Re: [microblaze-uclinux] question on the unaligned exception..

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi Prasad,

DeviPrasad Natesan wrote:
> This might be a dumb question. Do i need to enable unalign exception
> for the microblaze. Can i safely assume that all the uClinux drivers
> and the uClinux-dist application never use unaligned access.

It should not be necessary to enable the unaligned exception support for a
standard MicroBlaze kernel and core drivers.

I implemented the unaligned exception handling as part of an experiment to see
if it was quicker for the ethernet driver to do an alignment copy on incoming
packets, or take an unaligned exception on every TCP stack access to the packet
header.  Turned out the memcpy was quicker in almost every case (exceptions are
expensive!).

John

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