CentOS - Jun 2015 - Why is sha256-generic preferred over sha256-ssse3?

The newly-released kernel v2.6.32-504.23.4.el6 includes the back-ported
SHA256-SSSE3 driver.

Why is the generic version of the SHA256 driver selected at runtime instead of
the SSSE3 version on this x86_64 system?

Yes, my CPU does support the SSSE3 instruction set, and the use of SHA256 is
invoked by the LUKS "cipher=aes-cbc-essiv:sha256" option.

On the running system I see that the sha256-ssse3 driver is not loaded.  Further
evidence that the generic driver is in use:

# grep sha256 /proc/crypto
name         : sha256
driver       : sha256-generic

So... what's the trick to using the sha256-ssse3 driver instead of the
generic driver?

Thanks.

On 06/09/2015 10:37 AM, Steve Snyder wrote:
> Why is the generic version of the SHA256 driver selected at runtime instead
of the SSSE3 version on this x86_64 system?
Because that driver is built-in to the kernel.  If you want to use the 
ssse3 version, load it.  There are a handful of ways to do so. For 
instance, you could edit /etc/modules-load.d/sha256.conf and add one 
line with the name of the module.