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.
49 config GENERIC_STRNCPY_FROM_USER
52 config GENERIC_STRNLEN_USER
55 config GENERIC_NET_UTILS
58 config GENERIC_FIND_FIRST_BIT
61 source "lib/math/Kconfig"
63 config NO_GENERIC_PCI_IOPORT_MAP
66 config GENERIC_PCI_IOMAP
71 select GENERIC_PCI_IOMAP
76 config ARCH_USE_CMPXCHG_LOCKREF
79 config ARCH_HAS_FAST_MULTIPLIER
83 bool "Access I/O in non-MMIO mode"
86 On some platforms where no separate I/O space exists, there are I/O
87 hosts which can not be accessed in MMIO mode. Using the logical PIO
88 mechanism, the host-local I/O resource can be mapped into system
89 logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the
90 system can access the I/O devices with the mapped-logic PIO through
93 This way has relatively little I/O performance cost. Please make
94 sure your devices really need this configure item enabled.
99 tristate "CRC-CCITT functions"
101 This option is provided for the case where no in-kernel-tree
102 modules require CRC-CCITT functions, but a module built outside
103 the kernel tree does. Such modules that use library CRC-CCITT
104 functions require M here.
107 tristate "CRC16 functions"
109 This option is provided for the case where no in-kernel-tree
110 modules require CRC16 functions, but a module built outside
111 the kernel tree does. Such modules that use library CRC16
112 functions require M here.
115 tristate "CRC calculation for the T10 Data Integrity Field"
117 select CRYPTO_CRCT10DIF
119 This option is only needed if a module that's not in the
120 kernel tree needs to calculate CRC checks for use with the
121 SCSI data integrity subsystem.
124 tristate "CRC ITU-T V.41 functions"
126 This option is provided for the case where no in-kernel-tree
127 modules require CRC ITU-T V.41 functions, but a module built outside
128 the kernel tree does. Such modules that use library CRC ITU-T V.41
129 functions require M here.
132 tristate "CRC32/CRC32c functions"
136 This option is provided for the case where no in-kernel-tree
137 modules require CRC32/CRC32c functions, but a module built outside
138 the kernel tree does. Such modules that use library CRC32/CRC32c
139 functions require M here.
141 config CRC32_SELFTEST
142 tristate "CRC32 perform self test on init"
145 This option enables the CRC32 library functions to perform a
146 self test on initialization. The self test computes crc32_le
147 and crc32_be over byte strings with random alignment and length
148 and computes the total elapsed time and number of bytes processed.
151 prompt "CRC32 implementation"
153 default CRC32_SLICEBY8
155 This option allows a kernel builder to override the default choice
156 of CRC32 algorithm. Choose the default ("slice by 8") unless you
157 know that you need one of the others.
159 config CRC32_SLICEBY8
160 bool "Slice by 8 bytes"
162 Calculate checksum 8 bytes at a time with a clever slicing algorithm.
163 This is the fastest algorithm, but comes with a 8KiB lookup table.
164 Most modern processors have enough cache to hold this table without
167 This is the default implementation choice. Choose this one unless
168 you have a good reason not to.
170 config CRC32_SLICEBY4
171 bool "Slice by 4 bytes"
173 Calculate checksum 4 bytes at a time with a clever slicing algorithm.
174 This is a bit slower than slice by 8, but has a smaller 4KiB lookup
177 Only choose this option if you know what you are doing.
180 bool "Sarwate's Algorithm (one byte at a time)"
182 Calculate checksum a byte at a time using Sarwate's algorithm. This
183 is not particularly fast, but has a small 256 byte lookup table.
185 Only choose this option if you know what you are doing.
188 bool "Classic Algorithm (one bit at a time)"
190 Calculate checksum one bit at a time. This is VERY slow, but has
191 no lookup table. This is provided as a debugging option.
193 Only choose this option if you are debugging crc32.
198 tristate "CRC64 functions"
200 This option is provided for the case where no in-kernel-tree
201 modules require CRC64 functions, but a module built outside
202 the kernel tree does. Such modules that use library CRC64
203 functions require M here.
206 tristate "CRC4 functions"
208 This option is provided for the case where no in-kernel-tree
209 modules require CRC4 functions, but a module built outside
210 the kernel tree does. Such modules that use library CRC4
211 functions require M here.
214 tristate "CRC7 functions"
216 This option is provided for the case where no in-kernel-tree
217 modules require CRC7 functions, but a module built outside
218 the kernel tree does. Such modules that use library CRC7
219 functions require M here.
222 tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
226 This option is provided for the case where no in-kernel-tree
227 modules require CRC32c functions, but a module built outside the
228 kernel tree does. Such modules that use library CRC32c functions
229 require M here. See Castagnoli93.
230 Module will be libcrc32c.
233 tristate "CRC8 function"
235 This option provides CRC8 function. Drivers may select this
236 when they need to do cyclic redundancy check according CRC8
237 algorithm. Module will be called crc8.
244 depends on AUDIT && !AUDIT_ARCH
247 config AUDIT_ARCH_COMPAT_GENERIC
251 config AUDIT_COMPAT_GENERIC
253 depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
256 config RANDOM32_SELFTEST
257 bool "PRNG perform self test on init"
259 This option enables the 32 bit PRNG library functions to perform a
260 self test on initialization.
263 # compression support is select'ed if needed
269 config 842_DECOMPRESS
283 config LZO_DECOMPRESS
289 config LZ4HC_COMPRESS
292 config LZ4_DECOMPRESS
299 config ZSTD_DECOMPRESS
303 source "lib/xz/Kconfig"
306 # These all provide a common interface (hence the apparent duplication with
307 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
309 config DECOMPRESS_GZIP
313 config DECOMPRESS_BZIP2
316 config DECOMPRESS_LZMA
323 config DECOMPRESS_LZO
324 select LZO_DECOMPRESS
327 config DECOMPRESS_LZ4
328 select LZ4_DECOMPRESS
332 # Generic allocator support is selected if needed
334 config GENERIC_ALLOCATOR
338 # reed solomon support is select'ed if needed
343 config REED_SOLOMON_ENC8
346 config REED_SOLOMON_DEC8
349 config REED_SOLOMON_ENC16
352 config REED_SOLOMON_DEC16
356 # BCH support is selected if needed
361 config BCH_CONST_PARAMS
364 Drivers may select this option to force specific constant
365 values for parameters 'm' (Galois field order) and 't'
366 (error correction capability). Those specific values must
367 be set by declaring default values for symbols BCH_CONST_M
369 Doing so will enable extra compiler optimizations,
370 improving encoding and decoding performance up to 2x for
371 usual (m,t) values (typically such that m*t < 200).
372 When this option is selected, the BCH library supports
373 only a single (m,t) configuration. This is mainly useful
374 for NAND flash board drivers requiring known, fixed BCH
381 Constant value for Galois field order 'm'. If 'k' is the
382 number of data bits to protect, 'm' should be chosen such
383 that (k + m*t) <= 2**m - 1.
384 Drivers should declare a default value for this symbol if
385 they select option BCH_CONST_PARAMS.
390 Constant value for error correction capability in bits 't'.
391 Drivers should declare a default value for this symbol if
392 they select option BCH_CONST_PARAMS.
395 # Textsearch support is select'ed if needed
400 config TEXTSEARCH_KMP
406 config TEXTSEARCH_FSM
415 Simple, embeddable, interval-tree. Can find the start of an
416 overlapping range in log(n) time and then iterate over all
417 overlapping nodes. The algorithm is implemented as an
422 Documentation/rbtree.txt
424 for more information.
429 Support entries which occupy multiple consecutive indices in the
432 config ASSOCIATIVE_ARRAY
435 Generic associative array. Can be searched and iterated over whilst
436 it is being modified. It is also reasonably quick to search and
437 modify. The algorithms are non-recursive, and the trees are highly
442 Documentation/core-api/assoc_array.rst
444 for more information.
452 config HAS_IOPORT_MAP
454 depends on HAS_IOMEM && !NO_IOPORT_MAP
457 source "kernel/dma/Kconfig"
466 config CHECK_SIGNATURE
469 config CPUMASK_OFFSTACK
470 bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
472 Use dynamic allocation for cpumask_var_t, instead of putting
473 them on the stack. This is a bit more expensive, but avoids
485 # This actually supports modular compilation, but the module overhead
486 # is ridiculous for the amount of code involved. Until an out-of-tree
487 # driver asks for it, we'll just link it directly it into the kernel
488 # when required. Since we're ignoring out-of-tree users, there's also
489 # no need bother prompting for a manual decision:
490 # prompt "glob_match() function"
492 This option provides a glob_match function for performing
493 simple text pattern matching. It originated in the ATA code
494 to blacklist particular drive models, but other device drivers
495 may need similar functionality.
497 All drivers in the Linux kernel tree that require this function
498 should automatically select this option. Say N unless you
499 are compiling an out-of tree driver which tells you that it
503 tristate "glob self-test on init"
506 This option enables a simple self-test of the glob_match
507 function on startup. It is primarily useful for people
508 working on the code to ensure they haven't introduced any
511 It only adds a little bit of code and slows kernel boot (or
512 module load) by a small amount, so you're welcome to play with
513 it, but you probably don't need it.
516 # Netlink attribute parsing support is select'ed if needed
522 # Generic 64-bit atomic support is selected if needed
524 config GENERIC_ATOMIC64
534 bool "JEDEC DDR data"
536 Data from JEDEC specs for DDR SDRAM memories,
537 particularly the AC timing parameters and addressing
538 information. This data is useful for drivers handling
539 DDR SDRAM controllers.
542 bool "IRQ polling library"
544 Helper library to poll interrupt mitigation using polling.
550 Multiprecision maths library from GnuPG.
551 It is used to implement RSA digital signature verification,
552 which is used by IMA/EVM digital signature extension.
561 Digital signature verification. Currently only RSA is supported.
562 Implementation is done using GnuPG MPI library
565 # libfdt files, only selected if needed.
573 Enable fast lookup object identifier registry.
578 source "lib/fonts/Kconfig"
583 Provides a helper to split scatterlists into chunks, each chunk being
584 a scatterlist. This should be selected by a driver or an API which
585 whishes to split a scatterlist amongst multiple DMA channels.
590 Provides a helper to allocate chained scatterlists. This should be
591 selected by a driver or an API which whishes to allocate chained
598 config ARCH_NO_SG_CHAIN
601 config ARCH_HAS_PMEM_API
604 # use memcpy to implement user copies for nommu architectures
605 config UACCESS_MEMCPY
608 config ARCH_HAS_UACCESS_FLUSHCACHE
611 config ARCH_HAS_UACCESS_MCSAFE
614 # Temporary. Goes away when all archs are cleaned up
615 config ARCH_STACKWALK
626 tristate "parman" if COMPILE_TEST
628 config STRING_SELFTEST
629 tristate "Test string functions"
633 config GENERIC_LIB_ASHLDI3
636 config GENERIC_LIB_ASHRDI3
639 config GENERIC_LIB_LSHRDI3
642 config GENERIC_LIB_MULDI3
645 config GENERIC_LIB_CMPDI2
648 config GENERIC_LIB_UCMPDI2
652 tristate "objagg" if COMPILE_TEST