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
controllers (including SCSI id 7 on the 2100/3100).
- On the pmax (2100,3100) set the host SCSI id to 6.
- Move disk and tape config for the second ASC controller from the GENERIC
config file to scsi.pmax so all configurations can use the second
controller.
* dec_5100.c: sysconf, interrupt, and motherboard (drain writebuffer)
support for 5100.
* support for hardware kludge in 5100: sii DMA buffer is hardware
padded to alternate 32-bit words, not alternating 16-bit halfwords.
* 5100 has no framebuffer, console is wired to serial port 0.
With ibus support, boots as far as exec'ing init, and hangs.
(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.
simonb