2 # Library configuration
8 menu "Library routines"
13 config RAID6_PQ_BENCHMARK
14 bool "Automatically choose fastest RAID6 PQ functions"
18 Benchmark all available RAID6 PQ functions on init and choose the
22 bool "Generic bitfield packing and unpacking"
25 This option provides the packing() helper function, which permits
26 converting bitfields between a CPU-usable representation and a
27 memory representation that can have any combination of these quirks:
28 - Is little endian (bytes are reversed within a 32-bit group)
29 - The least-significant 32-bit word comes first (within a 64-bit
31 - The most significant bit of a byte is at its right (bit 0 of a
32 register description is numerically 2^7).
33 Drivers may use these helpers to match the bit indices as described
34 in the data sheets of the peripherals they are in control of.
41 config HAVE_ARCH_BITREVERSE
46 This option enables the use of hardware bit-reversal instructions on
47 architectures which support such operations.
52 config GENERIC_STRNCPY_FROM_USER
55 config GENERIC_STRNLEN_USER
58 config GENERIC_NET_UTILS
61 config GENERIC_FIND_FIRST_BIT
64 config NO_GENERIC_PCI_IOPORT_MAP
67 config GENERIC_PCI_IOMAP
72 select GENERIC_PCI_IOMAP
77 config ARCH_USE_CMPXCHG_LOCKREF
80 config ARCH_HAS_FAST_MULTIPLIER
84 bool "Access I/O in non-MMIO mode"
87 On some platforms where no separate I/O space exists, there are I/O
88 hosts which can not be accessed in MMIO mode. Using the logical PIO
89 mechanism, the host-local I/O resource can be mapped into system
90 logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the
91 system can access the I/O devices with the mapped-logic PIO through
94 This way has relatively little I/O performance cost. Please make
95 sure your devices really need this configure item enabled.
100 tristate "CRC-CCITT functions"
102 This option is provided for the case where no in-kernel-tree
103 modules require CRC-CCITT functions, but a module built outside
104 the kernel tree does. Such modules that use library CRC-CCITT
105 functions require M here.
108 tristate "CRC16 functions"
110 This option is provided for the case where no in-kernel-tree
111 modules require CRC16 functions, but a module built outside
112 the kernel tree does. Such modules that use library CRC16
113 functions require M here.
116 tristate "CRC calculation for the T10 Data Integrity Field"
118 select CRYPTO_CRCT10DIF
120 This option is only needed if a module that's not in the
121 kernel tree needs to calculate CRC checks for use with the
122 SCSI data integrity subsystem.
125 tristate "CRC ITU-T V.41 functions"
127 This option is provided for the case where no in-kernel-tree
128 modules require CRC ITU-T V.41 functions, but a module built outside
129 the kernel tree does. Such modules that use library CRC ITU-T V.41
130 functions require M here.
133 tristate "CRC32/CRC32c functions"
137 This option is provided for the case where no in-kernel-tree
138 modules require CRC32/CRC32c functions, but a module built outside
139 the kernel tree does. Such modules that use library CRC32/CRC32c
140 functions require M here.
142 config CRC32_SELFTEST
143 tristate "CRC32 perform self test on init"
146 This option enables the CRC32 library functions to perform a
147 self test on initialization. The self test computes crc32_le
148 and crc32_be over byte strings with random alignment and length
149 and computes the total elapsed time and number of bytes processed.
152 prompt "CRC32 implementation"
154 default CRC32_SLICEBY8
156 This option allows a kernel builder to override the default choice
157 of CRC32 algorithm. Choose the default ("slice by 8") unless you
158 know that you need one of the others.
160 config CRC32_SLICEBY8
161 bool "Slice by 8 bytes"
163 Calculate checksum 8 bytes at a time with a clever slicing algorithm.
164 This is the fastest algorithm, but comes with a 8KiB lookup table.
165 Most modern processors have enough cache to hold this table without
168 This is the default implementation choice. Choose this one unless
169 you have a good reason not to.
171 config CRC32_SLICEBY4
172 bool "Slice by 4 bytes"
174 Calculate checksum 4 bytes at a time with a clever slicing algorithm.
175 This is a bit slower than slice by 8, but has a smaller 4KiB lookup
178 Only choose this option if you know what you are doing.
181 bool "Sarwate's Algorithm (one byte at a time)"
183 Calculate checksum a byte at a time using Sarwate's algorithm. This
184 is not particularly fast, but has a small 256 byte lookup table.
186 Only choose this option if you know what you are doing.
189 bool "Classic Algorithm (one bit at a time)"
191 Calculate checksum one bit at a time. This is VERY slow, but has
192 no lookup table. This is provided as a debugging option.
194 Only choose this option if you are debugging crc32.
199 tristate "CRC64 functions"
201 This option is provided for the case where no in-kernel-tree
202 modules require CRC64 functions, but a module built outside
203 the kernel tree does. Such modules that use library CRC64
204 functions require M here.
207 tristate "CRC4 functions"
209 This option is provided for the case where no in-kernel-tree
210 modules require CRC4 functions, but a module built outside
211 the kernel tree does. Such modules that use library CRC4
212 functions require M here.
215 tristate "CRC7 functions"
217 This option is provided for the case where no in-kernel-tree
218 modules require CRC7 functions, but a module built outside
219 the kernel tree does. Such modules that use library CRC7
220 functions require M here.
223 tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
227 This option is provided for the case where no in-kernel-tree
228 modules require CRC32c functions, but a module built outside the
229 kernel tree does. Such modules that use library CRC32c functions
230 require M here. See Castagnoli93.
231 Module will be libcrc32c.
234 tristate "CRC8 function"
236 This option provides CRC8 function. Drivers may select this
237 when they need to do cyclic redundancy check according CRC8
238 algorithm. Module will be called crc8.
245 depends on AUDIT && !AUDIT_ARCH
248 config AUDIT_ARCH_COMPAT_GENERIC
252 config AUDIT_COMPAT_GENERIC
254 depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
257 config RANDOM32_SELFTEST
258 bool "PRNG perform self test on init"
260 This option enables the 32 bit PRNG library functions to perform a
261 self test on initialization.
264 # compression support is select'ed if needed
270 config 842_DECOMPRESS
284 config LZO_DECOMPRESS
290 config LZ4HC_COMPRESS
293 config LZ4_DECOMPRESS
300 config ZSTD_DECOMPRESS
304 source "lib/xz/Kconfig"
307 # These all provide a common interface (hence the apparent duplication with
308 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
310 config DECOMPRESS_GZIP
314 config DECOMPRESS_BZIP2
317 config DECOMPRESS_LZMA
324 config DECOMPRESS_LZO
325 select LZO_DECOMPRESS
328 config DECOMPRESS_LZ4
329 select LZ4_DECOMPRESS
333 # Generic allocator support is selected if needed
335 config GENERIC_ALLOCATOR
339 # reed solomon support is select'ed if needed
344 config REED_SOLOMON_ENC8
347 config REED_SOLOMON_DEC8
350 config REED_SOLOMON_ENC16
353 config REED_SOLOMON_DEC16
357 # BCH support is selected if needed
362 config BCH_CONST_PARAMS
365 Drivers may select this option to force specific constant
366 values for parameters 'm' (Galois field order) and 't'
367 (error correction capability). Those specific values must
368 be set by declaring default values for symbols BCH_CONST_M
370 Doing so will enable extra compiler optimizations,
371 improving encoding and decoding performance up to 2x for
372 usual (m,t) values (typically such that m*t < 200).
373 When this option is selected, the BCH library supports
374 only a single (m,t) configuration. This is mainly useful
375 for NAND flash board drivers requiring known, fixed BCH
382 Constant value for Galois field order 'm'. If 'k' is the
383 number of data bits to protect, 'm' should be chosen such
384 that (k + m*t) <= 2**m - 1.
385 Drivers should declare a default value for this symbol if
386 they select option BCH_CONST_PARAMS.
391 Constant value for error correction capability in bits 't'.
392 Drivers should declare a default value for this symbol if
393 they select option BCH_CONST_PARAMS.
396 # Textsearch support is select'ed if needed
401 config TEXTSEARCH_KMP
407 config TEXTSEARCH_FSM
416 Simple, embeddable, interval-tree. Can find the start of an
417 overlapping range in log(n) time and then iterate over all
418 overlapping nodes. The algorithm is implemented as an
423 Documentation/rbtree.txt
425 for more information.
430 Support entries which occupy multiple consecutive indices in the
433 config ASSOCIATIVE_ARRAY
436 Generic associative array. Can be searched and iterated over whilst
437 it is being modified. It is also reasonably quick to search and
438 modify. The algorithms are non-recursive, and the trees are highly
443 Documentation/core-api/assoc_array.rst
445 for more information.
453 config HAS_IOPORT_MAP
455 depends on HAS_IOMEM && !NO_IOPORT_MAP
458 source "kernel/dma/Kconfig"
467 config CHECK_SIGNATURE
470 config CPUMASK_OFFSTACK
471 bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
473 Use dynamic allocation for cpumask_var_t, instead of putting
474 them on the stack. This is a bit more expensive, but avoids
486 # This actually supports modular compilation, but the module overhead
487 # is ridiculous for the amount of code involved. Until an out-of-tree
488 # driver asks for it, we'll just link it directly it into the kernel
489 # when required. Since we're ignoring out-of-tree users, there's also
490 # no need bother prompting for a manual decision:
491 # prompt "glob_match() function"
493 This option provides a glob_match function for performing
494 simple text pattern matching. It originated in the ATA code
495 to blacklist particular drive models, but other device drivers
496 may need similar functionality.
498 All drivers in the Linux kernel tree that require this function
499 should automatically select this option. Say N unless you
500 are compiling an out-of tree driver which tells you that it
504 tristate "glob self-test on init"
507 This option enables a simple self-test of the glob_match
508 function on startup. It is primarily useful for people
509 working on the code to ensure they haven't introduced any
512 It only adds a little bit of code and slows kernel boot (or
513 module load) by a small amount, so you're welcome to play with
514 it, but you probably don't need it.
517 # Netlink attribute parsing support is select'ed if needed
523 # Generic 64-bit atomic support is selected if needed
525 config GENERIC_ATOMIC64
535 tristate "CORDIC algorithm"
537 This option provides an implementation of the CORDIC algorithm;
538 calculations are in fixed point. Module will be called cordic.
541 bool "JEDEC DDR data"
543 Data from JEDEC specs for DDR SDRAM memories,
544 particularly the AC timing parameters and addressing
545 information. This data is useful for drivers handling
546 DDR SDRAM controllers.
549 bool "IRQ polling library"
551 Helper library to poll interrupt mitigation using polling.
557 Multiprecision maths library from GnuPG.
558 It is used to implement RSA digital signature verification,
559 which is used by IMA/EVM digital signature extension.
568 Digital signature verification. Currently only RSA is supported.
569 Implementation is done using GnuPG MPI library
572 # libfdt files, only selected if needed.
580 Enable fast lookup object identifier registry.
585 source "lib/fonts/Kconfig"
590 Provides a helper to split scatterlists into chunks, each chunk being
591 a scatterlist. This should be selected by a driver or an API which
592 whishes to split a scatterlist amongst multiple DMA channels.
597 Provides a helper to allocate chained scatterlists. This should be
598 selected by a driver or an API which whishes to allocate chained
605 config ARCH_NO_SG_CHAIN
608 config ARCH_HAS_PMEM_API
611 config ARCH_HAS_UACCESS_FLUSHCACHE
614 config ARCH_HAS_UACCESS_MCSAFE
617 # Temporary. Goes away when all archs are cleaned up
618 config ARCH_STACKWALK
629 tristate "parman" if COMPILE_TEST
634 config STRING_SELFTEST
635 tristate "Test string functions"
639 config GENERIC_LIB_ASHLDI3
642 config GENERIC_LIB_ASHRDI3
645 config GENERIC_LIB_LSHRDI3
648 config GENERIC_LIB_MULDI3
651 config GENERIC_LIB_CMPDI2
654 config GENERIC_LIB_UCMPDI2
658 tristate "objagg" if COMPILE_TEST