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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>
262 lines
5.4 KiB
Plaintext
262 lines
5.4 KiB
Plaintext
#
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# Library configuration
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#
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config BINARY_PRINTF
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def_bool n
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menu "Library routines"
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config RAID6_PQ
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tristate
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config BITREVERSE
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tristate
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config RATIONAL
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boolean
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config GENERIC_FIND_FIRST_BIT
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bool
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config GENERIC_FIND_NEXT_BIT
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bool
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config GENERIC_FIND_LAST_BIT
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bool
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default y
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config CRC_CCITT
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tristate "CRC-CCITT functions"
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help
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This option is provided for the case where no in-kernel-tree
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modules require CRC-CCITT functions, but a module built outside
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the kernel tree does. Such modules that use library CRC-CCITT
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functions require M here.
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config CRC16
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tristate "CRC16 functions"
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help
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This option is provided for the case where no in-kernel-tree
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modules require CRC16 functions, but a module built outside
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the kernel tree does. Such modules that use library CRC16
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functions require M here.
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config CRC_T10DIF
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tristate "CRC calculation for the T10 Data Integrity Field"
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help
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This option is only needed if a module that's not in the
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kernel tree needs to calculate CRC checks for use with the
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SCSI data integrity subsystem.
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config CRC_ITU_T
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tristate "CRC ITU-T V.41 functions"
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help
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This option is provided for the case where no in-kernel-tree
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modules require CRC ITU-T V.41 functions, but a module built outside
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the kernel tree does. Such modules that use library CRC ITU-T V.41
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functions require M here.
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config CRC32
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tristate "CRC32 functions"
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default y
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select BITREVERSE
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help
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This option is provided for the case where no in-kernel-tree
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modules require CRC32 functions, but a module built outside the
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kernel tree does. Such modules that use library CRC32 functions
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require M here.
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config CRC7
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tristate "CRC7 functions"
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help
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This option is provided for the case where no in-kernel-tree
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modules require CRC7 functions, but a module built outside
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the kernel tree does. Such modules that use library CRC7
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functions require M here.
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config LIBCRC32C
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tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
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select CRYPTO
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select CRYPTO_CRC32C
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help
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This option is provided for the case where no in-kernel-tree
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modules require CRC32c functions, but a module built outside the
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kernel tree does. Such modules that use library CRC32c functions
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require M here. See Castagnoli93.
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Module will be libcrc32c.
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config AUDIT_GENERIC
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bool
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depends on AUDIT && !AUDIT_ARCH
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default y
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#
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# compression support is select'ed if needed
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#
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config ZLIB_INFLATE
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tristate
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config ZLIB_DEFLATE
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tristate
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config LZO_COMPRESS
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tristate
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config LZO_DECOMPRESS
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tristate
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source "lib/xz/Kconfig"
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#
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# These all provide a common interface (hence the apparent duplication with
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# ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
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#
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config DECOMPRESS_GZIP
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select ZLIB_INFLATE
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tristate
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config DECOMPRESS_BZIP2
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tristate
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config DECOMPRESS_LZMA
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tristate
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config DECOMPRESS_XZ
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select XZ_DEC
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tristate
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config DECOMPRESS_LZO
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select LZO_DECOMPRESS
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tristate
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#
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# Generic allocator support is selected if needed
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#
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config GENERIC_ALLOCATOR
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boolean
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#
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# reed solomon support is select'ed if needed
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#
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config REED_SOLOMON
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tristate
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config REED_SOLOMON_ENC8
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boolean
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config REED_SOLOMON_DEC8
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boolean
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config REED_SOLOMON_ENC16
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boolean
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config REED_SOLOMON_DEC16
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boolean
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#
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# BCH support is selected if needed
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#
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config BCH
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tristate
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config BCH_CONST_PARAMS
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boolean
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help
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Drivers may select this option to force specific constant
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values for parameters 'm' (Galois field order) and 't'
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(error correction capability). Those specific values must
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be set by declaring default values for symbols BCH_CONST_M
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and BCH_CONST_T.
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Doing so will enable extra compiler optimizations,
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improving encoding and decoding performance up to 2x for
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usual (m,t) values (typically such that m*t < 200).
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When this option is selected, the BCH library supports
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only a single (m,t) configuration. This is mainly useful
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for NAND flash board drivers requiring known, fixed BCH
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parameters.
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config BCH_CONST_M
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int
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range 5 15
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help
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Constant value for Galois field order 'm'. If 'k' is the
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number of data bits to protect, 'm' should be chosen such
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that (k + m*t) <= 2**m - 1.
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Drivers should declare a default value for this symbol if
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they select option BCH_CONST_PARAMS.
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config BCH_CONST_T
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int
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help
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Constant value for error correction capability in bits 't'.
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Drivers should declare a default value for this symbol if
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they select option BCH_CONST_PARAMS.
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#
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# Textsearch support is select'ed if needed
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#
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config TEXTSEARCH
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boolean
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config TEXTSEARCH_KMP
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tristate
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config TEXTSEARCH_BM
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tristate
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config TEXTSEARCH_FSM
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tristate
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config BTREE
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boolean
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config HAS_IOMEM
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boolean
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depends on !NO_IOMEM
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default y
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config HAS_IOPORT
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boolean
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depends on HAS_IOMEM && !NO_IOPORT
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default y
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config HAS_DMA
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boolean
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depends on !NO_DMA
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default y
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config CHECK_SIGNATURE
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bool
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config CPUMASK_OFFSTACK
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bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
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help
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Use dynamic allocation for cpumask_var_t, instead of putting
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them on the stack. This is a bit more expensive, but avoids
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stack overflow.
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config DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
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bool "Disable obsolete cpumask functions" if DEBUG_PER_CPU_MAPS
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depends on EXPERIMENTAL && BROKEN
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#
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# Netlink attribute parsing support is select'ed if needed
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#
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config NLATTR
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bool
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#
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# Generic 64-bit atomic support is selected if needed
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#
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config GENERIC_ATOMIC64
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bool
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config LRU_CACHE
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tristate
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config AVERAGE
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bool
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endmenu
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