[Libre-soc-dev] Wishbone and House Contract Of Sale Proposition

[Andrey Miroshnikov]

On 28/10/2021 19:22, Richard Wilbur wrote:
> I guess I was looking at this initially from the perspective of a
> multi-master backplane bus, such as PCI.  It sounds like we must be
> talking about an on-chip bus.Yeah, the Wishbone bus was designed to be an open-source interconnect 
solution for connecting IP together (in FPGAs and ASICs). Here's the 
spec (for 128 pages, it's very readable, I have a printed copy for 
reference):
http://cdn.opencores.org/downloads/wbspec_b4.pdf


As for speculative execution, I'm not too knowledgable as to why the 
queue is dropped. I think of it as a failed branch-prediction, where the 
cpu pipe-line would have to be flushed, except in this case the 
Shadowing principle is more generalised than branch-prediction.
As mentioned by Luke in IRC 
(https://libre-soc.org/irclog/%23libre-soc.2021-10-28.log.html):
'''
Shadowing can be used for
Branch Prediction
Speculative Execution
Predication
Memory "Total Store Order" preservation
Cache access resolution
'''


Andrey