The patch titled Subject: crc32: select an algorithm via Kconfig has been added to the -mm tree. Its filename is crc32-select-an-algorithm-via-kconfig.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: "Darrick J. Wong" <djwong@xxxxxxxxxx> Subject: crc32: select an algorithm via Kconfig Allow the kernel builder to choose a crc32* algorithm for the kernel. Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> Cc: Bob Pearson <rpearson@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/Kconfig | 43 +++++++++++++++++++++++++++++++++++++++++++ lib/crc32defs.h | 18 ++++++++++++++++++ 2 files changed, 61 insertions(+) diff -puN lib/Kconfig~crc32-select-an-algorithm-via-kconfig lib/Kconfig --- a/lib/Kconfig~crc32-select-an-algorithm-via-kconfig +++ a/lib/Kconfig @@ -77,6 +77,49 @@ config CRC32_SELFTEST 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 + +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 CRC7 tristate "CRC7 functions" help diff -puN lib/crc32defs.h~crc32-select-an-algorithm-via-kconfig lib/crc32defs.h --- a/lib/crc32defs.h~crc32-select-an-algorithm-via-kconfig +++ a/lib/crc32defs.h @@ -13,6 +13,24 @@ */ #define CRC32C_POLY_LE 0x82F63B78 +/* Try to choose an implementation variant via Kconfig */ +#ifdef CONFIG_CRC32_SLICEBY8 +# define CRC_LE_BITS 64 +# define CRC_BE_BITS 64 +#endif +#ifdef CONFIG_CRC32_SLICEBY4 +# define CRC_LE_BITS 32 +# define CRC_BE_BITS 32 +#endif +#ifdef CONFIG_CRC32_SARWATE +# define CRC_LE_BITS 8 +# define CRC_BE_BITS 8 +#endif +#ifdef CONFIG_CRC32_BIT +# define CRC_LE_BITS 1 +# define CRC_BE_BITS 1 +#endif + /* * How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64. * For less performance-sensitive, use 4 or 8 to save table size. _ Subject: Subject: crc32: select an algorithm via Kconfig Patches currently in -mm which might be from djwong@xxxxxxxxxx are linux-next.patch crc32-removed-two-instances-of-trailing-whitespaces.patch crc32-move-long-comment-about-crc32-fundamentals-to-documentation.patch crc32-simplify-unit-test-code.patch crc32-miscellaneous-cleanups.patch crc32-fix-mixing-of-endian-specific-types.patch crc32-make-crc__bits-definition-correspond-to-actual-bit-counts.patch crc32-add-slice-by-8-algorithm-to-existing-code.patch crc32-optimize-loop-counter-for-x86.patch crc32-add-note-about-this-patchset-to-crc32c.patch crc32-bolt-on-crc32c.patch crypto-crc32c-should-use-library-implementation.patch crc32-add-self-test-code-for-crc32c.patch crc32-select-an-algorithm-via-kconfig.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html