Network buffers, MPC860 and data caching

[Charles-Antoine Gauthier]

Nick.SIMON at syntegra.bt.co.uk wrote:
> 
> I'd like to use data caching to speed things up on my MPC860-based board.
> However, buffers used by the SCCs e.g. for network transmit & receive must
> not be in cached memory.  To achieve this I intend to reserve a chunk of
> memory which has caching turned off.  This means the network buffers have to
> be allocated from this reserved memory.
> 
> Does anyone know of a tidy way to take control of the network stack's buffer
> allocation?
> 
> -- Nick Simon

The buffer descriptors go into non-cachable memory that is shared
between the PPC core and the I/O processor. The buffers themselves can
live happily in cachable RAM. We introduced a cache manager to deal with
this very issue. It works well for us. Our code should be available in
the OARcorp CVS repository under the mpc8xx and mbx8xx nodes.

-- 
Charles-Antoine Gauthier
Institute for Information Technology   Institut de technologie de
l'information
National Research Council of Canada    Conseil national de recherches du
Canada