In order to support pre-boot and legacy technologies, our PCI Express MAC families support IO Map mode access to the controller.  IO Map mode is using OUT and IN commands to push data via an old ISA technology.  While it works really well for real mode software, it can be very limiting for large install bases.  The IO address space is only 65535 bytes, and with some technologies taking large chunks of it, it is easy to run out of space.  When a BIOS runs out of space what happens next is always messy and often fatal.  While this “back door” is needed for PXE, NDIS2 and iSCSI boot, we have a method within our non-volatile storage to turn it off.  We’ve had this ability for a long time, but this is the first time we’ve shipped an end user tool for turning IO mode off.


IOUtil will allow the adapter to be configured to change whether or not it will request IO map mode access to the device.  It is located in the \tools\apps\IOUtil folder on the release media or within the 15.3 or greater Administrative Tools for Intel® Network Adapters webpack.


This utility is designed for system integrators. Only use it if your system has a high port density or you know you don’t need IO mapped access to the card.  Disabling IO access will prevent some pre-boot and DOS driver technologies from working.


So don’t turn it off just because.  When you get more than a couple quad port adapters, I would consider it.  If you have a bunch of other cards and bunch of Intel® Ethernet adapters in the system and it won’t POST, then remove a couple of the cards and try IOUtil.



1)      If you don’t need IO mapped access to the HW, turn it off using IOUtil

2)     Be careful if you do, some things won’t work

3)     Thanks for using Intel® Ethernet