crc32c_intel vs libcrc32c

crc32c_intel vs libcrc32c

[Peter Butler]

I have a system with SSE4.2 and thus hardware support for CRC32C 
calculations.  I can manually load the crc32c_intel module, however when I 
do an lsmod I see:

[root@peterFC16 ~]# lsmod | grep -E 'crc|sctp'
crc32c_intel           12770  0 
libcrc32c              12603  1 sctp
sctp                  203671  2 

Does this mean that SCTP is not actually using the crc32c_intel module? If 
so, how do I remedy that?

Re: crc32c_intel vs libcrc32c

[Vlad Yasevich]

On 05/31/2012 12:28 PM, Peter Butler wrote:
> I have a system with SSE4.2 and thus hardware support for CRC32C
> calculations.  I can manually load the crc32c_intel module, however when I
> do an lsmod I see:
>
> [root@peterFC16 ~]# lsmod | grep -E 'crc|sctp'
> crc32c_intel           12770  0
> libcrc32c              12603  1 sctp
> sctp                  203671  2
>
> Does this mean that SCTP is not actually using the crc32c_intel module? If
> so, how do I remedy that?
>
>

What happens if you don't manually load crc32c_intel?  Does it still 
show up in lsmod output?

I think you are already using it.  libcrc32c doesn't do anything itself 
any more.  It's a wrapper that's calling the crypto api to compute the 
checksum.  Here it depends which crypto module it loads.  It could load 
crc32c_intel or it could load crc32c_generic.  If you see intel loaded, 
that's what you are using.  If you see _generic loaded, then that's 
what's available.

-vlad

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