Microblaze PLB vs. OPB busses

Now that Microblaze has support for either PLB or OPB, what are the
advantages and disadvantages of PLB?  I started looking at the PLB
specification, but I don't yet understand it well enough to have any
feel for how it compares to OPB, or why it might be preferred.

Thanks,
Eric

Eric Smith wrote:
> Now that Microblaze has support for either PLB or OPB, what are the
> advantages and disadvantages of PLB?

PLB can arbitrate and queue the next transaction address during the 
current transaction's dataphase. This potentially reduces the dead time 
between transactions.

Also PLB has separate read and write datapaths, which can operate 
simultaneously in some cases.

I don't know if PLB will make your microblaze go faster, but it 
certainly has potential to make your DMA devices go faster.

-Jeff