In addition to implementing all device accesses through the ddi_get8(9F) and ddi_put8(9F) families of interfaces, the Solaris OS provides interfaces that are specific to particular bus implementations. While these functions can be more efficient on some platforms, use of these routines can limit the ability of the driver to remain portable across different bus versions of the device.
With memory mapped access, device registers appear in memory address space. The ddi_getX family of routines and the ddi_putX family are available for use by drivers as an alternative to the standard device access interfaces.
With I/O space access, the device registers appear in I/O space, where each addressable element is called an I/O port. The ddi_io_get8(9F) and ddi_io_put8(9F) routines are available for use by drivers as an alternative to the standard device access interfaces.
To access PCI configuration space without using the normal device access interfaces, a driver is required to map PCI configuration space by calling pci_config_setup(9F) in place of ddi_regs_map_setup(9F). The driver can then call the pci_config_get8(9F) and pci_config_put8(9F) families of interfaces to access PCI configuration space.