PTI: Chained Q elements

Joe Breher joe at
Mon Mar 21 14:05:04 PDT 2011

* From the T10 Reflector (t10 at, posted by:
* Joe Breher <joe at>
In regards to the PTI chaining mechanism, there are a couple other things
that occurred to me after we left the topic. If we are chaining elements, it
seems to me that there would still be a requirement for multiple DMAs in
order to transfer an 'operation' between controller and host memory.
- We don't know that there would be chained elements until we DMA the first
element, and check it's CHAINING COUNT.
- with a circular Q, there is a discontinuity in memory addresses where the Q
wraps. Will a typical DMA controller wrap appropriately without further
Am I missing something?
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