linux-yocto/lib/Kconfig

SPDX-License-Identifier: GPL-2.0-only

Library configuration

config BINARY_PRINTF def_bool n

menu "Library routines"

config RAID6_PQ tristate

config RAID6_PQ_BENCHMARK bool "Automatically choose fastest RAID6 PQ functions" depends on RAID6_PQ default y help Benchmark all available RAID6 PQ functions on init and choose the fastest one.

config LINEAR_RANGES tristate

config PACKING bool "Generic bitfield packing and unpacking" default n help This option provides the packing() helper function, which permits converting bitfields between a CPU-usable representation and a memory representation that can have any combination of these quirks: - Is little endian (bytes are reversed within a 32-bit group) - The least-significant 32-bit word comes first (within a 64-bit group) - The most significant bit of a byte is at its right (bit 0 of a register description is numerically 2^7). Drivers may use these helpers to match the bit indices as described in the data sheets of the peripherals they are in control of.

  When in doubt, say N.

config BITREVERSE tristate

config HAVE_ARCH_BITREVERSE bool default n depends on BITREVERSE help This option enables the use of hardware bit-reversal instructions on architectures which support such operations.

config ARCH_HAS_STRNCPY_FROM_USER bool

config ARCH_HAS_STRNLEN_USER bool

config GENERIC_STRNCPY_FROM_USER def_bool !ARCH_HAS_STRNCPY_FROM_USER

config GENERIC_STRNLEN_USER def_bool !ARCH_HAS_STRNLEN_USER

config GENERIC_NET_UTILS bool

config GENERIC_FIND_FIRST_BIT bool

source "lib/math/Kconfig"

config NO_GENERIC_PCI_IOPORT_MAP bool

config GENERIC_PCI_IOMAP bool

config GENERIC_IOMAP bool select GENERIC_PCI_IOMAP

config STMP_DEVICE bool

config ARCH_USE_CMPXCHG_LOCKREF bool

config ARCH_HAS_FAST_MULTIPLIER bool

config ARCH_USE_SYM_ANNOTATIONS bool

config INDIRECT_PIO bool "Access I/O in non-MMIO mode" depends on ARM64 help On some platforms where no separate I/O space exists, there are I/O hosts which can not be accessed in MMIO mode. Using the logical PIO mechanism, the host-local I/O resource can be mapped into system logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the system can access the I/O devices with the mapped-logic PIO through I/O accessors.

  This way has relatively little I/O performance cost. Please make
  sure your devices really need this configure item enabled.

  When in doubt, say N.

config INDIRECT_IOMEM bool help This is selected by other options/architectures to provide the emulated iomem accessors.

config INDIRECT_IOMEM_FALLBACK bool depends on INDIRECT_IOMEM help If INDIRECT_IOMEM is selected, this enables falling back to plain mmio accesses when the IO memory address is not a registered emulated region.

config CRC_CCITT tristate "CRC-CCITT functions" help This option is provided for the case where no in-kernel-tree modules require CRC-CCITT functions, but a module built outside the kernel tree does. Such modules that use library CRC-CCITT functions require M here.

config CRC16 tristate "CRC16 functions" help This option is provided for the case where no in-kernel-tree modules require CRC16 functions, but a module built outside the kernel tree does. Such modules that use library CRC16 functions require M here.

config CRC_T10DIF tristate "CRC calculation for the T10 Data Integrity Field" select CRYPTO select CRYPTO_CRCT10DIF help This option is only needed if a module that's not in the kernel tree needs to calculate CRC checks for use with the SCSI data integrity subsystem.

config CRC_ITU_T tristate "CRC ITU-T V.41 functions" help This option is provided for the case where no in-kernel-tree modules require CRC ITU-T V.41 functions, but a module built outside the kernel tree does. Such modules that use library CRC ITU-T V.41 functions require M here.

config CRC32 tristate "CRC32/CRC32c functions" default y select BITREVERSE help This option is provided for the case where no in-kernel-tree modules require CRC32/CRC32c functions, but a module built outside the kernel tree does. Such modules that use library CRC32/CRC32c functions require M here.

config CRC32_SELFTEST tristate "CRC32 perform self test on init" depends on CRC32 help This option enables the CRC32 library functions to perform a self test on initialization. The self test computes crc32_le and crc32_be over byte strings with random alignment and length and computes the total elapsed time and number of bytes processed.

choice prompt "CRC32 implementation" depends on CRC32 default CRC32_SLICEBY8 help This option allows a kernel builder to override the default choice of CRC32 algorithm. Choose the default ("slice by 8") unless you know that you need one of the others.

config CRC32_SLICEBY8 bool "Slice by 8 bytes" help Calculate checksum 8 bytes at a time with a clever slicing algorithm. This is the fastest algorithm, but comes with a 8KiB lookup table. Most modern processors have enough cache to hold this table without thrashing the cache.

  This is the default implementation choice.  Choose this one unless
  you have a good reason not to.

config CRC32_SLICEBY4 bool "Slice by 4 bytes" help Calculate checksum 4 bytes at a time with a clever slicing algorithm. This is a bit slower than slice by 8, but has a smaller 4KiB lookup table.

  Only choose this option if you know what you are doing.

config CRC32_SARWATE bool "Sarwate's Algorithm (one byte at a time)" help Calculate checksum a byte at a time using Sarwate's algorithm. This is not particularly fast, but has a small 256 byte lookup table.

  Only choose this option if you know what you are doing.

config CRC32_BIT bool "Classic Algorithm (one bit at a time)" help Calculate checksum one bit at a time. This is VERY slow, but has no lookup table. This is provided as a debugging option.

  Only choose this option if you are debugging crc32.

endchoice

config CRC64 tristate "CRC64 functions" help This option is provided for the case where no in-kernel-tree modules require CRC64 functions, but a module built outside the kernel tree does. Such modules that use library CRC64 functions require M here.

config CRC4 tristate "CRC4 functions" help This option is provided for the case where no in-kernel-tree modules require CRC4 functions, but a module built outside the kernel tree does. Such modules that use library CRC4 functions require M here.

config CRC7 tristate "CRC7 functions" help This option is provided for the case where no in-kernel-tree modules require CRC7 functions, but a module built outside the kernel tree does. Such modules that use library CRC7 functions require M here.

config LIBCRC32C tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check" select CRYPTO select CRYPTO_CRC32C help This option is provided for the case where no in-kernel-tree modules require CRC32c functions, but a module built outside the kernel tree does. Such modules that use library CRC32c functions require M here. See Castagnoli93. Module will be libcrc32c.

config CRC8 tristate "CRC8 function" help This option provides CRC8 function. Drivers may select this when they need to do cyclic redundancy check according CRC8 algorithm. Module will be called crc8.

config XXHASH tristate

config AUDIT_GENERIC bool depends on AUDIT && !AUDIT_ARCH default y

config AUDIT_ARCH_COMPAT_GENERIC bool default n

config AUDIT_COMPAT_GENERIC bool depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT default y

config RANDOM32_SELFTEST bool "PRNG perform self test on init" help This option enables the 32 bit PRNG library functions to perform a self test on initialization.

compression support is select'ed if needed

config 842_COMPRESS select CRC32 tristate

config 842_DECOMPRESS select CRC32 tristate

config ZLIB_INFLATE tristate

config ZLIB_DEFLATE tristate select BITREVERSE

config ZLIB_DFLTCC def_bool y depends on S390 prompt "Enable s390x DEFLATE CONVERSION CALL support for kernel zlib" help Enable s390x hardware support for zlib in the kernel.

config LZO_COMPRESS tristate

config LZO_DECOMPRESS tristate

config LZ4_COMPRESS tristate

config LZ4HC_COMPRESS tristate

config LZ4_DECOMPRESS tristate

config ZSTD_COMPRESS select XXHASH tristate

config ZSTD_DECOMPRESS select XXHASH tristate

source "lib/xz/Kconfig"

These all provide a common interface (hence the apparent duplication with

ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)

config DECOMPRESS_GZIP select ZLIB_INFLATE tristate

config DECOMPRESS_BZIP2 tristate

config DECOMPRESS_LZMA tristate

config DECOMPRESS_XZ select XZ_DEC tristate

config DECOMPRESS_LZO select LZO_DECOMPRESS tristate

config DECOMPRESS_LZ4 select LZ4_DECOMPRESS tristate

config DECOMPRESS_ZSTD select ZSTD_DECOMPRESS tristate

Generic allocator support is selected if needed

config GENERIC_ALLOCATOR bool

reed solomon support is select'ed if needed

config REED_SOLOMON tristate

config REED_SOLOMON_ENC8 bool

config REED_SOLOMON_DEC8 bool

config REED_SOLOMON_ENC16 bool

config REED_SOLOMON_DEC16 bool

BCH support is selected if needed

config BCH tristate

config BCH_CONST_PARAMS bool help Drivers may select this option to force specific constant values for parameters 'm' (Galois field order) and 't' (error correction capability). Those specific values must be set by declaring default values for symbols BCH_CONST_M and BCH_CONST_T. Doing so will enable extra compiler optimizations, improving encoding and decoding performance up to 2x for usual (m,t) values (typically such that m*t < 200). When this option is selected, the BCH library supports only a single (m,t) configuration. This is mainly useful for NAND flash board drivers requiring known, fixed BCH parameters.

config BCH_CONST_M int range 5 15 help Constant value for Galois field order 'm'. If 'k' is the number of data bits to protect, 'm' should be chosen such that (k + m*t) <= 2**m - 1. Drivers should declare a default value for this symbol if they select option BCH_CONST_PARAMS.

config BCH_CONST_T int help Constant value for error correction capability in bits 't'. Drivers should declare a default value for this symbol if they select option BCH_CONST_PARAMS.

Textsearch support is select'ed if needed

config TEXTSEARCH bool

config TEXTSEARCH_KMP tristate

config TEXTSEARCH_BM tristate

config TEXTSEARCH_FSM tristate

config BTREE bool

config INTERVAL_TREE bool help Simple, embeddable, interval-tree. Can find the start of an overlapping range in log(n) time and then iterate over all overlapping nodes. The algorithm is implemented as an augmented rbtree.

  See:

	Documentation/core-api/rbtree.rst

  for more information.

config XARRAY_MULTI bool help Support entries which occupy multiple consecutive indices in the XArray.

config ASSOCIATIVE_ARRAY bool help Generic associative array. Can be searched and iterated over whilst it is being modified. It is also reasonably quick to search and modify. The algorithms are non-recursive, and the trees are highly capacious.

  See:

	Documentation/core-api/assoc_array.rst

  for more information.

config HAS_IOMEM bool depends on !NO_IOMEM default y

config HAS_IOPORT_MAP bool depends on HAS_IOMEM && !NO_IOPORT_MAP default y

source "kernel/dma/Kconfig"

config SGL_ALLOC bool default n

config IOMMU_HELPER bool

config CHECK_SIGNATURE bool

config CPUMASK_OFFSTACK bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS help Use dynamic allocation for cpumask_var_t, instead of putting them on the stack. This is a bit more expensive, but avoids stack overflow.

config CPU_RMAP bool depends on SMP

config DQL bool

config GLOB bool

This actually supports modular compilation, but the module overhead

is ridiculous for the amount of code involved. Until an out-of-tree

driver asks for it, we'll just link it directly it into the kernel

when required. Since we're ignoring out-of-tree users, there's also

no need bother prompting for a manual decision:

prompt "glob_match() function"

help
  This option provides a glob_match function for performing
  simple text pattern matching.  It originated in the ATA code
  to blacklist particular drive models, but other device drivers
  may need similar functionality.

  All drivers in the Linux kernel tree that require this function
  should automatically select this option.  Say N unless you
  are compiling an out-of tree driver which tells you that it
  depends on this.

config GLOB_SELFTEST tristate "glob self-test on init" depends on GLOB help This option enables a simple self-test of the glob_match function on startup. It is primarily useful for people working on the code to ensure they haven't introduced any regressions.

  It only adds a little bit of code and slows kernel boot (or
  module load) by a small amount, so you're welcome to play with
  it, but you probably don't need it.

Netlink attribute parsing support is select'ed if needed

config NLATTR bool

Generic 64-bit atomic support is selected if needed

config GENERIC_ATOMIC64 bool

config LRU_CACHE tristate

config CLZ_TAB bool

config IRQ_POLL bool "IRQ polling library" help Helper library to poll interrupt mitigation using polling.

config MPILIB tristate select CLZ_TAB help Multiprecision maths library from GnuPG. It is used to implement RSA digital signature verification, which is used by IMA/EVM digital signature extension.

config SIGNATURE tristate depends on KEYS select CRYPTO select CRYPTO_SHA1 select MPILIB help Digital signature verification. Currently only RSA is supported. Implementation is done using GnuPG MPI library

config DIMLIB bool help Dynamic Interrupt Moderation library. Implements an algorithm for dynamically changing CQ moderation values according to run time performance.

libfdt files, only selected if needed.

config LIBFDT bool

config OID_REGISTRY tristate help Enable fast lookup object identifier registry.

config UCS2_STRING tristate

generic vdso

source "lib/vdso/Kconfig"

source "lib/fonts/Kconfig"

config SG_SPLIT def_bool n help Provides a helper to split scatterlists into chunks, each chunk being a scatterlist. This should be selected by a driver or an API which whishes to split a scatterlist amongst multiple DMA channels.

config SG_POOL def_bool n help Provides a helper to allocate chained scatterlists. This should be selected by a driver or an API which whishes to allocate chained scatterlist.

sg chaining option

config ARCH_NO_SG_CHAIN def_bool n

config ARCH_HAS_PMEM_API bool

config MEMREGION bool

config ARCH_HAS_MEMREMAP_COMPAT_ALIGN bool

use memcpy to implement user copies for nommu architectures

config UACCESS_MEMCPY bool

config ARCH_HAS_UACCESS_FLUSHCACHE bool

arch has a concept of a recoverable synchronous exception due to a

memory-read error like x86 machine-check or ARM data-abort, and

implements copy_mc_to_{user,kernel} to abort and report

'bytes-transferred' if that exception fires when accessing the source

buffer.

config ARCH_HAS_COPY_MC bool

Temporary. Goes away when all archs are cleaned up

config ARCH_STACKWALK bool

config STACKDEPOT bool select STACKTRACE

config STACK_HASH_ORDER int "stack depot hash size (12 => 4KB, 20 => 1024KB)" range 12 20 default 20 depends on STACKDEPOT help Select the hash size as a power of 2 for the stackdepot hash table. Choose a lower value to reduce the memory impact.

config SBITMAP bool

config PARMAN tristate "parman" if COMPILE_TEST

config OBJAGG tristate "objagg" if COMPILE_TEST

endmenu

config GENERIC_IOREMAP bool

config GENERIC_LIB_ASHLDI3 bool

config GENERIC_LIB_ASHRDI3 bool

config GENERIC_LIB_LSHRDI3 bool

config GENERIC_LIB_MULDI3 bool

config GENERIC_LIB_CMPDI2 bool

config GENERIC_LIB_UCMPDI2 bool

config GENERIC_LIB_DEVMEM_IS_ALLOWED bool

config PLDMFW bool default n

config ASN1_ENCODER tristate