configure properly. Also fix devices with TurboChannel and mainbus
attachments so they will work if no TurboChannel was configured.
Fix a panic when the dtop keyboard handler receieves a character
before the device has been opened.
- 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.
independent TC support in sys/dev/tc/tc.c and sys/dev/tc/tcvar.h:
* Change the tc autoconfiguration tables to use a struct tc_attach_args
instead of the ad-hoc structure.
* Change all pmax device drivers to use a `struct confargs' that's
assignment-compatible with sys/dev/tc/tcvar.h `struct tcdev_attach_args'.
Devices that can be present on a TC or as ioctl asic/mainbus builtins
use the same `struct confargs'.
* Eliminate the `BUS_CVTADDR()' macros which the pmax port inherited from
an old, now-obsolete sys/arch/alpha snapshot.
* Update the comments and debugging code in interrupt handlers to
be consistent with the machine-independent TC support.
Other commits that overlap the same source files include: re-enabling
clock-tick interrupts earlier, and counting hardclock ticks for vmstat -i.
old-style pmax polled input for cn_getc(). Needed because the
input side of rcons is not initialized in time for GENERIC kernels
to use it to read a root/swap devicename from /dev/console.
