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
succeeds, note that we now are valid.
- Don't attempt to try and run initialize element status from interrupt level-
we don't really support that yet. Also, key more correctly off of ASC/ASCQ
instead of just the sense key.
- Make the practice of doing an INITIALIZE ELEMENT STATUS automatically when
we get params (from chopen time even) a policy decision that is not the
default for now- this can be a dangerous practice as well as time consuming.
It's dangerous in that you can have a hung open when all you really want
to do is do a read of parameters- and parameters, including slot status,
are perfectly fine to read even before an INITIALIZE ELEMENT STATUS is
done- all the elements whos status your read are going to be marked with
an exception- so leave it up to the application to decide how important
this is.
- `flags' is now gone, replaced with `xs_control' and `xs_status'.
- Massive cleanup of the control flags. Now we explicitly say that
a job is to complete asynchronously, rather than relying on side-effects,
and use a new flag to now that device discovery is being performed.
- Do SCSI device discovery interrupt-driven.
- Take note of magazine changes, and enqueue "Element Status Changed" events
that user processes can read or select on.
- Normalize some structure names.
- Report back more status about changer elements:
* Volume tags (e.g. barcode labels on the backs of your tapes)
* External device names (for drive units in a changer)
* Last element a unit of media was moved from
* Sense information for SCSI changer elements in EXCEPT condition
* Vendor-specific data if the user requests it.
- Add support for setting volume tags.
takes to do IELEM can be proportional to the number of elements, but is
also affected by wierd things like how readable the barcodes on the
media are. There are worst case scenarios I've seen where there are
white labels on the back of tapes with pencilled in labels which is
*just* close enough to being a bar code that an Exabyte 120 would
peer at them myopically and long enough for a *really* long time to
pass in inventorying the jukebox.
I've upped the limit to be proportional to 5 minutes per element. That
is long enough that someone I'm sure will complain about "you wait
to long and should time out" for broken h/w.
As is also noted in the PR, there are a lot of other issues here. It's
really also a question as to whether to update this driver or go
with CAM's driver. This one doesn't have switching between block
descriptors and not, doesn't support volume tag setting, and so on.
Time is limited. This PR should have been closed and fixed right away,
tho.
- Indent with tab of width 8.
- Use four column to indent continuation line.
- Fold long line if possible.
- Use return (xx) instead of return xx.
- Compare pointer against NULL instead of testing like boolean.
- Delete whitespace at the end of line.
- Delete whitespace in front of function call operator.
- Delete whitespace after cast.
- Dereference a pointer to function explicitly.
- Add an empty line after local variable declaration.
- Use NULL instead of (char *)0.
- Dont use block for single statement.
(currently only CD-ROM drives on i386). The sys/dev/scsipi system provides 2
busses to which devices can attach (scsibus and atapibus). This needed to
change some include files and structure names in the low level scsi drivers.
- Implement a simple quirks framework for changers.
- Add a quirk for the Spectra 9000 8mm tape library; it requires a
slightly-longer-than-1-minute delay to take tape inventory. Many
thanks to David Webster at Cygnus Solutions for testing this for me.
influence from the old driver (written by Stefan Grefen) and from
an autochanger driver written by the Systems Programming Group at the
University of Utah Computer Science Department (currently residing
in src/sys/arch/hp300/dev/ac.c).
- split softc size and match/attach out from cfdriver into
a new struct cfattach.
- new "attach" directive for files.*. May specify the name of
the cfattach structure, so that devices may be easily attached
to parents with different autoconfiguration semantics.
bouyer