config NTB_IDT tristate "IDT PCIe-switch Non-Transparent Bridge support" depends on PCI select HWMON help This driver supports NTB of cappable IDT PCIe-switches. Some of the pre-initializations must be made before IDT PCIe-switch exposes it NT-functions correctly. It should be done by either proper initialisation of EEPROM connected to master smbus of the switch or by BIOS using slave-SMBus interface changing corresponding registers value. Evidently it must be done before PCI bus enumeration is finished in Linux kernel. First of all partitions must be activated and properly assigned to all the ports with NT-functions intended to be activated (see SWPARTxCTL and SWPORTxCTL registers). Then all NT-function BARs must be enabled with chosen valid aperture. For memory windows related BARs the aperture settings shall determine the maximum size of memory windows accepted by a BAR. Note that BAR0 must map PCI configuration space registers. It's worth to note, that since a part of this driver relies on the BAR settings of peer NT-functions, the BAR setups can't be done over kernel PCI fixups. That's why the alternative pre-initialization techniques like BIOS using SMBus interface or EEPROM should be utilized. If unsure, say N.