summaryrefslogtreecommitdiffstats
path: root/init/Kconfig
diff options
context:
space:
mode:
Diffstat (limited to 'init/Kconfig')
-rw-r--r--init/Kconfig2010
1 files changed, 2010 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
new file mode 100644
index 000000000..148704640
--- /dev/null
+++ b/init/Kconfig
@@ -0,0 +1,2010 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config CC_VERSION_TEXT
+ string
+ default "$(CC_VERSION_TEXT)"
+ help
+ This is used in unclear ways:
+
+ - Re-run Kconfig when the compiler is updated
+ The 'default' property references the environment variable,
+ CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.
+ When the compiler is updated, Kconfig will be invoked.
+
+ - Ensure full rebuild when the compiler is updated
+ include/linux/compiler-version.h contains this option in the comment
+ line so fixdep adds include/config/CC_VERSION_TEXT into the
+ auto-generated dependency. When the compiler is updated, syncconfig
+ will touch it and then every file will be rebuilt.
+
+config CC_IS_GCC
+ def_bool $(success,test "$(cc-name)" = GCC)
+
+config GCC_VERSION
+ int
+ default $(cc-version) if CC_IS_GCC
+ default 0
+
+config CC_IS_CLANG
+ def_bool $(success,test "$(cc-name)" = Clang)
+
+config CLANG_VERSION
+ int
+ default $(cc-version) if CC_IS_CLANG
+ default 0
+
+config AS_IS_GNU
+ def_bool $(success,test "$(as-name)" = GNU)
+
+config AS_IS_LLVM
+ def_bool $(success,test "$(as-name)" = LLVM)
+
+config AS_VERSION
+ int
+ # Use clang version if this is the integrated assembler
+ default CLANG_VERSION if AS_IS_LLVM
+ default $(as-version)
+
+config LD_IS_BFD
+ def_bool $(success,test "$(ld-name)" = BFD)
+
+config LD_VERSION
+ int
+ default $(ld-version) if LD_IS_BFD
+ default 0
+
+config LD_IS_LLD
+ def_bool $(success,test "$(ld-name)" = LLD)
+
+config LLD_VERSION
+ int
+ default $(ld-version) if LD_IS_LLD
+ default 0
+
+config RUST_IS_AVAILABLE
+ def_bool $(success,$(srctree)/scripts/rust_is_available.sh)
+ help
+ This shows whether a suitable Rust toolchain is available (found).
+
+ Please see Documentation/rust/quick-start.rst for instructions on how
+ to satisfy the build requirements of Rust support.
+
+ In particular, the Makefile target 'rustavailable' is useful to check
+ why the Rust toolchain is not being detected.
+
+config CC_CAN_LINK
+ bool
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))
+
+config CC_CAN_LINK_STATIC
+ bool
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static)
+
+config CC_HAS_ASM_GOTO_OUTPUT
+ def_bool $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
+
+config CC_HAS_ASM_GOTO_TIED_OUTPUT
+ depends on CC_HAS_ASM_GOTO_OUTPUT
+ # Detect buggy gcc and clang, fixed in gcc-11 clang-14.
+ def_bool $(success,echo 'int foo(int *x) { asm goto (".long (%l[bar]) - .": "+m"(*x) ::: bar); return *x; bar: return 0; }' | $CC -x c - -c -o /dev/null)
+
+config TOOLS_SUPPORT_RELR
+ def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
+
+config CC_HAS_ASM_INLINE
+ def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
+
+config CC_HAS_NO_PROFILE_FN_ATTR
+ def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
+
+config PAHOLE_VERSION
+ int
+ default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
+
+config CONSTRUCTORS
+ bool
+
+config IRQ_WORK
+ bool
+
+config BUILDTIME_TABLE_SORT
+ bool
+
+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.
+
+ 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().
+
+menu "General setup"
+
+config BROKEN
+ bool
+
+config BROKEN_ON_SMP
+ bool
+ depends on BROKEN || !SMP
+ default y
+
+config INIT_ENV_ARG_LIMIT
+ int
+ default 32 if !UML
+ default 128 if UML
+ help
+ Maximum of each of the number of arguments and environment
+ variables passed to init from the kernel command line.
+
+config COMPILE_TEST
+ bool "Compile also drivers which will not load"
+ depends on HAS_IOMEM
+ 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.
+
+config WERROR
+ bool "Compile the kernel with warnings as errors"
+ default COMPILE_TEST
+ help
+ A kernel build should not cause any compiler warnings, and this
+ enables the '-Werror' (for C) and '-Dwarnings' (for Rust) flags
+ to enforce that rule by default.
+
+ However, if you have a new (or very old) compiler with odd and
+ unusual warnings, or you have some architecture with problems,
+ you may need to disable this config option in order to
+ successfully build the kernel.
+
+ If in doubt, say Y.
+
+config UAPI_HEADER_TEST
+ bool "Compile test UAPI headers"
+ depends on HEADERS_INSTALL && CC_CAN_LINK
+ 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.
+
+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.
+
+config LOCALVERSION_AUTO
+ bool "Automatically append version information to the version string"
+ default y
+ depends on !COMPILE_TEST
+ help
+ This will try to automatically determine if the current tree is a
+ release tree by looking for git tags that belong to the current
+ top of tree revision.
+
+ A string of the format -gxxxxxxxx will be added to the localversion
+ if a git-based tree is found. The string generated by this will be
+ appended after any matching localversion* files, and after the value
+ set in CONFIG_LOCALVERSION.
+
+ (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".)
+
+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.
+
+config HAVE_KERNEL_GZIP
+ bool
+
+config HAVE_KERNEL_BZIP2
+ bool
+
+config HAVE_KERNEL_LZMA
+ bool
+
+config HAVE_KERNEL_XZ
+ bool
+
+config HAVE_KERNEL_LZO
+ bool
+
+config HAVE_KERNEL_LZ4
+ bool
+
+config HAVE_KERNEL_ZSTD
+ bool
+
+config HAVE_KERNEL_UNCOMPRESSED
+ bool
+
+choice
+ prompt "Kernel compression mode"
+ default KERNEL_GZIP
+ depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4 || HAVE_KERNEL_ZSTD || HAVE_KERNEL_UNCOMPRESSED
+ help
+ 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
+ bool "Gzip"
+ depends on HAVE_KERNEL_GZIP
+ help
+ The old and tried gzip compression. It provides a good balance
+ between compression ratio and decompression speed.
+
+config KERNEL_BZIP2
+ bool "Bzip2"
+ depends on HAVE_KERNEL_BZIP2
+ help
+ Its compression ratio and speed is intermediate.
+ Decompression speed is slowest among the choices. The kernel
+ 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.
+
+config KERNEL_LZMA
+ bool "LZMA"
+ depends on HAVE_KERNEL_LZMA
+ help
+ 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.
+
+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.
+
+config KERNEL_LZO
+ bool "LZO"
+ depends on HAVE_KERNEL_LZO
+ help
+ Its compression ratio is the poorest among the choices. The kernel
+ size is about 10% bigger than gzip; however its speed
+ (both compression and decompression) is the fastest.
+
+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.
+
+config KERNEL_ZSTD
+ bool "ZSTD"
+ depends on HAVE_KERNEL_ZSTD
+ help
+ ZSTD is a compression algorithm targeting intermediate compression
+ with fast decompression speed. It will compress better than GZIP and
+ decompress around the same speed as LZO, but slower than LZ4. You
+ will need at least 192 KB RAM or more for booting. The zstd command
+ line tool is required for compression.
+
+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.
+
+endchoice
+
+config DEFAULT_INIT
+ string "Default init path"
+ default ""
+ help
+ This option determines the default init for the system if no init=
+ option is passed on the kernel command line. If the requested path is
+ not present, we will still then move on to attempting further
+ locations (e.g. /sbin/init, etc). If this is empty, we will just use
+ the fallback list when init= is not passed.
+
+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.
+
+config SYSVIPC
+ bool "System V IPC"
+ 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>.
+
+config SYSVIPC_SYSCTL
+ bool
+ depends on SYSVIPC
+ depends on SYSCTL
+ default y
+
+config SYSVIPC_COMPAT
+ def_bool y
+ depends on COMPAT && SYSVIPC
+
+config POSIX_MQUEUE
+ bool "POSIX Message Queues"
+ depends on NET
+ 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
+ queues (functions mq_*) say Y here.
+
+ 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.
+
+config POSIX_MQUEUE_SYSCTL
+ bool
+ depends on POSIX_MQUEUE
+ depends on SYSCTL
+ default y
+
+config WATCH_QUEUE
+ bool "General notification queue"
+ default n
+ help
+
+ This is a general notification queue for the kernel to pass events to
+ userspace by splicing them into pipes. It can be used in conjunction
+ with watches for key/keyring change notifications and device
+ notifications.
+
+ See Documentation/core-api/watch_queue.rst
+
+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
+ to directly read from or write to another process' address space.
+ See the man page for more details.
+
+config USELIB
+ bool "uselib syscall (for libc5 and earlier)"
+ default ALPHA || M68K || SPARC
+ 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.
+
+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
+ logging of avc messages output). System call auditing is included
+ on architectures which support it.
+
+config HAVE_ARCH_AUDITSYSCALL
+ bool
+
+config AUDITSYSCALL
+ def_bool y
+ depends on AUDIT && HAVE_ARCH_AUDITSYSCALL
+ select FSNOTIFY
+
+source "kernel/irq/Kconfig"
+source "kernel/time/Kconfig"
+source "kernel/bpf/Kconfig"
+source "kernel/Kconfig.preempt"
+
+menu "CPU/Task time and stats accounting"
+
+config VIRT_CPU_ACCOUNTING
+ bool
+
+choice
+ prompt "Cputime accounting"
+ default TICK_CPU_ACCOUNTING
+
+# Kind of a stub config for the pure tick based cputime accounting
+config TICK_CPU_ACCOUNTING
+ bool "Simple tick based cputime accounting"
+ depends on !S390 && !NO_HZ_FULL
+ 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.
+
+config VIRT_CPU_ACCOUNTING_NATIVE
+ bool "Deterministic task and CPU time accounting"
+ depends on HAVE_VIRT_CPU_ACCOUNTING && !NO_HZ_FULL
+ select VIRT_CPU_ACCOUNTING
+ 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.
+
+config VIRT_CPU_ACCOUNTING_GEN
+ bool "Full dynticks CPU time accounting"
+ depends on HAVE_CONTEXT_TRACKING_USER
+ depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
+ depends on GENERIC_CLOCKEVENTS
+ select VIRT_CPU_ACCOUNTING
+ select CONTEXT_TRACKING_USER
+ 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.
+
+endchoice
+
+config IRQ_TIME_ACCOUNTING
+ bool "Fine granularity task level IRQ time accounting"
+ depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE
+ 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.
+
+config HAVE_SCHED_AVG_IRQ
+ def_bool y
+ depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
+ depends on SMP
+
+config SCHED_THERMAL_PRESSURE
+ bool
+ default y if ARM && ARM_CPU_TOPOLOGY
+ default y if ARM64
+ depends on SMP
+ depends on CPU_FREQ_THERMAL
+ help
+ Select this option to enable thermal pressure accounting in the
+ scheduler. Thermal pressure is the value conveyed to the scheduler
+ that reflects the reduction in CPU compute capacity resulted from
+ thermal throttling. Thermal throttling occurs when the performance of
+ a CPU is capped due to high operating temperatures.
+
+ If selected, the scheduler will be able to balance tasks accordingly,
+ i.e. put less load on throttled CPUs than on non/less throttled ones.
+
+ This requires the architecture to implement
+ arch_update_thermal_pressure() and arch_scale_thermal_pressure().
+
+config BSD_PROCESS_ACCT
+ bool "BSD Process Accounting"
+ depends on MULTIUSER
+ 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
+ process and its parent. Note that this file format is incompatible
+ with previous v0/v1/v2 file formats, so you will need updated tools
+ for processing it. A preliminary version of these tools is available
+ at <http://www.gnu.org/software/acct/>.
+
+config TASKSTATS
+ bool "Export task/process statistics through netlink"
+ depends on NET
+ depends on MULTIUSER
+ 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.
+
+config TASK_DELAY_ACCT
+ bool "Enable per-task delay accounting"
+ depends on TASKSTATS
+ select SCHED_INFO
+ 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.
+
+config TASK_XACCT
+ bool "Enable extended accounting over taskstats"
+ 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
+ bool "Enable per-task storage I/O accounting"
+ 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.
+
+config PSI
+ bool "Pressure stall information tracking"
+ select KERNFS
+ 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.
+
+ 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.
+
+ For more details see Documentation/accounting/psi.rst.
+
+ Say N if unsure.
+
+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
+ per default but can be enabled through passing psi=1 on the
+ kernel commandline during boot.
+
+ 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.
+
+endmenu # "CPU/Task time and stats accounting"
+
+config CPU_ISOLATION
+ bool "CPU isolation"
+ depends on SMP || COMPILE_TEST
+ default y
+ help
+ Make sure that CPUs running critical tasks are not disturbed by
+ any source of "noise" such as unbound workqueues, timers, kthreads...
+ Unbound jobs get offloaded to housekeeping CPUs. This is driven by
+ the "isolcpus=" boot parameter.
+
+ Say Y if unsure.
+
+source "kernel/rcu/Kconfig"
+
+config BUILD_BIN2C
+ bool
+ default n
+
+config IKCONFIG
+ tristate "Kernel .config support"
+ 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.
+
+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.
+
+config LOG_BUF_SHIFT
+ int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
+ range 12 25
+ default 17
+ depends on PRINTK
+ help
+ 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.
+
+ Examples:
+ 17 => 128 KB
+ 16 => 64 KB
+ 15 => 32 KB
+ 14 => 16 KB
+ 13 => 8 KB
+ 12 => 4 KB
+
+config LOG_CPU_MAX_BUF_SHIFT
+ int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
+ depends on SMP
+ range 0 21
+ default 12 if !BASE_SMALL
+ default 0 if BASE_SMALL
+ depends on PRINTK
+ 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 16 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
+ hotplugging making the computation optimal for the worst case
+ scenario while allowing a simple algorithm to be used from bootup.
+
+ 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
+
+config PRINTK_SAFE_LOG_BUF_SHIFT
+ int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
+ range 10 21
+ default 13
+ depends on PRINTK
+ help
+ 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.
+
+ Those messages are rare and limited. The largest one is when
+ 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
+
+config PRINTK_INDEX
+ bool "Printk indexing debugfs interface"
+ depends on PRINTK && DEBUG_FS
+ help
+ Add support for indexing of all printk formats known at compile time
+ at <debugfs>/printk/index/<module>.
+
+ This can be used as part of maintaining daemons which monitor
+ /dev/kmsg, as it permits auditing the printk formats present in a
+ kernel, allowing detection of cases where monitored printks are
+ changed or no longer present.
+
+ There is no additional runtime cost to printk with this enabled.
+
+#
+# Architectures with an unreliable sched_clock() should select this:
+#
+config HAVE_UNSTABLE_SCHED_CLOCK
+ bool
+
+config GENERIC_SCHED_CLOCK
+ bool
+
+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
+
+#
+# For architectures that want to enable the support for NUMA-affine scheduler
+# balancing logic:
+#
+config ARCH_SUPPORTS_NUMA_BALANCING
+ bool
+
+#
+# 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
+
+config CC_HAS_INT128
+ def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT
+
+config CC_IMPLICIT_FALLTHROUGH
+ string
+ default "-Wimplicit-fallthrough=5" if CC_IS_GCC && $(cc-option,-Wimplicit-fallthrough=5)
+ default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough)
+
+# Currently, disable gcc-11+ array-bounds globally.
+# It's still broken in gcc-13, so no upper bound yet.
+config GCC11_NO_ARRAY_BOUNDS
+ def_bool y
+
+config CC_NO_ARRAY_BOUNDS
+ bool
+ default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC11_NO_ARRAY_BOUNDS
+
+#
+# For architectures that know their GCC __int128 support is sound
+#
+config ARCH_SUPPORTS_INT128
+ bool
+
+# 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
+
+config NUMA_BALANCING
+ bool "Memory placement aware NUMA scheduler"
+ depends on ARCH_SUPPORTS_NUMA_BALANCING
+ depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
+ depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
+ help
+ This option adds support for automatic NUMA aware memory/task placement.
+ The mechanism is quite primitive and is based on migrating memory when
+ it has references to the node the task is running on.
+
+ This system will be inactive on UMA systems.
+
+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.
+
+menuconfig CGROUPS
+ bool "Control Group support"
+ select KERNFS
+ help
+ This option adds support for grouping sets of processes together, for
+ use with process control subsystems such as Cpusets, CFS, memory
+ controls or device isolation.
+ See
+ - Documentation/scheduler/sched-design-CFS.rst (CFS)
+ - Documentation/admin-guide/cgroup-v1/ (features for grouping, isolation
+ and resource control)
+
+ Say N if unsure.
+
+if CGROUPS
+
+config PAGE_COUNTER
+ bool
+
+config CGROUP_FAVOR_DYNMODS
+ bool "Favor dynamic modification latency reduction by default"
+ help
+ This option enables the "favordynmods" mount option by default
+ which reduces the latencies of dynamic cgroup modifications such
+ as task migrations and controller on/offs at the cost of making
+ hot path operations such as forks and exits more expensive.
+
+ Say N if unsure.
+
+config MEMCG
+ bool "Memory controller"
+ select PAGE_COUNTER
+ select EVENTFD
+ help
+ Provides control over the memory footprint of tasks in a cgroup.
+
+config MEMCG_KMEM
+ bool
+ depends on MEMCG && !SLOB
+ default y
+
+config BLK_CGROUP
+ bool "IO controller"
+ depends on BLOCK
+ default n
+ help
+ Generic block IO controller cgroup interface. This is the common
+ cgroup interface which should be used by various IO controlling
+ policies.
+
+ 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.
+
+ 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_BFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
+ CONFIG_BLK_DEV_THROTTLING=y.
+
+ See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.
+
+config CGROUP_WRITEBACK
+ bool
+ depends on MEMCG && BLK_CGROUP
+ default y
+
+menuconfig CGROUP_SCHED
+ bool "CPU controller"
+ 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
+
+config CFS_BANDWIDTH
+ bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
+ 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.
+ See Documentation/scheduler/sched-bwc.rst for more information.
+
+config RT_GROUP_SCHED
+ bool "Group scheduling for SCHED_RR/FIFO"
+ depends on CGROUP_SCHED
+ default n
+ help
+ This feature lets you explicitly allocate real CPU bandwidth
+ to task groups. If enabled, it will also make it impossible to
+ schedule realtime tasks for non-root users until you allocate
+ realtime bandwidth for them.
+ See Documentation/scheduler/sched-rt-group.rst for more information.
+
+endif #CGROUP_SCHED
+
+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.
+
+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
+ PIDs controller is designed to stop this from happening.
+
+ It should be noted that organisational operations (such as attaching
+ to a cgroup hierarchy) will *not* be blocked by the PIDs controller,
+ since the PIDs limit only affects a process's ability to fork, not to
+ attach to a cgroup.
+
+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.
+
+config CGROUP_FREEZER
+ bool "Freezer controller"
+ help
+ Provides a way to freeze and unfreeze all tasks in a
+ cgroup.
+
+ 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.
+
+config CGROUP_HUGETLB
+ bool "HugeTLB controller"
+ depends on HUGETLB_PAGE
+ select PAGE_COUNTER
+ default n
+ 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.
+
+config CPUSETS
+ bool "Cpuset controller"
+ depends on SMP
+ 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.
+
+ Say N if unsure.
+
+config PROC_PID_CPUSET
+ bool "Include legacy /proc/<pid>/cpuset file"
+ depends on CPUSETS
+ default y
+
+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. Or this can be used to have cgroup ID in samples
+ so that it can monitor performance events among cgroups.
+
+ Say N if unsure.
+
+config CGROUP_BPF
+ bool "Support for eBPF programs attached to cgroups"
+ depends on BPF_SYSCALL
+ select SOCK_CGROUP_DATA
+ 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.
+
+config CGROUP_MISC
+ bool "Misc resource controller"
+ default n
+ help
+ Provides a controller for miscellaneous resources on a host.
+
+ Miscellaneous scalar resources are the resources on the host system
+ which cannot be abstracted like the other cgroups. This controller
+ tracks and limits the miscellaneous resources used by a process
+ attached to a cgroup hierarchy.
+
+ For more information, please check misc cgroup section in
+ /Documentation/admin-guide/cgroup-v2.rst.
+
+config CGROUP_DEBUG
+ bool "Debug controller"
+ default n
+ depends on DEBUG_KERNEL
+ help
+ This option enables a simple controller that exports
+ debugging information about the cgroups framework. This
+ controller is for control cgroup debugging only. Its
+ interfaces are not stable.
+
+ Say N.
+
+config SOCK_CGROUP_DATA
+ bool
+ default n
+
+endif # CGROUPS
+
+menuconfig NAMESPACES
+ bool "Namespaces support" if EXPERT
+ depends on MULTIUSER
+ default !EXPERT
+ 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.
+
+if NAMESPACES
+
+config UTS_NS
+ bool "UTS namespace"
+ default y
+ help
+ In this namespace tasks see different info provided with the
+ uname() system call
+
+config TIME_NS
+ bool "TIME namespace"
+ depends on GENERIC_VDSO_TIME_NS
+ default y
+ help
+ In this namespace boottime and monotonic clocks can be set.
+ The time will keep going with the same pace.
+
+config IPC_NS
+ bool "IPC namespace"
+ depends on (SYSVIPC || POSIX_MQUEUE)
+ default y
+ help
+ In this namespace tasks work with IPC ids which correspond to
+ different IPC objects in different namespaces.
+
+config USER_NS
+ bool "User namespace"
+ default n
+ help
+ This allows containers, i.e. vservers, to use user namespaces
+ to provide different user info for different servers.
+
+ When user namespaces are enabled in the kernel it is
+ 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.
+
+ If unsure, say N.
+
+config PID_NS
+ bool "PID Namespaces"
+ default y
+ help
+ Support process id namespaces. This allows having multiple
+ processes with the same pid as long as they are in different
+ pid namespaces. This is a building block of containers.
+
+config NET_NS
+ bool "Network namespace"
+ depends on NET
+ default y
+ help
+ Allow user space to create what appear to be multiple instances
+ of the network stack.
+
+endif # NAMESPACES
+
+config CHECKPOINT_RESTORE
+ bool "Checkpoint/restore support"
+ depends on PROC_FS
+ select PROC_CHILDREN
+ select KCMP
+ 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.
+
+config SCHED_AUTOGROUP
+ bool "Automatic process group scheduling"
+ 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.
+
+config SYSFS_DEPRECATED
+ bool "Enable deprecated sysfs features to support old userspace tools"
+ 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
+ bool "Enable deprecated sysfs features by default"
+ 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)"
+ select IRQ_WORK
+ 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.
+
+config BLK_DEV_INITRD
+ bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
+ 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,
+ etc. See <file:Documentation/admin-guide/initrd.rst> for details.
+
+ 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.
+
+if BLK_DEV_INITRD
+
+source "usr/Kconfig"
+
+endif
+
+config BOOT_CONFIG
+ bool "Boot config support"
+ select BLK_DEV_INITRD if !BOOT_CONFIG_EMBED
+ help
+ Extra boot config allows system admin to pass a config file as
+ complemental extension of kernel cmdline when booting.
+ The boot config file must be attached at the end of initramfs
+ with checksum, size and magic word.
+ See <file:Documentation/admin-guide/bootconfig.rst> for details.
+
+ If unsure, say Y.
+
+config BOOT_CONFIG_EMBED
+ bool "Embed bootconfig file in the kernel"
+ depends on BOOT_CONFIG
+ help
+ Embed a bootconfig file given by BOOT_CONFIG_EMBED_FILE in the
+ kernel. Usually, the bootconfig file is loaded with the initrd
+ image. But if the system doesn't support initrd, this option will
+ help you by embedding a bootconfig file while building the kernel.
+
+ If unsure, say N.
+
+config BOOT_CONFIG_EMBED_FILE
+ string "Embedded bootconfig file path"
+ depends on BOOT_CONFIG_EMBED
+ help
+ Specify a bootconfig file which will be embedded to the kernel.
+ This bootconfig will be used if there is no initrd or no other
+ bootconfig in the initrd.
+
+config INITRAMFS_PRESERVE_MTIME
+ bool "Preserve cpio archive mtimes in initramfs"
+ default y
+ help
+ Each entry in an initramfs cpio archive carries an mtime value. When
+ enabled, extracted cpio items take this mtime, with directory mtime
+ setting deferred until after creation of any child entries.
+
+ If unsure, say Y.
+
+choice
+ prompt "Compiler optimization level"
+ default CC_OPTIMIZE_FOR_PERFORMANCE
+
+config CC_OPTIMIZE_FOR_PERFORMANCE
+ bool "Optimize for performance (-O2)"
+ 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.
+
+config CC_OPTIMIZE_FOR_SIZE
+ bool "Optimize for size (-Os)"
+ help
+ Choosing this option will pass "-Os" to your compiler resulting
+ in a smaller kernel.
+
+endchoice
+
+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
+ depends on $(cc-option,-ffunction-sections -fdata-sections)
+ depends on $(ld-option,--gc-sections)
+ help
+ 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.
+
+ 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.
+
+config LD_ORPHAN_WARN
+ def_bool y
+ depends on ARCH_WANT_LD_ORPHAN_WARN
+ depends on $(ld-option,--orphan-handling=warn)
+
+config SYSCTL
+ bool
+
+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
+
+config HAVE_PCSPKR_PLATFORM
+ bool
+
+# interpreter that classic socket filters depend on
+config BPF
+ bool
+ select CRYPTO_LIB_SHA1
+
+menuconfig EXPERT
+ bool "Configure standard kernel features (expert users)"
+ # Unhide debug options, to make the on-by-default options visible
+ select DEBUG_KERNEL
+ 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.
+
+config UID16
+ bool "Enable 16-bit UID system calls" if EXPERT
+ depends on HAVE_UID16 && MULTIUSER
+ default y
+ help
+ This enables the legacy 16-bit UID syscall wrappers.
+
+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.
+
+config SGETMASK_SYSCALL
+ bool "sgetmask/ssetmask syscalls support" if EXPERT
+ def_bool PARISC || M68K || PPC || MIPS || X86 || SPARC || MICROBLAZE || SUPERH
+ 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.
+
+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.
+
+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.
+
+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.
+
+config PRINTK
+ default y
+ bool "Enable support for printk" if EXPERT
+ select IRQ_WORK
+ 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.
+
+config BUG
+ bool "BUG() support" if EXPERT
+ 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.
+
+config ELF_CORE
+ depends on COREDUMP
+ default y
+ bool "Enable ELF core dumps" if EXPERT
+ help
+ Enable support for generating core dumps. Disabling saves about 4k.
+
+
+config PCSPKR_PLATFORM
+ bool "Enable PC-Speaker support" if EXPERT
+ depends on HAVE_PCSPKR_PLATFORM
+ select I8253_LOCK
+ default y
+ help
+ This option allows to disable the internal PC-Speaker
+ support, saving some memory.
+
+config BASE_FULL
+ default y
+ bool "Enable full-sized data structures for core" if EXPERT
+ 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
+ bool "Enable futex support" if EXPERT
+ depends on !(SPARC32 && SMP)
+ default y
+ imply RT_MUTEXES
+ 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.
+
+config FUTEX_PI
+ bool
+ depends on FUTEX && RT_MUTEXES
+ default y
+
+config EPOLL
+ bool "Enable eventpoll support" if EXPERT
+ default y
+ help
+ Disabling this option will cause the kernel to be built without
+ support for epoll family of system calls.
+
+config SIGNALFD
+ bool "Enable signalfd() system call" if EXPERT
+ default y
+ help
+ Enable the signalfd() system call that allows to receive signals
+ on a file descriptor.
+
+ If unsure, say Y.
+
+config TIMERFD
+ bool "Enable timerfd() system call" if EXPERT
+ default y
+ help
+ Enable the timerfd() system call that allows to receive timer
+ events on a file descriptor.
+
+ If unsure, say Y.
+
+config EVENTFD
+ bool "Enable eventfd() system call" if EXPERT
+ default y
+ help
+ Enable the eventfd() system call that allows to receive both
+ kernel notification (ie. KAIO) or userspace notifications.
+
+ If unsure, say Y.
+
+config SHMEM
+ bool "Use full shmem filesystem" if EXPERT
+ 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.
+
+config AIO
+ bool "Enable AIO support" if EXPERT
+ default y
+ help
+ This option enables POSIX asynchronous I/O which may by used
+ by some high performance threaded applications. Disabling
+ this option saves about 7k.
+
+config IO_URING
+ bool "Enable IO uring support" if EXPERT
+ select IO_WQ
+ 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.
+
+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.
+
+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.
+
+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 if you want to
+ enable kernel live patching, or other less common use cases (e.g.,
+ when a debugger is used) all symbols are required (i.e., 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, or kernel live patching.
+
+config KALLSYMS_ABSOLUTE_PERCPU
+ bool
+ depends on KALLSYMS
+ default X86_64 && SMP
+
+config KALLSYMS_BASE_RELATIVE
+ bool
+ depends on KALLSYMS
+ default !IA64
+ 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 ARCH_HAS_MEMBARRIER_CALLBACKS
+ bool
+
+config ARCH_HAS_MEMBARRIER_SYNC_CORE
+ bool
+
+config KCMP
+ bool "Enable kcmp() system call" if EXPERT
+ help
+ Enable the kernel resource comparison system call. It provides
+ user-space with the ability to compare two processes to see if they
+ share a common resource, such as a file descriptor or even virtual
+ memory space.
+
+ If unsure, say N.
+
+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.
+
+config EMBEDDED
+ bool "Embedded system"
+ select EXPERT
+ help
+ This option should be enabled if compiling the kernel for
+ an embedded system so certain expert options are available
+ for configuration.
+
+config HAVE_PERF_EVENTS
+ bool
+ help
+ See tools/perf/design.txt for details.
+
+config GUEST_PERF_EVENTS
+ bool
+ depends on HAVE_PERF_EVENTS
+
+config PERF_USE_VMALLOC
+ bool
+ help
+ See tools/perf/design.txt for details
+
+config PC104
+ bool "PC/104 support" if EXPERT
+ 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.
+
+menu "Kernel Performance Events And Counters"
+
+config PERF_EVENTS
+ bool "Kernel performance events and counters"
+ default y if PROFILING
+ depends on HAVE_PERF_EVENTS
+ select IRQ_WORK
+ select SRCU
+ help
+ Enable kernel support for various performance events provided
+ by software and hardware.
+
+ Software events are supported either built-in or via the
+ use of generic tracepoints.
+
+ Most modern CPUs support performance events via performance
+ counter registers. These registers count the number of certain
+ 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.
+
+ The Linux Performance Event subsystem provides an abstraction of
+ these software and hardware event capabilities, available via a
+ system call and used by the "perf" utility in tools/perf/. It
+ provides per task and per CPU counters, and it provides event
+ capabilities on top of those.
+
+ Say Y if unsure.
+
+config DEBUG_PERF_USE_VMALLOC
+ default n
+ bool "Debug: use vmalloc to back perf mmap() buffers"
+ depends on PERF_EVENTS && DEBUG_KERNEL && !PPC
+ 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.
+
+endmenu
+
+config SYSTEM_DATA_VERIFICATION
+ def_bool n
+ select SYSTEM_TRUSTED_KEYRING
+ select KEYS
+ select CRYPTO
+ select CRYPTO_RSA
+ select ASYMMETRIC_KEY_TYPE
+ select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+ select ASN1
+ select OID_REGISTRY
+ select X509_CERTIFICATE_PARSER
+ select PKCS7_MESSAGE_PARSER
+ help
+ 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.
+
+config PROFILING
+ bool "Profiling support"
+ help
+ Say Y here to enable the extended profiling support mechanisms used
+ by profilers.
+
+config RUST
+ bool "Rust support"
+ depends on HAVE_RUST
+ depends on RUST_IS_AVAILABLE
+ depends on !MODVERSIONS
+ depends on !GCC_PLUGINS
+ depends on !RANDSTRUCT
+ depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
+ select CONSTRUCTORS
+ help
+ Enables Rust support in the kernel.
+
+ This allows other Rust-related options, like drivers written in Rust,
+ to be selected.
+
+ It is also required to be able to load external kernel modules
+ written in Rust.
+
+ See Documentation/rust/ for more information.
+
+ If unsure, say N.
+
+config RUSTC_VERSION_TEXT
+ string
+ depends on RUST
+ default $(shell,command -v $(RUSTC) >/dev/null 2>&1 && $(RUSTC) --version || echo n)
+
+config BINDGEN_VERSION_TEXT
+ string
+ depends on RUST
+ default $(shell,command -v $(BINDGEN) >/dev/null 2>&1 && $(BINDGEN) --version || echo n)
+
+#
+# Place an empty function call at each tracepoint site. Can be
+# dynamically changed for a probe function.
+#
+config TRACEPOINTS
+ bool
+
+endmenu # General setup
+
+source "arch/Kconfig"
+
+config RT_MUTEXES
+ bool
+ default y if PREEMPT_RT
+
+config BASE_SMALL
+ int
+ default 0 if BASE_FULL
+ default 1 if !BASE_FULL
+
+config MODULE_SIG_FORMAT
+ def_bool n
+ select SYSTEM_DATA_VERIFICATION
+
+source "kernel/module/Kconfig"
+
+config INIT_ALL_POSSIBLE
+ bool
+ help
+ 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
+ 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
+ and have several arch maintainers pursuing me down dark alleys.
+
+source "block/Kconfig"
+
+config PREEMPT_NOTIFIERS
+ bool
+
+config PADATA
+ depends on SMP
+ bool
+
+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.
+
+source "kernel/Kconfig.locks"
+
+config ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+ bool
+
+config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
+ bool
+
+# It may be useful for an architecture to override the definitions of the
+# 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>.
+config ARCH_HAS_SYSCALL_WRAPPER
+ def_bool n