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
49 This option enables the use of hardware bit-reversal instructions on
50 architectures which support such operations.
52 config ARCH_HAS_STRNCPY_FROM_USER
55 config ARCH_HAS_STRNLEN_USER
58 config GENERIC_STRNCPY_FROM_USER
59 def_bool !ARCH_HAS_STRNCPY_FROM_USER
61 config GENERIC_STRNLEN_USER
62 def_bool !ARCH_HAS_STRNLEN_USER
64 config GENERIC_NET_UTILS
67 config GENERIC_FIND_FIRST_BIT
70 source "lib/math/Kconfig"
72 config NO_GENERIC_PCI_IOPORT_MAP
75 config GENERIC_PCI_IOMAP
80 select GENERIC_PCI_IOMAP
85 config ARCH_USE_CMPXCHG_LOCKREF
88 config ARCH_HAS_FAST_MULTIPLIER
91 config ARCH_USE_SYM_ANNOTATIONS
95 bool "Access I/O in non-MMIO mode"
98 On some platforms where no separate I/O space exists, there are I/O
99 hosts which can not be accessed in MMIO mode. Using the logical PIO
100 mechanism, the host-local I/O resource can be mapped into system
101 logic PIO space shared with MMIO hosts, such as PCI/PCIe, then the
102 system can access the I/O devices with the mapped-logic PIO through
105 This way has relatively little I/O performance cost. Please make
106 sure your devices really need this configure item enabled.
108 When in doubt, say N.
110 config INDIRECT_IOMEM
113 This is selected by other options/architectures to provide the
114 emulated iomem accessors.
116 config INDIRECT_IOMEM_FALLBACK
118 depends on INDIRECT_IOMEM
120 If INDIRECT_IOMEM is selected, this enables falling back to plain
121 mmio accesses when the IO memory address is not a registered
125 tristate "CRC-CCITT functions"
127 This option is provided for the case where no in-kernel-tree
128 modules require CRC-CCITT functions, but a module built outside
129 the kernel tree does. Such modules that use library CRC-CCITT
130 functions require M here.
133 tristate "CRC16 functions"
135 This option is provided for the case where no in-kernel-tree
136 modules require CRC16 functions, but a module built outside
137 the kernel tree does. Such modules that use library CRC16
138 functions require M here.
141 tristate "CRC calculation for the T10 Data Integrity Field"
143 select CRYPTO_CRCT10DIF
145 This option is only needed if a module that's not in the
146 kernel tree needs to calculate CRC checks for use with the
147 SCSI data integrity subsystem.
150 tristate "CRC ITU-T V.41 functions"
152 This option is provided for the case where no in-kernel-tree
153 modules require CRC ITU-T V.41 functions, but a module built outside
154 the kernel tree does. Such modules that use library CRC ITU-T V.41
155 functions require M here.
158 tristate "CRC32/CRC32c functions"
162 This option is provided for the case where no in-kernel-tree
163 modules require CRC32/CRC32c functions, but a module built outside
164 the kernel tree does. Such modules that use library CRC32/CRC32c
165 functions require M here.
167 config CRC32_SELFTEST
168 tristate "CRC32 perform self test on init"
171 This option enables the CRC32 library functions to perform a
172 self test on initialization. The self test computes crc32_le
173 and crc32_be over byte strings with random alignment and length
174 and computes the total elapsed time and number of bytes processed.
177 prompt "CRC32 implementation"
179 default CRC32_SLICEBY8
181 This option allows a kernel builder to override the default choice
182 of CRC32 algorithm. Choose the default ("slice by 8") unless you
183 know that you need one of the others.
185 config CRC32_SLICEBY8
186 bool "Slice by 8 bytes"
188 Calculate checksum 8 bytes at a time with a clever slicing algorithm.
189 This is the fastest algorithm, but comes with a 8KiB lookup table.
190 Most modern processors have enough cache to hold this table without
193 This is the default implementation choice. Choose this one unless
194 you have a good reason not to.
196 config CRC32_SLICEBY4
197 bool "Slice by 4 bytes"
199 Calculate checksum 4 bytes at a time with a clever slicing algorithm.
200 This is a bit slower than slice by 8, but has a smaller 4KiB lookup
203 Only choose this option if you know what you are doing.
206 bool "Sarwate's Algorithm (one byte at a time)"
208 Calculate checksum a byte at a time using Sarwate's algorithm. This
209 is not particularly fast, but has a small 256 byte lookup table.
211 Only choose this option if you know what you are doing.
214 bool "Classic Algorithm (one bit at a time)"
216 Calculate checksum one bit at a time. This is VERY slow, but has
217 no lookup table. This is provided as a debugging option.
219 Only choose this option if you are debugging crc32.
224 tristate "CRC64 functions"
226 This option is provided for the case where no in-kernel-tree
227 modules require CRC64 functions, but a module built outside
228 the kernel tree does. Such modules that use library CRC64
229 functions require M here.
232 tristate "CRC4 functions"
234 This option is provided for the case where no in-kernel-tree
235 modules require CRC4 functions, but a module built outside
236 the kernel tree does. Such modules that use library CRC4
237 functions require M here.
240 tristate "CRC7 functions"
242 This option is provided for the case where no in-kernel-tree
243 modules require CRC7 functions, but a module built outside
244 the kernel tree does. Such modules that use library CRC7
245 functions require M here.
248 tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
252 This option is provided for the case where no in-kernel-tree
253 modules require CRC32c functions, but a module built outside the
254 kernel tree does. Such modules that use library CRC32c functions
255 require M here. See Castagnoli93.
256 Module will be libcrc32c.
259 tristate "CRC8 function"
261 This option provides CRC8 function. Drivers may select this
262 when they need to do cyclic redundancy check according CRC8
263 algorithm. Module will be called crc8.
270 depends on AUDIT && !AUDIT_ARCH
273 config AUDIT_ARCH_COMPAT_GENERIC
277 config AUDIT_COMPAT_GENERIC
279 depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
282 config RANDOM32_SELFTEST
283 bool "PRNG perform self test on init"
285 This option enables the 32 bit PRNG library functions to perform a
286 self test on initialization.
289 # compression support is select'ed if needed
295 config 842_DECOMPRESS
309 prompt "Enable s390x DEFLATE CONVERSION CALL support for kernel zlib"
311 Enable s390x hardware support for zlib in the kernel.
316 config LZO_DECOMPRESS
322 config LZ4HC_COMPRESS
325 config LZ4_DECOMPRESS
332 config ZSTD_DECOMPRESS
336 source "lib/xz/Kconfig"
339 # These all provide a common interface (hence the apparent duplication with
340 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
342 config DECOMPRESS_GZIP
346 config DECOMPRESS_BZIP2
349 config DECOMPRESS_LZMA
356 config DECOMPRESS_LZO
357 select LZO_DECOMPRESS
360 config DECOMPRESS_LZ4
361 select LZ4_DECOMPRESS
364 config DECOMPRESS_ZSTD
365 select ZSTD_DECOMPRESS
369 # Generic allocator support is selected if needed
371 config GENERIC_ALLOCATOR
375 # reed solomon support is select'ed if needed
380 config REED_SOLOMON_ENC8
383 config REED_SOLOMON_DEC8
386 config REED_SOLOMON_ENC16
389 config REED_SOLOMON_DEC16
393 # BCH support is selected if needed
398 config BCH_CONST_PARAMS
401 Drivers may select this option to force specific constant
402 values for parameters 'm' (Galois field order) and 't'
403 (error correction capability). Those specific values must
404 be set by declaring default values for symbols BCH_CONST_M
406 Doing so will enable extra compiler optimizations,
407 improving encoding and decoding performance up to 2x for
408 usual (m,t) values (typically such that m*t < 200).
409 When this option is selected, the BCH library supports
410 only a single (m,t) configuration. This is mainly useful
411 for NAND flash board drivers requiring known, fixed BCH
418 Constant value for Galois field order 'm'. If 'k' is the
419 number of data bits to protect, 'm' should be chosen such
420 that (k + m*t) <= 2**m - 1.
421 Drivers should declare a default value for this symbol if
422 they select option BCH_CONST_PARAMS.
427 Constant value for error correction capability in bits 't'.
428 Drivers should declare a default value for this symbol if
429 they select option BCH_CONST_PARAMS.
432 # Textsearch support is select'ed if needed
437 config TEXTSEARCH_KMP
443 config TEXTSEARCH_FSM
452 Simple, embeddable, interval-tree. Can find the start of an
453 overlapping range in log(n) time and then iterate over all
454 overlapping nodes. The algorithm is implemented as an
459 Documentation/core-api/rbtree.rst
461 for more information.
466 Support entries which occupy multiple consecutive indices in the
469 config ASSOCIATIVE_ARRAY
472 Generic associative array. Can be searched and iterated over whilst
473 it is being modified. It is also reasonably quick to search and
474 modify. The algorithms are non-recursive, and the trees are highly
479 Documentation/core-api/assoc_array.rst
481 for more information.
488 config HAS_IOPORT_MAP
490 depends on HAS_IOMEM && !NO_IOPORT_MAP
493 source "kernel/dma/Kconfig"
502 config CHECK_SIGNATURE
505 config CPUMASK_OFFSTACK
506 bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
508 Use dynamic allocation for cpumask_var_t, instead of putting
509 them on the stack. This is a bit more expensive, but avoids
521 # This actually supports modular compilation, but the module overhead
522 # is ridiculous for the amount of code involved. Until an out-of-tree
523 # driver asks for it, we'll just link it directly it into the kernel
524 # when required. Since we're ignoring out-of-tree users, there's also
525 # no need bother prompting for a manual decision:
526 # prompt "glob_match() function"
528 This option provides a glob_match function for performing
529 simple text pattern matching. It originated in the ATA code
530 to blacklist particular drive models, but other device drivers
531 may need similar functionality.
533 All drivers in the Linux kernel tree that require this function
534 should automatically select this option. Say N unless you
535 are compiling an out-of tree driver which tells you that it
539 tristate "glob self-test on init"
542 This option enables a simple self-test of the glob_match
543 function on startup. It is primarily useful for people
544 working on the code to ensure they haven't introduced any
547 It only adds a little bit of code and slows kernel boot (or
548 module load) by a small amount, so you're welcome to play with
549 it, but you probably don't need it.
552 # Netlink attribute parsing support is select'ed if needed
558 # Generic 64-bit atomic support is selected if needed
560 config GENERIC_ATOMIC64
570 bool "IRQ polling library"
572 Helper library to poll interrupt mitigation using polling.
578 Multiprecision maths library from GnuPG.
579 It is used to implement RSA digital signature verification,
580 which is used by IMA/EVM digital signature extension.
589 Digital signature verification. Currently only RSA is supported.
590 Implementation is done using GnuPG MPI library
595 Dynamic Interrupt Moderation library.
596 Implements an algorithm for dynamically changing CQ moderation values
597 according to run time performance.
600 # libfdt files, only selected if needed.
608 Enable fast lookup object identifier registry.
616 source "lib/vdso/Kconfig"
618 source "lib/fonts/Kconfig"
623 Provides a helper to split scatterlists into chunks, each chunk being
624 a scatterlist. This should be selected by a driver or an API which
625 whishes to split a scatterlist amongst multiple DMA channels.
630 Provides a helper to allocate chained scatterlists. This should be
631 selected by a driver or an API which whishes to allocate chained
638 config ARCH_NO_SG_CHAIN
641 config ARCH_HAS_PMEM_API
647 config ARCH_HAS_MEMREMAP_COMPAT_ALIGN
650 # use memcpy to implement user copies for nommu architectures
651 config UACCESS_MEMCPY
654 config ARCH_HAS_UACCESS_FLUSHCACHE
657 # arch has a concept of a recoverable synchronous exception due to a
658 # memory-read error like x86 machine-check or ARM data-abort, and
659 # implements copy_mc_to_{user,kernel} to abort and report
660 # 'bytes-transferred' if that exception fires when accessing the source
662 config ARCH_HAS_COPY_MC
665 # Temporary. Goes away when all archs are cleaned up
666 config ARCH_STACKWALK
673 config STACK_HASH_ORDER
674 int "stack depot hash size (12 => 4KB, 20 => 1024KB)"
677 depends on STACKDEPOT
679 Select the hash size as a power of 2 for the stackdepot hash table.
680 Choose a lower value to reduce the memory impact.
686 tristate "parman" if COMPILE_TEST
689 tristate "objagg" if COMPILE_TEST
693 config GENERIC_IOREMAP
696 config GENERIC_LIB_ASHLDI3
699 config GENERIC_LIB_ASHRDI3
702 config GENERIC_LIB_LSHRDI3
705 config GENERIC_LIB_MULDI3
708 config GENERIC_LIB_CMPDI2
711 config GENERIC_LIB_UCMPDI2
714 config GENERIC_LIB_DEVMEM_IS_ALLOWED