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
need to explicitly relatch the interrupt when firing it up again. So, in the
trigger routines, explicitly disable and reenable the interrupt to relatch it,
like we do in the interrupt routine.
Also clean up some broken loop overrun checks.
My ES1371 seems to be more reliable now, but I'm not going to pretend to fully
understand this chip.
XXX Currently disabled by default because it has some problems on macppc.
XXX Maybe some more initialization is needed, but there is few information
XXX about the chips.
change DLT type to cisco HDLC, as lmc driver is hardwired to cisco HDLC
on driver attach. XXX we may need to revisit this, as if_spppsubr may want
to alter this later.
saves about 2.2MB under /usr/include/dev/. Discussed on tech-kern@
recently.
I HOPE to get the list right. The headers I left in are ones
used for MI tools and those whose usage I discovered by grep over tree sources.
Feel free to put needed includes back in if you encounter anything which
should not be removed from lists.
This now provides slightly more functionality than the FreeBSD layer1-newbus
interface. It was meant to be a simple change to one header and a few
c files, but the change rippled all through various stuff.
To prevent a change to the kernel<->userland interface right now the kernel
is now lying about card types to userland (but who cares). This will be fixed
when the userland interface changes, after layer 3 <-> layer 4 has been
fixed.
Functional changes:
Provide a clean interface for hardware drivers to attach to the upper
layers. This will need another small change in the B-channel handling
when a similar change to the layer 3 <-> layer 4 interface happens.
Avoid passing indices into global arrays of pointers around, instead pass
the pointers itself. Don't code hardware driver types by predefined magic
numbers (think LKM). Prepare for detachable drivers (think pcmcia).
While there remove some sets of function pointers always pointing to the
same function (meant to be the configurable set of D channel protocol
handlers). It is unlikely another supported D-channel protocol will fit into
that (maximal layer interface) abstraction. When we get support for another
protocol, we will need to come up with a workable interface. Besides, the
old implementation was, uhm, strange.
Revert the revert. Naturally, I considered OpenBSD and FreeBSD when I fixed
the incorrect use of the spl*() interface. The change I made is _required_
for both NetBSD _and_ OpenBSD, or the code won't even COMPILE except on
i386, and it is acceptable on FreeBSD. Your revert and mod rebroke it on
OpenBSD and tangled things up on NetBSD. It made no difference on FreeBSD.
In particular, there are 2,895 uses of splx() within the FreeBSD kernel,
and only a mere 21, that's "twenty one" uses of intrmask_t, and those are
almost exclusively in the guts of the interrupt implementation, _not_ in
the _use_ of the exported spl*() functions. It's perfectly OK to `int s
= spltty()' in a portable driver in FreeBSD.
For that matter, FreeBSD (-current at least) does not even *use* spl*()
any more and stubs them all out with inlines that do _nothing_ except return
0, making intrmask_t vs int _even less_ important there than it already
was.
I think it's great that you want to start hacking on the kernel, but do
note that this is certainly the most simple of the kernel interfaces. It
just gets worse from here. Be careful out there!
