st0 at atapibus0 drive 1: <Seagate STT8000A, , 5.51> type 1 sequential
removable
Major changes may still happen in order to properly support other ATAPI
tape drives.
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
we have it.
* st_unmount(): reset density to the device default. This prevents using
stale density values after changing to a medium with different density.
Section 9.3.3 of the SCSI specs states that a device shall return the
density value specified in the last succesfull MODE SELECT after an
unload operation, in case it is not able to automatically determine
the density of the new medium.
after all, probing the device for acceptable parameters.
* In st_loadquirks(), copy mode-specific quirks from the quirk table
to `st_softc'; otherwise all such quirks save ST_Q_FORCE_BLKSIZE are ignored.
This is an attempt to allow people to change the default configuration
to try harder at 'mounting' a tape. This allows you to specify, in
seconds, the amount of time a non-control unit open will retry
(once per second) the scsipi_test_unit_ready when it tries to mount
the tape. It also turns off the over-verbose error reporting at
this time unless SCSIDEBUG is set.
The reason this is not enabled as a default is that it's a large change
of behaviour. I find it useful to 'try harder' at mounting a tape in
the tape driver, particularly when loaded via a media changer device
rather than specifying the delays in the backup program.
- `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.
Anyway, just because a drive doesn't support the LOAD (to BOT) command does
not mean that the drive doesn't support the UNLOAD command. Also note and
print errors in rewinds and unloads (and errors in writing closing filemarks
for same).
scsi_base.c to scsipi_base.c. Rename the functions from scsi_verbose.c
too, and rename the file itself. Cleaup includes too (scsi_*.h should not
be #included in scsipi_*.h files, which are supposed to be
common to atapi and scsi).
opened norewind and 2 filemarks are written at the end a phantom file
is left (just what I was afraid of, but I didn't think about it in
the last delta because somehow I had managed to convince myself that
this was a nonissue. It's not.).
So- in stdone clear ST_WRITTEN for regular reads. In st_close, preserve
the state of ST_WRITTEN, and if no error and 2FM@EOD for this device and
this is a no-rewind open, backspace one filemark. This should preserve
(for this mount session) FILE - FMK - FILE - FMK - FILE ... FILE FMK FMK EOD
sequencing.
This doesn't clean up the case of EOM appends- in this case you *will* still
get (after an MTEOM operation and a write of a file) a phantom empty file,
e.g. FILE - FMK FMK - FILE - FMK FMK EOD *unless* you follow the EOM operation
with an explicit backspace. The trouble is that this makes it difficult for
seamless interchange with other systems which don't necessarily follow.
The preferrable alternative would be to eliminate the 2FM@EOD except for
1/2" Reel tapes, but that has been pretty much nixed within developers.
filemark 'coz you opened write only and didn't do anything else,
call st_check_eod to possibly write TWO furshlugginer filemarks.
Also- return any errors from writing filemarks out of stclose.
like a no-rewind device. Secondly figure out whether the initial TUR
for a CTRL_MODE open resulted in a tape being actually found (if so,
then do a mount session).
Move the 'sun compatibility' behaviour into stdone && stclose- don't
mark a tape as having been written in stopenm, fer gosh sakes.
Also- to be fair and on review, kern/391 isn't really addressed by
the previous commits. In reviewing, I'm embarassed to find that this
talks about reading at EOT. I'm actually going to claim that this
is 'not a bug' or 'fixed already' in that at the end of media (at the
edge of recorded media), you may continuously open the tape (should
you choose to) issue a read, and zero bytes will transfer- this is a
sufficient EOF indicator.
a now unused variable. Also, remove the restriction against at density
code being greater than the max SCSI 2 density code: 0x80..0xff are the
Vendor Unique codes and most certainly should be allowed. The check for
invalid values should be less than 0 or greater than 255.
Oh- yeah, the previous commit addressed kern/391.
thorpej