Use MMIO instead of PIO

configname: CONFIG_VIA_RHINE_MMIO

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Ethernet driver support
└─>Use MMIO instead of PIO
In linux kernel since version 2.6.12  
This instructs the driver to use PCI shared memory (MMIO) instead of
programmed I/O ports (PIO). Enabling this gives an improvement in
processing time in parts of the driver.

If unsure, say Y.