Note1: the correct interrupt level is invoked correctly for each driver.
For this purpose, drivers request the bus before being able to
call BUS_SETUP_INTR and BUS_TEARDOWN_INTR call is forced by the ppbus
core when drivers release it. Thus, when BUS_SETUP_INTR is called
at ppbus driver level, ppbus checks that the caller owns the
bus and stores the interrupt handler cookie (in order to unregister
it later).
Printing is impossible while plip link is up is still TRUE.
vpo (ZIP driver) and lpt are make in such a way that
using the ZIP and printing concurrently is permitted is also TRUE.
Note2: specific chipset detection is not done by default. PPC_PROBE_CHIPSET
is now needed to force chipset detection. If set, the flags 0x40
still avoid detection at boot.
Port of the pcf(4) driver to the newbus system (was previously directly
connected to the rootbus and attached by a bogus pcf_isa_probe function).
