unsure.
1147
1148config PERF_COUNTERS
1149	bool "Kernel performance counters (old config option)"
1150	depends on HAVE_PERF_EVENTS
1151	help
1152	  This config has been obsoleted by the PERF_EVENTS
1153	  config option - please see that one for details.
1154
1155	  It has no effect on the kernel whether you enable
1156	  it or not, it is a compatibility placeholder.
1157
1158	  Say N if unsure.
1159
1160config DEBUG_PERF_USE_VMALLOC
1161	default n
1162	bool "Debug: use vmalloc to back perf mmap() buffers"
1163	depends on PERF_EVENTS && DEBUG_KERNEL
1164	select PERF_USE_VMALLOC
1165	help
1166	 Use vmalloc memory to back perf mmap() buffers.
1167
1168	 Mostly useful for debugging the vmalloc code on platforms
1169	 that don't require it.
1170
1171	 Say N if unsure.
1172
1173endmenu
1174
1175config VM_EVENT_COUNTERS
1176	default y
1177	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1178	help
1179	  VM event counters are needed for event counts to be shown.
1180	  This option allows the disabling of the VM event counters
1181	  on EXPERT systems.  /proc/vmstat will only show page counts
1182	  if VM event counters are disabled.
1183
1184config PCI_QUIRKS
1185	default y
1186	bool "Enable PCI quirk workarounds" if EXPERT
1187	depends on PCI
1188	help
1189	  This enables workarounds for various PCI chipset
1190          bugs/quirks. Disable this only if your target machine is
1191          unaffected by PCI quirks.
1192
1193config SLUB_DEBUG
1194	default y
1195	bool "Enable SLUB debugging support" if EXPERT
1196	depends on SLUB && SYSFS
1197	help
1198	  SLUB has extensive debug support features. Disabling these can
1199	  result in significant savings in code size. This also disables
1200	  SLUB sysfs support. /sys/slab will not exist and there will be
1201	  no support for cache validation etc.
1202
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1203config COMPAT_BRK
1204	bool "Disable heap randomization"
1205	default y
1206	help
1207	  Randomizing heap placement makes heap exploits harder, but it
1208	  also breaks ancient binaries (including anything libc5 based).
1209	  This option changes the bootup default to heap randomization
1210	  disabled, and can be overridden at runtime by setting
1211	  /proc/sys/kernel/randomize_va_space to 2.
1212
1213	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
1214
1215choice
1216	prompt "Choose SLAB allocator"
1217	default SLUB
1218	help
1219	   This option allows to select a slab allocator.
1220
1221config SLAB
1222	bool "SLAB"
 
1223	help
1224	  The regular slab allocator that is established and known to work
1225	  well in all environments. It organizes cache hot objects in
1226	  per cpu and per node queues.
1227
1228config SLUB
1229	bool "SLUB (Unqueued Allocator)"
 
1230	help
1231	   SLUB is a slab allocator that minimizes cache line usage
1232	   instead of managing queues of cached objects (SLAB approach).
1233	   Per cpu caching is realized using slabs of objects instead
1234	   of queues of objects. SLUB can use memory efficiently
1235	   and has enhanced diagnostics. SLUB is the default choice for
1236	   a slab allocator.
1237
1238config SLOB
1239	depends on EXPERT
1240	bool "SLOB (Simple Allocator)"
1241	help
1242	   SLOB replaces the stock allocator with a drastically simpler
1243	   allocator. SLOB is generally more space efficient but
1244	   does not perform as well on large systems.
1245
1246endchoice
1247
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1248config MMAP_ALLOW_UNINITIALIZED
1249	bool "Allow mmapped anonymous memory to be uninitialized"
1250	depends on EXPERT && !MMU
1251	default n
1252	help
1253	  Normally, and according to the Linux spec, anonymous memory obtained
1254	  from mmap() has it's contents cleared before it is passed to
1255	  userspace.  Enabling this config option allows you to request that
1256	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1257	  providing a huge performance boost.  If this option is not enabled,
1258	  then the flag will be ignored.
1259
1260	  This is taken advantage of by uClibc's malloc(), and also by
1261	  ELF-FDPIC binfmt's brk and stack allocator.
1262
1263	  Because of the obvious security issues, this option should only be
1264	  enabled on embedded devices where you control what is run in
1265	  userspace.  Since that isn't generally a problem on no-MMU systems,
1266	  it is normally safe to say Y here.
1267
1268	  See Documentation/nommu-mmap.txt for more information.
1269
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1270config PROFILING
1271	bool "Profiling support"
1272	help
1273	  Say Y here to enable the extended profiling support mechanisms used
1274	  by profilers such as OProfile.
1275
1276#
1277# Place an empty function call at each tracepoint site. Can be
1278# dynamically changed for a probe function.
1279#
1280config TRACEPOINTS
1281	bool
1282
1283source "arch/Kconfig"
1284
1285endmenu		# General setup
1286
1287config HAVE_GENERIC_DMA_COHERENT
1288	bool
1289	default n
1290
1291config SLABINFO
1292	bool
1293	depends on PROC_FS
1294	depends on SLAB || SLUB_DEBUG
1295	default y
1296
1297config RT_MUTEXES
1298	boolean
1299
1300config BASE_SMALL
1301	int
1302	default 0 if BASE_FULL
1303	default 1 if !BASE_FULL
1304
1305menuconfig MODULES
1306	bool "Enable loadable module support"
 
1307	help
1308	  Kernel modules are small pieces of compiled code which can
1309	  be inserted in the running kernel, rather than being
1310	  permanently built into the kernel.  You use the "modprobe"
1311	  tool to add (and sometimes remove) them.  If you say Y here,
1312	  many parts of the kernel can be built as modules (by
1313	  answering M instead of Y where indicated): this is most
1314	  useful for infrequently used options which are not required
1315	  for booting.  For more information, see the man pages for
1316	  modprobe, lsmod, modinfo, insmod and rmmod.
1317
1318	  If you say Y here, you will need to run "make
1319	  modules_install" to put the modules under /lib/modules/
1320	  where modprobe can find them (you may need to be root to do
1321	  this).
1322
1323	  If unsure, say Y.
1324
1325if MODULES
1326
1327config MODULE_FORCE_LOAD
1328	bool "Forced module loading"
1329	default n
1330	help
1331	  Allow loading of modules without version information (ie. modprobe
1332	  --force).  Forced module loading sets the 'F' (forced) taint flag and
1333	  is usually a really bad idea.
1334
1335config MODULE_UNLOAD
1336	bool "Module unloading"
1337	help
1338	  Without this option you will not be able to unload any
1339	  modules (note that some modules may not be unloadable
1340	  anyway), which makes your kernel smaller, faster
1341	  and simpler.  If unsure, say Y.
1342
1343config MODULE_FORCE_UNLOAD
1344	bool "Forced module unloading"
1345	depends on MODULE_UNLOAD && EXPERIMENTAL
1346	help
1347	  This option allows you to force a module to unload, even if the
1348	  kernel believes it is unsafe: the kernel will remove the module
1349	  without waiting for anyone to stop using it (using the -f option to
1350	  rmmod).  This is mainly for kernel developers and desperate users.
1351	  If unsure, say N.
1352
1353config MODVERSIONS
1354	bool "Module versioning support"
1355	help
1356	  Usually, you have to use modules compiled with your kernel.
1357	  Saying Y here makes it sometimes possible to use modules
1358	  compiled for different kernels, by adding enough information
1359	  to the modules to (hopefully) spot any changes which would
1360	  make them incompatible with the kernel you are running.  If
1361	  unsure, say N.
1362
 
 
 
 
1363config MODULE_SRCVERSION_ALL
1364	bool "Source checksum for all modules"
1365	help
1366	  Modules which contain a MODULE_VERSION get an extra "srcversion"
1367	  field inserted into their modinfo section, which contains a
1368    	  sum of the source files which made it.  This helps maintainers
1369	  see exactly which source was used to build a module (since
1370	  others sometimes change the module source without updating
1371	  the version).  With this option, such a "srcversion" field
1372	  will be created for all modules.  If unsure, say N.
1373
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1374endif # MODULES
1375
 
 
 
 
1376config INIT_ALL_POSSIBLE
1377	bool
1378	help
1379	  Back when each arch used to define their own cpu_online_map and
1380	  cpu_possible_map, some of them chose to initialize cpu_possible_map
1381	  with all 1s, and others with all 0s.  When they were centralised,
1382	  it was better to provide this option than to break all the archs
1383	  and have several arch maintainers pursuing me down dark alleys.
1384
1385config STOP_MACHINE
1386	bool
1387	default y
1388	depends on (SMP && MODULE_UNLOAD) || HOTPLUG_CPU
1389	help
1390	  Need stop_machine() primitive.
1391
1392source "block/Kconfig"
1393
1394config PREEMPT_NOTIFIERS
1395	bool
1396
1397config PADATA
1398	depends on SMP
1399	bool
1400
 
 
 
 
 
 
 
 
1401source "kernel/Kconfig.locks"
v4.17
   1config ARCH
   2	string
   3	option env="ARCH"
   4
   5config KERNELVERSION
   6	string
   7	option env="KERNELVERSION"
   8
   9config DEFCONFIG_LIST
  10	string
  11	depends on !UML
  12	option defconfig_list
  13	default "/lib/modules/$UNAME_RELEASE/.config"
  14	default "/etc/kernel-config"
  15	default "/boot/config-$UNAME_RELEASE"
  16	default "$ARCH_DEFCONFIG"
  17	default "arch/$ARCH/defconfig"
  18
  19config CONSTRUCTORS
  20	bool
  21	depends on !UML
  22
  23config IRQ_WORK
  24	bool
  25
  26config BUILDTIME_EXTABLE_SORT
  27	bool
 
  28
  29config THREAD_INFO_IN_TASK
  30	bool
  31	help
  32	  Select this to move thread_info off the stack into task_struct.  To
  33	  make this work, an arch will need to remove all thread_info fields
  34	  except flags and fix any runtime bugs.
  35
  36	  One subtle change that will be needed is to use try_get_task_stack()
  37	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
  38
  39menu "General setup"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  40
  41config BROKEN
  42	bool
  43
  44config BROKEN_ON_SMP
  45	bool
  46	depends on BROKEN || !SMP
  47	default y
  48
  49config INIT_ENV_ARG_LIMIT
  50	int
  51	default 32 if !UML
  52	default 128 if UML
  53	help
  54	  Maximum of each of the number of arguments and environment
  55	  variables passed to init from the kernel command line.
  56
  57
  58config CROSS_COMPILE
  59	string "Cross-compiler tool prefix"
  60	help
  61	  Same as running 'make CROSS_COMPILE=prefix-' but stored for
  62	  default make runs in this kernel build directory.  You don't
  63	  need to set this unless you want the configured kernel build
  64	  directory to select the cross-compiler automatically.
  65
  66config COMPILE_TEST
  67	bool "Compile also drivers which will not load"
  68	depends on !UML
  69	default n
  70	help
  71	  Some drivers can be compiled on a different platform than they are
  72	  intended to be run on. Despite they cannot be loaded there (or even
  73	  when they load they cannot be used due to missing HW support),
  74	  developers still, opposing to distributors, might want to build such
  75	  drivers to compile-test them.
  76
  77	  If you are a developer and want to build everything available, say Y
  78	  here. If you are a user/distributor, say N here to exclude useless
  79	  drivers to be distributed.
  80
  81config LOCALVERSION
  82	string "Local version - append to kernel release"
  83	help
  84	  Append an extra string to the end of your kernel version.
  85	  This will show up when you type uname, for example.
  86	  The string you set here will be appended after the contents of
  87	  any files with a filename matching localversion* in your
  88	  object and source tree, in that order.  Your total string can
  89	  be a maximum of 64 characters.
  90
  91config LOCALVERSION_AUTO
  92	bool "Automatically append version information to the version string"
  93	default y
  94	depends on !COMPILE_TEST
  95	help
  96	  This will try to automatically determine if the current tree is a
  97	  release tree by looking for git tags that belong to the current
  98	  top of tree revision.
  99
 100	  A string of the format -gxxxxxxxx will be added to the localversion
 101	  if a git-based tree is found.  The string generated by this will be
 102	  appended after any matching localversion* files, and after the value
 103	  set in CONFIG_LOCALVERSION.
 104
 105	  (The actual string used here is the first eight characters produced
 106	  by running the command:
 107
 108	    $ git rev-parse --verify HEAD
 109
 110	  which is done within the script "scripts/setlocalversion".)
 111
 112config HAVE_KERNEL_GZIP
 113	bool
 114
 115config HAVE_KERNEL_BZIP2
 116	bool
 117
 118config HAVE_KERNEL_LZMA
 119	bool
 120
 121config HAVE_KERNEL_XZ
 122	bool
 123
 124config HAVE_KERNEL_LZO
 125	bool
 126
 127config HAVE_KERNEL_LZ4
 128	bool
 129
 130choice
 131	prompt "Kernel compression mode"
 132	default KERNEL_GZIP
 133	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
 134	help
 135	  The linux kernel is a kind of self-extracting executable.
 136	  Several compression algorithms are available, which differ
 137	  in efficiency, compression and decompression speed.
 138	  Compression speed is only relevant when building a kernel.
 139	  Decompression speed is relevant at each boot.
 140
 141	  If you have any problems with bzip2 or lzma compressed
 142	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
 143	  version of this functionality (bzip2 only), for 2.4, was
 144	  supplied by Christian Ludwig)
 145
 146	  High compression options are mostly useful for users, who
 147	  are low on disk space (embedded systems), but for whom ram
 148	  size matters less.
 149
 150	  If in doubt, select 'gzip'
 151
 152config KERNEL_GZIP
 153	bool "Gzip"
 154	depends on HAVE_KERNEL_GZIP
 155	help
 156	  The old and tried gzip compression. It provides a good balance
 157	  between compression ratio and decompression speed.
 158
 159config KERNEL_BZIP2
 160	bool "Bzip2"
 161	depends on HAVE_KERNEL_BZIP2
 162	help
 163	  Its compression ratio and speed is intermediate.
 164	  Decompression speed is slowest among the choices.  The kernel
 165	  size is about 10% smaller with bzip2, in comparison to gzip.
 166	  Bzip2 uses a large amount of memory. For modern kernels you
 167	  will need at least 8MB RAM or more for booting.
 168
 169config KERNEL_LZMA
 170	bool "LZMA"
 171	depends on HAVE_KERNEL_LZMA
 172	help
 173	  This compression algorithm's ratio is best.  Decompression speed
 174	  is between gzip and bzip2.  Compression is slowest.
 175	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
 
 176
 177config KERNEL_XZ
 178	bool "XZ"
 179	depends on HAVE_KERNEL_XZ
 180	help
 181	  XZ uses the LZMA2 algorithm and instruction set specific
 182	  BCJ filters which can improve compression ratio of executable
 183	  code. The size of the kernel is about 30% smaller with XZ in
 184	  comparison to gzip. On architectures for which there is a BCJ
 185	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
 186	  will create a few percent smaller kernel than plain LZMA.
 187
 188	  The speed is about the same as with LZMA: The decompression
 189	  speed of XZ is better than that of bzip2 but worse than gzip
 190	  and LZO. Compression is slow.
 191
 192config KERNEL_LZO
 193	bool "LZO"
 194	depends on HAVE_KERNEL_LZO
 195	help
 196	  Its compression ratio is the poorest among the choices. The kernel
 197	  size is about 10% bigger than gzip; however its speed
 198	  (both compression and decompression) is the fastest.
 199
 200config KERNEL_LZ4
 201	bool "LZ4"
 202	depends on HAVE_KERNEL_LZ4
 203	help
 204	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
 205	  A preliminary version of LZ4 de/compression tool is available at
 206	  <https://code.google.com/p/lz4/>.
 207
 208	  Its compression ratio is worse than LZO. The size of the kernel
 209	  is about 8% bigger than LZO. But the decompression speed is
 210	  faster than LZO.
 211
 212endchoice
 213
 214config DEFAULT_HOSTNAME
 215	string "Default hostname"
 216	default "(none)"
 217	help
 218	  This option determines the default system hostname before userspace
 219	  calls sethostname(2). The kernel traditionally uses "(none)" here,
 220	  but you may wish to use a different default here to make a minimal
 221	  system more usable with less configuration.
 222
 223config SWAP
 224	bool "Support for paging of anonymous memory (swap)"
 225	depends on MMU && BLOCK
 226	default y
 227	help
 228	  This option allows you to choose whether you want to have support
 229	  for so called swap devices or swap files in your kernel that are
 230	  used to provide more virtual memory than the actual RAM present
 231	  in your computer.  If unsure say Y.
 232
 233config SYSVIPC
 234	bool "System V IPC"
 235	---help---
 236	  Inter Process Communication is a suite of library functions and
 237	  system calls which let processes (running programs) synchronize and
 238	  exchange information. It is generally considered to be a good thing,
 239	  and some programs won't run unless you say Y here. In particular, if
 240	  you want to run the DOS emulator dosemu under Linux (read the
 241	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
 242	  you'll need to say Y here.
 243
 244	  You can find documentation about IPC with "info ipc" and also in
 245	  section 6.4 of the Linux Programmer's Guide, available from
 246	  <http://www.tldp.org/guides.html>.
 247
 248config SYSVIPC_SYSCTL
 249	bool
 250	depends on SYSVIPC
 251	depends on SYSCTL
 252	default y
 253
 254config POSIX_MQUEUE
 255	bool "POSIX Message Queues"
 256	depends on NET
 257	---help---
 258	  POSIX variant of message queues is a part of IPC. In POSIX message
 259	  queues every message has a priority which decides about succession
 260	  of receiving it by a process. If you want to compile and run
 261	  programs written e.g. for Solaris with use of its POSIX message
 262	  queues (functions mq_*) say Y here.
 263
 264	  POSIX message queues are visible as a filesystem called 'mqueue'
 265	  and can be mounted somewhere if you want to do filesystem
 266	  operations on message queues.
 267
 268	  If unsure, say Y.
 269
 270config POSIX_MQUEUE_SYSCTL
 271	bool
 272	depends on POSIX_MQUEUE
 273	depends on SYSCTL
 274	default y
 275
 276config CROSS_MEMORY_ATTACH
 277	bool "Enable process_vm_readv/writev syscalls"
 278	depends on MMU
 279	default y
 280	help
 281	  Enabling this option adds the system calls process_vm_readv and
 282	  process_vm_writev which allow a process with the correct privileges
 283	  to directly read from or write to another process' address space.
 284	  See the man page for more details.
 285
 286config USELIB
 287	bool "uselib syscall"
 288	def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
 289	help
 290	  This option enables the uselib syscall, a system call used in the
 291	  dynamic linker from libc5 and earlier.  glibc does not use this
 292	  system call.  If you intend to run programs built on libc5 or
 293	  earlier, you may need to enable this syscall.  Current systems
 294	  running glibc can safely disable this.
 295
 296config AUDIT
 297	bool "Auditing support"
 298	depends on NET
 299	help
 300	  Enable auditing infrastructure that can be used with another
 301	  kernel subsystem, such as SELinux (which requires this for
 302	  logging of avc messages output).  System call auditing is included
 303	  on architectures which support it.
 304
 305config HAVE_ARCH_AUDITSYSCALL
 306	bool
 307
 308config AUDITSYSCALL
 309	def_bool y
 310	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
 311
 312config AUDIT_WATCH
 313	def_bool y
 314	depends on AUDITSYSCALL
 315	select FSNOTIFY
 316
 317config AUDIT_TREE
 318	def_bool y
 319	depends on AUDITSYSCALL
 320	select FSNOTIFY
 321
 322source "kernel/irq/Kconfig"
 323source "kernel/time/Kconfig"
 324
 325menu "CPU/Task time and stats accounting"
 326
 327config VIRT_CPU_ACCOUNTING
 328	bool
 329
 330choice
 331	prompt "Cputime accounting"
 332	default TICK_CPU_ACCOUNTING if !PPC64
 333	default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
 334
 335# Kind of a stub config for the pure tick based cputime accounting
 336config TICK_CPU_ACCOUNTING
 337	bool "Simple tick based cputime accounting"
 338	depends on !S390 && !NO_HZ_FULL
 339	help
 340	  This is the basic tick based cputime accounting that maintains
 341	  statistics about user, system and idle time spent on per jiffies
 342	  granularity.
 343
 344	  If unsure, say Y.
 345
 346config VIRT_CPU_ACCOUNTING_NATIVE
 347	bool "Deterministic task and CPU time accounting"
 348	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
 349	select VIRT_CPU_ACCOUNTING
 350	help
 351	  Select this option to enable more accurate task and CPU time
 352	  accounting.  This is done by reading a CPU counter on each
 353	  kernel entry and exit and on transitions within the kernel
 354	  between system, softirq and hardirq state, so there is a
 355	  small performance impact.  In the case of s390 or IBM POWER > 5,
 356	  this also enables accounting of stolen time on logically-partitioned
 357	  systems.
 358
 359config VIRT_CPU_ACCOUNTING_GEN
 360	bool "Full dynticks CPU time accounting"
 361	depends on HAVE_CONTEXT_TRACKING
 362	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 363	select VIRT_CPU_ACCOUNTING
 364	select CONTEXT_TRACKING
 365	help
 366	  Select this option to enable task and CPU time accounting on full
 367	  dynticks systems. This accounting is implemented by watching every
 368	  kernel-user boundaries using the context tracking subsystem.
 369	  The accounting is thus performed at the expense of some significant
 370	  overhead.
 371
 372	  For now this is only useful if you are working on the full
 373	  dynticks subsystem development.
 374
 375	  If unsure, say N.
 376
 377endchoice
 378
 379config IRQ_TIME_ACCOUNTING
 380	bool "Fine granularity task level IRQ time accounting"
 381	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
 382	help
 383	  Select this option to enable fine granularity task irq time
 384	  accounting. This is done by reading a timestamp on each
 385	  transitions between softirq and hardirq state, so there can be a
 386	  small performance impact.
 387
 388	  If in doubt, say N here.
 389
 390config BSD_PROCESS_ACCT
 391	bool "BSD Process Accounting"
 392	depends on MULTIUSER
 393	help
 394	  If you say Y here, a user level program will be able to instruct the
 395	  kernel (via a special system call) to write process accounting
 396	  information to a file: whenever a process exits, information about
 397	  that process will be appended to the file by the kernel.  The
 398	  information includes things such as creation time, owning user,
 399	  command name, memory usage, controlling terminal etc. (the complete
 400	  list is in the struct acct in <file:include/linux/acct.h>).  It is
 401	  up to the user level program to do useful things with this
 402	  information.  This is generally a good idea, so say Y.
 403
 404config BSD_PROCESS_ACCT_V3
 405	bool "BSD Process Accounting version 3 file format"
 406	depends on BSD_PROCESS_ACCT
 407	default n
 408	help
 409	  If you say Y here, the process accounting information is written
 410	  in a new file format that also logs the process IDs of each
 411	  process and it's parent. Note that this file format is incompatible
 412	  with previous v0/v1/v2 file formats, so you will need updated tools
 413	  for processing it. A preliminary version of these tools is available
 414	  at <http://www.gnu.org/software/acct/>.
 415
 
 
 
 
 
 
 
 
 
 
 
 
 416config TASKSTATS
 417	bool "Export task/process statistics through netlink"
 418	depends on NET
 419	depends on MULTIUSER
 420	default n
 421	help
 422	  Export selected statistics for tasks/processes through the
 423	  generic netlink interface. Unlike BSD process accounting, the
 424	  statistics are available during the lifetime of tasks/processes as
 425	  responses to commands. Like BSD accounting, they are sent to user
 426	  space on task exit.
 427
 428	  Say N if unsure.
 429
 430config TASK_DELAY_ACCT
 431	bool "Enable per-task delay accounting"
 432	depends on TASKSTATS
 433	select SCHED_INFO
 434	help
 435	  Collect information on time spent by a task waiting for system
 436	  resources like cpu, synchronous block I/O completion and swapping
 437	  in pages. Such statistics can help in setting a task's priorities
 438	  relative to other tasks for cpu, io, rss limits etc.
 439
 440	  Say N if unsure.
 441
 442config TASK_XACCT
 443	bool "Enable extended accounting over taskstats"
 444	depends on TASKSTATS
 445	help
 446	  Collect extended task accounting data and send the data
 447	  to userland for processing over the taskstats interface.
 448
 449	  Say N if unsure.
 450
 451config TASK_IO_ACCOUNTING
 452	bool "Enable per-task storage I/O accounting"
 453	depends on TASK_XACCT
 454	help
 455	  Collect information on the number of bytes of storage I/O which this
 456	  task has caused.
 457
 458	  Say N if unsure.
 459
 460endmenu # "CPU/Task time and stats accounting"
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 461
 462config CPU_ISOLATION
 463	bool "CPU isolation"
 464	depends on SMP || COMPILE_TEST
 465	default y
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 466	help
 467	  Make sure that CPUs running critical tasks are not disturbed by
 468	  any source of "noise" such as unbound workqueues, timers, kthreads...
 469	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
 470	  the "isolcpus=" boot parameter.
 
 
 
 
 471
 472	  Say Y if unsure.
 473
 474source "kernel/rcu/Kconfig"
 
 
 
 
 
 
 475
 476config BUILD_BIN2C
 477	bool
 
 478	default n
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 479
 480config IKCONFIG
 481	tristate "Kernel .config support"
 482	select BUILD_BIN2C
 483	---help---
 484	  This option enables the complete Linux kernel ".config" file
 485	  contents to be saved in the kernel. It provides documentation
 486	  of which kernel options are used in a running kernel or in an
 487	  on-disk kernel.  This information can be extracted from the kernel
 488	  image file with the script scripts/extract-ikconfig and used as
 489	  input to rebuild the current kernel or to build another kernel.
 490	  It can also be extracted from a running kernel by reading
 491	  /proc/config.gz if enabled (below).
 492
 493config IKCONFIG_PROC
 494	bool "Enable access to .config through /proc/config.gz"
 495	depends on IKCONFIG && PROC_FS
 496	---help---
 497	  This option enables access to the kernel configuration file
 498	  through /proc/config.gz.
 499
 500config LOG_BUF_SHIFT
 501	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 502	range 12 25
 503	default 17
 504	depends on PRINTK
 505	help
 506	  Select the minimal kernel log buffer size as a power of 2.
 507	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
 508	  parameter, see below. Any higher size also might be forced
 509	  by "log_buf_len" boot parameter.
 510
 511	  Examples:
 512		     17 => 128 KB
 513		     16 => 64 KB
 514		     15 => 32 KB
 515		     14 => 16 KB
 516		     13 =>  8 KB
 517		     12 =>  4 KB
 518
 519config LOG_CPU_MAX_BUF_SHIFT
 520	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
 521	depends on SMP
 522	range 0 21
 523	default 12 if !BASE_SMALL
 524	default 0 if BASE_SMALL
 525	depends on PRINTK
 526	help
 527	  This option allows to increase the default ring buffer size
 528	  according to the number of CPUs. The value defines the contribution
 529	  of each CPU as a power of 2. The used space is typically only few
 530	  lines however it might be much more when problems are reported,
 531	  e.g. backtraces.
 532
 533	  The increased size means that a new buffer has to be allocated and
 534	  the original static one is unused. It makes sense only on systems
 535	  with more CPUs. Therefore this value is used only when the sum of
 536	  contributions is greater than the half of the default kernel ring
 537	  buffer as defined by LOG_BUF_SHIFT. The default values are set
 538	  so that more than 64 CPUs are needed to trigger the allocation.
 539
 540	  Also this option is ignored when "log_buf_len" kernel parameter is
 541	  used as it forces an exact (power of two) size of the ring buffer.
 542
 543	  The number of possible CPUs is used for this computation ignoring
 544	  hotplugging making the computation optimal for the worst case
 545	  scenario while allowing a simple algorithm to be used from bootup.
 546
 547	  Examples shift values and their meaning:
 548		     17 => 128 KB for each CPU
 549		     16 =>  64 KB for each CPU
 550		     15 =>  32 KB for each CPU
 551		     14 =>  16 KB for each CPU
 552		     13 =>   8 KB for each CPU
 553		     12 =>   4 KB for each CPU
 554
 555config PRINTK_SAFE_LOG_BUF_SHIFT
 556	int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
 557	range 10 21
 558	default 13
 559	depends on PRINTK
 560	help
 561	  Select the size of an alternate printk per-CPU buffer where messages
 562	  printed from usafe contexts are temporary stored. One example would
 563	  be NMI messages, another one - printk recursion. The messages are
 564	  copied to the main log buffer in a safe context to avoid a deadlock.
 565	  The value defines the size as a power of 2.
 566
 567	  Those messages are rare and limited. The largest one is when
 568	  a backtrace is printed. It usually fits into 4KB. Select
 569	  8KB if you want to be on the safe side.
 570
 571	  Examples:
 572		     17 => 128 KB for each CPU
 573		     16 =>  64 KB for each CPU
 574		     15 =>  32 KB for each CPU
 575		     14 =>  16 KB for each CPU
 576		     13 =>   8 KB for each CPU
 577		     12 =>   4 KB for each CPU
 578
 579#
 580# Architectures with an unreliable sched_clock() should select this:
 581#
 582config HAVE_UNSTABLE_SCHED_CLOCK
 583	bool
 584
 585config GENERIC_SCHED_CLOCK
 586	bool
 
 
 
 
 
 
 
 
 
 587
 588#
 589# For architectures that want to enable the support for NUMA-affine scheduler
 590# balancing logic:
 591#
 592config ARCH_SUPPORTS_NUMA_BALANCING
 593	bool
 594
 595#
 596# For architectures that prefer to flush all TLBs after a number of pages
 597# are unmapped instead of sending one IPI per page to flush. The architecture
 598# must provide guarantees on what happens if a clean TLB cache entry is
 599# written after the unmap. Details are in mm/rmap.c near the check for
 600# should_defer_flush. The architecture should also consider if the full flush
 601# and the refill costs are offset by the savings of sending fewer IPIs.
 602config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 603	bool
 604
 605#
 606# For architectures that know their GCC __int128 support is sound
 607#
 608config ARCH_SUPPORTS_INT128
 609	bool
 
 
 610
 611# For architectures that (ab)use NUMA to represent different memory regions
 612# all cpu-local but of different latencies, such as SuperH.
 613#
 614config ARCH_WANT_NUMA_VARIABLE_LOCALITY
 615	bool
 616
 617config NUMA_BALANCING
 618	bool "Memory placement aware NUMA scheduler"
 619	depends on ARCH_SUPPORTS_NUMA_BALANCING
 620	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
 621	depends on SMP && NUMA && MIGRATION
 622	help
 623	  This option adds support for automatic NUMA aware memory/task placement.
 624	  The mechanism is quite primitive and is based on migrating memory when
 625	  it has references to the node the task is running on.
 626
 627	  This system will be inactive on UMA systems.
 628
 629config NUMA_BALANCING_DEFAULT_ENABLED
 630	bool "Automatically enable NUMA aware memory/task placement"
 631	default y
 632	depends on NUMA_BALANCING
 633	help
 634	  If set, automatic NUMA balancing will be enabled if running on a NUMA
 635	  machine.
 636
 637menuconfig CGROUPS
 638	bool "Control Group support"
 639	select KERNFS
 640	help
 641	  This option adds support for grouping sets of processes together, for
 642	  use with process control subsystems such as Cpusets, CFS, memory
 643	  controls or device isolation.
 644	  See
 645		- Documentation/scheduler/sched-design-CFS.txt	(CFS)
 646		- Documentation/cgroup-v1/ (features for grouping, isolation
 647					  and resource control)
 648
 649	  Say N if unsure.
 650
 651if CGROUPS
 
 
 
 652
 653config PAGE_COUNTER
 654       bool
 655
 656config MEMCG
 657	bool "Memory controller"
 658	select PAGE_COUNTER
 659	select EVENTFD
 660	help
 661	  Provides control over the memory footprint of tasks in a cgroup.
 
 662
 663config MEMCG_SWAP
 664	bool "Swap controller"
 665	depends on MEMCG && SWAP
 666	help
 667	  Provides control over the swap space consumed by tasks in a cgroup.
 
 668
 669config MEMCG_SWAP_ENABLED
 670	bool "Swap controller enabled by default"
 671	depends on MEMCG_SWAP
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 672	default y
 673	help
 674	  Memory Resource Controller Swap Extension comes with its price in
 675	  a bigger memory consumption. General purpose distribution kernels
 676	  which want to enable the feature but keep it disabled by default
 677	  and let the user enable it by swapaccount=1 boot command line
 678	  parameter should have this option unselected.
 679	  For those who want to have the feature enabled by default should
 680	  select this option (if, for some reason, they need to disable it
 681	  then swapaccount=0 does the trick).
 682
 683config BLK_CGROUP
 684	bool "IO controller"
 685	depends on BLOCK
 686	default n
 687	---help---
 688	Generic block IO controller cgroup interface. This is the common
 689	cgroup interface which should be used by various IO controlling
 690	policies.
 691
 692	Currently, CFQ IO scheduler uses it to recognize task groups and
 693	control disk bandwidth allocation (proportional time slice allocation)
 694	to such task groups. It is also used by bio throttling logic in
 695	block layer to implement upper limit in IO rates on a device.
 696
 697	This option only enables generic Block IO controller infrastructure.
 698	One needs to also enable actual IO controlling logic/policy. For
 699	enabling proportional weight division of disk bandwidth in CFQ, set
 700	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
 701	CONFIG_BLK_DEV_THROTTLING=y.
 702
 703	See Documentation/cgroup-v1/blkio-controller.txt for more information.
 704
 705config DEBUG_BLK_CGROUP
 706	bool "IO controller debugging"
 707	depends on BLK_CGROUP
 708	default n
 709	---help---
 710	Enable some debugging help. Currently it exports additional stat
 711	files in a cgroup which can be useful for debugging.
 712
 713config CGROUP_WRITEBACK
 714	bool
 715	depends on MEMCG && BLK_CGROUP
 716	default y
 717
 718menuconfig CGROUP_SCHED
 719	bool "CPU controller"
 
 720	default n
 721	help
 722	  This feature lets CPU scheduler recognize task groups and control CPU
 723	  bandwidth allocation to such task groups. It uses cgroups to group
 724	  tasks.
 725
 726if CGROUP_SCHED
 727config FAIR_GROUP_SCHED
 728	bool "Group scheduling for SCHED_OTHER"
 729	depends on CGROUP_SCHED
 730	default CGROUP_SCHED
 731
 732config CFS_BANDWIDTH
 733	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
 734	depends on FAIR_GROUP_SCHED
 735	default n
 736	help
 737	  This option allows users to define CPU bandwidth rates (limits) for
 738	  tasks running within the fair group scheduler.  Groups with no limit
 739	  set are considered to be unconstrained and will run with no
 740	  restriction.
 741	  See Documentation/scheduler/sched-bwc.txt for more information.
 742
 743config RT_GROUP_SCHED
 744	bool "Group scheduling for SCHED_RR/FIFO"
 
 745	depends on CGROUP_SCHED
 746	default n
 747	help
 748	  This feature lets you explicitly allocate real CPU bandwidth
 749	  to task groups. If enabled, it will also make it impossible to
 750	  schedule realtime tasks for non-root users until you allocate
 751	  realtime bandwidth for them.
 752	  See Documentation/scheduler/sched-rt-group.txt for more information.
 753
 754endif #CGROUP_SCHED
 755
 756config CGROUP_PIDS
 757	bool "PIDs controller"
 758	help
 759	  Provides enforcement of process number limits in the scope of a
 760	  cgroup. Any attempt to fork more processes than is allowed in the
 761	  cgroup will fail. PIDs are fundamentally a global resource because it
 762	  is fairly trivial to reach PID exhaustion before you reach even a
 763	  conservative kmemcg limit. As a result, it is possible to grind a
 764	  system to halt without being limited by other cgroup policies. The
 765	  PIDs controller is designed to stop this from happening.
 766
 767	  It should be noted that organisational operations (such as attaching
 768	  to a cgroup hierarchy will *not* be blocked by the PIDs controller),
 769	  since the PIDs limit only affects a process's ability to fork, not to
 770	  attach to a cgroup.
 771
 772config CGROUP_RDMA
 773	bool "RDMA controller"
 774	help
 775	  Provides enforcement of RDMA resources defined by IB stack.
 776	  It is fairly easy for consumers to exhaust RDMA resources, which
 777	  can result into resource unavailability to other consumers.
 778	  RDMA controller is designed to stop this from happening.
 779	  Attaching processes with active RDMA resources to the cgroup
 780	  hierarchy is allowed even if can cross the hierarchy's limit.
 781
 782config CGROUP_FREEZER
 783	bool "Freezer controller"
 784	help
 785	  Provides a way to freeze and unfreeze all tasks in a
 786	  cgroup.
 787
 788	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
 789	  controller includes important in-kernel memory consumers per default.
 790
 791	  If you're using cgroup2, say N.
 792
 793config CGROUP_HUGETLB
 794	bool "HugeTLB controller"
 795	depends on HUGETLB_PAGE
 796	select PAGE_COUNTER
 797	default n
 798	help
 799	  Provides a cgroup controller for HugeTLB pages.
 800	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
 801	  The limit is enforced during page fault. Since HugeTLB doesn't
 802	  support page reclaim, enforcing the limit at page fault time implies
 803	  that, the application will get SIGBUS signal if it tries to access
 804	  HugeTLB pages beyond its limit. This requires the application to know
 805	  beforehand how much HugeTLB pages it would require for its use. The
 806	  control group is tracked in the third page lru pointer. This means
 807	  that we cannot use the controller with huge page less than 3 pages.
 808
 809config CPUSETS
 810	bool "Cpuset controller"
 811	depends on SMP
 812	help
 813	  This option will let you create and manage CPUSETs which
 814	  allow dynamically partitioning a system into sets of CPUs and
 815	  Memory Nodes and assigning tasks to run only within those sets.
 816	  This is primarily useful on large SMP or NUMA systems.
 817
 818	  Say N if unsure.
 819
 820config PROC_PID_CPUSET
 821	bool "Include legacy /proc/<pid>/cpuset file"
 822	depends on CPUSETS
 823	default y
 824
 825config CGROUP_DEVICE
 826	bool "Device controller"
 827	help
 828	  Provides a cgroup controller implementing whitelists for
 829	  devices which a process in the cgroup can mknod or open.
 830
 831config CGROUP_CPUACCT
 832	bool "Simple CPU accounting controller"
 833	help
 834	  Provides a simple controller for monitoring the
 835	  total CPU consumed by the tasks in a cgroup.
 836
 837config CGROUP_PERF
 838	bool "Perf controller"
 839	depends on PERF_EVENTS
 840	help
 841	  This option extends the perf per-cpu mode to restrict monitoring
 842	  to threads which belong to the cgroup specified and run on the
 843	  designated cpu.
 844
 845	  Say N if unsure.
 846
 847config CGROUP_BPF
 848	bool "Support for eBPF programs attached to cgroups"
 849	depends on BPF_SYSCALL
 850	select SOCK_CGROUP_DATA
 851	help
 852	  Allow attaching eBPF programs to a cgroup using the bpf(2)
 853	  syscall command BPF_PROG_ATTACH.
 854
 855	  In which context these programs are accessed depends on the type
 856	  of attachment. For instance, programs that are attached using
 857	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
 858	  inet sockets.
 859
 860config CGROUP_DEBUG
 861	bool "Debug controller"
 862	default n
 863	depends on DEBUG_KERNEL
 864	help
 865	  This option enables a simple controller that exports
 866	  debugging information about the cgroups framework. This
 867	  controller is for control cgroup debugging only. Its
 868	  interfaces are not stable.
 869
 870	  Say N.
 871
 872config SOCK_CGROUP_DATA
 873	bool
 874	default n
 
 
 
 875
 876endif # CGROUPS
 877
 878menuconfig NAMESPACES
 879	bool "Namespaces support" if EXPERT
 880	depends on MULTIUSER
 881	default !EXPERT
 882	help
 883	  Provides the way to make tasks work with different objects using
 884	  the same id. For example same IPC id may refer to different objects
 885	  or same user id or pid may refer to different tasks when used in
 886	  different namespaces.
 887
 888if NAMESPACES
 889
 890config UTS_NS
 891	bool "UTS namespace"
 892	default y
 893	help
 894	  In this namespace tasks see different info provided with the
 895	  uname() system call
 896
 897config IPC_NS
 898	bool "IPC namespace"
 899	depends on (SYSVIPC || POSIX_MQUEUE)
 900	default y
 901	help
 902	  In this namespace tasks work with IPC ids which correspond to
 903	  different IPC objects in different namespaces.
 904
 905config USER_NS
 906	bool "User namespace"
 907	default n
 
 908	help
 909	  This allows containers, i.e. vservers, to use user namespaces
 910	  to provide different user info for different servers.
 911
 912	  When user namespaces are enabled in the kernel it is
 913	  recommended that the MEMCG option also be enabled and that
 914	  user-space use the memory control groups to limit the amount
 915	  of memory a memory unprivileged users can use.
 916
 917	  If unsure, say N.
 918
 919config PID_NS
 920	bool "PID Namespaces"
 921	default y
 922	help
 923	  Support process id namespaces.  This allows having multiple
 924	  processes with the same pid as long as they are in different
 925	  pid namespaces.  This is a building block of containers.
 926
 927config NET_NS
 928	bool "Network namespace"
 929	depends on NET
 930	default y
 931	help
 932	  Allow user space to create what appear to be multiple instances
 933	  of the network stack.
 934
 935endif # NAMESPACES
 936
 937config SCHED_AUTOGROUP
 938	bool "Automatic process group scheduling"
 
 939	select CGROUPS
 940	select CGROUP_SCHED
 941	select FAIR_GROUP_SCHED
 942	help
 943	  This option optimizes the scheduler for common desktop workloads by
 944	  automatically creating and populating task groups.  This separation
 945	  of workloads isolates aggressive CPU burners (like build jobs) from
 946	  desktop applications.  Task group autogeneration is currently based
 947	  upon task session.
 948
 
 
 
 949config SYSFS_DEPRECATED
 950	bool "Enable deprecated sysfs features to support old userspace tools"
 951	depends on SYSFS
 952	default n
 953	help
 954	  This option adds code that switches the layout of the "block" class
 955	  devices, to not show up in /sys/class/block/, but only in
 956	  /sys/block/.
 957
 958	  This switch is only active when the sysfs.deprecated=1 boot option is
 959	  passed or the SYSFS_DEPRECATED_V2 option is set.
 960
 961	  This option allows new kernels to run on old distributions and tools,
 962	  which might get confused by /sys/class/block/. Since 2007/2008 all
 963	  major distributions and tools handle this just fine.
 964
 965	  Recent distributions and userspace tools after 2009/2010 depend on
 966	  the existence of /sys/class/block/, and will not work with this
 967	  option enabled.
 968
 969	  Only if you are using a new kernel on an old distribution, you might
 970	  need to say Y here.
 971
 972config SYSFS_DEPRECATED_V2
 973	bool "Enable deprecated sysfs features by default"
 974	default n
 975	depends on SYSFS
 976	depends on SYSFS_DEPRECATED
 977	help
 978	  Enable deprecated sysfs by default.
 979
 980	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
 981	  option.
 982
 983	  Only if you are using a new kernel on an old distribution, you might
 984	  need to say Y here. Even then, odds are you would not need it
 985	  enabled, you can always pass the boot option if absolutely necessary.
 986
 987config RELAY
 988	bool "Kernel->user space relay support (formerly relayfs)"
 989	select IRQ_WORK
 990	help
 991	  This option enables support for relay interface support in
 992	  certain file systems (such as debugfs).
 993	  It is designed to provide an efficient mechanism for tools and
 994	  facilities to relay large amounts of data from kernel space to
 995	  user space.
 996
 997	  If unsure, say N.
 998
 999config BLK_DEV_INITRD
1000	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 
1001	help
1002	  The initial RAM filesystem is a ramfs which is loaded by the
1003	  boot loader (loadlin or lilo) and that is mounted as root
1004	  before the normal boot procedure. It is typically used to
1005	  load modules needed to mount the "real" root file system,
1006	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
1007
1008	  If RAM disk support (BLK_DEV_RAM) is also included, this
1009	  also enables initial RAM disk (initrd) support and adds
1010	  15 Kbytes (more on some other architectures) to the kernel size.
1011
1012	  If unsure say Y.
1013
1014if BLK_DEV_INITRD
1015
1016source "usr/Kconfig"
1017
1018endif
1019
1020choice
1021	prompt "Compiler optimization level"
1022	default CC_OPTIMIZE_FOR_PERFORMANCE
1023
1024config CC_OPTIMIZE_FOR_PERFORMANCE
1025	bool "Optimize for performance"
1026	help
1027	  This is the default optimization level for the kernel, building
1028	  with the "-O2" compiler flag for best performance and most
1029	  helpful compile-time warnings.
1030
1031config CC_OPTIMIZE_FOR_SIZE
1032	bool "Optimize for size"
1033	help
1034	  Enabling this option will pass "-Os" instead of "-O2" to
1035	  your compiler resulting in a smaller kernel.
1036
1037	  If unsure, say N.
1038
1039endchoice
1040
1041config SYSCTL
1042	bool
1043
1044config ANON_INODES
1045	bool
1046
1047config HAVE_UID16
1048	bool
1049
1050config SYSCTL_EXCEPTION_TRACE
1051	bool
1052	help
1053	  Enable support for /proc/sys/debug/exception-trace.
1054
1055config SYSCTL_ARCH_UNALIGN_NO_WARN
1056	bool
1057	help
1058	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
1059	  Allows arch to define/use @no_unaligned_warning to possibly warn
1060	  about unaligned access emulation going on under the hood.
1061
1062config SYSCTL_ARCH_UNALIGN_ALLOW
1063	bool
1064	help
1065	  Enable support for /proc/sys/kernel/unaligned-trap
1066	  Allows arches to define/use @unaligned_enabled to runtime toggle
1067	  the unaligned access emulation.
1068	  see arch/parisc/kernel/unaligned.c for reference
1069
1070config HAVE_PCSPKR_PLATFORM
1071	bool
1072
1073# interpreter that classic socket filters depend on
1074config BPF
1075	bool
1076
1077menuconfig EXPERT
1078	bool "Configure standard kernel features (expert users)"
1079	# Unhide debug options, to make the on-by-default options visible
1080	select DEBUG_KERNEL
1081	help
1082	  This option allows certain base kernel options and settings
1083          to be disabled or tweaked. This is for specialized
1084          environments which can tolerate a "non-standard" kernel.
1085          Only use this if you really know what you are doing.
1086
1087config UID16
1088	bool "Enable 16-bit UID system calls" if EXPERT
1089	depends on HAVE_UID16 && MULTIUSER
1090	default y
1091	help
1092	  This enables the legacy 16-bit UID syscall wrappers.
1093
1094config MULTIUSER
1095	bool "Multiple users, groups and capabilities support" if EXPERT
1096	default y
1097	help
1098	  This option enables support for non-root users, groups and
1099	  capabilities.
1100
1101	  If you say N here, all processes will run with UID 0, GID 0, and all
1102	  possible capabilities.  Saying N here also compiles out support for
1103	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
1104	  setgid, and capset.
1105
1106	  If unsure, say Y here.
1107
1108config SGETMASK_SYSCALL
1109	bool "sgetmask/ssetmask syscalls support" if EXPERT
1110	def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
1111	---help---
1112	  sys_sgetmask and sys_ssetmask are obsolete system calls
1113	  no longer supported in libc but still enabled by default in some
1114	  architectures.
1115
1116	  If unsure, leave the default option here.
1117
1118config SYSFS_SYSCALL
1119	bool "Sysfs syscall support" if EXPERT
1120	default y
1121	---help---
1122	  sys_sysfs is an obsolete system call no longer supported in libc.
1123	  Note that disabling this option is more secure but might break
1124	  compatibility with some systems.
1125
1126	  If unsure say Y here.
1127
1128config SYSCTL_SYSCALL
1129	bool "Sysctl syscall support" if EXPERT
1130	depends on PROC_SYSCTL
1131	default n
1132	select SYSCTL
1133	---help---
1134	  sys_sysctl uses binary paths that have been found challenging
1135	  to properly maintain and use.  The interface in /proc/sys
1136	  using paths with ascii names is now the primary path to this
1137	  information.
1138
1139	  Almost nothing using the binary sysctl interface so if you are
1140	  trying to save some space it is probably safe to disable this,
1141	  making your kernel marginally smaller.
1142
1143	  If unsure say N here.
1144
1145config FHANDLE
1146	bool "open by fhandle syscalls" if EXPERT
1147	select EXPORTFS
1148	default y
 
 
 
 
 
 
 
1149	help
1150	  If you say Y here, a user level program will be able to map
1151	  file names to handle and then later use the handle for
1152	  different file system operations. This is useful in implementing
1153	  userspace file servers, which now track files using handles instead
1154	  of names. The handle would remain the same even if file names
1155	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
1156	  syscalls.
 
 
 
 
 
1157
1158config POSIX_TIMERS
1159	bool "Posix Clocks & timers" if EXPERT
1160	default y
1161	help
1162	  This includes native support for POSIX timers to the kernel.
1163	  Some embedded systems have no use for them and therefore they
1164	  can be configured out to reduce the size of the kernel image.
1165
1166	  When this option is disabled, the following syscalls won't be
1167	  available: timer_create, timer_gettime: timer_getoverrun,
1168	  timer_settime, timer_delete, clock_adjtime, getitimer,
1169	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
1170	  clock_getres and clock_nanosleep syscalls will be limited to
1171	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
1172
1173	  If unsure say y.
1174
1175config PRINTK
1176	default y
1177	bool "Enable support for printk" if EXPERT
1178	select IRQ_WORK
1179	help
1180	  This option enables normal printk support. Removing it
1181	  eliminates most of the message strings from the kernel image
1182	  and makes the kernel more or less silent. As this makes it
1183	  very difficult to diagnose system problems, saying N here is
1184	  strongly discouraged.
1185
1186config PRINTK_NMI
1187	def_bool y
1188	depends on PRINTK
1189	depends on HAVE_NMI
1190
1191config BUG
1192	bool "BUG() support" if EXPERT
1193	default y
1194	help
1195          Disabling this option eliminates support for BUG and WARN, reducing
1196          the size of your kernel image and potentially quietly ignoring
1197          numerous fatal conditions. You should only consider disabling this
1198          option for embedded systems with no facilities for reporting errors.
1199          Just say Y.
1200
1201config ELF_CORE
1202	depends on COREDUMP
1203	default y
1204	bool "Enable ELF core dumps" if EXPERT
1205	help
1206	  Enable support for generating core dumps. Disabling saves about 4k.
1207
1208
1209config PCSPKR_PLATFORM
1210	bool "Enable PC-Speaker support" if EXPERT
1211	depends on HAVE_PCSPKR_PLATFORM
1212	select I8253_LOCK
1213	default y
1214	help
1215          This option allows to disable the internal PC-Speaker
1216          support, saving some memory.
1217
 
 
 
1218config BASE_FULL
1219	default y
1220	bool "Enable full-sized data structures for core" if EXPERT
1221	help
1222	  Disabling this option reduces the size of miscellaneous core
1223	  kernel data structures. This saves memory on small machines,
1224	  but may reduce performance.
1225
1226config FUTEX
1227	bool "Enable futex support" if EXPERT
1228	default y
1229	imply RT_MUTEXES
1230	help
1231	  Disabling this option will cause the kernel to be built without
1232	  support for "fast userspace mutexes".  The resulting kernel may not
1233	  run glibc-based applications correctly.
1234
1235config FUTEX_PI
1236	bool
1237	depends on FUTEX && RT_MUTEXES
1238	default y
1239
1240config HAVE_FUTEX_CMPXCHG
1241	bool
1242	depends on FUTEX
1243	help
1244	  Architectures should select this if futex_atomic_cmpxchg_inatomic()
1245	  is implemented and always working. This removes a couple of runtime
1246	  checks.
1247
1248config EPOLL
1249	bool "Enable eventpoll support" if EXPERT
1250	default y
1251	select ANON_INODES
1252	help
1253	  Disabling this option will cause the kernel to be built without
1254	  support for epoll family of system calls.
1255
1256config SIGNALFD
1257	bool "Enable signalfd() system call" if EXPERT
1258	select ANON_INODES
1259	default y
1260	help
1261	  Enable the signalfd() system call that allows to receive signals
1262	  on a file descriptor.
1263
1264	  If unsure, say Y.
1265
1266config TIMERFD
1267	bool "Enable timerfd() system call" if EXPERT
1268	select ANON_INODES
1269	default y
1270	help
1271	  Enable the timerfd() system call that allows to receive timer
1272	  events on a file descriptor.
1273
1274	  If unsure, say Y.
1275
1276config EVENTFD
1277	bool "Enable eventfd() system call" if EXPERT
1278	select ANON_INODES
1279	default y
1280	help
1281	  Enable the eventfd() system call that allows to receive both
1282	  kernel notification (ie. KAIO) or userspace notifications.
1283
1284	  If unsure, say Y.
1285
1286config SHMEM
1287	bool "Use full shmem filesystem" if EXPERT
1288	default y
1289	depends on MMU
1290	help
1291	  The shmem is an internal filesystem used to manage shared memory.
1292	  It is backed by swap and manages resource limits. It is also exported
1293	  to userspace as tmpfs if TMPFS is enabled. Disabling this
1294	  option replaces shmem and tmpfs with the much simpler ramfs code,
1295	  which may be appropriate on small systems without swap.
1296
1297config AIO
1298	bool "Enable AIO support" if EXPERT
1299	default y
1300	help
1301	  This option enables POSIX asynchronous I/O which may by used
1302	  by some high performance threaded applications. Disabling
1303	  this option saves about 7k.
1304
1305config ADVISE_SYSCALLS
1306	bool "Enable madvise/fadvise syscalls" if EXPERT
1307	default y
1308	help
1309	  This option enables the madvise and fadvise syscalls, used by
1310	  applications to advise the kernel about their future memory or file
1311	  usage, improving performance. If building an embedded system where no
1312	  applications use these syscalls, you can disable this option to save
1313	  space.
1314
1315config MEMBARRIER
1316	bool "Enable membarrier() system call" if EXPERT
1317	default y
1318	help
1319	  Enable the membarrier() system call that allows issuing memory
1320	  barriers across all running threads, which can be used to distribute
1321	  the cost of user-space memory barriers asymmetrically by transforming
1322	  pairs of memory barriers into pairs consisting of membarrier() and a
1323	  compiler barrier.
1324
1325	  If unsure, say Y.
1326
1327config CHECKPOINT_RESTORE
1328	bool "Checkpoint/restore support" if EXPERT
1329	select PROC_CHILDREN
1330	default n
1331	help
1332	  Enables additional kernel features in a sake of checkpoint/restore.
1333	  In particular it adds auxiliary prctl codes to setup process text,
1334	  data and heap segment sizes, and a few additional /proc filesystem
1335	  entries.
1336
1337	  If unsure, say N here.
1338
1339config KALLSYMS
1340	 bool "Load all symbols for debugging/ksymoops" if EXPERT
1341	 default y
1342	 help
1343	   Say Y here to let the kernel print out symbolic crash information and
1344	   symbolic stack backtraces. This increases the size of the kernel
1345	   somewhat, as all symbols have to be loaded into the kernel image.
1346
1347config KALLSYMS_ALL
1348	bool "Include all symbols in kallsyms"
1349	depends on DEBUG_KERNEL && KALLSYMS
1350	help
1351	   Normally kallsyms only contains the symbols of functions for nicer
1352	   OOPS messages and backtraces (i.e., symbols from the text and inittext
1353	   sections). This is sufficient for most cases. And only in very rare
1354	   cases (e.g., when a debugger is used) all symbols are required (e.g.,
1355	   names of variables from the data sections, etc).
1356
1357	   This option makes sure that all symbols are loaded into the kernel
1358	   image (i.e., symbols from all sections) in cost of increased kernel
1359	   size (depending on the kernel configuration, it may be 300KiB or
1360	   something like this).
1361
1362	   Say N unless you really need all symbols.
1363
1364config KALLSYMS_ABSOLUTE_PERCPU
1365	bool
1366	depends on KALLSYMS
1367	default X86_64 && SMP
1368
1369config KALLSYMS_BASE_RELATIVE
1370	bool
1371	depends on KALLSYMS
1372	default !IA64
1373	help
1374	  Instead of emitting them as absolute values in the native word size,
1375	  emit the symbol references in the kallsyms table as 32-bit entries,
1376	  each containing a relative value in the range [base, base + U32_MAX]
1377	  or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
1378	  an absolute value in the range [0, S32_MAX] or a relative value in the
1379	  range [base, base + S32_MAX], where base is the lowest relative symbol
1380	  address encountered in the image.
1381
1382	  On 64-bit builds, this reduces the size of the address table by 50%,
1383	  but more importantly, it results in entries whose values are build
1384	  time constants, and no relocation pass is required at runtime to fix
1385	  up the entries based on the runtime load address of the kernel.
1386
1387# end of the "standard kernel features (expert users)" menu
1388
1389# syscall, maps, verifier
1390config BPF_SYSCALL
1391	bool "Enable bpf() system call"
1392	select ANON_INODES
1393	select BPF
1394	default n
1395	help
1396	  Enable the bpf() system call that allows to manipulate eBPF
1397	  programs and maps via file descriptors.
1398
1399config BPF_JIT_ALWAYS_ON
1400	bool "Permanently enable BPF JIT and remove BPF interpreter"
1401	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
1402	help
1403	  Enables BPF JIT and removes BPF interpreter to avoid
1404	  speculative execution of BPF instructions by the interpreter
1405
1406config USERFAULTFD
1407	bool "Enable userfaultfd() system call"
1408	select ANON_INODES
1409	depends on MMU
1410	help
1411	  Enable the userfaultfd() system call that allows to intercept and
1412	  handle page faults in userland.
1413
1414config ARCH_HAS_MEMBARRIER_CALLBACKS
1415	bool
1416
1417config ARCH_HAS_MEMBARRIER_SYNC_CORE
1418	bool
1419
1420config EMBEDDED
1421	bool "Embedded system"
1422	option allnoconfig_y
1423	select EXPERT
1424	help
1425	  This option should be enabled if compiling the kernel for
1426	  an embedded system so certain expert options are available
1427	  for configuration.
1428
1429config HAVE_PERF_EVENTS
1430	bool
1431	help
1432	  See tools/perf/design.txt for details.
1433
1434config PERF_USE_VMALLOC
1435	bool
1436	help
1437	  See tools/perf/design.txt for details
1438
1439config PC104
1440	bool "PC/104 support" if EXPERT
1441	help
1442	  Expose PC/104 form factor device drivers and options available for
1443	  selection and configuration. Enable this option if your target
1444	  machine has a PC/104 bus.
1445
1446menu "Kernel Performance Events And Counters"
1447
1448config PERF_EVENTS
1449	bool "Kernel performance events and counters"
1450	default y if PROFILING
1451	depends on HAVE_PERF_EVENTS
1452	select ANON_INODES
1453	select IRQ_WORK
1454	select SRCU
1455	help
1456	  Enable kernel support for various performance events provided
1457	  by software and hardware.
1458
1459	  Software events are supported either built-in or via the
1460	  use of generic tracepoints.
1461
1462	  Most modern CPUs support performance events via performance
1463	  counter registers. These registers count the number of certain
1464	  types of hw events: such as instructions executed, cachemisses
1465	  suffered, or branches mis-predicted - without slowing down the
1466	  kernel or applications. These registers can also trigger interrupts
1467	  when a threshold number of events have passed - and can thus be
1468	  used to profile the code that runs on that CPU.
1469
1470	  The Linux Performance Event subsystem provides an abstraction of
1471	  these software and hardware event capabilities, available via a
1472	  system call and used by the "perf" utility in tools/perf/. It
1473	  provides per task and per CPU counters, and it provides event
1474	  capabilities on top of those.
1475
1476	  Say Y if unsure.
1477
 
 
 
 
 
 
 
 
 
 
 
 
1478config DEBUG_PERF_USE_VMALLOC
1479	default n
1480	bool "Debug: use vmalloc to back perf mmap() buffers"
1481	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
1482	select PERF_USE_VMALLOC
1483	help
1484	 Use vmalloc memory to back perf mmap() buffers.
1485
1486	 Mostly useful for debugging the vmalloc code on platforms
1487	 that don't require it.
1488
1489	 Say N if unsure.
1490
1491endmenu
1492
1493config VM_EVENT_COUNTERS
1494	default y
1495	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1496	help
1497	  VM event counters are needed for event counts to be shown.
1498	  This option allows the disabling of the VM event counters
1499	  on EXPERT systems.  /proc/vmstat will only show page counts
1500	  if VM event counters are disabled.
1501
 
 
 
 
 
 
 
 
 
1502config SLUB_DEBUG
1503	default y
1504	bool "Enable SLUB debugging support" if EXPERT
1505	depends on SLUB && SYSFS
1506	help
1507	  SLUB has extensive debug support features. Disabling these can
1508	  result in significant savings in code size. This also disables
1509	  SLUB sysfs support. /sys/slab will not exist and there will be
1510	  no support for cache validation etc.
1511
1512config SLUB_MEMCG_SYSFS_ON
1513	default n
1514	bool "Enable memcg SLUB sysfs support by default" if EXPERT
1515	depends on SLUB && SYSFS && MEMCG
1516	help
1517	  SLUB creates a directory under /sys/kernel/slab for each
1518	  allocation cache to host info and debug files. If memory
1519	  cgroup is enabled, each cache can have per memory cgroup
1520	  caches. SLUB can create the same sysfs directories for these
1521	  caches under /sys/kernel/slab/CACHE/cgroup but it can lead
1522	  to a very high number of debug files being created. This is
1523	  controlled by slub_memcg_sysfs boot parameter and this
1524	  config option determines the parameter's default value.
1525
1526config COMPAT_BRK
1527	bool "Disable heap randomization"
1528	default y
1529	help
1530	  Randomizing heap placement makes heap exploits harder, but it
1531	  also breaks ancient binaries (including anything libc5 based).
1532	  This option changes the bootup default to heap randomization
1533	  disabled, and can be overridden at runtime by setting
1534	  /proc/sys/kernel/randomize_va_space to 2.
1535
1536	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
1537
1538choice
1539	prompt "Choose SLAB allocator"
1540	default SLUB
1541	help
1542	   This option allows to select a slab allocator.
1543
1544config SLAB
1545	bool "SLAB"
1546	select HAVE_HARDENED_USERCOPY_ALLOCATOR
1547	help
1548	  The regular slab allocator that is established and known to work
1549	  well in all environments. It organizes cache hot objects in
1550	  per cpu and per node queues.
1551
1552config SLUB
1553	bool "SLUB (Unqueued Allocator)"
1554	select HAVE_HARDENED_USERCOPY_ALLOCATOR
1555	help
1556	   SLUB is a slab allocator that minimizes cache line usage
1557	   instead of managing queues of cached objects (SLAB approach).
1558	   Per cpu caching is realized using slabs of objects instead
1559	   of queues of objects. SLUB can use memory efficiently
1560	   and has enhanced diagnostics. SLUB is the default choice for
1561	   a slab allocator.
1562
1563config SLOB
1564	depends on EXPERT
1565	bool "SLOB (Simple Allocator)"
1566	help
1567	   SLOB replaces the stock allocator with a drastically simpler
1568	   allocator. SLOB is generally more space efficient but
1569	   does not perform as well on large systems.
1570
1571endchoice
1572
1573config SLAB_MERGE_DEFAULT
1574	bool "Allow slab caches to be merged"
1575	default y
1576	help
1577	  For reduced kernel memory fragmentation, slab caches can be
1578	  merged when they share the same size and other characteristics.
1579	  This carries a risk of kernel heap overflows being able to
1580	  overwrite objects from merged caches (and more easily control
1581	  cache layout), which makes such heap attacks easier to exploit
1582	  by attackers. By keeping caches unmerged, these kinds of exploits
1583	  can usually only damage objects in the same cache. To disable
1584	  merging at runtime, "slab_nomerge" can be passed on the kernel
1585	  command line.
1586
1587config SLAB_FREELIST_RANDOM
1588	default n
1589	depends on SLAB || SLUB
1590	bool "SLAB freelist randomization"
1591	help
1592	  Randomizes the freelist order used on creating new pages. This
1593	  security feature reduces the predictability of the kernel slab
1594	  allocator against heap overflows.
1595
1596config SLAB_FREELIST_HARDENED
1597	bool "Harden slab freelist metadata"
1598	depends on SLUB
1599	help
1600	  Many kernel heap attacks try to target slab cache metadata and
1601	  other infrastructure. This options makes minor performance
1602	  sacrifies to harden the kernel slab allocator against common
1603	  freelist exploit methods.
1604
1605config SLUB_CPU_PARTIAL
1606	default y
1607	depends on SLUB && SMP
1608	bool "SLUB per cpu partial cache"
1609	help
1610	  Per cpu partial caches accellerate objects allocation and freeing
1611	  that is local to a processor at the price of more indeterminism
1612	  in the latency of the free. On overflow these caches will be cleared
1613	  which requires the taking of locks that may cause latency spikes.
1614	  Typically one would choose no for a realtime system.
1615
1616config MMAP_ALLOW_UNINITIALIZED
1617	bool "Allow mmapped anonymous memory to be uninitialized"
1618	depends on EXPERT && !MMU
1619	default n
1620	help
1621	  Normally, and according to the Linux spec, anonymous memory obtained
1622	  from mmap() has it's contents cleared before it is passed to
1623	  userspace.  Enabling this config option allows you to request that
1624	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
1625	  providing a huge performance boost.  If this option is not enabled,
1626	  then the flag will be ignored.
1627
1628	  This is taken advantage of by uClibc's malloc(), and also by
1629	  ELF-FDPIC binfmt's brk and stack allocator.
1630
1631	  Because of the obvious security issues, this option should only be
1632	  enabled on embedded devices where you control what is run in
1633	  userspace.  Since that isn't generally a problem on no-MMU systems,
1634	  it is normally safe to say Y here.
1635
1636	  See Documentation/nommu-mmap.txt for more information.
1637
1638config SYSTEM_DATA_VERIFICATION
1639	def_bool n
1640	select SYSTEM_TRUSTED_KEYRING
1641	select KEYS
1642	select CRYPTO
1643	select CRYPTO_RSA
1644	select ASYMMETRIC_KEY_TYPE
1645	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
1646	select ASN1
1647	select OID_REGISTRY
1648	select X509_CERTIFICATE_PARSER
1649	select PKCS7_MESSAGE_PARSER
1650	help
1651	  Provide PKCS#7 message verification using the contents of the system
1652	  trusted keyring to provide public keys.  This then can be used for
1653	  module verification, kexec image verification and firmware blob
1654	  verification.
1655
1656config PROFILING
1657	bool "Profiling support"
1658	help
1659	  Say Y here to enable the extended profiling support mechanisms used
1660	  by profilers such as OProfile.
1661
1662#
1663# Place an empty function call at each tracepoint site. Can be
1664# dynamically changed for a probe function.
1665#
1666config TRACEPOINTS
1667	bool
1668
1669source "arch/Kconfig"
1670
1671endmenu		# General setup
1672
1673config HAVE_GENERIC_DMA_COHERENT
1674	bool
1675	default n
1676
 
 
 
 
 
 
1677config RT_MUTEXES
1678	bool
1679
1680config BASE_SMALL
1681	int
1682	default 0 if BASE_FULL
1683	default 1 if !BASE_FULL
1684
1685menuconfig MODULES
1686	bool "Enable loadable module support"
1687	option modules
1688	help
1689	  Kernel modules are small pieces of compiled code which can
1690	  be inserted in the running kernel, rather than being
1691	  permanently built into the kernel.  You use the "modprobe"
1692	  tool to add (and sometimes remove) them.  If you say Y here,
1693	  many parts of the kernel can be built as modules (by
1694	  answering M instead of Y where indicated): this is most
1695	  useful for infrequently used options which are not required
1696	  for booting.  For more information, see the man pages for
1697	  modprobe, lsmod, modinfo, insmod and rmmod.
1698
1699	  If you say Y here, you will need to run "make
1700	  modules_install" to put the modules under /lib/modules/
1701	  where modprobe can find them (you may need to be root to do
1702	  this).
1703
1704	  If unsure, say Y.
1705
1706if MODULES
1707
1708config MODULE_FORCE_LOAD
1709	bool "Forced module loading"
1710	default n
1711	help
1712	  Allow loading of modules without version information (ie. modprobe
1713	  --force).  Forced module loading sets the 'F' (forced) taint flag and
1714	  is usually a really bad idea.
1715
1716config MODULE_UNLOAD
1717	bool "Module unloading"
1718	help
1719	  Without this option you will not be able to unload any
1720	  modules (note that some modules may not be unloadable
1721	  anyway), which makes your kernel smaller, faster
1722	  and simpler.  If unsure, say Y.
1723
1724config MODULE_FORCE_UNLOAD
1725	bool "Forced module unloading"
1726	depends on MODULE_UNLOAD
1727	help
1728	  This option allows you to force a module to unload, even if the
1729	  kernel believes it is unsafe: the kernel will remove the module
1730	  without waiting for anyone to stop using it (using the -f option to
1731	  rmmod).  This is mainly for kernel developers and desperate users.
1732	  If unsure, say N.
1733
1734config MODVERSIONS
1735	bool "Module versioning support"
1736	help
1737	  Usually, you have to use modules compiled with your kernel.
1738	  Saying Y here makes it sometimes possible to use modules
1739	  compiled for different kernels, by adding enough information
1740	  to the modules to (hopefully) spot any changes which would
1741	  make them incompatible with the kernel you are running.  If
1742	  unsure, say N.
1743
1744config MODULE_REL_CRCS
1745	bool
1746	depends on MODVERSIONS
1747
1748config MODULE_SRCVERSION_ALL
1749	bool "Source checksum for all modules"
1750	help
1751	  Modules which contain a MODULE_VERSION get an extra "srcversion"
1752	  field inserted into their modinfo section, which contains a
1753    	  sum of the source files which made it.  This helps maintainers
1754	  see exactly which source was used to build a module (since
1755	  others sometimes change the module source without updating
1756	  the version).  With this option, such a "srcversion" field
1757	  will be created for all modules.  If unsure, say N.
1758
1759config MODULE_SIG
1760	bool "Module signature verification"
1761	depends on MODULES
1762	select SYSTEM_DATA_VERIFICATION
1763	help
1764	  Check modules for valid signatures upon load: the signature
1765	  is simply appended to the module. For more information see
1766	  <file:Documentation/admin-guide/module-signing.rst>.
1767
1768	  Note that this option adds the OpenSSL development packages as a
1769	  kernel build dependency so that the signing tool can use its crypto
1770	  library.
1771
1772	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
1773	  module DOES NOT get stripped after being signed.  This includes the
1774	  debuginfo strip done by some packagers (such as rpmbuild) and
1775	  inclusion into an initramfs that wants the module size reduced.
1776
1777config MODULE_SIG_FORCE
1778	bool "Require modules to be validly signed"
1779	depends on MODULE_SIG
1780	help
1781	  Reject unsigned modules or signed modules for which we don't have a
1782	  key.  Without this, such modules will simply taint the kernel.
1783
1784config MODULE_SIG_ALL
1785	bool "Automatically sign all modules"
1786	default y
1787	depends on MODULE_SIG
1788	help
1789	  Sign all modules during make modules_install. Without this option,
1790	  modules must be signed manually, using the scripts/sign-file tool.
1791
1792comment "Do not forget to sign required modules with scripts/sign-file"
1793	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
1794
1795choice
1796	prompt "Which hash algorithm should modules be signed with?"
1797	depends on MODULE_SIG
1798	help
1799	  This determines which sort of hashing algorithm will be used during
1800	  signature generation.  This algorithm _must_ be built into the kernel
1801	  directly so that signature verification can take place.  It is not
1802	  possible to load a signed module containing the algorithm to check
1803	  the signature on that module.
1804
1805config MODULE_SIG_SHA1
1806	bool "Sign modules with SHA-1"
1807	select CRYPTO_SHA1
1808
1809config MODULE_SIG_SHA224
1810	bool "Sign modules with SHA-224"
1811	select CRYPTO_SHA256
1812
1813config MODULE_SIG_SHA256
1814	bool "Sign modules with SHA-256"
1815	select CRYPTO_SHA256
1816
1817config MODULE_SIG_SHA384
1818	bool "Sign modules with SHA-384"
1819	select CRYPTO_SHA512
1820
1821config MODULE_SIG_SHA512
1822	bool "Sign modules with SHA-512"
1823	select CRYPTO_SHA512
1824
1825endchoice
1826
1827config MODULE_SIG_HASH
1828	string
1829	depends on MODULE_SIG
1830	default "sha1" if MODULE_SIG_SHA1
1831	default "sha224" if MODULE_SIG_SHA224
1832	default "sha256" if MODULE_SIG_SHA256
1833	default "sha384" if MODULE_SIG_SHA384
1834	default "sha512" if MODULE_SIG_SHA512
1835
1836config MODULE_COMPRESS
1837	bool "Compress modules on installation"
1838	depends on MODULES
1839	help
1840
1841	  Compresses kernel modules when 'make modules_install' is run; gzip or
1842	  xz depending on "Compression algorithm" below.
1843
1844	  module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
1845
1846	  Out-of-tree kernel modules installed using Kbuild will also be
1847	  compressed upon installation.
1848
1849	  Note: for modules inside an initrd or initramfs, it's more efficient
1850	  to compress the whole initrd or initramfs instead.
1851
1852	  Note: This is fully compatible with signed modules.
1853
1854	  If in doubt, say N.
1855
1856choice
1857	prompt "Compression algorithm"
1858	depends on MODULE_COMPRESS
1859	default MODULE_COMPRESS_GZIP
1860	help
1861	  This determines which sort of compression will be used during
1862	  'make modules_install'.
1863
1864	  GZIP (default) and XZ are supported.
1865
1866config MODULE_COMPRESS_GZIP
1867	bool "GZIP"
1868
1869config MODULE_COMPRESS_XZ
1870	bool "XZ"
1871
1872endchoice
1873
1874config TRIM_UNUSED_KSYMS
1875	bool "Trim unused exported kernel symbols"
1876	depends on MODULES && !UNUSED_SYMBOLS
1877	help
1878	  The kernel and some modules make many symbols available for
1879	  other modules to use via EXPORT_SYMBOL() and variants. Depending
1880	  on the set of modules being selected in your kernel configuration,
1881	  many of those exported symbols might never be used.
1882
1883	  This option allows for unused exported symbols to be dropped from
1884	  the build. In turn, this provides the compiler more opportunities
1885	  (especially when using LTO) for optimizing the code and reducing
1886	  binary size.  This might have some security advantages as well.
1887
1888	  If unsure, or if you need to build out-of-tree modules, say N.
1889
1890endif # MODULES
1891
1892config MODULES_TREE_LOOKUP
1893	def_bool y
1894	depends on PERF_EVENTS || TRACING
1895
1896config INIT_ALL_POSSIBLE
1897	bool
1898	help
1899	  Back when each arch used to define their own cpu_online_mask and
1900	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
1901	  with all 1s, and others with all 0s.  When they were centralised,
1902	  it was better to provide this option than to break all the archs
1903	  and have several arch maintainers pursuing me down dark alleys.
1904
 
 
 
 
 
 
 
1905source "block/Kconfig"
1906
1907config PREEMPT_NOTIFIERS
1908	bool
1909
1910config PADATA
1911	depends on SMP
1912	bool
1913
1914config ASN1
1915	tristate
1916	help
1917	  Build a simple ASN.1 grammar compiler that produces a bytecode output
1918	  that can be interpreted by the ASN.1 stream decoder and used to
1919	  inform it as to what tags are to be expected in a stream and what
1920	  functions to call on what tags.
1921
1922source "kernel/Kconfig.locks"
1923
1924config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
1925	bool
1926
1927# It may be useful for an architecture to override the definitions of the
1928# SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
1929# and the COMPAT_ variants in <linux/compat.h>, in particular to use a
1930# different calling convention for syscalls. They can also override the
1931# macros for not-implemented syscalls in kernel/sys_ni.c and
1932# kernel/time/posix-stubs.c. All these overrides need to be available in
1933# <asm/syscall_wrapper.h>.
1934config ARCH_HAS_SYSCALL_WRAPPER
1935	def_bool n