linux/lib/Kconfig

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#
# Library configuration
#
config BINARY_PRINTF
def_bool n
menu "Library routines"
config RAID6_PQ
tristate
config BITREVERSE
tristate
config HAVE_ARCH_BITREVERSE
bool
default n
depends on BITREVERSE
help
This option enables the use of hardware bit-reversal instructions on
architectures which support such operations.
config RATIONAL
bool
config GENERIC_STRNCPY_FROM_USER
bool
config GENERIC_STRNLEN_USER
bool
config GENERIC_NET_UTILS
bool
config GENERIC_FIND_FIRST_BIT
bool
config NO_GENERIC_PCI_IOPORT_MAP
bool
config GENERIC_PCI_IOMAP
bool
config GENERIC_IOMAP
bool
select GENERIC_PCI_IOMAP
config STMP_DEVICE
bool
lockref: implement lockless reference count updates using cmpxchg() Instead of taking the spinlock, the lockless versions atomically check that the lock is not taken, and do the reference count update using a cmpxchg() loop. This is semantically identical to doing the reference count update protected by the lock, but avoids the "wait for lock" contention that you get when accesses to the reference count are contended. Note that a "lockref" is absolutely _not_ equivalent to an atomic_t. Even when the lockref reference counts are updated atomically with cmpxchg, the fact that they also verify the state of the spinlock means that the lockless updates can never happen while somebody else holds the spinlock. So while "lockref_put_or_lock()" looks a lot like just another name for "atomic_dec_and_lock()", and both optimize to lockless updates, they are fundamentally different: the decrement done by atomic_dec_and_lock() is truly independent of any lock (as long as it doesn't decrement to zero), so a locked region can still see the count change. The lockref structure, in contrast, really is a *locked* reference count. If you hold the spinlock, the reference count will be stable and you can modify the reference count without using atomics, because even the lockless updates will see and respect the state of the lock. In order to enable the cmpxchg lockless code, the architecture needs to do three things: (1) Make sure that the "arch_spinlock_t" and an "unsigned int" can fit in an aligned u64, and have a "cmpxchg()" implementation that works on such a u64 data type. (2) define a helper function to test for a spinlock being unlocked ("arch_spin_value_unlocked()") (3) select the "ARCH_USE_CMPXCHG_LOCKREF" config variable in its Kconfig file. This enables it for x86-64 (but not 32-bit, we'd need to make sure cmpxchg() turns into the proper cmpxchg8b in order to enable it for 32-bit mode). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-02 23:12:15 +04:00
config ARCH_USE_CMPXCHG_LOCKREF
bool
config ARCH_HAS_FAST_MULTIPLIER
bool
config CRC_CCITT
tristate "CRC-CCITT functions"
help
This option is provided for the case where no in-kernel-tree
modules require CRC-CCITT functions, but a module built outside
the kernel tree does. Such modules that use library CRC-CCITT
functions require M here.
config CRC16
tristate "CRC16 functions"
help
This option is provided for the case where no in-kernel-tree
modules require CRC16 functions, but a module built outside
the kernel tree does. Such modules that use library CRC16
functions require M here.
config CRC_T10DIF
tristate "CRC calculation for the T10 Data Integrity Field"
select CRYPTO
select CRYPTO_CRCT10DIF
help
This option is only needed if a module that's not in the
kernel tree needs to calculate CRC checks for use with the
SCSI data integrity subsystem.
config CRC_ITU_T
tristate "CRC ITU-T V.41 functions"
help
This option is provided for the case where no in-kernel-tree
modules require CRC ITU-T V.41 functions, but a module built outside
the kernel tree does. Such modules that use library CRC ITU-T V.41
functions require M here.
config CRC32
tristate "CRC32/CRC32c functions"
default y
select BITREVERSE
help
This option is provided for the case where no in-kernel-tree
modules require CRC32/CRC32c functions, but a module built outside
the kernel tree does. Such modules that use library CRC32/CRC32c
functions require M here.
config CRC32_SELFTEST
tristate "CRC32 perform self test on init"
depends on CRC32
help
This option enables the CRC32 library functions to perform a
self test on initialization. The self test computes crc32_le
and crc32_be over byte strings with random alignment and length
and computes the total elapsed time and number of bytes processed.
choice
prompt "CRC32 implementation"
depends on CRC32
default CRC32_SLICEBY8
help
This option allows a kernel builder to override the default choice
of CRC32 algorithm. Choose the default ("slice by 8") unless you
know that you need one of the others.
config CRC32_SLICEBY8
bool "Slice by 8 bytes"
help
Calculate checksum 8 bytes at a time with a clever slicing algorithm.
This is the fastest algorithm, but comes with a 8KiB lookup table.
Most modern processors have enough cache to hold this table without
thrashing the cache.
This is the default implementation choice. Choose this one unless
you have a good reason not to.
config CRC32_SLICEBY4
bool "Slice by 4 bytes"
help
Calculate checksum 4 bytes at a time with a clever slicing algorithm.
This is a bit slower than slice by 8, but has a smaller 4KiB lookup
table.
Only choose this option if you know what you are doing.
config CRC32_SARWATE
bool "Sarwate's Algorithm (one byte at a time)"
help
Calculate checksum a byte at a time using Sarwate's algorithm. This
is not particularly fast, but has a small 256 byte lookup table.
Only choose this option if you know what you are doing.
config CRC32_BIT
bool "Classic Algorithm (one bit at a time)"
help
Calculate checksum one bit at a time. This is VERY slow, but has
no lookup table. This is provided as a debugging option.
Only choose this option if you are debugging crc32.
endchoice
config CRC4
tristate "CRC4 functions"
help
This option is provided for the case where no in-kernel-tree
modules require CRC4 functions, but a module built outside
the kernel tree does. Such modules that use library CRC4
functions require M here.
config CRC7
tristate "CRC7 functions"
help
This option is provided for the case where no in-kernel-tree
modules require CRC7 functions, but a module built outside
the kernel tree does. Such modules that use library CRC7
functions require M here.
config LIBCRC32C
tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
select CRYPTO
select CRYPTO_CRC32C
help
This option is provided for the case where no in-kernel-tree
modules require CRC32c functions, but a module built outside the
kernel tree does. Such modules that use library CRC32c functions
require M here. See Castagnoli93.
Module will be libcrc32c.
config CRC8
tristate "CRC8 function"
help
This option provides CRC8 function. Drivers may select this
when they need to do cyclic redundancy check according CRC8
algorithm. Module will be called crc8.
lib: Add xxhash module Adds xxhash kernel module with xxh32 and xxh64 hashes. xxhash is an extremely fast non-cryptographic hash algorithm for checksumming. The zstd compression and decompression modules added in the next patch require xxhash. I extracted it out from zstd since it is useful on its own. I copied the code from the upstream XXHash source repository and translated it into kernel style. I ran benchmarks and tests in the kernel and tests in userland. I benchmarked xxhash as a special character device. I ran in four modes, no-op, xxh32, xxh64, and crc32. The no-op mode simply copies the data to kernel space and ignores it. The xxh32, xxh64, and crc32 modes compute hashes on the copied data. I also ran it with four different buffer sizes. The benchmark file is located in the upstream zstd source repository under `contrib/linux-kernel/xxhash_test.c` [1]. I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM. The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor, 16 GB of RAM, and a SSD. I benchmarked using the file `filesystem.squashfs` from `ubuntu-16.10-desktop-amd64.iso`, which is 1,536,217,088 B large. Run the following commands for the benchmark: modprobe xxhash_test mknod xxhash_test c 245 0 time cp filesystem.squashfs xxhash_test The time is reported by the time of the userland `cp`. The GB/s is computed with 1,536,217,008 B / time(buffer size, hash) which includes the time to copy from userland. The Normalized GB/s is computed with 1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)). | Buffer Size (B) | Hash | Time (s) | GB/s | Adjusted GB/s | |-----------------|-------|----------|------|---------------| | 1024 | none | 0.408 | 3.77 | - | | 1024 | xxh32 | 0.649 | 2.37 | 6.37 | | 1024 | xxh64 | 0.542 | 2.83 | 11.46 | | 1024 | crc32 | 1.290 | 1.19 | 1.74 | | 4096 | none | 0.380 | 4.04 | - | | 4096 | xxh32 | 0.645 | 2.38 | 5.79 | | 4096 | xxh64 | 0.500 | 3.07 | 12.80 | | 4096 | crc32 | 1.168 | 1.32 | 1.95 | | 8192 | none | 0.351 | 4.38 | - | | 8192 | xxh32 | 0.614 | 2.50 | 5.84 | | 8192 | xxh64 | 0.464 | 3.31 | 13.60 | | 8192 | crc32 | 1.163 | 1.32 | 1.89 | | 16384 | none | 0.346 | 4.43 | - | | 16384 | xxh32 | 0.590 | 2.60 | 6.30 | | 16384 | xxh64 | 0.466 | 3.30 | 12.80 | | 16384 | crc32 | 1.183 | 1.30 | 1.84 | Tested in userland using the test-suite in the zstd repo under `contrib/linux-kernel/test/XXHashUserlandTest.cpp` [2] by mocking the kernel functions. A line in each branch of every function in `xxhash.c` was commented out to ensure that the test-suite fails. Additionally tested while testing zstd and with SMHasher [3]. [1] https://phabricator.intern.facebook.com/P57526246 [2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/XXHashUserlandTest.cpp [3] https://github.com/aappleby/smhasher zstd source repository: https://github.com/facebook/zstd XXHash source repository: https://github.com/cyan4973/xxhash Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
2017-08-04 23:19:17 +03:00
config XXHASH
tristate
config AUDIT_GENERIC
bool
depends on AUDIT && !AUDIT_ARCH
default y
config AUDIT_ARCH_COMPAT_GENERIC
bool
default n
config AUDIT_COMPAT_GENERIC
bool
depends on AUDIT_GENERIC && AUDIT_ARCH_COMPAT_GENERIC && COMPAT
default y
config RANDOM32_SELFTEST
bool "PRNG perform self test on init"
default n
help
This option enables the 32 bit PRNG library functions to perform a
self test on initialization.
#
# compression support is select'ed if needed
#
config 842_COMPRESS
select CRC32
tristate
config 842_DECOMPRESS
select CRC32
tristate
config ZLIB_INFLATE
tristate
config ZLIB_DEFLATE
tristate
select BITREVERSE
config LZO_COMPRESS
tristate
config LZO_DECOMPRESS
tristate
lib: add lz4 compressor module This patchset is for supporting LZ4 compression and the crypto API using it. As shown below, the size of data is a little bit bigger but compressing speed is faster under the enabled unaligned memory access. We can use lz4 de/compression through crypto API as well. Also, It will be useful for another potential user of lz4 compression. lz4 Compression Benchmark: Compiler: ARM gcc 4.6.4 ARMv7, 1 GHz based board Kernel: linux 3.4 Uncompressed data Size: 101 MB Compressed Size compression Speed LZO 72.1MB 32.1MB/s, 33.0MB/s(UA) LZ4 75.1MB 30.4MB/s, 35.9MB/s(UA) LZ4HC 59.8MB 2.4MB/s, 2.5MB/s(UA) - UA: Unaligned memory Access support - Latest patch set for LZO applied This patch: Add support for LZ4 compression in the Linux Kernel. LZ4 Compression APIs for kernel are based on LZ4 implementation by Yann Collet and were changed for kernel coding style. LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html LZ4 source repository : http://code.google.com/p/lz4/ svn revision : r90 Two APIs are added: lz4_compress() support basic lz4 compression whereas lz4hc_compress() support high compression or CPU performance get lower but compression ratio get higher. Also, we require the pre-allocated working memory with the defined size and destination buffer must be allocated with the size of lz4_compressbound. [akpm@linux-foundation.org: make lz4_compresshcctx() static] Signed-off-by: Chanho Min <chanho.min@lge.com> Cc: "Darrick J. Wong" <djwong@us.ibm.com> Cc: Bob Pearson <rpearson@systemfabricworks.com> Cc: Richard Weinberger <richard@nod.at> Cc: Herbert Xu <herbert@gondor.hengli.com.au> Cc: Yann Collet <yann.collet.73@gmail.com> Cc: Kyungsik Lee <kyungsik.lee@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09 03:01:49 +04:00
config LZ4_COMPRESS
tristate
config LZ4HC_COMPRESS
tristate
config LZ4_DECOMPRESS
tristate
lib: Add zstd modules Add zstd compression and decompression kernel modules. zstd offers a wide varity of compression speed and quality trade-offs. It can compress at speeds approaching lz4, and quality approaching lzma. zstd decompressions at speeds more than twice as fast as zlib, and decompression speed remains roughly the same across all compression levels. The code was ported from the upstream zstd source repository. The `linux/zstd.h` header was modified to match linux kernel style. The cross-platform and allocation code was stripped out. Instead zstd requires the caller to pass a preallocated workspace. The source files were clang-formatted [1] to match the Linux Kernel style as much as possible. Otherwise, the code was unmodified. We would like to avoid as much further manual modification to the source code as possible, so it will be easier to keep the kernel zstd up to date. I benchmarked zstd compression as a special character device. I ran zstd and zlib compression at several levels, as well as performing no compression, which measure the time spent copying the data to kernel space. Data is passed to the compresser 4096 B at a time. The benchmark file is located in the upstream zstd source repository under `contrib/linux-kernel/zstd_compress_test.c` [2]. I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM. The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor, 16 GB of RAM, and a SSD. I benchmarked using `silesia.tar` [3], which is 211,988,480 B large. Run the following commands for the benchmark: sudo modprobe zstd_compress_test sudo mknod zstd_compress_test c 245 0 sudo cp silesia.tar zstd_compress_test The time is reported by the time of the userland `cp`. The MB/s is computed with 1,536,217,008 B / time(buffer size, hash) which includes the time to copy from userland. The Adjusted MB/s is computed with 1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)). The memory reported is the amount of memory the compressor requests. | Method | Size (B) | Time (s) | Ratio | MB/s | Adj MB/s | Mem (MB) | |----------|----------|----------|-------|---------|----------|----------| | none | 11988480 | 0.100 | 1 | 2119.88 | - | - | | zstd -1 | 73645762 | 1.044 | 2.878 | 203.05 | 224.56 | 1.23 | | zstd -3 | 66988878 | 1.761 | 3.165 | 120.38 | 127.63 | 2.47 | | zstd -5 | 65001259 | 2.563 | 3.261 | 82.71 | 86.07 | 2.86 | | zstd -10 | 60165346 | 13.242 | 3.523 | 16.01 | 16.13 | 13.22 | | zstd -15 | 58009756 | 47.601 | 3.654 | 4.45 | 4.46 | 21.61 | | zstd -19 | 54014593 | 102.835 | 3.925 | 2.06 | 2.06 | 60.15 | | zlib -1 | 77260026 | 2.895 | 2.744 | 73.23 | 75.85 | 0.27 | | zlib -3 | 72972206 | 4.116 | 2.905 | 51.50 | 52.79 | 0.27 | | zlib -6 | 68190360 | 9.633 | 3.109 | 22.01 | 22.24 | 0.27 | | zlib -9 | 67613382 | 22.554 | 3.135 | 9.40 | 9.44 | 0.27 | I benchmarked zstd decompression using the same method on the same machine. The benchmark file is located in the upstream zstd repo under `contrib/linux-kernel/zstd_decompress_test.c` [4]. The memory reported is the amount of memory required to decompress data compressed with the given compression level. If you know the maximum size of your input, you can reduce the memory usage of decompression irrespective of the compression level. | Method | Time (s) | MB/s | Adjusted MB/s | Memory (MB) | |----------|----------|---------|---------------|-------------| | none | 0.025 | 8479.54 | - | - | | zstd -1 | 0.358 | 592.15 | 636.60 | 0.84 | | zstd -3 | 0.396 | 535.32 | 571.40 | 1.46 | | zstd -5 | 0.396 | 535.32 | 571.40 | 1.46 | | zstd -10 | 0.374 | 566.81 | 607.42 | 2.51 | | zstd -15 | 0.379 | 559.34 | 598.84 | 4.61 | | zstd -19 | 0.412 | 514.54 | 547.77 | 8.80 | | zlib -1 | 0.940 | 225.52 | 231.68 | 0.04 | | zlib -3 | 0.883 | 240.08 | 247.07 | 0.04 | | zlib -6 | 0.844 | 251.17 | 258.84 | 0.04 | | zlib -9 | 0.837 | 253.27 | 287.64 | 0.04 | Tested in userland using the test-suite in the zstd repo under `contrib/linux-kernel/test/UserlandTest.cpp` [5] by mocking the kernel functions. Fuzz tested using libfuzzer [6] with the fuzz harnesses under `contrib/linux-kernel/test/{RoundTripCrash.c,DecompressCrash.c}` [7] [8] with ASAN, UBSAN, and MSAN. Additionaly, it was tested while testing the BtrFS and SquashFS patches coming next. [1] https://clang.llvm.org/docs/ClangFormat.html [2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/zstd_compress_test.c [3] http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia [4] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/zstd_decompress_test.c [5] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/UserlandTest.cpp [6] http://llvm.org/docs/LibFuzzer.html [7] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/RoundTripCrash.c [8] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/DecompressCrash.c zstd source repository: https://github.com/facebook/zstd Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
2017-08-10 05:35:53 +03:00
config ZSTD_COMPRESS
select XXHASH
tristate
config ZSTD_DECOMPRESS
select XXHASH
tristate
source "lib/xz/Kconfig"
#
# These all provide a common interface (hence the apparent duplication with
# ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
#
config DECOMPRESS_GZIP
select ZLIB_INFLATE
tristate
config DECOMPRESS_BZIP2
tristate
config DECOMPRESS_LZMA
tristate
config DECOMPRESS_XZ
select XZ_DEC
tristate
config DECOMPRESS_LZO
select LZO_DECOMPRESS
tristate
config DECOMPRESS_LZ4
select LZ4_DECOMPRESS
tristate
[PATCH] ia64 uncached alloc This patch contains the ia64 uncached page allocator and the generic allocator (genalloc). The uncached allocator was formerly part of the SN2 mspec driver but there are several other users of it so it has been split off from the driver. The generic allocator can be used by device driver to manage special memory etc. The generic allocator is based on the allocator from the sym53c8xx_2 driver. Various users on ia64 needs uncached memory. The SGI SN architecture requires it for inter-partition communication between partitions within a large NUMA cluster. The specific user for this is the XPC code. Another application is large MPI style applications which use it for synchronization, on SN this can be done using special 'fetchop' operations but it also benefits non SN hardware which may use regular uncached memory for this purpose. Performance of doing this through uncached vs cached memory is pretty substantial. This is handled by the mspec driver which I will push out in a seperate patch. Rather than creating a specific allocator for just uncached memory I came up with genalloc which is a generic purpose allocator that can be used by device drivers and other subsystems as they please. For instance to handle onboard device memory. It was derived from the sym53c7xx_2 driver's allocator which is also an example of a potential user (I am refraining from modifying sym2 right now as it seems to have been under fairly heavy development recently). On ia64 memory has various properties within a granule, ie. it isn't safe to access memory as uncached within the same granule as currently has memory accessed in cached mode. The regular system therefore doesn't utilize memory in the lower granules which is mixed in with device PAL code etc. The uncached driver walks the EFI memmap and pulls out the spill uncached pages and sticks them into the uncached pool. Only after these chunks have been utilized, will it start converting regular cached memory into uncached memory. Hence the reason for the EFI related code additions. Signed-off-by: Jes Sorensen <jes@wildopensource.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-22 04:15:02 +04:00
#
# Generic allocator support is selected if needed
#
config GENERIC_ALLOCATOR
bool
[PATCH] ia64 uncached alloc This patch contains the ia64 uncached page allocator and the generic allocator (genalloc). The uncached allocator was formerly part of the SN2 mspec driver but there are several other users of it so it has been split off from the driver. The generic allocator can be used by device driver to manage special memory etc. The generic allocator is based on the allocator from the sym53c8xx_2 driver. Various users on ia64 needs uncached memory. The SGI SN architecture requires it for inter-partition communication between partitions within a large NUMA cluster. The specific user for this is the XPC code. Another application is large MPI style applications which use it for synchronization, on SN this can be done using special 'fetchop' operations but it also benefits non SN hardware which may use regular uncached memory for this purpose. Performance of doing this through uncached vs cached memory is pretty substantial. This is handled by the mspec driver which I will push out in a seperate patch. Rather than creating a specific allocator for just uncached memory I came up with genalloc which is a generic purpose allocator that can be used by device drivers and other subsystems as they please. For instance to handle onboard device memory. It was derived from the sym53c7xx_2 driver's allocator which is also an example of a potential user (I am refraining from modifying sym2 right now as it seems to have been under fairly heavy development recently). On ia64 memory has various properties within a granule, ie. it isn't safe to access memory as uncached within the same granule as currently has memory accessed in cached mode. The regular system therefore doesn't utilize memory in the lower granules which is mixed in with device PAL code etc. The uncached driver walks the EFI memmap and pulls out the spill uncached pages and sticks them into the uncached pool. Only after these chunks have been utilized, will it start converting regular cached memory into uncached memory. Hence the reason for the EFI related code additions. Signed-off-by: Jes Sorensen <jes@wildopensource.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-22 04:15:02 +04:00
#
# reed solomon support is select'ed if needed
#
config REED_SOLOMON
tristate
config REED_SOLOMON_ENC8
bool
config REED_SOLOMON_DEC8
bool
config REED_SOLOMON_ENC16
bool
config REED_SOLOMON_DEC16
bool
lib: add shared BCH ECC library This is a new software BCH encoding/decoding library, similar to the shared Reed-Solomon library. Binary BCH (Bose-Chaudhuri-Hocquenghem) codes are widely used to correct errors in NAND flash devices requiring more than 1-bit ecc correction; they are generally better suited for NAND flash than RS codes because NAND bit errors do not occur in bursts. Latest SLC NAND devices typically require at least 4-bit ecc protection per 512 bytes block. This library provides software encoding/decoding, but may also be used with ASIC/SoC hardware BCH engines to perform error correction. It is being currently used for this purpose on an OMAP3630 board (4bit/8bit HW BCH). It has also been used to decode raw dumps of NAND devices with on-die BCH ecc engines (e.g. Micron 4bit ecc SLC devices). Latest NAND devices (including SLC) can exhibit high error rates (typically a dozen or more bitflips per hour during stress tests); in order to minimize the performance impact of error correction, this library implements recently developed algorithms for fast polynomial root finding (see bch.c header for details) instead of the traditional exhaustive Chien root search; a few performance figures are provided below: Platform: arm926ejs @ 468 MHz, 32 KiB icache, 16 KiB dcache BCH ecc : 4-bit per 512 bytes Encoding average throughput: 250 Mbits/s Error correction time (compared with Chien search): average worst average (Chien) worst (Chien) ---------------------------------------------------------- 1 bit 8.5 µs 11 µs 200 µs 383 µs 2 bit 9.7 µs 12.5 µs 477 µs 728 µs 3 bit 18.1 µs 20.6 µs 758 µs 1010 µs 4 bit 19.5 µs 23 µs 1028 µs 1280 µs In the above figures, "worst" is meant in terms of error pattern, not in terms of cache miss / page faults effects (not taken into account here). The library has been extensively tested on the following platforms: x86, x86_64, arm926ejs, omap3630, qemu-ppc64, qemu-mips. Signed-off-by: Ivan Djelic <ivan.djelic@parrot.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2011-03-11 13:05:32 +03:00
#
# BCH support is selected if needed
#
config BCH
tristate
config BCH_CONST_PARAMS
bool
lib: add shared BCH ECC library This is a new software BCH encoding/decoding library, similar to the shared Reed-Solomon library. Binary BCH (Bose-Chaudhuri-Hocquenghem) codes are widely used to correct errors in NAND flash devices requiring more than 1-bit ecc correction; they are generally better suited for NAND flash than RS codes because NAND bit errors do not occur in bursts. Latest SLC NAND devices typically require at least 4-bit ecc protection per 512 bytes block. This library provides software encoding/decoding, but may also be used with ASIC/SoC hardware BCH engines to perform error correction. It is being currently used for this purpose on an OMAP3630 board (4bit/8bit HW BCH). It has also been used to decode raw dumps of NAND devices with on-die BCH ecc engines (e.g. Micron 4bit ecc SLC devices). Latest NAND devices (including SLC) can exhibit high error rates (typically a dozen or more bitflips per hour during stress tests); in order to minimize the performance impact of error correction, this library implements recently developed algorithms for fast polynomial root finding (see bch.c header for details) instead of the traditional exhaustive Chien root search; a few performance figures are provided below: Platform: arm926ejs @ 468 MHz, 32 KiB icache, 16 KiB dcache BCH ecc : 4-bit per 512 bytes Encoding average throughput: 250 Mbits/s Error correction time (compared with Chien search): average worst average (Chien) worst (Chien) ---------------------------------------------------------- 1 bit 8.5 µs 11 µs 200 µs 383 µs 2 bit 9.7 µs 12.5 µs 477 µs 728 µs 3 bit 18.1 µs 20.6 µs 758 µs 1010 µs 4 bit 19.5 µs 23 µs 1028 µs 1280 µs In the above figures, "worst" is meant in terms of error pattern, not in terms of cache miss / page faults effects (not taken into account here). The library has been extensively tested on the following platforms: x86, x86_64, arm926ejs, omap3630, qemu-ppc64, qemu-mips. Signed-off-by: Ivan Djelic <ivan.djelic@parrot.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2011-03-11 13:05:32 +03:00
help
Drivers may select this option to force specific constant
values for parameters 'm' (Galois field order) and 't'
(error correction capability). Those specific values must
be set by declaring default values for symbols BCH_CONST_M
and BCH_CONST_T.
Doing so will enable extra compiler optimizations,
improving encoding and decoding performance up to 2x for
usual (m,t) values (typically such that m*t < 200).
When this option is selected, the BCH library supports
only a single (m,t) configuration. This is mainly useful
for NAND flash board drivers requiring known, fixed BCH
parameters.
config BCH_CONST_M
int
range 5 15
help
Constant value for Galois field order 'm'. If 'k' is the
number of data bits to protect, 'm' should be chosen such
that (k + m*t) <= 2**m - 1.
Drivers should declare a default value for this symbol if
they select option BCH_CONST_PARAMS.
config BCH_CONST_T
int
help
Constant value for error correction capability in bits 't'.
Drivers should declare a default value for this symbol if
they select option BCH_CONST_PARAMS.
#
# Textsearch support is select'ed if needed
#
config TEXTSEARCH
bool
config TEXTSEARCH_KMP
tristate
config TEXTSEARCH_BM
tristate
config TEXTSEARCH_FSM
tristate
config BTREE
bool
config INTERVAL_TREE
bool
help
Simple, embeddable, interval-tree. Can find the start of an
overlapping range in log(n) time and then iterate over all
overlapping nodes. The algorithm is implemented as an
augmented rbtree.
See:
Documentation/rbtree.txt
for more information.
config RADIX_TREE_MULTIORDER
bool
Add a generic associative array implementation. Add a generic associative array implementation that can be used as the container for keyrings, thereby massively increasing the capacity available whilst also speeding up searching in keyrings that contain a lot of keys. This may also be useful in FS-Cache for tracking cookies. Documentation is added into Documentation/associative_array.txt Some of the properties of the implementation are: (1) Objects are opaque pointers. The implementation does not care where they point (if anywhere) or what they point to (if anything). [!] NOTE: Pointers to objects _must_ be zero in the two least significant bits. (2) Objects do not need to contain linkage blocks for use by the array. This permits an object to be located in multiple arrays simultaneously. Rather, the array is made up of metadata blocks that point to objects. (3) Objects are labelled as being one of two types (the type is a bool value). This information is stored in the array, but has no consequence to the array itself or its algorithms. (4) Objects require index keys to locate them within the array. (5) Index keys must be unique. Inserting an object with the same key as one already in the array will replace the old object. (6) Index keys can be of any length and can be of different lengths. (7) Index keys should encode the length early on, before any variation due to length is seen. (8) Index keys can include a hash to scatter objects throughout the array. (9) The array can iterated over. The objects will not necessarily come out in key order. (10) The array can be iterated whilst it is being modified, provided the RCU readlock is being held by the iterator. Note, however, under these circumstances, some objects may be seen more than once. If this is a problem, the iterator should lock against modification. Objects will not be missed, however, unless deleted. (11) Objects in the array can be looked up by means of their index key. (12) Objects can be looked up whilst the array is being modified, provided the RCU readlock is being held by the thread doing the look up. The implementation uses a tree of 16-pointer nodes internally that are indexed on each level by nibbles from the index key. To improve memory efficiency, shortcuts can be emplaced to skip over what would otherwise be a series of single-occupancy nodes. Further, nodes pack leaf object pointers into spare space in the node rather than making an extra branch until as such time an object needs to be added to a full node. Signed-off-by: David Howells <dhowells@redhat.com>
2013-09-24 13:35:17 +04:00
config ASSOCIATIVE_ARRAY
bool
help
Generic associative array. Can be searched and iterated over whilst
it is being modified. It is also reasonably quick to search and
modify. The algorithms are non-recursive, and the trees are highly
capacious.
See:
Documentation/assoc_array.txt
for more information.
config HAS_IOMEM
bool
depends on !NO_IOMEM
select GENERIC_IO
default y
config HAS_IOPORT_MAP
bool
depends on HAS_IOMEM && !NO_IOPORT_MAP
default y
config HAS_DMA
bool
depends on !NO_DMA
default y
config SGL_ALLOC
bool
default n
config DMA_DIRECT_OPS
bool
depends on HAS_DMA && (!64BIT || ARCH_DMA_ADDR_T_64BIT)
default n
config DMA_VIRT_OPS
bool
depends on HAS_DMA && (!64BIT || ARCH_DMA_ADDR_T_64BIT)
default n
config CHECK_SIGNATURE
bool
config CPUMASK_OFFSTACK
bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
help
Use dynamic allocation for cpumask_var_t, instead of putting
them on the stack. This is a bit more expensive, but avoids
stack overflow.
config CPU_RMAP
bool
depends on SMP
dql: Dynamic queue limits Implementation of dynamic queue limits (dql). This is a libary which allows a queue limit to be dynamically managed. The goal of dql is to set the queue limit, number of objects to the queue, to be minimized without allowing the queue to be starved. dql would be used with a queue which has these properties: 1) Objects are queued up to some limit which can be expressed as a count of objects. 2) Periodically a completion process executes which retires consumed objects. 3) Starvation occurs when limit has been reached, all queued data has actually been consumed but completion processing has not yet run, so queuing new data is blocked. 4) Minimizing the amount of queued data is desirable. A canonical example of such a queue would be a NIC HW transmit queue. The queue limit is dynamic, it will increase or decrease over time depending on the workload. The queue limit is recalculated each time completion processing is done. Increases occur when the queue is starved and can exponentially increase over successive intervals. Decreases occur when more data is being maintained in the queue than needed to prevent starvation. The number of extra objects, or "slack", is measured over successive intervals, and to avoid hysteresis the limit is only reduced by the miminum slack seen over a configurable time period. dql API provides routines to manage the queue: - dql_init is called to intialize the dql structure - dql_reset is called to reset dynamic values - dql_queued called when objects are being enqueued - dql_avail returns availability in the queue - dql_completed is called when objects have be consumed in the queue Configuration consists of: - max_limit, maximum limit - min_limit, minimum limit - slack_hold_time, time to measure instances of slack before reducing queue limit Signed-off-by: Tom Herbert <therbert@google.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-11-28 20:32:35 +04:00
config DQL
bool
config GLOB
bool
# This actually supports modular compilation, but the module overhead
# is ridiculous for the amount of code involved. Until an out-of-tree
# driver asks for it, we'll just link it directly it into the kernel
# when required. Since we're ignoring out-of-tree users, there's also
# no need bother prompting for a manual decision:
# prompt "glob_match() function"
help
This option provides a glob_match function for performing
simple text pattern matching. It originated in the ATA code
to blacklist particular drive models, but other device drivers
may need similar functionality.
All drivers in the Linux kernel tree that require this function
should automatically select this option. Say N unless you
are compiling an out-of tree driver which tells you that it
depends on this.
config GLOB_SELFTEST
tristate "glob self-test on init"
depends on GLOB
help
This option enables a simple self-test of the glob_match
function on startup. It is primarily useful for people
working on the code to ensure they haven't introduced any
regressions.
It only adds a little bit of code and slows kernel boot (or
module load) by a small amount, so you're welcome to play with
it, but you probably don't need it.
#
# Netlink attribute parsing support is select'ed if needed
#
config NLATTR
bool
#
# Generic 64-bit atomic support is selected if needed
#
config GENERIC_ATOMIC64
bool
config LRU_CACHE
tristate
config CLZ_TAB
bool
config CORDIC
tristate "CORDIC algorithm"
help
This option provides an implementation of the CORDIC algorithm;
calculations are in fixed point. Module will be called cordic.
config DDR
bool "JEDEC DDR data"
help
Data from JEDEC specs for DDR SDRAM memories,
particularly the AC timing parameters and addressing
information. This data is useful for drivers handling
DDR SDRAM controllers.
config IRQ_POLL
bool "IRQ polling library"
help
Helper library to poll interrupt mitigation using polling.
config MPILIB
tristate
select CLZ_TAB
help
Multiprecision maths library from GnuPG.
It is used to implement RSA digital signature verification,
which is used by IMA/EVM digital signature extension.
config SIGNATURE
tristate
depends on KEYS
select CRYPTO
select CRYPTO_SHA1
select MPILIB
help
Digital signature verification. Currently only RSA is supported.
Implementation is done using GnuPG MPI library
#
# libfdt files, only selected if needed.
#
config LIBFDT
bool
config OID_REGISTRY
tristate
help
Enable fast lookup object identifier registry.
config UCS2_STRING
tristate
source "lib/fonts/Kconfig"
config SG_SPLIT
def_bool n
help
Provides a helper to split scatterlists into chunks, each chunk being
a scatterlist. This should be selected by a driver or an API which
whishes to split a scatterlist amongst multiple DMA channels.
config SG_POOL
def_bool n
help
Provides a helper to allocate chained scatterlists. This should be
selected by a driver or an API which whishes to allocate chained
scatterlist.
#
# sg chaining option
#
config ARCH_HAS_SG_CHAIN
def_bool n
config ARCH_HAS_PMEM_API
bool
x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations The pmem driver has a need to transfer data with a persistent memory destination and be able to rely on the fact that the destination writes are not cached. It is sufficient for the writes to be flushed to a cpu-store-buffer (non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync() to ensure data-writes have reached a power-fail-safe zone in the platform. The fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn around and fence previous writes with an "sfence". Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and memcpy_flushcache, that guarantee that the destination buffer is not dirty in the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines will be used to replace the "pmem api" (include/linux/pmem.h + arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache() and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE config symbol, and fallback to copy_from_iter_nocache() and plain memcpy() otherwise. This is meant to satisfy the concern from Linus that if a driver wants to do something beyond the normal nocache semantics it should be something private to that driver [1], and Al's concern that anything uaccess related belongs with the rest of the uaccess code [2]. The first consumer of this interface is a new 'copy_from_iter' dax operation so that pmem can inject cache maintenance operations without imposing this overhead on other dax-capable drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html Cc: <x86@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-05-29 22:22:50 +03:00
config ARCH_HAS_UACCESS_FLUSHCACHE
bool
mm, kasan: stackdepot implementation. Enable stackdepot for SLAB Implement the stack depot and provide CONFIG_STACKDEPOT. Stack depot will allow KASAN store allocation/deallocation stack traces for memory chunks. The stack traces are stored in a hash table and referenced by handles which reside in the kasan_alloc_meta and kasan_free_meta structures in the allocated memory chunks. IRQ stack traces are cut below the IRQ entry point to avoid unnecessary duplication. Right now stackdepot support is only enabled in SLAB allocator. Once KASAN features in SLAB are on par with those in SLUB we can switch SLUB to stackdepot as well, thus removing the dependency on SLUB stack bookkeeping, which wastes a lot of memory. This patch is based on the "mm: kasan: stack depots" patch originally prepared by Dmitry Chernenkov. Joonsoo has said that he plans to reuse the stackdepot code for the mm/page_owner.c debugging facility. [akpm@linux-foundation.org: s/depot_stack_handle/depot_stack_handle_t] [aryabinin@virtuozzo.com: comment style fixes] Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrey Konovalov <adech.fo@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-26 00:22:08 +03:00
config STACKDEPOT
bool
select STACKTRACE
config SBITMAP
bool
config PARMAN
tristate "parman" if COMPILE_TEST
config PRIME_NUMBERS
tristate
config STRING_SELFTEST
tristate "Test string functions"
endmenu
config GENERIC_ASHLDI3
bool
config GENERIC_ASHRDI3
bool
config GENERIC_LSHRDI3
bool
config GENERIC_MULDI3
bool
config GENERIC_CMPDI2
bool
config GENERIC_UCMPDI2
bool