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Date:      Tue, 25 May 2010 09:34:48 -0700
From:      "Matthew Fleming" <matthew.fleming@isilon.com>
To:        <freebsd-arch@freebsd.org>
Subject:   crc32 table
Message-ID:  <06D5F9F6F655AD4C92E28B662F7F853E021D4D9D@seaxch09.desktop.isilon.com>

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The crc32 table in sys/libkern/crc32.c uses the polynomial 0xedb88320, =
which Wikipedia tells me is the standard for IEEE 802.3 and is used for =
MPEG-2 among other things.  I am curious why this polynomial was chosen =
for the one crc32 implementation currently supported by the kernel.  One =
reason I ask is that SSE 4.2 has a crc32 instruction, but it uses the =
Castagnoli polynomial of 0x82f63b78, which is used by iSCSI and SCTP.

Is there an interest in another crc32 implementation for the kernel =
which uses this polynomial and uses the SSE 4.2 instruction when =
available?  (This support would require kib's FPU patch).

Thanks,
matthew



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