[Linux-cluster] Re: [PATCH 00/14] GFS

[Jörn Engel]

On Fri, 5 August 2005 17:44:52 +0800, David Teigland wrote:
> 
> linux/lib/crc32table.h : crc32table_le[] is the same as our crc_32_tab[].
> This looks like a standard that's not going to change, as you've said, so
> including crc32table.h and getting rid of our own table would work fine.
> 
> Do we go a step beyond this and use say the crc32() function from
> linux/crc32.h?  Is this _function_ as standard and unchanging as the table
> of crcs?  In my tests it doesn't produce the same results as our
> gfs2_disk_hash() function, even with both using the same crc table.  I
> don't mind adopting a new function and just writing a user space
> equivalent for the tools if it's a fixed standard.

The function is basically set in stone.  Variants exists depending on
how it is called.  I know of four variants, but there may be more:

1. Initial value is 0
2. Initial value is 0xffffffff
a) Result is taken as-is
b) Result is XORed with 0xffffffff

Maybe your code implements 1a, while you tried 2b with the lib/crc32.c
function or something similar?

Jörn

-- 
And spam is a useful source of entropy for /dev/random too!
-- Jasmine Strong