This is a completely rewritten scsipi_xfer execution engine, and the
associated changes to HBA drivers. Overview of changes & features:
- All xfers are queued in the mid-layer, rather than doing so in an
ad-hoc fashion in individual adapter drivers.
- Adapter/channel resource management in the mid-layer, avoids even trying
to start running an xfer if the adapter/channel doesn't have the resources.
- Better communication between the mid-layer and the adapters.
- Asynchronous event notification mechanism from adapter to mid-layer and
peripherals.
- Better peripheral queue management: freeze/thaw, sorted requeueing during
recovery, etc.
- Clean separation of peripherals, adapters, and adapter channels (no more
scsipi_link).
- Kernel thread for each scsipi_channel makes error recovery much easier
(no more dealing with interrupt context when recovering from an error).
- Mid-layer support for tagged queueing: commands can have the tag type
set explicitly, tag IDs are allocated in the mid-layer (thus eliminating
the need to use buggy tag ID allocation schemes in many adapter drivers).
- support for QUEUE FULL and CHECK CONDITION status in mid-layer; the command
will be requeued, or a REQUEST SENSE will be sent as appropriate.
Just before the merge syssrc has been tagged with thorpej_scsipi_beforemerge
This is the way that e.g. HP recommends (but then some of their printers
have a bug that makes the input pipe useless anyway).
Also try reset both the 1.0 and 1.1 ways.
fine for systems without generic soft interrupts, even if it is
a little sub-optimal. Consider it a penalty for ports not
implementing a kernel API.
Addresses kern/11957. The PR has been open for 4 months, and
I have work blocked on the continued existence of splimp() in
the networking code.
(because we register the interrupt with IPL_SOFTNET). However, if
we're using a callout, then splusb == splsoftclock (because the
callouts happen from the softclock interrupt).
Note that splsoftnet blocks softclock interrupts, but this is
meant to better describe what's going on.
