2 # Library configuration
8 menu "Library routines"
16 config HAVE_ARCH_BITREVERSE
21 This option enables the use of hardware bit-reversal instructions on
22 architectures which support such operations.
27 config GENERIC_STRNCPY_FROM_USER
30 config GENERIC_STRNLEN_USER
33 config GENERIC_NET_UTILS
36 config GENERIC_FIND_FIRST_BIT
39 config NO_GENERIC_PCI_IOPORT_MAP
42 config GENERIC_PCI_IOMAP
47 select GENERIC_PCI_IOMAP
52 config ARCH_USE_CMPXCHG_LOCKREF
55 config ARCH_HAS_FAST_MULTIPLIER
59 bool "Access I/O in non-MMIO mode"
62 On some platforms where no separate I/O space exists, there are I/O
63 hosts which can not be accessed in MMIO mode. Using the logical PIO
64 mechanism, the host-local I/O resource can be mapped into system
65 logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the
66 system can access the I/O devices with the mapped-logic PIO through
69 This way has relatively little I/O performance cost. Please make
70 sure your devices really need this configure item enabled.
75 tristate "CRC-CCITT functions"
77 This option is provided for the case where no in-kernel-tree
78 modules require CRC-CCITT functions, but a module built outside
79 the kernel tree does. Such modules that use library CRC-CCITT
80 functions require M here.
83 tristate "CRC16 functions"
85 This option is provided for the case where no in-kernel-tree
86 modules require CRC16 functions, but a module built outside
87 the kernel tree does. Such modules that use library CRC16
88 functions require M here.
91 tristate "CRC calculation for the T10 Data Integrity Field"
93 select CRYPTO_CRCT10DIF
95 This option is only needed if a module that's not in the
96 kernel tree needs to calculate CRC checks for use with the
97 SCSI data integrity subsystem.
100 tristate "CRC ITU-T V.41 functions"
102 This option is provided for the case where no in-kernel-tree
103 modules require CRC ITU-T V.41 functions, but a module built outside
104 the kernel tree does. Such modules that use library CRC ITU-T V.41
105 functions require M here.
108 tristate "CRC32/CRC32c functions"
112 This option is provided for the case where no in-kernel-tree
113 modules require CRC32/CRC32c functions, but a module built outside
114 the kernel tree does. Such modules that use library CRC32/CRC32c
115 functions require M here.
117 config CRC32_SELFTEST
118 tristate "CRC32 perform self test on init"
121 This option enables the CRC32 library functions to perform a
122 self test on initialization. The self test computes crc32_le
123 and crc32_be over byte strings with random alignment and length
124 and computes the total elapsed time and number of bytes processed.
127 prompt "CRC32 implementation"
129 default CRC32_SLICEBY8
131 This option allows a kernel builder to override the default choice
132 of CRC32 algorithm. Choose the default ("slice by 8") unless you
133 know that you need one of the others.
135 config CRC32_SLICEBY8
136 bool "Slice by 8 bytes"
138 Calculate checksum 8 bytes at a time with a clever slicing algorithm.
139 This is the fastest algorithm, but comes with a 8KiB lookup table.
140 Most modern processors have enough cache to hold this table without
143 This is the default implementation choice. Choose this one unless
144 you have a good reason not to.
146 config CRC32_SLICEBY4
147 bool "Slice by 4 bytes"
149 Calculate checksum 4 bytes at a time with a clever slicing algorithm.
150 This is a bit slower than slice by 8, but has a smaller 4KiB lookup
153 Only choose this option if you know what you are doing.
156 bool "Sarwate's Algorithm (one byte at a time)"
158 Calculate checksum a byte at a time using Sarwate's algorithm. This
159 is not particularly fast, but has a small 256 byte lookup table.
161 Only choose this option if you know what you are doing.
164 bool "Classic Algorithm (one bit at a time)"
166 Calculate checksum one bit at a time. This is VERY slow, but has
167 no lookup table. This is provided as a debugging option.
169 Only choose this option if you are debugging crc32.
174 tristate "CRC64 functions"
176 This option is provided for the case where no in-kernel-tree
177 modules require CRC64 functions, but a module built outside
178 the kernel tree does. Such modules that use library CRC64
179 functions require M here.
182 tristate "CRC4 functions"
184 This option is provided for the case where no in-kernel-tree
185 modules require CRC4 functions, but a module built outside
186 the kernel tree does. Such modules that use library CRC4
187 functions require M here.
190 tristate "CRC7 functions"
192 This option is provided for the case where no in-kernel-tree
193 modules require CRC7 functions, but a module built outside
194 the kernel tree does. Such modules that use library CRC7
195 functions require M here.
198 tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
202 This option is provided for the case where no in-kernel-tree
203 modules require CRC32c functions, but a module built outside the
204 kernel tree does. Such modules that use library CRC32c functions
205 require M here. See Castagnoli93.
206 Module will be libcrc32c.
209 tristate "CRC8 function"
211 This option provides CRC8 function. Drivers may select this
212 when they need to do cyclic redundancy check according CRC8
213 algorithm. Module will be called crc8.
220 depends on AUDIT && !AUDIT_ARCH
223 config AUDIT_ARCH_COMPAT_GENERIC
227 config AUDIT_COMPAT_GENERIC
229 depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
232 config RANDOM32_SELFTEST
233 bool "PRNG perform self test on init"
235 This option enables the 32 bit PRNG library functions to perform a
236 self test on initialization.
239 # compression support is select'ed if needed
245 config 842_DECOMPRESS
259 config LZO_DECOMPRESS
265 config LZ4HC_COMPRESS
268 config LZ4_DECOMPRESS
275 config ZSTD_DECOMPRESS
279 source "lib/xz/Kconfig"
282 # These all provide a common interface (hence the apparent duplication with
283 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
285 config DECOMPRESS_GZIP
289 config DECOMPRESS_BZIP2
292 config DECOMPRESS_LZMA
299 config DECOMPRESS_LZO
300 select LZO_DECOMPRESS
303 config DECOMPRESS_LZ4
304 select LZ4_DECOMPRESS
308 # Generic allocator support is selected if needed
310 config GENERIC_ALLOCATOR
314 # reed solomon support is select'ed if needed
319 config REED_SOLOMON_ENC8
322 config REED_SOLOMON_DEC8
325 config REED_SOLOMON_ENC16
328 config REED_SOLOMON_DEC16
332 # BCH support is selected if needed
337 config BCH_CONST_PARAMS
340 Drivers may select this option to force specific constant
341 values for parameters 'm' (Galois field order) and 't'
342 (error correction capability). Those specific values must
343 be set by declaring default values for symbols BCH_CONST_M
345 Doing so will enable extra compiler optimizations,
346 improving encoding and decoding performance up to 2x for
347 usual (m,t) values (typically such that m*t < 200).
348 When this option is selected, the BCH library supports
349 only a single (m,t) configuration. This is mainly useful
350 for NAND flash board drivers requiring known, fixed BCH
357 Constant value for Galois field order 'm'. If 'k' is the
358 number of data bits to protect, 'm' should be chosen such
359 that (k + m*t) <= 2**m - 1.
360 Drivers should declare a default value for this symbol if
361 they select option BCH_CONST_PARAMS.
366 Constant value for error correction capability in bits 't'.
367 Drivers should declare a default value for this symbol if
368 they select option BCH_CONST_PARAMS.
371 # Textsearch support is select'ed if needed
376 config TEXTSEARCH_KMP
382 config TEXTSEARCH_FSM
391 Simple, embeddable, interval-tree. Can find the start of an
392 overlapping range in log(n) time and then iterate over all
393 overlapping nodes. The algorithm is implemented as an
398 Documentation/rbtree.txt
400 for more information.
405 Support entries which occupy multiple consecutive indices in the
408 config ASSOCIATIVE_ARRAY
411 Generic associative array. Can be searched and iterated over whilst
412 it is being modified. It is also reasonably quick to search and
413 modify. The algorithms are non-recursive, and the trees are highly
418 Documentation/core-api/assoc_array.rst
420 for more information.
428 config HAS_IOPORT_MAP
430 depends on HAS_IOMEM && !NO_IOPORT_MAP
433 source "kernel/dma/Kconfig"
442 config CHECK_SIGNATURE
445 config CPUMASK_OFFSTACK
446 bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
448 Use dynamic allocation for cpumask_var_t, instead of putting
449 them on the stack. This is a bit more expensive, but avoids
461 # This actually supports modular compilation, but the module overhead
462 # is ridiculous for the amount of code involved. Until an out-of-tree
463 # driver asks for it, we'll just link it directly it into the kernel
464 # when required. Since we're ignoring out-of-tree users, there's also
465 # no need bother prompting for a manual decision:
466 # prompt "glob_match() function"
468 This option provides a glob_match function for performing
469 simple text pattern matching. It originated in the ATA code
470 to blacklist particular drive models, but other device drivers
471 may need similar functionality.
473 All drivers in the Linux kernel tree that require this function
474 should automatically select this option. Say N unless you
475 are compiling an out-of tree driver which tells you that it
479 tristate "glob self-test on init"
482 This option enables a simple self-test of the glob_match
483 function on startup. It is primarily useful for people
484 working on the code to ensure they haven't introduced any
487 It only adds a little bit of code and slows kernel boot (or
488 module load) by a small amount, so you're welcome to play with
489 it, but you probably don't need it.
492 # Netlink attribute parsing support is select'ed if needed
498 # Generic 64-bit atomic support is selected if needed
500 config GENERIC_ATOMIC64
510 tristate "CORDIC algorithm"
512 This option provides an implementation of the CORDIC algorithm;
513 calculations are in fixed point. Module will be called cordic.
516 bool "JEDEC DDR data"
518 Data from JEDEC specs for DDR SDRAM memories,
519 particularly the AC timing parameters and addressing
520 information. This data is useful for drivers handling
521 DDR SDRAM controllers.
524 bool "IRQ polling library"
526 Helper library to poll interrupt mitigation using polling.
532 Multiprecision maths library from GnuPG.
533 It is used to implement RSA digital signature verification,
534 which is used by IMA/EVM digital signature extension.
543 Digital signature verification. Currently only RSA is supported.
544 Implementation is done using GnuPG MPI library
547 # libfdt files, only selected if needed.
555 Enable fast lookup object identifier registry.
560 source "lib/fonts/Kconfig"
565 Provides a helper to split scatterlists into chunks, each chunk being
566 a scatterlist. This should be selected by a driver or an API which
567 whishes to split a scatterlist amongst multiple DMA channels.
572 Provides a helper to allocate chained scatterlists. This should be
573 selected by a driver or an API which whishes to allocate chained
580 config ARCH_NO_SG_CHAIN
583 config ARCH_HAS_PMEM_API
586 config ARCH_HAS_UACCESS_FLUSHCACHE
589 config ARCH_HAS_UACCESS_MCSAFE
600 tristate "parman" if COMPILE_TEST
605 config STRING_SELFTEST
606 tristate "Test string functions"
610 config GENERIC_LIB_ASHLDI3
613 config GENERIC_LIB_ASHRDI3
616 config GENERIC_LIB_LSHRDI3
619 config GENERIC_LIB_MULDI3
622 config GENERIC_LIB_CMPDI2
625 config GENERIC_LIB_UCMPDI2