1 # SPDX-License-Identifier: GPL-2.0-only
3 # Library configuration
9 menu "Library routines"
14 config RAID6_PQ_BENCHMARK
15 bool "Automatically choose fastest RAID6 PQ functions"
19 Benchmark all available RAID6 PQ functions on init and choose the
26 bool "Generic bitfield packing and unpacking"
29 This option provides the packing() helper function, which permits
30 converting bitfields between a CPU-usable representation and a
31 memory representation that can have any combination of these quirks:
32 - Is little endian (bytes are reversed within a 32-bit group)
33 - The least-significant 32-bit word comes first (within a 64-bit
35 - The most significant bit of a byte is at its right (bit 0 of a
36 register description is numerically 2^7).
37 Drivers may use these helpers to match the bit indices as described
38 in the data sheets of the peripherals they are in control of.
45 config HAVE_ARCH_BITREVERSE
50 This option enables the use of hardware bit-reversal instructions on
51 architectures which support such operations.
53 config ARCH_HAS_STRNCPY_FROM_USER
56 config ARCH_HAS_STRNLEN_USER
59 config GENERIC_STRNCPY_FROM_USER
60 def_bool !ARCH_HAS_STRNCPY_FROM_USER
62 config GENERIC_STRNLEN_USER
63 def_bool !ARCH_HAS_STRNLEN_USER
65 config GENERIC_NET_UTILS
68 config GENERIC_FIND_FIRST_BIT
71 source "lib/math/Kconfig"
73 config NO_GENERIC_PCI_IOPORT_MAP
76 config GENERIC_PCI_IOMAP
81 select GENERIC_PCI_IOMAP
86 config ARCH_USE_CMPXCHG_LOCKREF
89 config ARCH_HAS_FAST_MULTIPLIER
92 config ARCH_USE_SYM_ANNOTATIONS
96 bool "Access I/O in non-MMIO mode"
99 On some platforms where no separate I/O space exists, there are I/O
100 hosts which can not be accessed in MMIO mode. Using the logical PIO
101 mechanism, the host-local I/O resource can be mapped into system
102 logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the
103 system can access the I/O devices with the mapped-logic PIO through
106 This way has relatively little I/O performance cost. Please make
107 sure your devices really need this configure item enabled.
109 When in doubt, say N.
111 config INDIRECT_IOMEM
114 This is selected by other options/architectures to provide the
115 emulated iomem accessors.
117 config INDIRECT_IOMEM_FALLBACK
119 depends on INDIRECT_IOMEM
121 If INDIRECT_IOMEM is selected, this enables falling back to plain
122 mmio accesses when the IO memory address is not a registered
125 source "lib/crypto/Kconfig"
128 tristate "CRC-CCITT functions"
130 This option is provided for the case where no in-kernel-tree
131 modules require CRC-CCITT functions, but a module built outside
132 the kernel tree does. Such modules that use library CRC-CCITT
133 functions require M here.
136 tristate "CRC16 functions"
138 This option is provided for the case where no in-kernel-tree
139 modules require CRC16 functions, but a module built outside
140 the kernel tree does. Such modules that use library CRC16
141 functions require M here.
144 tristate "CRC calculation for the T10 Data Integrity Field"
146 select CRYPTO_CRCT10DIF
148 This option is only needed if a module that's not in the
149 kernel tree needs to calculate CRC checks for use with the
150 SCSI data integrity subsystem.
153 tristate "CRC ITU-T V.41 functions"
155 This option is provided for the case where no in-kernel-tree
156 modules require CRC ITU-T V.41 functions, but a module built outside
157 the kernel tree does. Such modules that use library CRC ITU-T V.41
158 functions require M here.
161 tristate "CRC32/CRC32c functions"
165 This option is provided for the case where no in-kernel-tree
166 modules require CRC32/CRC32c functions, but a module built outside
167 the kernel tree does. Such modules that use library CRC32/CRC32c
168 functions require M here.
170 config CRC32_SELFTEST
171 tristate "CRC32 perform self test on init"
174 This option enables the CRC32 library functions to perform a
175 self test on initialization. The self test computes crc32_le
176 and crc32_be over byte strings with random alignment and length
177 and computes the total elapsed time and number of bytes processed.
180 prompt "CRC32 implementation"
182 default CRC32_SLICEBY8
184 This option allows a kernel builder to override the default choice
185 of CRC32 algorithm. Choose the default ("slice by 8") unless you
186 know that you need one of the others.
188 config CRC32_SLICEBY8
189 bool "Slice by 8 bytes"
191 Calculate checksum 8 bytes at a time with a clever slicing algorithm.
192 This is the fastest algorithm, but comes with a 8KiB lookup table.
193 Most modern processors have enough cache to hold this table without
196 This is the default implementation choice. Choose this one unless
197 you have a good reason not to.
199 config CRC32_SLICEBY4
200 bool "Slice by 4 bytes"
202 Calculate checksum 4 bytes at a time with a clever slicing algorithm.
203 This is a bit slower than slice by 8, but has a smaller 4KiB lookup
206 Only choose this option if you know what you are doing.
209 bool "Sarwate's Algorithm (one byte at a time)"
211 Calculate checksum a byte at a time using Sarwate's algorithm. This
212 is not particularly fast, but has a small 256 byte lookup table.
214 Only choose this option if you know what you are doing.
217 bool "Classic Algorithm (one bit at a time)"
219 Calculate checksum one bit at a time. This is VERY slow, but has
220 no lookup table. This is provided as a debugging option.
222 Only choose this option if you are debugging crc32.
227 tristate "CRC64 functions"
229 This option is provided for the case where no in-kernel-tree
230 modules require CRC64 functions, but a module built outside
231 the kernel tree does. Such modules that use library CRC64
232 functions require M here.
235 tristate "CRC4 functions"
237 This option is provided for the case where no in-kernel-tree
238 modules require CRC4 functions, but a module built outside
239 the kernel tree does. Such modules that use library CRC4
240 functions require M here.
243 tristate "CRC7 functions"
245 This option is provided for the case where no in-kernel-tree
246 modules require CRC7 functions, but a module built outside
247 the kernel tree does. Such modules that use library CRC7
248 functions require M here.
251 tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
255 This option is provided for the case where no in-kernel-tree
256 modules require CRC32c functions, but a module built outside the
257 kernel tree does. Such modules that use library CRC32c functions
258 require M here. See Castagnoli93.
259 Module will be libcrc32c.
262 tristate "CRC8 function"
264 This option provides CRC8 function. Drivers may select this
265 when they need to do cyclic redundancy check according CRC8
266 algorithm. Module will be called crc8.
273 depends on AUDIT && !AUDIT_ARCH
276 config AUDIT_ARCH_COMPAT_GENERIC
280 config AUDIT_COMPAT_GENERIC
282 depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
285 config RANDOM32_SELFTEST
286 bool "PRNG perform self test on init"
288 This option enables the 32 bit PRNG library functions to perform a
289 self test on initialization.
292 # compression support is select'ed if needed
298 config 842_DECOMPRESS
312 prompt "Enable s390x DEFLATE CONVERSION CALL support for kernel zlib"
314 Enable s390x hardware support for zlib in the kernel.
319 config LZO_DECOMPRESS
325 config LZ4HC_COMPRESS
328 config LZ4_DECOMPRESS
335 config ZSTD_DECOMPRESS
339 source "lib/xz/Kconfig"
342 # These all provide a common interface (hence the apparent duplication with
343 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
345 config DECOMPRESS_GZIP
349 config DECOMPRESS_BZIP2
352 config DECOMPRESS_LZMA
359 config DECOMPRESS_LZO
360 select LZO_DECOMPRESS
363 config DECOMPRESS_LZ4
364 select LZ4_DECOMPRESS
367 config DECOMPRESS_ZSTD
368 select ZSTD_DECOMPRESS
372 # Generic allocator support is selected if needed
374 config GENERIC_ALLOCATOR
378 # reed solomon support is select'ed if needed
383 config REED_SOLOMON_ENC8
386 config REED_SOLOMON_DEC8
389 config REED_SOLOMON_ENC16
392 config REED_SOLOMON_DEC16
396 # BCH support is selected if needed
401 config BCH_CONST_PARAMS
404 Drivers may select this option to force specific constant
405 values for parameters 'm' (Galois field order) and 't'
406 (error correction capability). Those specific values must
407 be set by declaring default values for symbols BCH_CONST_M
409 Doing so will enable extra compiler optimizations,
410 improving encoding and decoding performance up to 2x for
411 usual (m,t) values (typically such that m*t < 200).
412 When this option is selected, the BCH library supports
413 only a single (m,t) configuration. This is mainly useful
414 for NAND flash board drivers requiring known, fixed BCH
421 Constant value for Galois field order 'm'. If 'k' is the
422 number of data bits to protect, 'm' should be chosen such
423 that (k + m*t) <= 2**m - 1.
424 Drivers should declare a default value for this symbol if
425 they select option BCH_CONST_PARAMS.
430 Constant value for error correction capability in bits 't'.
431 Drivers should declare a default value for this symbol if
432 they select option BCH_CONST_PARAMS.
435 # Textsearch support is select'ed if needed
440 config TEXTSEARCH_KMP
446 config TEXTSEARCH_FSM
455 Simple, embeddable, interval-tree. Can find the start of an
456 overlapping range in log(n) time and then iterate over all
457 overlapping nodes. The algorithm is implemented as an
462 Documentation/core-api/rbtree.rst
464 for more information.
469 Support entries which occupy multiple consecutive indices in the
472 config ASSOCIATIVE_ARRAY
475 Generic associative array. Can be searched and iterated over whilst
476 it is being modified. It is also reasonably quick to search and
477 modify. The algorithms are non-recursive, and the trees are highly
482 Documentation/core-api/assoc_array.rst
484 for more information.
491 config HAS_IOPORT_MAP
493 depends on HAS_IOMEM && !NO_IOPORT_MAP
496 source "kernel/dma/Kconfig"
505 config CHECK_SIGNATURE
508 config CPUMASK_OFFSTACK
509 bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
511 Use dynamic allocation for cpumask_var_t, instead of putting
512 them on the stack. This is a bit more expensive, but avoids
524 # This actually supports modular compilation, but the module overhead
525 # is ridiculous for the amount of code involved. Until an out-of-tree
526 # driver asks for it, we'll just link it directly it into the kernel
527 # when required. Since we're ignoring out-of-tree users, there's also
528 # no need bother prompting for a manual decision:
529 # prompt "glob_match() function"
531 This option provides a glob_match function for performing
532 simple text pattern matching. It originated in the ATA code
533 to blacklist particular drive models, but other device drivers
534 may need similar functionality.
536 All drivers in the Linux kernel tree that require this function
537 should automatically select this option. Say N unless you
538 are compiling an out-of tree driver which tells you that it
542 tristate "glob self-test on init"
545 This option enables a simple self-test of the glob_match
546 function on startup. It is primarily useful for people
547 working on the code to ensure they haven't introduced any
550 It only adds a little bit of code and slows kernel boot (or
551 module load) by a small amount, so you're welcome to play with
552 it, but you probably don't need it.
555 # Netlink attribute parsing support is select'ed if needed
561 # Generic 64-bit atomic support is selected if needed
563 config GENERIC_ATOMIC64
573 bool "IRQ polling library"
575 Helper library to poll interrupt mitigation using polling.
581 Multiprecision maths library from GnuPG.
582 It is used to implement RSA digital signature verification,
583 which is used by IMA/EVM digital signature extension.
592 Digital signature verification. Currently only RSA is supported.
593 Implementation is done using GnuPG MPI library
598 Dynamic Interrupt Moderation library.
599 Implements an algorithm for dynamically changing CQ moderation values
600 according to run time performance.
603 # libfdt files, only selected if needed.
611 Enable fast lookup object identifier registry.
619 source "lib/vdso/Kconfig"
621 source "lib/fonts/Kconfig"
626 Provides a helper to split scatterlists into chunks, each chunk being
627 a scatterlist. This should be selected by a driver or an API which
628 whishes to split a scatterlist amongst multiple DMA channels.
633 Provides a helper to allocate chained scatterlists. This should be
634 selected by a driver or an API which whishes to allocate chained
641 config ARCH_NO_SG_CHAIN
644 config ARCH_HAS_PMEM_API
650 config ARCH_HAS_MEMREMAP_COMPAT_ALIGN
653 # use memcpy to implement user copies for nommu architectures
654 config UACCESS_MEMCPY
657 config ARCH_HAS_UACCESS_FLUSHCACHE
660 # arch has a concept of a recoverable synchronous exception due to a
661 # memory-read error like x86 machine-check or ARM data-abort, and
662 # implements copy_mc_to_{user,kernel} to abort and report
663 # 'bytes-transferred' if that exception fires when accessing the source
665 config ARCH_HAS_COPY_MC
668 # Temporary. Goes away when all archs are cleaned up
669 config ARCH_STACKWALK
676 config STACK_HASH_ORDER
677 int "stack depot hash size (12 => 4KB, 20 => 1024KB)"
680 depends on STACKDEPOT
682 Select the hash size as a power of 2 for the stackdepot hash table.
683 Choose a lower value to reduce the memory impact.
687 depends on STACKTRACE_SUPPORT
694 tristate "parman" if COMPILE_TEST
697 tristate "objagg" if COMPILE_TEST
701 config GENERIC_IOREMAP
704 config GENERIC_LIB_ASHLDI3
707 config GENERIC_LIB_ASHRDI3
710 config GENERIC_LIB_LSHRDI3
713 config GENERIC_LIB_MULDI3
716 config GENERIC_LIB_CMPDI2
719 config GENERIC_LIB_UCMPDI2
722 config GENERIC_LIB_DEVMEM_IS_ALLOWED