the bus is configured, interrupts are handled, etc. machine-dependent
header (machine/eisa/eisa_machdep.h) defines eisa_chipset_tag_t and
eisa_intr_handle_t types, and the following functions:
eisa_attach_hook()
eisa_maxslots()
eisa_intr_map()
eisa_intr_string()
eisa_intr_establish()
eisa_intr_disestablish()
Don't define the interrupt establish/disestablish functions directly
in terms of the ISA functions any more (on some wacked out systems,
there can be a difference).
