Drop it when there's no obvious reason why device_add could not work.
Else keep and document why.
* isa-fdc: drop
* i8042: drop, even though its I/O base is hardcoded (because you
could conceivably still add one to a board that has none), and even
though PC board code wires up the A20 line (because that wiring is
optional)
* port92: keep because it needs additional wiring by port92_init()
* mc146818rtc: keep because it needs to be wired up by rtc_init()
* m48t59_isa: keep because needs to be wired up by m48t59_init_isa()
* isa-pit, kvm-pit: keep (in their abstract base pic-common) because
the PIT needs additional wiring by board code, depending on HPET
presence
* pcspk: keep because of pointer property pit, and because realize
sets global pcspk_state
* vmmouse: keep because of pointer property ps2_mouse
* vmport: keep because realize sets global port_state
* isa-i8259, kvm-i8259: keep (in their abstract base pic-common),
because the PICs' IRQ input lines are set up by board code, and the
wiring of the slave to the master is hard-coded in device model code
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>