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init/Kconfig 72.1 KB
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  # SPDX-License-Identifier: GPL-2.0-only
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  config DEFCONFIG_LIST
  	string
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  	depends on !UML
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  	option defconfig_list
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  	default "/lib/modules/$(shell,uname -r)/.config"
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  	default "/etc/kernel-config"
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  	default "/boot/config-$(shell,uname -r)"
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  	default ARCH_DEFCONFIG
  	default "arch/$(ARCH)/defconfig"
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  config CC_IS_GCC
  	def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
  
  config GCC_VERSION
  	int
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  	default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
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  	default 0
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  config CC_IS_CLANG
  	def_bool $(success,$(CC) --version | head -n 1 | grep -q clang)
  
  config CLANG_VERSION
  	int
  	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
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  config CC_CAN_LINK
  	def_bool $(success,$(srctree)/scripts/cc-can-link.sh $(CC))
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  config CC_HAS_ASM_GOTO
  	def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
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  config TOOLS_SUPPORT_RELR
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  	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
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  config CC_HAS_ASM_INLINE
  	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
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  config CC_HAS_WARN_MAYBE_UNINITIALIZED
  	def_bool $(cc-option,-Wmaybe-uninitialized)
  	help
  	  GCC >= 4.7 supports this option.
  
  config CC_DISABLE_WARN_MAYBE_UNINITIALIZED
  	bool
  	depends on CC_HAS_WARN_MAYBE_UNINITIALIZED
  	default CC_IS_GCC && GCC_VERSION < 40900  # unreliable for GCC < 4.9
  	help
  	  GCC's -Wmaybe-uninitialized is not reliable by definition.
  	  Lots of false positive warnings are produced in some cases.
  
  	  If this option is enabled, -Wno-maybe-uninitialzed is passed
  	  to the compiler to suppress maybe-uninitialized warnings.
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  config CONSTRUCTORS
  	bool
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  	depends on !UML
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  config IRQ_WORK
  	bool
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  config BUILDTIME_EXTABLE_SORT
  	bool
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  config THREAD_INFO_IN_TASK
  	bool
  	help
  	  Select this to move thread_info off the stack into task_struct.  To
  	  make this work, an arch will need to remove all thread_info fields
  	  except flags and fix any runtime bugs.
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  	  One subtle change that will be needed is to use try_get_task_stack()
  	  and put_task_stack() in save_thread_stack_tsk() and get_wchan().
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  menu "General setup"
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  config BROKEN
  	bool
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  config BROKEN_ON_SMP
  	bool
  	depends on BROKEN || !SMP
  	default y
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  config INIT_ENV_ARG_LIMIT
  	int
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  	default 32 if !UML
  	default 128 if UML
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  	help
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  	  Maximum of each of the number of arguments and environment
  	  variables passed to init from the kernel command line.
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  config COMPILE_TEST
  	bool "Compile also drivers which will not load"
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  	depends on !UML
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  	default n
  	help
  	  Some drivers can be compiled on a different platform than they are
  	  intended to be run on. Despite they cannot be loaded there (or even
  	  when they load they cannot be used due to missing HW support),
  	  developers still, opposing to distributors, might want to build such
  	  drivers to compile-test them.
  
  	  If you are a developer and want to build everything available, say Y
  	  here. If you are a user/distributor, say N here to exclude useless
  	  drivers to be distributed.
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  config UAPI_HEADER_TEST
  	bool "Compile test UAPI headers"
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  	depends on HEADERS_INSTALL && CC_CAN_LINK
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  	help
  	  Compile test headers exported to user-space to ensure they are
  	  self-contained, i.e. compilable as standalone units.
  
  	  If you are a developer or tester and want to ensure the exported
  	  headers are self-contained, say Y here. Otherwise, choose N.
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  config LOCALVERSION
  	string "Local version - append to kernel release"
  	help
  	  Append an extra string to the end of your kernel version.
  	  This will show up when you type uname, for example.
  	  The string you set here will be appended after the contents of
  	  any files with a filename matching localversion* in your
  	  object and source tree, in that order.  Your total string can
  	  be a maximum of 64 characters.
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  config LOCALVERSION_AUTO
  	bool "Automatically append version information to the version string"
  	default y
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  	depends on !COMPILE_TEST
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  	help
  	  This will try to automatically determine if the current tree is a
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  	  release tree by looking for git tags that belong to the current
  	  top of tree revision.
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  	  A string of the format -gxxxxxxxx will be added to the localversion
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  	  if a git-based tree is found.  The string generated by this will be
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  	  appended after any matching localversion* files, and after the value
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  	  set in CONFIG_LOCALVERSION.
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  	  (The actual string used here is the first eight characters produced
  	  by running the command:
  
  	    $ git rev-parse --verify HEAD
  
  	  which is done within the script "scripts/setlocalversion".)
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  config BUILD_SALT
         string "Build ID Salt"
         default ""
         help
            The build ID is used to link binaries and their debug info. Setting
            this option will use the value in the calculation of the build id.
            This is mostly useful for distributions which want to ensure the
            build is unique between builds. It's safe to leave the default.
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  config HAVE_KERNEL_GZIP
  	bool
  
  config HAVE_KERNEL_BZIP2
  	bool
  
  config HAVE_KERNEL_LZMA
  	bool
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  config HAVE_KERNEL_XZ
  	bool
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  config HAVE_KERNEL_LZO
  	bool
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  config HAVE_KERNEL_LZ4
  	bool
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  config HAVE_KERNEL_UNCOMPRESSED
  	bool
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  choice
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  	prompt "Kernel compression mode"
  	default KERNEL_GZIP
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  	depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_UNCOMPRESSED
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  	help
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  	  The linux kernel is a kind of self-extracting executable.
  	  Several compression algorithms are available, which differ
  	  in efficiency, compression and decompression speed.
  	  Compression speed is only relevant when building a kernel.
  	  Decompression speed is relevant at each boot.
  
  	  If you have any problems with bzip2 or lzma compressed
  	  kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
  	  version of this functionality (bzip2 only), for 2.4, was
  	  supplied by Christian Ludwig)
  
  	  High compression options are mostly useful for users, who
  	  are low on disk space (embedded systems), but for whom ram
  	  size matters less.
  
  	  If in doubt, select 'gzip'
  
  config KERNEL_GZIP
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  	bool "Gzip"
  	depends on HAVE_KERNEL_GZIP
  	help
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  	  The old and tried gzip compression. It provides a good balance
  	  between compression ratio and decompression speed.
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  config KERNEL_BZIP2
  	bool "Bzip2"
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  	depends on HAVE_KERNEL_BZIP2
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  	help
  	  Its compression ratio and speed is intermediate.
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  	  Decompression speed is slowest among the choices.  The kernel
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  	  size is about 10% smaller with bzip2, in comparison to gzip.
  	  Bzip2 uses a large amount of memory. For modern kernels you
  	  will need at least 8MB RAM or more for booting.
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  config KERNEL_LZMA
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  	bool "LZMA"
  	depends on HAVE_KERNEL_LZMA
  	help
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  	  This compression algorithm's ratio is best.  Decompression speed
  	  is between gzip and bzip2.  Compression is slowest.
  	  The kernel size is about 33% smaller with LZMA in comparison to gzip.
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  config KERNEL_XZ
  	bool "XZ"
  	depends on HAVE_KERNEL_XZ
  	help
  	  XZ uses the LZMA2 algorithm and instruction set specific
  	  BCJ filters which can improve compression ratio of executable
  	  code. The size of the kernel is about 30% smaller with XZ in
  	  comparison to gzip. On architectures for which there is a BCJ
  	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
  	  will create a few percent smaller kernel than plain LZMA.
  
  	  The speed is about the same as with LZMA: The decompression
  	  speed of XZ is better than that of bzip2 but worse than gzip
  	  and LZO. Compression is slow.
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  config KERNEL_LZO
  	bool "LZO"
  	depends on HAVE_KERNEL_LZO
  	help
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  	  Its compression ratio is the poorest among the choices. The kernel
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  	  size is about 10% bigger than gzip; however its speed
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  	  (both compression and decompression) is the fastest.
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  config KERNEL_LZ4
  	bool "LZ4"
  	depends on HAVE_KERNEL_LZ4
  	help
  	  LZ4 is an LZ77-type compressor with a fixed, byte-oriented encoding.
  	  A preliminary version of LZ4 de/compression tool is available at
  	  <https://code.google.com/p/lz4/>.
  
  	  Its compression ratio is worse than LZO. The size of the kernel
  	  is about 8% bigger than LZO. But the decompression speed is
  	  faster than LZO.
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  config KERNEL_UNCOMPRESSED
  	bool "None"
  	depends on HAVE_KERNEL_UNCOMPRESSED
  	help
  	  Produce uncompressed kernel image. This option is usually not what
  	  you want. It is useful for debugging the kernel in slow simulation
  	  environments, where decompressing and moving the kernel is awfully
  	  slow. This option allows early boot code to skip the decompressor
  	  and jump right at uncompressed kernel image.
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  endchoice
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  config DEFAULT_HOSTNAME
  	string "Default hostname"
  	default "(none)"
  	help
  	  This option determines the default system hostname before userspace
  	  calls sethostname(2). The kernel traditionally uses "(none)" here,
  	  but you may wish to use a different default here to make a minimal
  	  system more usable with less configuration.
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  #
  # For some reason microblaze and nios2 hard code SWAP=n.  Hopefully we can
  # add proper SWAP support to them, in which case this can be remove.
  #
  config ARCH_NO_SWAP
  	bool
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  config SWAP
  	bool "Support for paging of anonymous memory (swap)"
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  	depends on MMU && BLOCK && !ARCH_NO_SWAP
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  	default y
  	help
  	  This option allows you to choose whether you want to have support
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  	  for so called swap devices or swap files in your kernel that are
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  	  used to provide more virtual memory than the actual RAM present
  	  in your computer.  If unsure say Y.
  
  config SYSVIPC
  	bool "System V IPC"
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  	---help---
  	  Inter Process Communication is a suite of library functions and
  	  system calls which let processes (running programs) synchronize and
  	  exchange information. It is generally considered to be a good thing,
  	  and some programs won't run unless you say Y here. In particular, if
  	  you want to run the DOS emulator dosemu under Linux (read the
  	  DOSEMU-HOWTO, available from <http://www.tldp.org/docs.html#howto>),
  	  you'll need to say Y here.
  
  	  You can find documentation about IPC with "info ipc" and also in
  	  section 6.4 of the Linux Programmer's Guide, available from
  	  <http://www.tldp.org/guides.html>.
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  config SYSVIPC_SYSCTL
  	bool
  	depends on SYSVIPC
  	depends on SYSCTL
  	default y
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  config POSIX_MQUEUE
  	bool "POSIX Message Queues"
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  	depends on NET
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  	---help---
  	  POSIX variant of message queues is a part of IPC. In POSIX message
  	  queues every message has a priority which decides about succession
  	  of receiving it by a process. If you want to compile and run
  	  programs written e.g. for Solaris with use of its POSIX message
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  	  queues (functions mq_*) say Y here.
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  	  POSIX message queues are visible as a filesystem called 'mqueue'
  	  and can be mounted somewhere if you want to do filesystem
  	  operations on message queues.
  
  	  If unsure, say Y.
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  config POSIX_MQUEUE_SYSCTL
  	bool
  	depends on POSIX_MQUEUE
  	depends on SYSCTL
  	default y
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  config CROSS_MEMORY_ATTACH
  	bool "Enable process_vm_readv/writev syscalls"
  	depends on MMU
  	default y
  	help
  	  Enabling this option adds the system calls process_vm_readv and
  	  process_vm_writev which allow a process with the correct privileges
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  	  to directly read from or write to another process' address space.
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  	  See the man page for more details.
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  config USELIB
  	bool "uselib syscall"
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  	def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
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  	help
  	  This option enables the uselib syscall, a system call used in the
  	  dynamic linker from libc5 and earlier.  glibc does not use this
  	  system call.  If you intend to run programs built on libc5 or
  	  earlier, you may need to enable this syscall.  Current systems
  	  running glibc can safely disable this.
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  config AUDIT
  	bool "Auditing support"
  	depends on NET
  	help
  	  Enable auditing infrastructure that can be used with another
  	  kernel subsystem, such as SELinux (which requires this for
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  	  logging of avc messages output).  System call auditing is included
  	  on architectures which support it.
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  config HAVE_ARCH_AUDITSYSCALL
  	bool
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  config AUDITSYSCALL
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  	def_bool y
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  	depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
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  	select FSNOTIFY
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  source "kernel/irq/Kconfig"
  source "kernel/time/Kconfig"
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  source "kernel/Kconfig.preempt"
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  menu "CPU/Task time and stats accounting"
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  config VIRT_CPU_ACCOUNTING
  	bool
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  choice
  	prompt "Cputime accounting"
  	default TICK_CPU_ACCOUNTING if !PPC64
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  	default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
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  # Kind of a stub config for the pure tick based cputime accounting
  config TICK_CPU_ACCOUNTING
  	bool "Simple tick based cputime accounting"
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  	depends on !S390 && !NO_HZ_FULL
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  	help
  	  This is the basic tick based cputime accounting that maintains
  	  statistics about user, system and idle time spent on per jiffies
  	  granularity.
  
  	  If unsure, say Y.
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  config VIRT_CPU_ACCOUNTING_NATIVE
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  	bool "Deterministic task and CPU time accounting"
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  	depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
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  	select VIRT_CPU_ACCOUNTING
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  	help
  	  Select this option to enable more accurate task and CPU time
  	  accounting.  This is done by reading a CPU counter on each
  	  kernel entry and exit and on transitions within the kernel
  	  between system, softirq and hardirq state, so there is a
  	  small performance impact.  In the case of s390 or IBM POWER > 5,
  	  this also enables accounting of stolen time on logically-partitioned
  	  systems.
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  config VIRT_CPU_ACCOUNTING_GEN
  	bool "Full dynticks CPU time accounting"
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  	depends on HAVE_CONTEXT_TRACKING
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  	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
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  	depends on GENERIC_CLOCKEVENTS
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  	select VIRT_CPU_ACCOUNTING
  	select CONTEXT_TRACKING
  	help
  	  Select this option to enable task and CPU time accounting on full
  	  dynticks systems. This accounting is implemented by watching every
  	  kernel-user boundaries using the context tracking subsystem.
  	  The accounting is thus performed at the expense of some significant
  	  overhead.
  
  	  For now this is only useful if you are working on the full
  	  dynticks subsystem development.
  
  	  If unsure, say N.
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  endchoice
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  config IRQ_TIME_ACCOUNTING
  	bool "Fine granularity task level IRQ time accounting"
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  	depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
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  	help
  	  Select this option to enable fine granularity task irq time
  	  accounting. This is done by reading a timestamp on each
  	  transitions between softirq and hardirq state, so there can be a
  	  small performance impact.
  
  	  If in doubt, say N here.
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  config HAVE_SCHED_AVG_IRQ
  	def_bool y
  	depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
  	depends on SMP
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  config BSD_PROCESS_ACCT
  	bool "BSD Process Accounting"
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  	depends on MULTIUSER
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  	help
  	  If you say Y here, a user level program will be able to instruct the
  	  kernel (via a special system call) to write process accounting
  	  information to a file: whenever a process exits, information about
  	  that process will be appended to the file by the kernel.  The
  	  information includes things such as creation time, owning user,
  	  command name, memory usage, controlling terminal etc. (the complete
  	  list is in the struct acct in <file:include/linux/acct.h>).  It is
  	  up to the user level program to do useful things with this
  	  information.  This is generally a good idea, so say Y.
  
  config BSD_PROCESS_ACCT_V3
  	bool "BSD Process Accounting version 3 file format"
  	depends on BSD_PROCESS_ACCT
  	default n
  	help
  	  If you say Y here, the process accounting information is written
  	  in a new file format that also logs the process IDs of each
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  	  process and its parent. Note that this file format is incompatible
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  	  with previous v0/v1/v2 file formats, so you will need updated tools
  	  for processing it. A preliminary version of these tools is available
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  	  at <http://www.gnu.org/software/acct/>.
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  config TASKSTATS
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  	bool "Export task/process statistics through netlink"
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  	depends on NET
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  	depends on MULTIUSER
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  	default n
  	help
  	  Export selected statistics for tasks/processes through the
  	  generic netlink interface. Unlike BSD process accounting, the
  	  statistics are available during the lifetime of tasks/processes as
  	  responses to commands. Like BSD accounting, they are sent to user
  	  space on task exit.
  
  	  Say N if unsure.
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  config TASK_DELAY_ACCT
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  	bool "Enable per-task delay accounting"
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  	depends on TASKSTATS
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  	select SCHED_INFO
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  	help
  	  Collect information on time spent by a task waiting for system
  	  resources like cpu, synchronous block I/O completion and swapping
  	  in pages. Such statistics can help in setting a task's priorities
  	  relative to other tasks for cpu, io, rss limits etc.
  
  	  Say N if unsure.
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  config TASK_XACCT
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  	bool "Enable extended accounting over taskstats"
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  	depends on TASKSTATS
  	help
  	  Collect extended task accounting data and send the data
  	  to userland for processing over the taskstats interface.
  
  	  Say N if unsure.
  
  config TASK_IO_ACCOUNTING
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  	bool "Enable per-task storage I/O accounting"
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  	depends on TASK_XACCT
  	help
  	  Collect information on the number of bytes of storage I/O which this
  	  task has caused.
  
  	  Say N if unsure.
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  config PSI
  	bool "Pressure stall information tracking"
  	help
  	  Collect metrics that indicate how overcommitted the CPU, memory,
  	  and IO capacity are in the system.
  
  	  If you say Y here, the kernel will create /proc/pressure/ with the
  	  pressure statistics files cpu, memory, and io. These will indicate
  	  the share of walltime in which some or all tasks in the system are
  	  delayed due to contention of the respective resource.
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  	  In kernels with cgroup support, cgroups (cgroup2 only) will
  	  have cpu.pressure, memory.pressure, and io.pressure files,
  	  which aggregate pressure stalls for the grouped tasks only.
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  	  For more details see Documentation/accounting/psi.rst.
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  	  Say N if unsure.
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  config PSI_DEFAULT_DISABLED
  	bool "Require boot parameter to enable pressure stall information tracking"
  	default n
  	depends on PSI
  	help
  	  If set, pressure stall information tracking will be disabled
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  	  per default but can be enabled through passing psi=1 on the
  	  kernel commandline during boot.
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  	  This feature adds some code to the task wakeup and sleep
  	  paths of the scheduler. The overhead is too low to affect
  	  common scheduling-intense workloads in practice (such as
  	  webservers, memcache), but it does show up in artificial
  	  scheduler stress tests, such as hackbench.
  
  	  If you are paranoid and not sure what the kernel will be
  	  used for, say Y.
  
  	  Say N if unsure.
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  endmenu # "CPU/Task time and stats accounting"
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  config CPU_ISOLATION
  	bool "CPU isolation"
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  	depends on SMP || COMPILE_TEST
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  	default y
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  	help
  	  Make sure that CPUs running critical tasks are not disturbed by
  	  any source of "noise" such as unbound workqueues, timers, kthreads...
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  	  Unbound jobs get offloaded to housekeeping CPUs. This is driven by
  	  the "isolcpus=" boot parameter.
  
  	  Say Y if unsure.
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  source "kernel/rcu/Kconfig"
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  config BUILD_BIN2C
  	bool
  	default n
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  config IKCONFIG
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  	tristate "Kernel .config support"
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  	---help---
  	  This option enables the complete Linux kernel ".config" file
  	  contents to be saved in the kernel. It provides documentation
  	  of which kernel options are used in a running kernel or in an
  	  on-disk kernel.  This information can be extracted from the kernel
  	  image file with the script scripts/extract-ikconfig and used as
  	  input to rebuild the current kernel or to build another kernel.
  	  It can also be extracted from a running kernel by reading
  	  /proc/config.gz if enabled (below).
  
  config IKCONFIG_PROC
  	bool "Enable access to .config through /proc/config.gz"
  	depends on IKCONFIG && PROC_FS
  	---help---
  	  This option enables access to the kernel configuration file
  	  through /proc/config.gz.
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  config IKHEADERS
  	tristate "Enable kernel headers through /sys/kernel/kheaders.tar.xz"
  	depends on SYSFS
  	help
  	  This option enables access to the in-kernel headers that are generated during
  	  the build process. These can be used to build eBPF tracing programs,
  	  or similar programs.  If you build the headers as a module, a module called
  	  kheaders.ko is built which can be loaded on-demand to get access to headers.
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  config LOG_BUF_SHIFT
  	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
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  	range 12 25
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  	default 17
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  	depends on PRINTK
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  	help
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  	  Select the minimal kernel log buffer size as a power of 2.
  	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
  	  parameter, see below. Any higher size also might be forced
  	  by "log_buf_len" boot parameter.
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  	  Examples:
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  		     17 => 128 KB
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  		     16 => 64 KB
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  		     15 => 32 KB
  		     14 => 16 KB
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  		     13 =>  8 KB
  		     12 =>  4 KB
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  config LOG_CPU_MAX_BUF_SHIFT
  	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
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  	depends on SMP
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  	range 0 21
  	default 12 if !BASE_SMALL
  	default 0 if BASE_SMALL
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  	depends on PRINTK
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  	help
  	  This option allows to increase the default ring buffer size
  	  according to the number of CPUs. The value defines the contribution
  	  of each CPU as a power of 2. The used space is typically only few
  	  lines however it might be much more when problems are reported,
  	  e.g. backtraces.
  
  	  The increased size means that a new buffer has to be allocated and
  	  the original static one is unused. It makes sense only on systems
  	  with more CPUs. Therefore this value is used only when the sum of
  	  contributions is greater than the half of the default kernel ring
  	  buffer as defined by LOG_BUF_SHIFT. The default values are set
  	  so that more than 64 CPUs are needed to trigger the allocation.
  
  	  Also this option is ignored when "log_buf_len" kernel parameter is
  	  used as it forces an exact (power of two) size of the ring buffer.
  
  	  The number of possible CPUs is used for this computation ignoring
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  	  hotplugging making the computation optimal for the worst case
  	  scenario while allowing a simple algorithm to be used from bootup.
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  	  Examples shift values and their meaning:
  		     17 => 128 KB for each CPU
  		     16 =>  64 KB for each CPU
  		     15 =>  32 KB for each CPU
  		     14 =>  16 KB for each CPU
  		     13 =>   8 KB for each CPU
  		     12 =>   4 KB for each CPU
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  config PRINTK_SAFE_LOG_BUF_SHIFT
  	int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
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  	range 10 21
  	default 13
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  	depends on PRINTK
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  	help
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  	  Select the size of an alternate printk per-CPU buffer where messages
  	  printed from usafe contexts are temporary stored. One example would
  	  be NMI messages, another one - printk recursion. The messages are
  	  copied to the main log buffer in a safe context to avoid a deadlock.
  	  The value defines the size as a power of 2.
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  	  Those messages are rare and limited. The largest one is when
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  	  a backtrace is printed. It usually fits into 4KB. Select
  	  8KB if you want to be on the safe side.
  
  	  Examples:
  		     17 => 128 KB for each CPU
  		     16 =>  64 KB for each CPU
  		     15 =>  32 KB for each CPU
  		     14 =>  16 KB for each CPU
  		     13 =>   8 KB for each CPU
  		     12 =>   4 KB for each CPU
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  #
  # Architectures with an unreliable sched_clock() should select this:
  #
  config HAVE_UNSTABLE_SCHED_CLOCK
  	bool
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  config GENERIC_SCHED_CLOCK
  	bool
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  menu "Scheduler features"
  
  config UCLAMP_TASK
  	bool "Enable utilization clamping for RT/FAIR tasks"
  	depends on CPU_FREQ_GOV_SCHEDUTIL
  	help
  	  This feature enables the scheduler to track the clamped utilization
  	  of each CPU based on RUNNABLE tasks scheduled on that CPU.
  
  	  With this option, the user can specify the min and max CPU
  	  utilization allowed for RUNNABLE tasks. The max utilization defines
  	  the maximum frequency a task should use while the min utilization
  	  defines the minimum frequency it should use.
  
  	  Both min and max utilization clamp values are hints to the scheduler,
  	  aiming at improving its frequency selection policy, but they do not
  	  enforce or grant any specific bandwidth for tasks.
  
  	  If in doubt, say N.
  
  config UCLAMP_BUCKETS_COUNT
  	int "Number of supported utilization clamp buckets"
  	range 5 20
  	default 5
  	depends on UCLAMP_TASK
  	help
  	  Defines the number of clamp buckets to use. The range of each bucket
  	  will be SCHED_CAPACITY_SCALE/UCLAMP_BUCKETS_COUNT. The higher the
  	  number of clamp buckets the finer their granularity and the higher
  	  the precision of clamping aggregation and tracking at run-time.
  
  	  For example, with the minimum configuration value we will have 5
  	  clamp buckets tracking 20% utilization each. A 25% boosted tasks will
  	  be refcounted in the [20..39]% bucket and will set the bucket clamp
  	  effective value to 25%.
  	  If a second 30% boosted task should be co-scheduled on the same CPU,
  	  that task will be refcounted in the same bucket of the first task and
  	  it will boost the bucket clamp effective value to 30%.
  	  The clamp effective value of a bucket is reset to its nominal value
  	  (20% in the example above) when there are no more tasks refcounted in
  	  that bucket.
  
  	  An additional boost/capping margin can be added to some tasks. In the
  	  example above the 25% task will be boosted to 30% until it exits the
  	  CPU. If that should be considered not acceptable on certain systems,
  	  it's always possible to reduce the margin by increasing the number of
  	  clamp buckets to trade off used memory for run-time tracking
  	  precision.
  
  	  If in doubt, use the default value.
  
  endmenu
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  #
  # For architectures that want to enable the support for NUMA-affine scheduler
  # balancing logic:
  #
  config ARCH_SUPPORTS_NUMA_BALANCING
  	bool
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  #
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  # For architectures that prefer to flush all TLBs after a number of pages
  # are unmapped instead of sending one IPI per page to flush. The architecture
  # must provide guarantees on what happens if a clean TLB cache entry is
  # written after the unmap. Details are in mm/rmap.c near the check for
  # should_defer_flush. The architecture should also consider if the full flush
  # and the refill costs are offset by the savings of sending fewer IPIs.
  config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
  	bool
  
  #
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  # For architectures that know their GCC __int128 support is sound
  #
  config ARCH_SUPPORTS_INT128
  	bool
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  # For architectures that (ab)use NUMA to represent different memory regions
  # all cpu-local but of different latencies, such as SuperH.
  #
  config ARCH_WANT_NUMA_VARIABLE_LOCALITY
  	bool
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  config NUMA_BALANCING
  	bool "Memory placement aware NUMA scheduler"
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  	depends on ARCH_SUPPORTS_NUMA_BALANCING
  	depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
  	depends on SMP && NUMA && MIGRATION
  	help
  	  This option adds support for automatic NUMA aware memory/task placement.
  	  The mechanism is quite primitive and is based on migrating memory when
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  	  it has references to the node the task is running on.
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  	  This system will be inactive on UMA systems.
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  config NUMA_BALANCING_DEFAULT_ENABLED
  	bool "Automatically enable NUMA aware memory/task placement"
  	default y
  	depends on NUMA_BALANCING
  	help
  	  If set, automatic NUMA balancing will be enabled if running on a NUMA
  	  machine.
23964d2d0   Li Zefan   cgroups: clean up...
738
  menuconfig CGROUPS
6341e62b2   Christoph Jaeger   kconfig: use bool...
739
  	bool "Control Group support"
2bd59d48e   Tejun Heo   cgroup: convert t...
740
  	select KERNFS
5cdc38f98   KAMEZAWA Hiroyuki   cgroups: make cgr...
741
  	help
23964d2d0   Li Zefan   cgroups: clean up...
742
  	  This option adds support for grouping sets of processes together, for
5cdc38f98   KAMEZAWA Hiroyuki   cgroups: make cgr...
743
744
745
  	  use with process control subsystems such as Cpusets, CFS, memory
  	  controls or device isolation.
  	  See
d6a3b2476   Mauro Carvalho Chehab   docs: scheduler: ...
746
  		- Documentation/scheduler/sched-design-CFS.rst	(CFS)
da82c92f1   Mauro Carvalho Chehab   docs: cgroup-v1: ...
747
  		- Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
45ce80fb6   Li Zefan   cgroups: consolid...
748
  					  and resource control)
5cdc38f98   KAMEZAWA Hiroyuki   cgroups: make cgr...
749
750
  
  	  Say N if unsure.
23964d2d0   Li Zefan   cgroups: clean up...
751
  if CGROUPS
3e32cb2e0   Johannes Weiner   mm: memcontrol: l...
752
753
  config PAGE_COUNTER
         bool
c255a4580   Andrew Morton   memcg: rename con...
754
  config MEMCG
a0166ec4b   Johannes Weiner   cgroup: clean up ...
755
  	bool "Memory controller"
3e32cb2e0   Johannes Weiner   mm: memcontrol: l...
756
  	select PAGE_COUNTER
79bd9814e   Tejun Heo   cgroup, memcg: mo...
757
  	select EVENTFD
00f0b8259   Balbir Singh   Memory controller...
758
  	help
a0166ec4b   Johannes Weiner   cgroup: clean up ...
759
  	  Provides control over the memory footprint of tasks in a cgroup.
00f0b8259   Balbir Singh   Memory controller...
760

c255a4580   Andrew Morton   memcg: rename con...
761
  config MEMCG_SWAP
a0166ec4b   Johannes Weiner   cgroup: clean up ...
762
  	bool "Swap controller"
c255a4580   Andrew Morton   memcg: rename con...
763
  	depends on MEMCG && SWAP
c077719be   KAMEZAWA Hiroyuki   memcg: mem+swap c...
764
  	help
a0166ec4b   Johannes Weiner   cgroup: clean up ...
765
  	  Provides control over the swap space consumed by tasks in a cgroup.
c255a4580   Andrew Morton   memcg: rename con...
766
  config MEMCG_SWAP_ENABLED
a0166ec4b   Johannes Weiner   cgroup: clean up ...
767
  	bool "Swap controller enabled by default"
c255a4580   Andrew Morton   memcg: rename con...
768
  	depends on MEMCG_SWAP
a42c390cf   Michal Hocko   cgroups: make swa...
769
770
771
772
  	default y
  	help
  	  Memory Resource Controller Swap Extension comes with its price in
  	  a bigger memory consumption. General purpose distribution kernels
43d547f9c   Jim Cromie   init/Kconfig: fix...
773
  	  which want to enable the feature but keep it disabled by default
07555ac14   Michal Hocko   memcg: get rid of...
774
  	  and let the user enable it by swapaccount=1 boot command line
a42c390cf   Michal Hocko   cgroups: make swa...
775
776
777
  	  parameter should have this option unselected.
  	  For those who want to have the feature enabled by default should
  	  select this option (if, for some reason, they need to disable it
00a66d297   WANG Cong   mm: remove the le...
778
  	  then swapaccount=0 does the trick).
c077719be   KAMEZAWA Hiroyuki   memcg: mem+swap c...
779

84c07d11a   Kirill Tkhai   mm: introduce CON...
780
781
782
783
  config MEMCG_KMEM
  	bool
  	depends on MEMCG && !SLOB
  	default y
6bf024e69   Johannes Weiner   cgroup: put contr...
784
785
786
  config BLK_CGROUP
  	bool "IO controller"
  	depends on BLOCK
2bc64a204   Aneesh Kumar K.V   mm/hugetlb: add n...
787
  	default n
6bf024e69   Johannes Weiner   cgroup: put contr...
788
789
790
791
  	---help---
  	Generic block IO controller cgroup interface. This is the common
  	cgroup interface which should be used by various IO controlling
  	policies.
2bc64a204   Aneesh Kumar K.V   mm/hugetlb: add n...
792

6bf024e69   Johannes Weiner   cgroup: put contr...
793
794
795
796
  	Currently, CFQ IO scheduler uses it to recognize task groups and
  	control disk bandwidth allocation (proportional time slice allocation)
  	to such task groups. It is also used by bio throttling logic in
  	block layer to implement upper limit in IO rates on a device.
e5d1367f1   Stephane Eranian   perf: Add cgroup ...
797

6bf024e69   Johannes Weiner   cgroup: put contr...
798
799
800
801
802
  	This option only enables generic Block IO controller infrastructure.
  	One needs to also enable actual IO controlling logic/policy. For
  	enabling proportional weight division of disk bandwidth in CFQ, set
  	CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
  	CONFIG_BLK_DEV_THROTTLING=y.
da82c92f1   Mauro Carvalho Chehab   docs: cgroup-v1: ...
803
  	See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
6bf024e69   Johannes Weiner   cgroup: put contr...
804

6bf024e69   Johannes Weiner   cgroup: put contr...
805
806
807
808
  config CGROUP_WRITEBACK
  	bool
  	depends on MEMCG && BLK_CGROUP
  	default y
e5d1367f1   Stephane Eranian   perf: Add cgroup ...
809

7c9414385   Dhaval Giani   sched: Remove USE...
810
  menuconfig CGROUP_SCHED
a0166ec4b   Johannes Weiner   cgroup: clean up ...
811
  	bool "CPU controller"
7c9414385   Dhaval Giani   sched: Remove USE...
812
813
814
815
816
817
818
819
820
821
822
  	default n
  	help
  	  This feature lets CPU scheduler recognize task groups and control CPU
  	  bandwidth allocation to such task groups. It uses cgroups to group
  	  tasks.
  
  if CGROUP_SCHED
  config FAIR_GROUP_SCHED
  	bool "Group scheduling for SCHED_OTHER"
  	depends on CGROUP_SCHED
  	default CGROUP_SCHED
ab84d31e1   Paul Turner   sched: Introduce ...
823
824
  config CFS_BANDWIDTH
  	bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
ab84d31e1   Paul Turner   sched: Introduce ...
825
826
827
828
829
830
831
  	depends on FAIR_GROUP_SCHED
  	default n
  	help
  	  This option allows users to define CPU bandwidth rates (limits) for
  	  tasks running within the fair group scheduler.  Groups with no limit
  	  set are considered to be unconstrained and will run with no
  	  restriction.
d6a3b2476   Mauro Carvalho Chehab   docs: scheduler: ...
832
  	  See Documentation/scheduler/sched-bwc.rst for more information.
ab84d31e1   Paul Turner   sched: Introduce ...
833

7c9414385   Dhaval Giani   sched: Remove USE...
834
835
  config RT_GROUP_SCHED
  	bool "Group scheduling for SCHED_RR/FIFO"
7c9414385   Dhaval Giani   sched: Remove USE...
836
837
838
839
  	depends on CGROUP_SCHED
  	default n
  	help
  	  This feature lets you explicitly allocate real CPU bandwidth
32bd7eb5a   Li Zefan   sched: Remove rem...
840
  	  to task groups. If enabled, it will also make it impossible to
7c9414385   Dhaval Giani   sched: Remove USE...
841
842
  	  schedule realtime tasks for non-root users until you allocate
  	  realtime bandwidth for them.
d6a3b2476   Mauro Carvalho Chehab   docs: scheduler: ...
843
  	  See Documentation/scheduler/sched-rt-group.rst for more information.
7c9414385   Dhaval Giani   sched: Remove USE...
844
845
  
  endif #CGROUP_SCHED
2480c0931   Patrick Bellasi   sched/uclamp: Ext...
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
  config UCLAMP_TASK_GROUP
  	bool "Utilization clamping per group of tasks"
  	depends on CGROUP_SCHED
  	depends on UCLAMP_TASK
  	default n
  	help
  	  This feature enables the scheduler to track the clamped utilization
  	  of each CPU based on RUNNABLE tasks currently scheduled on that CPU.
  
  	  When this option is enabled, the user can specify a min and max
  	  CPU bandwidth which is allowed for each single task in a group.
  	  The max bandwidth allows to clamp the maximum frequency a task
  	  can use, while the min bandwidth allows to define a minimum
  	  frequency a task will always use.
  
  	  When task group based utilization clamping is enabled, an eventually
  	  specified task-specific clamp value is constrained by the cgroup
  	  specified clamp value. Both minimum and maximum task clamping cannot
  	  be bigger than the corresponding clamping defined at task group level.
  
  	  If in doubt, say N.
6bf024e69   Johannes Weiner   cgroup: put contr...
867
868
869
870
871
872
873
874
875
  config CGROUP_PIDS
  	bool "PIDs controller"
  	help
  	  Provides enforcement of process number limits in the scope of a
  	  cgroup. Any attempt to fork more processes than is allowed in the
  	  cgroup will fail. PIDs are fundamentally a global resource because it
  	  is fairly trivial to reach PID exhaustion before you reach even a
  	  conservative kmemcg limit. As a result, it is possible to grind a
  	  system to halt without being limited by other cgroup policies. The
6cc578df4   Parav Pandit   cgroup: Trivial c...
876
  	  PIDs controller is designed to stop this from happening.
6bf024e69   Johannes Weiner   cgroup: put contr...
877
878
  
  	  It should be noted that organisational operations (such as attaching
980768338   Jonathan Neuschäfer   init/Kconfig: fix...
879
  	  to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
6bf024e69   Johannes Weiner   cgroup: put contr...
880
881
  	  since the PIDs limit only affects a process's ability to fork, not to
  	  attach to a cgroup.
39d3e7584   Parav Pandit   rdmacg: Added rdm...
882
883
884
885
886
887
888
889
890
  config CGROUP_RDMA
  	bool "RDMA controller"
  	help
  	  Provides enforcement of RDMA resources defined by IB stack.
  	  It is fairly easy for consumers to exhaust RDMA resources, which
  	  can result into resource unavailability to other consumers.
  	  RDMA controller is designed to stop this from happening.
  	  Attaching processes with active RDMA resources to the cgroup
  	  hierarchy is allowed even if can cross the hierarchy's limit.
6bf024e69   Johannes Weiner   cgroup: put contr...
891
892
893
894
895
  config CGROUP_FREEZER
  	bool "Freezer controller"
  	help
  	  Provides a way to freeze and unfreeze all tasks in a
  	  cgroup.
489c2a20a   Johannes Weiner   mm: memcontrol: i...
896
897
898
899
  	  This option affects the ORIGINAL cgroup interface. The cgroup2 memory
  	  controller includes important in-kernel memory consumers per default.
  
  	  If you're using cgroup2, say N.
6bf024e69   Johannes Weiner   cgroup: put contr...
900
901
902
903
  config CGROUP_HUGETLB
  	bool "HugeTLB controller"
  	depends on HUGETLB_PAGE
  	select PAGE_COUNTER
afc24d49c   Vivek Goyal   blk-cgroup: confi...
904
  	default n
6bf024e69   Johannes Weiner   cgroup: put contr...
905
906
907
908
909
910
911
912
913
914
  	help
  	  Provides a cgroup controller for HugeTLB pages.
  	  When you enable this, you can put a per cgroup limit on HugeTLB usage.
  	  The limit is enforced during page fault. Since HugeTLB doesn't
  	  support page reclaim, enforcing the limit at page fault time implies
  	  that, the application will get SIGBUS signal if it tries to access
  	  HugeTLB pages beyond its limit. This requires the application to know
  	  beforehand how much HugeTLB pages it would require for its use. The
  	  control group is tracked in the third page lru pointer. This means
  	  that we cannot use the controller with huge page less than 3 pages.
afc24d49c   Vivek Goyal   blk-cgroup: confi...
915

6bf024e69   Johannes Weiner   cgroup: put contr...
916
917
  config CPUSETS
  	bool "Cpuset controller"
e1d4eeec5   Nicolas Pitre   sched/cpuset: Onl...
918
  	depends on SMP
6bf024e69   Johannes Weiner   cgroup: put contr...
919
920
921
922
923
  	help
  	  This option will let you create and manage CPUSETs which
  	  allow dynamically partitioning a system into sets of CPUs and
  	  Memory Nodes and assigning tasks to run only within those sets.
  	  This is primarily useful on large SMP or NUMA systems.
afc24d49c   Vivek Goyal   blk-cgroup: confi...
924

6bf024e69   Johannes Weiner   cgroup: put contr...
925
  	  Say N if unsure.
afc24d49c   Vivek Goyal   blk-cgroup: confi...
926

6bf024e69   Johannes Weiner   cgroup: put contr...
927
928
929
930
  config PROC_PID_CPUSET
  	bool "Include legacy /proc/<pid>/cpuset file"
  	depends on CPUSETS
  	default y
afc24d49c   Vivek Goyal   blk-cgroup: confi...
931

6bf024e69   Johannes Weiner   cgroup: put contr...
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
  config CGROUP_DEVICE
  	bool "Device controller"
  	help
  	  Provides a cgroup controller implementing whitelists for
  	  devices which a process in the cgroup can mknod or open.
  
  config CGROUP_CPUACCT
  	bool "Simple CPU accounting controller"
  	help
  	  Provides a simple controller for monitoring the
  	  total CPU consumed by the tasks in a cgroup.
  
  config CGROUP_PERF
  	bool "Perf controller"
  	depends on PERF_EVENTS
  	help
  	  This option extends the perf per-cpu mode to restrict monitoring
  	  to threads which belong to the cgroup specified and run on the
  	  designated cpu.
  
  	  Say N if unsure.
300709849   Daniel Mack   cgroup: add suppo...
953
954
  config CGROUP_BPF
  	bool "Support for eBPF programs attached to cgroups"
483c4933e   Andy Lutomirski   cgroup: Fix CGROU...
955
956
  	depends on BPF_SYSCALL
  	select SOCK_CGROUP_DATA
300709849   Daniel Mack   cgroup: add suppo...
957
958
959
960
961
962
963
964
  	help
  	  Allow attaching eBPF programs to a cgroup using the bpf(2)
  	  syscall command BPF_PROG_ATTACH.
  
  	  In which context these programs are accessed depends on the type
  	  of attachment. For instance, programs that are attached using
  	  BPF_CGROUP_INET_INGRESS will be executed on the ingress path of
  	  inet sockets.
6bf024e69   Johannes Weiner   cgroup: put contr...
965
  config CGROUP_DEBUG
23b0be480   Waiman Long   cgroup: Make Kcon...
966
  	bool "Debug controller"
afc24d49c   Vivek Goyal   blk-cgroup: confi...
967
  	default n
23b0be480   Waiman Long   cgroup: Make Kcon...
968
  	depends on DEBUG_KERNEL
6bf024e69   Johannes Weiner   cgroup: put contr...
969
970
  	help
  	  This option enables a simple controller that exports
23b0be480   Waiman Long   cgroup: Make Kcon...
971
972
973
  	  debugging information about the cgroups framework. This
  	  controller is for control cgroup debugging only. Its
  	  interfaces are not stable.
afc24d49c   Vivek Goyal   blk-cgroup: confi...
974

6bf024e69   Johannes Weiner   cgroup: put contr...
975
  	  Say N.
89e9b9e07   Tejun Heo   writeback: add {C...
976

73b351473   Arnd Bergmann   cgroup: move CONF...
977
978
979
  config SOCK_CGROUP_DATA
  	bool
  	default n
23964d2d0   Li Zefan   cgroups: clean up...
980
  endif # CGROUPS
c077719be   KAMEZAWA Hiroyuki   memcg: mem+swap c...
981

8dd2a82c2   Daniel Lezcano   namespaces Kconfi...
982
  menuconfig NAMESPACES
6a108a14f   David Rientjes   kconfig: rename C...
983
  	bool "Namespaces support" if EXPERT
2813893f8   Iulia Manda   kernel: condition...
984
  	depends on MULTIUSER
6a108a14f   David Rientjes   kconfig: rename C...
985
  	default !EXPERT
c5289a694   Pavel Emelyanov   namespaces: add t...
986
987
988
989
990
  	help
  	  Provides the way to make tasks work with different objects using
  	  the same id. For example same IPC id may refer to different objects
  	  or same user id or pid may refer to different tasks when used in
  	  different namespaces.
8dd2a82c2   Daniel Lezcano   namespaces Kconfi...
991
  if NAMESPACES
58bfdd6de   Pavel Emelyanov   namespaces: move ...
992
993
  config UTS_NS
  	bool "UTS namespace"
17a6d4411   Daniel Lezcano   namespaces: defau...
994
  	default y
58bfdd6de   Pavel Emelyanov   namespaces: move ...
995
996
997
  	help
  	  In this namespace tasks see different info provided with the
  	  uname() system call
ae5e1b22f   Pavel Emelyanov   namespaces: move ...
998
999
  config IPC_NS
  	bool "IPC namespace"
8dd2a82c2   Daniel Lezcano   namespaces Kconfi...
1000
  	depends on (SYSVIPC || POSIX_MQUEUE)
17a6d4411   Daniel Lezcano   namespaces: defau...
1001
  	default y
ae5e1b22f   Pavel Emelyanov   namespaces: move ...
1002
1003
  	help
  	  In this namespace tasks work with IPC ids which correspond to
614b84cf4   Serge E. Hallyn   namespaces: mqueu...
1004
  	  different IPC objects in different namespaces.
ae5e1b22f   Pavel Emelyanov   namespaces: move ...
1005

aee16ce73   Pavel Emelyanov   namespaces: clean...
1006
  config USER_NS
19c923998   Kees Cook   init: remove depe...
1007
  	bool "User namespace"
5673a94c1   Eric W. Biederman   userns: Add a Kco...
1008
  	default n
aee16ce73   Pavel Emelyanov   namespaces: clean...
1009
1010
1011
  	help
  	  This allows containers, i.e. vservers, to use user namespaces
  	  to provide different user info for different servers.
e11f0ae38   Eric W. Biederman   userns: Recommend...
1012
1013
  
  	  When user namespaces are enabled in the kernel it is
d886f4e48   Johannes Weiner   mm: memcontrol: r...
1014
1015
1016
  	  recommended that the MEMCG option also be enabled and that
  	  user-space use the memory control groups to limit the amount
  	  of memory a memory unprivileged users can use.
e11f0ae38   Eric W. Biederman   userns: Recommend...
1017

aee16ce73   Pavel Emelyanov   namespaces: clean...
1018
  	  If unsure, say N.
74bd59bb3   Pavel Emelyanov   namespaces: clean...
1019
  config PID_NS
9bd38c2cd   Daniel Lezcano   namespaces: remov...
1020
  	bool "PID Namespaces"
17a6d4411   Daniel Lezcano   namespaces: defau...
1021
  	default y
74bd59bb3   Pavel Emelyanov   namespaces: clean...
1022
  	help
12d2b8f95   Heikki Orsila   kconfig: fix typo...
1023
  	  Support process id namespaces.  This allows having multiple
692105b8a   Matt LaPlante   trivial: fix typo...
1024
  	  processes with the same pid as long as they are in different
74bd59bb3   Pavel Emelyanov   namespaces: clean...
1025
  	  pid namespaces.  This is a building block of containers.
d6eb633fe   Matt Helsley   net: Move config ...
1026
1027
  config NET_NS
  	bool "Network namespace"
8dd2a82c2   Daniel Lezcano   namespaces Kconfi...
1028
  	depends on NET
17a6d4411   Daniel Lezcano   namespaces: defau...
1029
  	default y
d6eb633fe   Matt Helsley   net: Move config ...
1030
1031
1032
  	help
  	  Allow user space to create what appear to be multiple instances
  	  of the network stack.
8dd2a82c2   Daniel Lezcano   namespaces Kconfi...
1033
  endif # NAMESPACES
5cb366bb3   Adrian Reber   init/Kconfig: rem...
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
  config CHECKPOINT_RESTORE
  	bool "Checkpoint/restore support"
  	select PROC_CHILDREN
  	default n
  	help
  	  Enables additional kernel features in a sake of checkpoint/restore.
  	  In particular it adds auxiliary prctl codes to setup process text,
  	  data and heap segment sizes, and a few additional /proc filesystem
  	  entries.
  
  	  If unsure, say N here.
5091faa44   Mike Galbraith   sched: Add 'autog...
1045
1046
  config SCHED_AUTOGROUP
  	bool "Automatic process group scheduling"
5091faa44   Mike Galbraith   sched: Add 'autog...
1047
1048
1049
1050
1051
1052
1053
1054
1055
  	select CGROUPS
  	select CGROUP_SCHED
  	select FAIR_GROUP_SCHED
  	help
  	  This option optimizes the scheduler for common desktop workloads by
  	  automatically creating and populating task groups.  This separation
  	  of workloads isolates aggressive CPU burners (like build jobs) from
  	  desktop applications.  Task group autogeneration is currently based
  	  upon task session.
7af37bec4   Daniel Lezcano   namespaces Kconfi...
1056
  config SYSFS_DEPRECATED
5d6a4ea57   Ferenc Wagner   sysfs: Capitalize...
1057
  	bool "Enable deprecated sysfs features to support old userspace tools"
7af37bec4   Daniel Lezcano   namespaces Kconfi...
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
  	depends on SYSFS
  	default n
  	help
  	  This option adds code that switches the layout of the "block" class
  	  devices, to not show up in /sys/class/block/, but only in
  	  /sys/block/.
  
  	  This switch is only active when the sysfs.deprecated=1 boot option is
  	  passed or the SYSFS_DEPRECATED_V2 option is set.
  
  	  This option allows new kernels to run on old distributions and tools,
  	  which might get confused by /sys/class/block/. Since 2007/2008 all
  	  major distributions and tools handle this just fine.
  
  	  Recent distributions and userspace tools after 2009/2010 depend on
  	  the existence of /sys/class/block/, and will not work with this
  	  option enabled.
  
  	  Only if you are using a new kernel on an old distribution, you might
  	  need to say Y here.
  
  config SYSFS_DEPRECATED_V2
5d6a4ea57   Ferenc Wagner   sysfs: Capitalize...
1080
  	bool "Enable deprecated sysfs features by default"
7af37bec4   Daniel Lezcano   namespaces Kconfi...
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
  	default n
  	depends on SYSFS
  	depends on SYSFS_DEPRECATED
  	help
  	  Enable deprecated sysfs by default.
  
  	  See the CONFIG_SYSFS_DEPRECATED option for more details about this
  	  option.
  
  	  Only if you are using a new kernel on an old distribution, you might
  	  need to say Y here. Even then, odds are you would not need it
  	  enabled, you can always pass the boot option if absolutely necessary.
  
  config RELAY
  	bool "Kernel->user space relay support (formerly relayfs)"
26b5679e4   Peter Zijlstra   relay: Use irq_wo...
1096
  	select IRQ_WORK
7af37bec4   Daniel Lezcano   namespaces Kconfi...
1097
1098
1099
1100
1101
1102
1103
1104
  	help
  	  This option enables support for relay interface support in
  	  certain file systems (such as debugfs).
  	  It is designed to provide an efficient mechanism for tools and
  	  facilities to relay large amounts of data from kernel space to
  	  user space.
  
  	  If unsure, say N.
f991633de   Dimitri Gorokhovik   [PATCH] initramfs...
1105
1106
  config BLK_DEV_INITRD
  	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
f991633de   Dimitri Gorokhovik   [PATCH] initramfs...
1107
1108
1109
1110
1111
  	help
  	  The initial RAM filesystem is a ramfs which is loaded by the
  	  boot loader (loadlin or lilo) and that is mounted as root
  	  before the normal boot procedure. It is typically used to
  	  load modules needed to mount the "real" root file system,
8c27ceff3   Mauro Carvalho Chehab   docs: fix locatio...
1112
  	  etc. See <file:Documentation/admin-guide/initrd.rst> for details.
f991633de   Dimitri Gorokhovik   [PATCH] initramfs...
1113
1114
1115
1116
1117
1118
  
  	  If RAM disk support (BLK_DEV_RAM) is also included, this
  	  also enables initial RAM disk (initrd) support and adds
  	  15 Kbytes (more on some other architectures) to the kernel size.
  
  	  If unsure say Y.
c33df4eaa   Jean-Paul Saman   [PATCH] disable i...
1119
  if BLK_DEV_INITRD
dbec48663   Sam Ravnborg   kconfig: move ini...
1120
  source "usr/Kconfig"
c33df4eaa   Jean-Paul Saman   [PATCH] disable i...
1121
  endif
877417e6f   Arnd Bergmann   Kbuild: change CC...
1122
1123
  choice
  	prompt "Compiler optimization level"
2cc3ce24a   Ulf Magnusson   kbuild: Fix optim...
1124
  	default CC_OPTIMIZE_FOR_PERFORMANCE
877417e6f   Arnd Bergmann   Kbuild: change CC...
1125
1126
  
  config CC_OPTIMIZE_FOR_PERFORMANCE
15f5db60a   Masahiro Yamada   kbuild,arc: add C...
1127
  	bool "Optimize for performance (-O2)"
877417e6f   Arnd Bergmann   Kbuild: change CC...
1128
1129
1130
1131
  	help
  	  This is the default optimization level for the kernel, building
  	  with the "-O2" compiler flag for best performance and most
  	  helpful compile-time warnings.
15f5db60a   Masahiro Yamada   kbuild,arc: add C...
1132
1133
1134
  config CC_OPTIMIZE_FOR_PERFORMANCE_O3
  	bool "Optimize more for performance (-O3)"
  	depends on ARC
b303c6df8   Masahiro Yamada   kbuild: compute f...
1135
  	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
c45b4f1f1   Linus Torvalds   Move size optimiz...
1136
  	help
15f5db60a   Masahiro Yamada   kbuild,arc: add C...
1137
1138
  	  Choosing this option will pass "-O3" to your compiler to optimize
  	  the kernel yet more for performance.
c45b4f1f1   Linus Torvalds   Move size optimiz...
1139

c45b4f1f1   Linus Torvalds   Move size optimiz...
1140
  config CC_OPTIMIZE_FOR_SIZE
15f5db60a   Masahiro Yamada   kbuild,arc: add C...
1141
  	bool "Optimize for size (-Os)"
b303c6df8   Masahiro Yamada   kbuild: compute f...
1142
  	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
c45b4f1f1   Linus Torvalds   Move size optimiz...
1143
  	help
ce3b487f6   Masahiro Yamada   init/Kconfig: rew...
1144
1145
  	  Choosing this option will pass "-Os" to your compiler resulting
  	  in a smaller kernel.
c45b4f1f1   Linus Torvalds   Move size optimiz...
1146

877417e6f   Arnd Bergmann   Kbuild: change CC...
1147
  endchoice
5d20ee319   Nicholas Piggin   kbuild: Allow LD_...
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
  config HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  	bool
  	help
  	  This requires that the arch annotates or otherwise protects
  	  its external entry points from being discarded. Linker scripts
  	  must also merge .text.*, .data.*, and .bss.* correctly into
  	  output sections. Care must be taken not to pull in unrelated
  	  sections (e.g., '.text.init'). Typically '.' in section names
  	  is used to distinguish them from label names / C identifiers.
  
  config LD_DEAD_CODE_DATA_ELIMINATION
  	bool "Dead code and data elimination (EXPERIMENTAL)"
  	depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
  	depends on EXPERT
16fd20aa9   Paul Burton   kbuild: Disable L...
1162
  	depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
e85d1d65c   Masahiro Yamada   kbuild: test dead...
1163
1164
  	depends on $(cc-option,-ffunction-sections -fdata-sections)
  	depends on $(ld-option,--gc-sections)
5d20ee319   Nicholas Piggin   kbuild: Allow LD_...
1165
  	help
8b9d27124   Masahiro Yamada   kbuild: reword he...
1166
1167
1168
  	  Enable this if you want to do dead code and data elimination with
  	  the linker by compiling with -ffunction-sections -fdata-sections,
  	  and linking with --gc-sections.
5d20ee319   Nicholas Piggin   kbuild: Allow LD_...
1169
1170
1171
1172
1173
1174
1175
  
  	  This can reduce on disk and in-memory size of the kernel
  	  code and static data, particularly for small configs and
  	  on small systems. This has the possibility of introducing
  	  silently broken kernel if the required annotations are not
  	  present. This option is not well tested yet, so use at your
  	  own risk.
0847062ad   Randy Dunlap   [PATCH] fix EMBED...
1176
1177
  config SYSCTL
  	bool
657a52095   Mike Frysinger   init/Kconfig: re-...
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
  config HAVE_UID16
  	bool
  
  config SYSCTL_EXCEPTION_TRACE
  	bool
  	help
  	  Enable support for /proc/sys/debug/exception-trace.
  
  config SYSCTL_ARCH_UNALIGN_NO_WARN
  	bool
  	help
  	  Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
  	  Allows arch to define/use @no_unaligned_warning to possibly warn
  	  about unaligned access emulation going on under the hood.
  
  config SYSCTL_ARCH_UNALIGN_ALLOW
  	bool
  	help
  	  Enable support for /proc/sys/kernel/unaligned-trap
  	  Allows arches to define/use @unaligned_enabled to runtime toggle
  	  the unaligned access emulation.
  	  see arch/parisc/kernel/unaligned.c for reference
657a52095   Mike Frysinger   init/Kconfig: re-...
1200
1201
  config HAVE_PCSPKR_PLATFORM
  	bool
f89b7755f   Alexei Starovoitov   bpf: split eBPF o...
1202
1203
1204
  # interpreter that classic socket filters depend on
  config BPF
  	bool
6a108a14f   David Rientjes   kconfig: rename C...
1205
1206
  menuconfig EXPERT
  	bool "Configure standard kernel features (expert users)"
f505c553d   Josh Triplett   debug: Make CONFI...
1207
1208
  	# Unhide debug options, to make the on-by-default options visible
  	select DEBUG_KERNEL
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1209
1210
1211
1212
1213
  	help
  	  This option allows certain base kernel options and settings
            to be disabled or tweaked. This is for specialized
            environments which can tolerate a "non-standard" kernel.
            Only use this if you really know what you are doing.
ae81f9e37   Chuck Ebbert   [PATCH] Kconfig: ...
1214
  config UID16
6a108a14f   David Rientjes   kconfig: rename C...
1215
  	bool "Enable 16-bit UID system calls" if EXPERT
2813893f8   Iulia Manda   kernel: condition...
1216
  	depends on HAVE_UID16 && MULTIUSER
ae81f9e37   Chuck Ebbert   [PATCH] Kconfig: ...
1217
1218
1219
  	default y
  	help
  	  This enables the legacy 16-bit UID syscall wrappers.
2813893f8   Iulia Manda   kernel: condition...
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
  config MULTIUSER
  	bool "Multiple users, groups and capabilities support" if EXPERT
  	default y
  	help
  	  This option enables support for non-root users, groups and
  	  capabilities.
  
  	  If you say N here, all processes will run with UID 0, GID 0, and all
  	  possible capabilities.  Saying N here also compiles out support for
  	  system calls related to UIDs, GIDs, and capabilities, such as setuid,
  	  setgid, and capset.
  
  	  If unsure, say Y here.
f6187769d   Fabian Frederick   sys_sgetmask/sys_...
1233
1234
  config SGETMASK_SYSCALL
  	bool "sgetmask/ssetmask syscalls support" if EXPERT
a687a5337   Arnd Bergmann   treewide: simplif...
1235
  	def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
f6187769d   Fabian Frederick   sys_sgetmask/sys_...
1236
1237
1238
1239
1240
1241
  	---help---
  	  sys_sgetmask and sys_ssetmask are obsolete system calls
  	  no longer supported in libc but still enabled by default in some
  	  architectures.
  
  	  If unsure, leave the default option here.
6af9f7bf3   Fabian Frederick   sys_sysfs: Add CO...
1242
1243
1244
1245
1246
1247
1248
1249
1250
  config SYSFS_SYSCALL
  	bool "Sysfs syscall support" if EXPERT
  	default y
  	---help---
  	  sys_sysfs is an obsolete system call no longer supported in libc.
  	  Note that disabling this option is more secure but might break
  	  compatibility with some systems.
  
  	  If unsure say Y here.
b89a81712   Eric W. Biederman   [PATCH] sysctl: A...
1251
  config SYSCTL_SYSCALL
6a108a14f   David Rientjes   kconfig: rename C...
1252
  	bool "Sysctl syscall support" if EXPERT
26a7034b4   Eric W. Biederman   sysctl: Reduce sy...
1253
  	depends on PROC_SYSCTL
c736de60a   WANG Cong   sysctl: make CONF...
1254
  	default n
b89a81712   Eric W. Biederman   [PATCH] sysctl: A...
1255
  	select SYSCTL
ae81f9e37   Chuck Ebbert   [PATCH] Kconfig: ...
1256
  	---help---
13bb7e37e   Eric W. Biederman   [PATCH] sysctl: U...
1257
1258
1259
1260
  	  sys_sysctl uses binary paths that have been found challenging
  	  to properly maintain and use.  The interface in /proc/sys
  	  using paths with ascii names is now the primary path to this
  	  information.
b89a81712   Eric W. Biederman   [PATCH] sysctl: A...
1261

13bb7e37e   Eric W. Biederman   [PATCH] sysctl: U...
1262
1263
1264
  	  Almost nothing using the binary sysctl interface so if you are
  	  trying to save some space it is probably safe to disable this,
  	  making your kernel marginally smaller.
b89a81712   Eric W. Biederman   [PATCH] sysctl: A...
1265

c736de60a   WANG Cong   sysctl: make CONF...
1266
  	  If unsure say N here.
ae81f9e37   Chuck Ebbert   [PATCH] Kconfig: ...
1267

d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
  config FHANDLE
  	bool "open by fhandle syscalls" if EXPERT
  	select EXPORTFS
  	default y
  	help
  	  If you say Y here, a user level program will be able to map
  	  file names to handle and then later use the handle for
  	  different file system operations. This is useful in implementing
  	  userspace file servers, which now track files using handles instead
  	  of names. The handle would remain the same even if file names
  	  get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
  	  syscalls.
baa73d9e4   Nicolas Pitre   posix-timers: Mak...
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
  config POSIX_TIMERS
  	bool "Posix Clocks & timers" if EXPERT
  	default y
  	help
  	  This includes native support for POSIX timers to the kernel.
  	  Some embedded systems have no use for them and therefore they
  	  can be configured out to reduce the size of the kernel image.
  
  	  When this option is disabled, the following syscalls won't be
  	  available: timer_create, timer_gettime: timer_getoverrun,
  	  timer_settime, timer_delete, clock_adjtime, getitimer,
  	  setitimer, alarm. Furthermore, the clock_settime, clock_gettime,
  	  clock_getres and clock_nanosleep syscalls will be limited to
  	  CLOCK_REALTIME, CLOCK_MONOTONIC and CLOCK_BOOTTIME only.
  
  	  If unsure say y.
d59745ce3   Matt Mackall   [PATCH] clean up ...
1296
1297
  config PRINTK
  	default y
6a108a14f   David Rientjes   kconfig: rename C...
1298
  	bool "Enable support for printk" if EXPERT
74876a98a   Frederic Weisbecker   printk: Wake up k...
1299
  	select IRQ_WORK
d59745ce3   Matt Mackall   [PATCH] clean up ...
1300
1301
1302
1303
1304
1305
  	help
  	  This option enables normal printk support. Removing it
  	  eliminates most of the message strings from the kernel image
  	  and makes the kernel more or less silent. As this makes it
  	  very difficult to diagnose system problems, saying N here is
  	  strongly discouraged.
42a0bb3f7   Petr Mladek   printk/nmi: gener...
1306
1307
1308
1309
  config PRINTK_NMI
  	def_bool y
  	depends on PRINTK
  	depends on HAVE_NMI
c8538a7aa   Matt Mackall   [PATCH] remove al...
1310
  config BUG
6a108a14f   David Rientjes   kconfig: rename C...
1311
  	bool "BUG() support" if EXPERT
c8538a7aa   Matt Mackall   [PATCH] remove al...
1312
1313
1314
1315
1316
1317
1318
  	default y
  	help
            Disabling this option eliminates support for BUG and WARN, reducing
            the size of your kernel image and potentially quietly ignoring
            numerous fatal conditions. You should only consider disabling this
            option for embedded systems with no facilities for reporting errors.
            Just say Y.
708e9a794   Matt Mackall   [PATCH] tiny: Con...
1319
  config ELF_CORE
046d662f4   Alex Kelly   coredump: make co...
1320
  	depends on COREDUMP
708e9a794   Matt Mackall   [PATCH] tiny: Con...
1321
  	default y
6a108a14f   David Rientjes   kconfig: rename C...
1322
  	bool "Enable ELF core dumps" if EXPERT
708e9a794   Matt Mackall   [PATCH] tiny: Con...
1323
1324
  	help
  	  Enable support for generating core dumps. Disabling saves about 4k.
8761f1ab7   Ralf Baechle   pcspkr: Cleanup K...
1325

e5e1d3cb2   Stas Sergeev   pcspkr: fix depen...
1326
  config PCSPKR_PLATFORM
6a108a14f   David Rientjes   kconfig: rename C...
1327
  	bool "Enable PC-Speaker support" if EXPERT
8761f1ab7   Ralf Baechle   pcspkr: Cleanup K...
1328
  	depends on HAVE_PCSPKR_PLATFORM
15f304b66   Ralf Baechle   i8253: Consolidat...
1329
  	select I8253_LOCK
e5e1d3cb2   Stas Sergeev   pcspkr: fix depen...
1330
1331
1332
1333
  	default y
  	help
            This option allows to disable the internal PC-Speaker
            support, saving some memory.
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1334
1335
  config BASE_FULL
  	default y
6a108a14f   David Rientjes   kconfig: rename C...
1336
  	bool "Enable full-sized data structures for core" if EXPERT
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1337
1338
1339
1340
1341
1342
  	help
  	  Disabling this option reduces the size of miscellaneous core
  	  kernel data structures. This saves memory on small machines,
  	  but may reduce performance.
  
  config FUTEX
6a108a14f   David Rientjes   kconfig: rename C...
1343
  	bool "Enable futex support" if EXPERT
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1344
  	default y
bc2eecd7e   Nicolas Pitre   futex: Allow for ...
1345
  	imply RT_MUTEXES
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1346
1347
1348
1349
  	help
  	  Disabling this option will cause the kernel to be built without
  	  support for "fast userspace mutexes".  The resulting kernel may not
  	  run glibc-based applications correctly.
bc2eecd7e   Nicolas Pitre   futex: Allow for ...
1350
1351
1352
1353
  config FUTEX_PI
  	bool
  	depends on FUTEX && RT_MUTEXES
  	default y
03b8c7b62   Heiko Carstens   futex: Allow arch...
1354
1355
  config HAVE_FUTEX_CMPXCHG
  	bool
62b4d2041   Josh Triplett   init/Kconfig: Fix...
1356
  	depends on FUTEX
03b8c7b62   Heiko Carstens   futex: Allow arch...
1357
1358
1359
1360
  	help
  	  Architectures should select this if futex_atomic_cmpxchg_inatomic()
  	  is implemented and always working. This removes a couple of runtime
  	  checks.
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1361
  config EPOLL
6a108a14f   David Rientjes   kconfig: rename C...
1362
  	bool "Enable eventpoll support" if EXPERT
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1363
1364
1365
1366
  	default y
  	help
  	  Disabling this option will cause the kernel to be built without
  	  support for epoll family of system calls.
fba2afaae   Davide Libenzi   signal/timer/even...
1367
  config SIGNALFD
6a108a14f   David Rientjes   kconfig: rename C...
1368
  	bool "Enable signalfd() system call" if EXPERT
fba2afaae   Davide Libenzi   signal/timer/even...
1369
1370
1371
1372
1373
1374
  	default y
  	help
  	  Enable the signalfd() system call that allows to receive signals
  	  on a file descriptor.
  
  	  If unsure, say Y.
b215e2839   Davide Libenzi   signal/timer/even...
1375
  config TIMERFD
6a108a14f   David Rientjes   kconfig: rename C...
1376
  	bool "Enable timerfd() system call" if EXPERT
b215e2839   Davide Libenzi   signal/timer/even...
1377
1378
1379
1380
1381
1382
  	default y
  	help
  	  Enable the timerfd() system call that allows to receive timer
  	  events on a file descriptor.
  
  	  If unsure, say Y.
e1ad7468c   Davide Libenzi   signal/timer/even...
1383
  config EVENTFD
6a108a14f   David Rientjes   kconfig: rename C...
1384
  	bool "Enable eventfd() system call" if EXPERT
e1ad7468c   Davide Libenzi   signal/timer/even...
1385
1386
1387
1388
1389
1390
  	default y
  	help
  	  Enable the eventfd() system call that allows to receive both
  	  kernel notification (ie. KAIO) or userspace notifications.
  
  	  If unsure, say Y.
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1391
  config SHMEM
6a108a14f   David Rientjes   kconfig: rename C...
1392
  	bool "Use full shmem filesystem" if EXPERT
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1393
1394
1395
1396
1397
1398
1399
1400
  	default y
  	depends on MMU
  	help
  	  The shmem is an internal filesystem used to manage shared memory.
  	  It is backed by swap and manages resource limits. It is also exported
  	  to userspace as tmpfs if TMPFS is enabled. Disabling this
  	  option replaces shmem and tmpfs with the much simpler ramfs code,
  	  which may be appropriate on small systems without swap.
ebf3f09c6   Thomas Petazzoni   Configure out AIO...
1401
  config AIO
6a108a14f   David Rientjes   kconfig: rename C...
1402
  	bool "Enable AIO support" if EXPERT
ebf3f09c6   Thomas Petazzoni   Configure out AIO...
1403
1404
1405
  	default y
  	help
  	  This option enables POSIX asynchronous I/O which may by used
657a52095   Mike Frysinger   init/Kconfig: re-...
1406
1407
  	  by some high performance threaded applications. Disabling
  	  this option saves about 7k.
2b188cc1b   Jens Axboe   Add io_uring IO i...
1408
1409
1410
1411
1412
1413
1414
1415
  config IO_URING
  	bool "Enable IO uring support" if EXPERT
  	select ANON_INODES
  	default y
  	help
  	  This option enables support for the io_uring interface, enabling
  	  applications to submit and complete IO through submission and
  	  completion rings that are shared between the kernel and application.
d3ac21cac   Josh Triplett   mm: Support compi...
1416
1417
1418
1419
1420
1421
1422
1423
1424
  config ADVISE_SYSCALLS
  	bool "Enable madvise/fadvise syscalls" if EXPERT
  	default y
  	help
  	  This option enables the madvise and fadvise syscalls, used by
  	  applications to advise the kernel about their future memory or file
  	  usage, improving performance. If building an embedded system where no
  	  applications use these syscalls, you can disable this option to save
  	  space.
5b25b13ab   Mathieu Desnoyers   sys_membarrier():...
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
  config MEMBARRIER
  	bool "Enable membarrier() system call" if EXPERT
  	default y
  	help
  	  Enable the membarrier() system call that allows issuing memory
  	  barriers across all running threads, which can be used to distribute
  	  the cost of user-space memory barriers asymmetrically by transforming
  	  pairs of memory barriers into pairs consisting of membarrier() and a
  	  compiler barrier.
  
  	  If unsure, say Y.
d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
  config KALLSYMS
  	 bool "Load all symbols for debugging/ksymoops" if EXPERT
  	 default y
  	 help
  	   Say Y here to let the kernel print out symbolic crash information and
  	   symbolic stack backtraces. This increases the size of the kernel
  	   somewhat, as all symbols have to be loaded into the kernel image.
  
  config KALLSYMS_ALL
  	bool "Include all symbols in kallsyms"
  	depends on DEBUG_KERNEL && KALLSYMS
  	help
  	   Normally kallsyms only contains the symbols of functions for nicer
  	   OOPS messages and backtraces (i.e., symbols from the text and inittext
  	   sections). This is sufficient for most cases. And only in very rare
  	   cases (e.g., when a debugger is used) all symbols are required (e.g.,
  	   names of variables from the data sections, etc).
  
  	   This option makes sure that all symbols are loaded into the kernel
  	   image (i.e., symbols from all sections) in cost of increased kernel
  	   size (depending on the kernel configuration, it may be 300KiB or
  	   something like this).
  
  	   Say N unless you really need all symbols.
  
  config KALLSYMS_ABSOLUTE_PERCPU
  	bool
  	depends on KALLSYMS
  	default X86_64 && SMP
  
  config KALLSYMS_BASE_RELATIVE
  	bool
  	depends on KALLSYMS
a687a5337   Arnd Bergmann   treewide: simplif...
1469
  	default !IA64
d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
  	help
  	  Instead of emitting them as absolute values in the native word size,
  	  emit the symbol references in the kallsyms table as 32-bit entries,
  	  each containing a relative value in the range [base, base + U32_MAX]
  	  or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
  	  an absolute value in the range [0, S32_MAX] or a relative value in the
  	  range [base, base + S32_MAX], where base is the lowest relative symbol
  	  address encountered in the image.
  
  	  On 64-bit builds, this reduces the size of the address table by 50%,
  	  but more importantly, it results in entries whose values are build
  	  time constants, and no relocation pass is required at runtime to fix
  	  up the entries based on the runtime load address of the kernel.
  
  # end of the "standard kernel features (expert users)" menu
  
  # syscall, maps, verifier
  config BPF_SYSCALL
  	bool "Enable bpf() system call"
d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1489
  	select BPF
bae77c5eb   Song Liu   bpf: enable stack...
1490
  	select IRQ_WORK
d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1491
1492
1493
1494
  	default n
  	help
  	  Enable the bpf() system call that allows to manipulate eBPF
  	  programs and maps via file descriptors.
290af8662   Alexei Starovoitov   bpf: introduce BP...
1495
1496
1497
1498
1499
1500
  config BPF_JIT_ALWAYS_ON
  	bool "Permanently enable BPF JIT and remove BPF interpreter"
  	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
  	help
  	  Enables BPF JIT and removes BPF interpreter to avoid
  	  speculative execution of BPF instructions by the interpreter
d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1501
1502
  config USERFAULTFD
  	bool "Enable userfaultfd() system call"
d1b069f5f   Randy Dunlap   EXPERT Kconfig me...
1503
1504
1505
1506
  	depends on MMU
  	help
  	  Enable the userfaultfd() system call that allows to intercept and
  	  handle page faults in userland.
3ccfebedd   Mathieu Desnoyers   powerpc, membarri...
1507
1508
  config ARCH_HAS_MEMBARRIER_CALLBACKS
  	bool
70216e18e   Mathieu Desnoyers   membarrier: Provi...
1509
1510
  config ARCH_HAS_MEMBARRIER_SYNC_CORE
  	bool
d7822b1e2   Mathieu Desnoyers   rseq: Introduce r...
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
  config RSEQ
  	bool "Enable rseq() system call" if EXPERT
  	default y
  	depends on HAVE_RSEQ
  	select MEMBARRIER
  	help
  	  Enable the restartable sequences system call. It provides a
  	  user-space cache for the current CPU number value, which
  	  speeds up getting the current CPU number from user-space,
  	  as well as an ABI to speed up user-space operations on
  	  per-CPU data.
  
  	  If unsure, say Y.
  
  config DEBUG_RSEQ
  	default n
  	bool "Enabled debugging of rseq() system call" if EXPERT
  	depends on RSEQ && DEBUG_KERNEL
  	help
  	  Enable extra debugging checks for the rseq system call.
  
  	  If unsure, say N.
6befe5f69   Randy Dunlap   init/Kconfig: fix...
1533
1534
  config EMBEDDED
  	bool "Embedded system"
5d2acfc7b   Josh Triplett   kconfig: make all...
1535
  	option allnoconfig_y
6befe5f69   Randy Dunlap   init/Kconfig: fix...
1536
1537
1538
1539
1540
  	select EXPERT
  	help
  	  This option should be enabled if compiling the kernel for
  	  an embedded system so certain expert options are available
  	  for configuration.
cdd6c482c   Ingo Molnar   perf: Do the big ...
1541
  config HAVE_PERF_EVENTS
0793a61d4   Thomas Gleixner   performance count...
1542
  	bool
018df72dd   Mike Frysinger   perf_counter: Sta...
1543
1544
  	help
  	  See tools/perf/design.txt for details.
0793a61d4   Thomas Gleixner   performance count...
1545

906010b21   Peter Zijlstra   perf_event: Provi...
1546
1547
1548
1549
  config PERF_USE_VMALLOC
  	bool
  	help
  	  See tools/perf/design.txt for details
ad90a3de9   William Breathitt Gray   pc104: Introduce ...
1550
  config PC104
424529fb7   William Breathitt Gray   pc104: Add EXPERT...
1551
  	bool "PC/104 support" if EXPERT
ad90a3de9   William Breathitt Gray   pc104: Introduce ...
1552
1553
1554
1555
  	help
  	  Expose PC/104 form factor device drivers and options available for
  	  selection and configuration. Enable this option if your target
  	  machine has a PC/104 bus.
57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1556
  menu "Kernel Performance Events And Counters"
0793a61d4   Thomas Gleixner   performance count...
1557

cdd6c482c   Ingo Molnar   perf: Do the big ...
1558
  config PERF_EVENTS
57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1559
  	bool "Kernel performance events and counters"
392d65a9a   Robert Richter   perf: Remove PERF...
1560
  	default y if PROFILING
cdd6c482c   Ingo Molnar   perf: Do the big ...
1561
  	depends on HAVE_PERF_EVENTS
e360adbe2   Peter Zijlstra   irq_work: Add gen...
1562
  	select IRQ_WORK
83fe27ea5   Pranith Kumar   rcu: Make SRCU op...
1563
  	select SRCU
0793a61d4   Thomas Gleixner   performance count...
1564
  	help
57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1565
1566
  	  Enable kernel support for various performance events provided
  	  by software and hardware.
0793a61d4   Thomas Gleixner   performance count...
1567

dd77038d2   Thadeu Lima de Souza Cascardo   perf_events: Fix ...
1568
  	  Software events are supported either built-in or via the
57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1569
  	  use of generic tracepoints.
0793a61d4   Thomas Gleixner   performance count...
1570

57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1571
1572
  	  Most modern CPUs support performance events via performance
  	  counter registers. These registers count the number of certain
0793a61d4   Thomas Gleixner   performance count...
1573
1574
1575
1576
1577
  	  types of hw events: such as instructions executed, cachemisses
  	  suffered, or branches mis-predicted - without slowing down the
  	  kernel or applications. These registers can also trigger interrupts
  	  when a threshold number of events have passed - and can thus be
  	  used to profile the code that runs on that CPU.
57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1578
  	  The Linux Performance Event subsystem provides an abstraction of
dd77038d2   Thadeu Lima de Souza Cascardo   perf_events: Fix ...
1579
  	  these software and hardware event capabilities, available via a
57c0c15b5   Ingo Molnar   perf: Tidy up aft...
1580
  	  system call and used by the "perf" utility in tools/perf/. It
0793a61d4   Thomas Gleixner   performance count...
1581
1582
1583
1584
  	  provides per task and per CPU counters, and it provides event
  	  capabilities on top of those.
  
  	  Say Y if unsure.
906010b21   Peter Zijlstra   perf_event: Provi...
1585
1586
1587
  config DEBUG_PERF_USE_VMALLOC
  	default n
  	bool "Debug: use vmalloc to back perf mmap() buffers"
cb3071137   Michael Ellerman   perf_event: Don't...
1588
  	depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
906010b21   Peter Zijlstra   perf_event: Provi...
1589
1590
1591
1592
1593
1594
1595
1596
  	select PERF_USE_VMALLOC
  	help
  	 Use vmalloc memory to back perf mmap() buffers.
  
  	 Mostly useful for debugging the vmalloc code on platforms
  	 that don't require it.
  
  	 Say N if unsure.
0793a61d4   Thomas Gleixner   performance count...
1597
  endmenu
f8891e5e1   Christoph Lameter   [PATCH] Light wei...
1598
1599
  config VM_EVENT_COUNTERS
  	default y
6a108a14f   David Rientjes   kconfig: rename C...
1600
  	bool "Enable VM event counters for /proc/vmstat" if EXPERT
f8891e5e1   Christoph Lameter   [PATCH] Light wei...
1601
  	help
2aea4fb61   Paul Jackson   [PATCH] CONFIG_VM...
1602
1603
  	  VM event counters are needed for event counts to be shown.
  	  This option allows the disabling of the VM event counters
6a108a14f   David Rientjes   kconfig: rename C...
1604
  	  on EXPERT systems.  /proc/vmstat will only show page counts
2aea4fb61   Paul Jackson   [PATCH] CONFIG_VM...
1605
  	  if VM event counters are disabled.
f8891e5e1   Christoph Lameter   [PATCH] Light wei...
1606

41ecc55b8   Christoph Lameter   SLUB: add CONFIG_...
1607
1608
  config SLUB_DEBUG
  	default y
6a108a14f   David Rientjes   kconfig: rename C...
1609
  	bool "Enable SLUB debugging support" if EXPERT
f6acb6350   Christoph Lameter   slub: #ifdef simp...
1610
  	depends on SLUB && SYSFS
41ecc55b8   Christoph Lameter   SLUB: add CONFIG_...
1611
1612
1613
1614
1615
  	help
  	  SLUB has extensive debug support features. Disabling these can
  	  result in significant savings in code size. This also disables
  	  SLUB sysfs support. /sys/slab will not exist and there will be
  	  no support for cache validation etc.
1663f26df   Tejun Heo   slub: make sysfs ...
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
  config SLUB_MEMCG_SYSFS_ON
  	default n
  	bool "Enable memcg SLUB sysfs support by default" if EXPERT
  	depends on SLUB && SYSFS && MEMCG
  	help
  	  SLUB creates a directory under /sys/kernel/slab for each
  	  allocation cache to host info and debug files. If memory
  	  cgroup is enabled, each cache can have per memory cgroup
  	  caches. SLUB can create the same sysfs directories for these
  	  caches under /sys/kernel/slab/CACHE/cgroup but it can lead
  	  to a very high number of debug files being created. This is
  	  controlled by slub_memcg_sysfs boot parameter and this
  	  config option determines the parameter's default value.
b943c460f   Randy Dunlap   menu: fix embedde...
1629
1630
1631
1632
1633
1634
1635
  config COMPAT_BRK
  	bool "Disable heap randomization"
  	default y
  	help
  	  Randomizing heap placement makes heap exploits harder, but it
  	  also breaks ancient binaries (including anything libc5 based).
  	  This option changes the bootup default to heap randomization
692105b8a   Matt LaPlante   trivial: fix typo...
1636
  	  disabled, and can be overridden at runtime by setting
b943c460f   Randy Dunlap   menu: fix embedde...
1637
1638
1639
  	  /proc/sys/kernel/randomize_va_space to 2.
  
  	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
81819f0fc   Christoph Lameter   SLUB core
1640
1641
  choice
  	prompt "Choose SLAB allocator"
a0acd8208   Christoph Lameter   Make SLUB the def...
1642
  	default SLUB
81819f0fc   Christoph Lameter   SLUB core
1643
1644
1645
1646
1647
  	help
  	   This option allows to select a slab allocator.
  
  config SLAB
  	bool "SLAB"
04385fc5e   Kees Cook   mm: SLAB hardened...
1648
  	select HAVE_HARDENED_USERCOPY_ALLOCATOR
81819f0fc   Christoph Lameter   SLUB core
1649
1650
  	help
  	  The regular slab allocator that is established and known to work
34013886e   Christoph Lameter   Fix spellings of ...
1651
  	  well in all environments. It organizes cache hot objects in
02f562104   Simon Arlott   Kconfig: SLUB is ...
1652
  	  per cpu and per node queues.
81819f0fc   Christoph Lameter   SLUB core
1653
1654
  
  config SLUB
81819f0fc   Christoph Lameter   SLUB core
1655
  	bool "SLUB (Unqueued Allocator)"
ed18adc1c   Kees Cook   mm: SLUB hardened...
1656
  	select HAVE_HARDENED_USERCOPY_ALLOCATOR
81819f0fc   Christoph Lameter   SLUB core
1657
1658
1659
1660
1661
  	help
  	   SLUB is a slab allocator that minimizes cache line usage
  	   instead of managing queues of cached objects (SLAB approach).
  	   Per cpu caching is realized using slabs of objects instead
  	   of queues of objects. SLUB can use memory efficiently
02f562104   Simon Arlott   Kconfig: SLUB is ...
1662
1663
  	   and has enhanced diagnostics. SLUB is the default choice for
  	   a slab allocator.
81819f0fc   Christoph Lameter   SLUB core
1664
1665
  
  config SLOB
6a108a14f   David Rientjes   kconfig: rename C...
1666
  	depends on EXPERT
81819f0fc   Christoph Lameter   SLUB core
1667
1668
  	bool "SLOB (Simple Allocator)"
  	help
372914582   Matt Mackall   slob: correct Kco...
1669
1670
1671
  	   SLOB replaces the stock allocator with a drastically simpler
  	   allocator. SLOB is generally more space efficient but
  	   does not perform as well on large systems.
81819f0fc   Christoph Lameter   SLUB core
1672
1673
  
  endchoice
7660a6fdd   Kees Cook   mm: allow slab_no...
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
  config SLAB_MERGE_DEFAULT
  	bool "Allow slab caches to be merged"
  	default y
  	help
  	  For reduced kernel memory fragmentation, slab caches can be
  	  merged when they share the same size and other characteristics.
  	  This carries a risk of kernel heap overflows being able to
  	  overwrite objects from merged caches (and more easily control
  	  cache layout), which makes such heap attacks easier to exploit
  	  by attackers. By keeping caches unmerged, these kinds of exploits
  	  can usually only damage objects in the same cache. To disable
  	  merging at runtime, "slab_nomerge" can be passed on the kernel
  	  command line.
c7ce4f60a   Thomas Garnier   mm: SLAB freelist...
1687
1688
  config SLAB_FREELIST_RANDOM
  	default n
210e7a43f   Thomas Garnier   mm: SLUB freelist...
1689
  	depends on SLAB || SLUB
c7ce4f60a   Thomas Garnier   mm: SLAB freelist...
1690
1691
  	bool "SLAB freelist randomization"
  	help
210e7a43f   Thomas Garnier   mm: SLUB freelist...
1692
  	  Randomizes the freelist order used on creating new pages. This
c7ce4f60a   Thomas Garnier   mm: SLAB freelist...
1693
1694
  	  security feature reduces the predictability of the kernel slab
  	  allocator against heap overflows.
2482ddec6   Kees Cook   mm: add SLUB free...
1695
1696
1697
1698
1699
1700
  config SLAB_FREELIST_HARDENED
  	bool "Harden slab freelist metadata"
  	depends on SLUB
  	help
  	  Many kernel heap attacks try to target slab cache metadata and
  	  other infrastructure. This options makes minor performance
92bae787c   Kees Cook   init/Kconfig: fix...
1701
  	  sacrifices to harden the kernel slab allocator against common
2482ddec6   Kees Cook   mm: add SLUB free...
1702
  	  freelist exploit methods.
e900a918b   Dan Williams   mm: shuffle initi...
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
  config SHUFFLE_PAGE_ALLOCATOR
  	bool "Page allocator randomization"
  	default SLAB_FREELIST_RANDOM && ACPI_NUMA
  	help
  	  Randomization of the page allocator improves the average
  	  utilization of a direct-mapped memory-side-cache. See section
  	  5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
  	  6.2a specification for an example of how a platform advertises
  	  the presence of a memory-side-cache. There are also incidental
  	  security benefits as it reduces the predictability of page
  	  allocations to compliment SLAB_FREELIST_RANDOM, but the
  	  default granularity of shuffling on the "MAX_ORDER - 1" i.e,
  	  10th order of pages is selected based on cache utilization
  	  benefits on x86.
  
  	  While the randomization improves cache utilization it may
  	  negatively impact workloads on platforms without a cache. For
  	  this reason, by default, the randomization is enabled only
  	  after runtime detection of a direct-mapped memory-side-cache.
  	  Otherwise, the randomization may be force enabled with the
  	  'page_alloc.shuffle' kernel command line parameter.
  
  	  Say Y if unsure.
345c905d1   Joonsoo Kim   slub: Make cpu pa...
1726
1727
  config SLUB_CPU_PARTIAL
  	default y
b39ffbf8b   Uwe Kleine-König   slub: don't use c...
1728
  	depends on SLUB && SMP
345c905d1   Joonsoo Kim   slub: Make cpu pa...
1729
1730
  	bool "SLUB per cpu partial cache"
  	help
92bae787c   Kees Cook   init/Kconfig: fix...
1731
  	  Per cpu partial caches accelerate objects allocation and freeing
345c905d1   Joonsoo Kim   slub: Make cpu pa...
1732
1733
1734
1735
  	  that is local to a processor at the price of more indeterminism
  	  in the latency of the free. On overflow these caches will be cleared
  	  which requires the taking of locks that may cause latency spikes.
  	  Typically one would choose no for a realtime system.
ea6376395   Jie Zhang   nommu: fix malloc...
1736
1737
  config MMAP_ALLOW_UNINITIALIZED
  	bool "Allow mmapped anonymous memory to be uninitialized"
6a108a14f   David Rientjes   kconfig: rename C...
1738
  	depends on EXPERT && !MMU
ea6376395   Jie Zhang   nommu: fix malloc...
1739
1740
1741
  	default n
  	help
  	  Normally, and according to the Linux spec, anonymous memory obtained
3903bf940   Randy Dunlap   init/Kconfig: fix...
1742
  	  from mmap() has its contents cleared before it is passed to
ea6376395   Jie Zhang   nommu: fix malloc...
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
  	  userspace.  Enabling this config option allows you to request that
  	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
  	  providing a huge performance boost.  If this option is not enabled,
  	  then the flag will be ignored.
  
  	  This is taken advantage of by uClibc's malloc(), and also by
  	  ELF-FDPIC binfmt's brk and stack allocator.
  
  	  Because of the obvious security issues, this option should only be
  	  enabled on embedded devices where you control what is run in
  	  userspace.  Since that isn't generally a problem on no-MMU systems,
  	  it is normally safe to say Y here.
  
  	  See Documentation/nommu-mmap.txt for more information.
091f6e26e   David Howells   MODSIGN: Extract ...
1757
1758
1759
1760
1761
  config SYSTEM_DATA_VERIFICATION
  	def_bool n
  	select SYSTEM_TRUSTED_KEYRING
  	select KEYS
  	select CRYPTO
d43de6c78   David Howells   akcipher: Move th...
1762
  	select CRYPTO_RSA
091f6e26e   David Howells   MODSIGN: Extract ...
1763
1764
  	select ASYMMETRIC_KEY_TYPE
  	select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
091f6e26e   David Howells   MODSIGN: Extract ...
1765
1766
1767
1768
  	select ASN1
  	select OID_REGISTRY
  	select X509_CERTIFICATE_PARSER
  	select PKCS7_MESSAGE_PARSER
82c04ff89   Peter Foley   init/Kconfig: mov...
1769
  	help
091f6e26e   David Howells   MODSIGN: Extract ...
1770
1771
1772
1773
  	  Provide PKCS#7 message verification using the contents of the system
  	  trusted keyring to provide public keys.  This then can be used for
  	  module verification, kexec image verification and firmware blob
  	  verification.
82c04ff89   Peter Foley   init/Kconfig: mov...
1774

125e56458   Mathieu Desnoyers   Move Kconfig.inst...
1775
  config PROFILING
b309a294e   Robert Richter   oprofile: remove ...
1776
  	bool "Profiling support"
125e56458   Mathieu Desnoyers   Move Kconfig.inst...
1777
1778
1779
  	help
  	  Say Y here to enable the extended profiling support mechanisms used
  	  by profilers such as OProfile.
5f87f1121   Ingo Molnar   tracing: clean up...
1780
1781
1782
1783
  #
  # Place an empty function call at each tracepoint site. Can be
  # dynamically changed for a probe function.
  #
97e1c18e8   Mathieu Desnoyers   tracing: Kernel T...
1784
  config TRACEPOINTS
5f87f1121   Ingo Molnar   tracing: clean up...
1785
  	bool
97e1c18e8   Mathieu Desnoyers   tracing: Kernel T...
1786

1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1787
  endmenu		# General setup
1572497cb   Christoph Hellwig   kconfig: include ...
1788
  source "arch/Kconfig"
ae81f9e37   Chuck Ebbert   [PATCH] Kconfig: ...
1789
  config RT_MUTEXES
6341e62b2   Christoph Jaeger   kconfig: use bool...
1790
  	bool
ae81f9e37   Chuck Ebbert   [PATCH] Kconfig: ...
1791

1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1792
1793
1794
1795
  config BASE_SMALL
  	int
  	default 0 if BASE_FULL
  	default 1 if !BASE_FULL
c8424e776   Thiago Jung Bauermann   MODSIGN: Export m...
1796
1797
1798
  config MODULE_SIG_FORMAT
  	def_bool n
  	select SYSTEM_DATA_VERIFICATION
66da57332   Jan Engelhardt   Use menuconfig ob...
1799
  menuconfig MODULES
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
1800
  	bool "Enable loadable module support"
11097a036   Yann E. MORIN   modules: do not d...
1801
  	option modules
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  	help
  	  Kernel modules are small pieces of compiled code which can
  	  be inserted in the running kernel, rather than being
  	  permanently built into the kernel.  You use the "modprobe"
  	  tool to add (and sometimes remove) them.  If you say Y here,
  	  many parts of the kernel can be built as modules (by
  	  answering M instead of Y where indicated): this is most
  	  useful for infrequently used options which are not required
  	  for booting.  For more information, see the man pages for
  	  modprobe, lsmod, modinfo, insmod and rmmod.
  
  	  If you say Y here, you will need to run "make
  	  modules_install" to put the modules under /lib/modules/
  	  where modprobe can find them (you may need to be root to do
  	  this).
  
  	  If unsure, say Y.
0b0de1443   Robert P. J. Day   Kconfig: Extend "...
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  if MODULES
826e4506a   Linus Torvalds   Make forced modul...
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  config MODULE_FORCE_LOAD
  	bool "Forced module loading"
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  	default n
  	help
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  	  Allow loading of modules without version information (ie. modprobe
  	  --force).  Forced module loading sets the 'F' (forced) taint flag and
  	  is usually a really bad idea.
826e4506a   Linus Torvalds   Make forced modul...
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1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  config MODULE_UNLOAD
  	bool "Module unloading"
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  	help
  	  Without this option you will not be able to unload any
  	  modules (note that some modules may not be unloadable
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  	  anyway), which makes your kernel smaller, faster
  	  and simpler.  If unsure, say Y.
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  config MODULE_FORCE_UNLOAD
  	bool "Forced module unloading"
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  	depends on MODULE_UNLOAD
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  	help
  	  This option allows you to force a module to unload, even if the
  	  kernel believes it is unsafe: the kernel will remove the module
  	  without waiting for anyone to stop using it (using the -f option to
  	  rmmod).  This is mainly for kernel developers and desperate users.
  	  If unsure, say N.
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  config MODVERSIONS
0d5416433   Sam Ravnborg   kbuild: remove EX...
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  	bool "Module versioning support"
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  	help
  	  Usually, you have to use modules compiled with your kernel.
  	  Saying Y here makes it sometimes possible to use modules
  	  compiled for different kernels, by adding enough information
  	  to the modules to (hopefully) spot any changes which would
  	  make them incompatible with the kernel you are running.  If
  	  unsure, say N.
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  config ASM_MODVERSIONS
  	bool
  	default HAVE_ASM_MODVERSIONS && MODVERSIONS
  	help
  	  This enables module versioning for exported symbols also from
  	  assembly. This can be enabled only when the target architecture
  	  supports it.
56067812d   Ard Biesheuvel   kbuild: modversio...
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  config MODULE_REL_CRCS
  	bool
  	depends on MODVERSIONS
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  config MODULE_SRCVERSION_ALL
  	bool "Source checksum for all modules"
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2
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  	help
  	  Modules which contain a MODULE_VERSION get an extra "srcversion"
  	  field inserted into their modinfo section, which contains a
      	  sum of the source files which made it.  This helps maintainers
  	  see exactly which source was used to build a module (since
  	  others sometimes change the module source without updating
  	  the version).  With this option, such a "srcversion" field
  	  will be created for all modules.  If unsure, say N.
106a4ee25   Rusty Russell   module: signature...
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  config MODULE_SIG
  	bool "Module signature verification"
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  	select MODULE_SIG_FORMAT
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  	help
  	  Check modules for valid signatures upon load: the signature
  	  is simply appended to the module. For more information see
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  	  <file:Documentation/admin-guide/module-signing.rst>.
106a4ee25   Rusty Russell   module: signature...
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  	  Note that this option adds the OpenSSL development packages as a
  	  kernel build dependency so that the signing tool can use its crypto
  	  library.
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  	  You should enable this option if you wish to use either
  	  CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
  	  another LSM - otherwise unsigned modules will be loadable regardless
  	  of the lockdown policy.
ea0b6dcf7   David Howells   MODSIGN: Provide ...
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  	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
  	  module DOES NOT get stripped after being signed.  This includes the
  	  debuginfo strip done by some packagers (such as rpmbuild) and
  	  inclusion into an initramfs that wants the module size reduced.
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  config MODULE_SIG_FORCE
  	bool "Require modules to be validly signed"
  	depends on MODULE_SIG
  	help
  	  Reject unsigned modules or signed modules for which we don't have a
  	  key.  Without this, such modules will simply taint the kernel.
ea0b6dcf7   David Howells   MODSIGN: Provide ...
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  config MODULE_SIG_ALL
  	bool "Automatically sign all modules"
  	default y
  	depends on MODULE_SIG
  	help
  	  Sign all modules during make modules_install. Without this option,
  	  modules must be signed manually, using the scripts/sign-file tool.
  
  comment "Do not forget to sign required modules with scripts/sign-file"
  	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
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  choice
  	prompt "Which hash algorithm should modules be signed with?"
  	depends on MODULE_SIG
  	help
  	  This determines which sort of hashing algorithm will be used during
  	  signature generation.  This algorithm _must_ be built into the kernel
  	  directly so that signature verification can take place.  It is not
  	  possible to load a signed module containing the algorithm to check
  	  the signature on that module.
  
  config MODULE_SIG_SHA1
  	bool "Sign modules with SHA-1"
  	select CRYPTO_SHA1
  
  config MODULE_SIG_SHA224
  	bool "Sign modules with SHA-224"
  	select CRYPTO_SHA256
  
  config MODULE_SIG_SHA256
  	bool "Sign modules with SHA-256"
  	select CRYPTO_SHA256
  
  config MODULE_SIG_SHA384
  	bool "Sign modules with SHA-384"
  	select CRYPTO_SHA512
  
  config MODULE_SIG_SHA512
  	bool "Sign modules with SHA-512"
  	select CRYPTO_SHA512
  
  endchoice
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  config MODULE_SIG_HASH
  	string
  	depends on MODULE_SIG
  	default "sha1" if MODULE_SIG_SHA1
  	default "sha224" if MODULE_SIG_SHA224
  	default "sha256" if MODULE_SIG_SHA256
  	default "sha384" if MODULE_SIG_SHA384
  	default "sha512" if MODULE_SIG_SHA512
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  config MODULE_COMPRESS
  	bool "Compress modules on installation"
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  	help
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  	  Compresses kernel modules when 'make modules_install' is run; gzip or
  	  xz depending on "Compression algorithm" below.
beb50df39   Bertrand Jacquin   kbuild: handle mo...
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  	  module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
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  	  Out-of-tree kernel modules installed using Kbuild will also be
  	  compressed upon installation.
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  	  Note: for modules inside an initrd or initramfs, it's more efficient
  	  to compress the whole initrd or initramfs instead.
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  	  Note: This is fully compatible with signed modules.
  
  	  If in doubt, say N.
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  choice
  	prompt "Compression algorithm"
  	depends on MODULE_COMPRESS
  	default MODULE_COMPRESS_GZIP
  	help
  	  This determines which sort of compression will be used during
  	  'make modules_install'.
  
  	  GZIP (default) and XZ are supported.
  
  config MODULE_COMPRESS_GZIP
  	bool "GZIP"
  
  config MODULE_COMPRESS_XZ
  	bool "XZ"
  
  endchoice
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  config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
  	bool "Allow loading of modules with missing namespace imports"
  	help
  	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
  	  a namespace. A module that makes use of a symbol exported with such a
  	  namespace is required to import the namespace via MODULE_IMPORT_NS().
  	  There is no technical reason to enforce correct namespace imports,
  	  but it creates consistency between symbols defining namespaces and
  	  users importing namespaces they make use of. This option relaxes this
  	  requirement and lifts the enforcement when loading a module.
  
  	  If unsure, say N.
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  config UNUSED_SYMBOLS
  	bool "Enable unused/obsolete exported symbols"
  	default y if X86
  	help
  	  Unused but exported symbols make the kernel needlessly bigger.  For
  	  that reason most of these unused exports will soon be removed.  This
  	  option is provided temporarily to provide a transition period in case
  	  some external kernel module needs one of these symbols anyway. If you
  	  encounter such a case in your module, consider if you are actually
  	  using the right API.  (rationale: since nobody in the kernel is using
  	  this in a module, there is a pretty good chance it's actually the
  	  wrong interface to use).  If you really need the symbol, please send a
  	  mail to the linux kernel mailing list mentioning the symbol and why
  	  you really need it, and what the merge plan to the mainline kernel for
  	  your module is.
dbacb0ef6   Nicolas Pitre   kconfig option fo...
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  config TRIM_UNUSED_KSYMS
  	bool "Trim unused exported kernel symbols"
d189c2a4b   Masahiro Yamada   module: remove re...
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  	depends on !UNUSED_SYMBOLS
dbacb0ef6   Nicolas Pitre   kconfig option fo...
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  	help
  	  The kernel and some modules make many symbols available for
  	  other modules to use via EXPORT_SYMBOL() and variants. Depending
  	  on the set of modules being selected in your kernel configuration,
  	  many of those exported symbols might never be used.
  
  	  This option allows for unused exported symbols to be dropped from
  	  the build. In turn, this provides the compiler more opportunities
  	  (especially when using LTO) for optimizing the code and reducing
  	  binary size.  This might have some security advantages as well.
f1cb637e7   Valdis Kletnieks   init/Kconfig: add...
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  	  If unsure, or if you need to build out-of-tree modules, say N.
dbacb0ef6   Nicolas Pitre   kconfig option fo...
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0b0de1443   Robert P. J. Day   Kconfig: Extend "...
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  endif # MODULES
6c9692e2d   Peter Zijlstra   module: Make the ...
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  config MODULES_TREE_LOOKUP
  	def_bool y
  	depends on PERF_EVENTS || TRACING
98a79d6a5   Rusty Russell   cpumask: centrali...
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  config INIT_ALL_POSSIBLE
  	bool
  	help
5f054e31c   Rusty Russell   documentation: re...
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  	  Back when each arch used to define their own cpu_online_mask and
  	  cpu_possible_mask, some of them chose to initialize cpu_possible_mask
98a79d6a5   Rusty Russell   cpumask: centrali...
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  	  with all 1s, and others with all 0s.  When they were centralised,
  	  it was better to provide this option than to break all the archs
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  	  and have several arch maintainers pursuing me down dark alleys.
98a79d6a5   Rusty Russell   cpumask: centrali...
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3a65dfe8c   Jens Axboe   [BLOCK] Move all ...
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  source "block/Kconfig"
e98c32029   Avi Kivity   Move PREEMPT_NOTI...
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  config PREEMPT_NOTIFIERS
  	bool
e260be673   Paul E. McKenney   Preempt-RCU: impl...
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16295bec6   Steffen Klassert   padata: Generic p...
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  config PADATA
  	depends on SMP
  	bool
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  config ASN1
  	tristate
  	help
  	  Build a simple ASN.1 grammar compiler that produces a bytecode output
  	  that can be interpreted by the ASN.1 stream decoder and used to
  	  inform it as to what tags are to be expected in a stream and what
  	  functions to call on what tags.
6beb00092   Thomas Gleixner   locking: Make inl...
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  source "kernel/Kconfig.locks"
e61938a92   Mathieu Desnoyers   locking: Introduc...
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  config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
  	bool
1bd21c6c2   Dominik Brodowski   syscalls/core: In...
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  # It may be useful for an architecture to override the definitions of the
7303e30ec   Dominik Brodowski   syscalls/core: Pr...
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  # SYSCALL_DEFINE() and __SYSCALL_DEFINEx() macros in <linux/syscalls.h>
  # and the COMPAT_ variants in <linux/compat.h>, in particular to use a
  # different calling convention for syscalls. They can also override the
  # macros for not-implemented syscalls in kernel/sys_ni.c and
  # kernel/time/posix-stubs.c. All these overrides need to be available in
  # <asm/syscall_wrapper.h>.
1bd21c6c2   Dominik Brodowski   syscalls/core: In...
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  config ARCH_HAS_SYSCALL_WRAPPER
  	def_bool n