diff options
| author | Eric Biggers <ebiggers@google.com> | 2025-01-29 19:51:22 -0800 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2025-02-08 20:06:24 -0800 |
| commit | f6c3f6fb32301dfb35fed3ef8a39de3e13c67ad2 (patch) | |
| tree | f2a3e8d2e3f7dc1b44e898c9999612fbe6c3af8d /lib/crc64.c | |
| parent | 0fcec0b73adc5f86597d342062114b77bcf7ec9d (diff) | |
lib/crc64: rename CRC64-Rocksoft to CRC64-NVME
This CRC64 variant comes from the NVME NVM Command Set Specification
(https://nvmexpress.org/wp-content/uploads/NVM-Express-NVM-Command-Set-Specification-1.0e-2024.07.29-Ratified.pdf).
The "Rocksoft Model CRC Algorithm", published in 1993 and available at
https://www.zlib.net/crc_v3.txt, is a generalized CRC algorithm that can
calculate any variant of CRC, given a list of parameters such as
polynomial, bit order, etc. It is not a CRC variant.
The NVME NVM Command Set Specification has a table that gives the
"Rocksoft Model Parameters" for the CRC variant it uses. When support
for this CRC variant was added to Linux, this table seems to have been
misinterpreted as naming the CRC variant the "Rocksoft" CRC. In fact,
the table names the CRC variant as the "NVM Express 64b CRC".
Most implementations of this CRC variant outside Linux have been calling
it CRC64-NVME. Therefore, update Linux to match.
While at it, remove the superfluous "update" from the function name, so
crc64_rocksoft_update() is now just crc64_nvme(), matching most of the
other CRC library functions.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250130035130.180676-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'lib/crc64.c')
| -rw-r--r-- | lib/crc64.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/lib/crc64.c b/lib/crc64.c index b5136fb4c199..d6f3f245eede 100644 --- a/lib/crc64.c +++ b/lib/crc64.c @@ -22,8 +22,8 @@ * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 + * x^7 + x^4 + x + 1 * - * crc64rocksoft[256] table is from the Rocksoft specification polynomial - * defined as, + * crc64nvmetable[256] uses the CRC64 polynomial from the NVME NVM Command Set + * Specification and uses least-significant-bit first bit order: * * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 + * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 + @@ -63,7 +63,7 @@ u64 __pure crc64_be(u64 crc, const void *p, size_t len) } EXPORT_SYMBOL_GPL(crc64_be); -u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len) +u64 __pure crc64_nvme_generic(u64 crc, const void *p, size_t len) { const unsigned char *_p = p; size_t i; @@ -71,8 +71,8 @@ u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len) crc = ~crc; for (i = 0; i < len; i++) - crc = (crc >> 8) ^ crc64rocksofttable[(crc & 0xff) ^ *_p++]; + crc = (crc >> 8) ^ crc64nvmetable[(crc & 0xff) ^ *_p++]; return ~crc; } -EXPORT_SYMBOL_GPL(crc64_rocksoft_generic); +EXPORT_SYMBOL_GPL(crc64_nvme_generic); |