Problem with error 01C9 - More than one Ethernet devices

Problem Description

Certain ThinkPads show a warning message during POST when a WLAN card with an Atheros chipset is present in the MiniPCI slot:

  WARNING
  01C9: More than one Ethernet devices are found. Remove one of them.
  Press <Esc> to continue.

At POST, the BIOS conducts a scan for ethernet devices. It does this by reading the "PCI Class Codes" of every connected device. If more than one ethernet device is found, it produces the 01C9 error message. Unlike other wireless cards, which identify themselves as "other" network adapters, Atheros identify themselves as "ethernet". This collides with the internal ethernet controller (also a PCI device) and produces the 01C9.

Affected Models

• ThinkPad A31p
• ThinkPad T23 2647-3QG
• ThinkPad T30
• ThinkPad R40
• ThinkPad X22

Not affected are:

• ThinkPad T23, (seemingly most) T40
• ThinkPad X40

Solution

The solution is to modify the Atheros EEPROM so that the card correctly identifies itself as a "other" instead of "ethernet" network adapter. No messing with vendor and device ID is necessary. Madwifi drivers will function properly.

(code to do this in Linux will be posted)