Caution:
- Following instructions are not perfect but would a give general idea what I did to get my adapter working again.
- If you are to try this on your system: remember that not all real men take backups, but they cry often.
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Situation:
- My Thunderbolt Ethernet Adapter:
- Vendor Name: Apple Inc.
- Device Name: Thunderbolt to Gigabit Ethernet Adapter
- Vendor ID: 0x1
- Device ID: 0x8003
- No "Thunderbolt Ethernet" instance in Preferences -> Network, not even available to be added under + -sign
- Apple-icon -> About This Mac -> System Report -> Hardware -> Thunderbolt -view shows "Thunderbolt to Gigabit Ethernet Adapter" when adapter is plugged in
- After rebooting my rMBP without Thunderbolt Ethernet Adapter attached:
1. Attached Thunderbolt Ethernet Adapter
2. Open Terminal.app
3. Executed following: sudo dmesg | grep -i "ethernet"
Got back things related to adapter in question:
..
Feb 28 00:19:40 <censored> kernel[0]: Kext com.apple.iokit.AppleBCM5701Ethernet is in exclude list, not loadable
Feb 28 00:19:40 <censored> kernel[0]: Can't load kext com.apple.iokit.AppleBCM5701Ethernet - not found.
...
Troubleshooting:
1. Took a look in to this .plist file which has excluded kexts listed:
/System/Library/Extensions/AppleKextExcludeList.kext/Contents/Info.plist
and found out that it indeed had my Thunderbolt Ethernet Adapter listed as "AppleBCM5701Ethernet" under key "OSKextExcludeList".
2. Tried to remove "AppleBCM5701Ethernet" key from the list, but failed as even root user could not write to file
-> Probably feature of System Integrity Protection which I know I've on
Solution:
1. With rMBP shutoff turn it on while pressing and holding CMD + R to enter recovery
2. In recovery mode I had to first unlock my Mac OS X volume with Disk Utility as I have FileVault on
3. After closing Disk Utility, Utilities -> Terminal
4. vi /Volumes/<your system partition name>/System/Library/Extensions/AppleKextExcludeList.kext/Contents/Info.plist
5. Removed key-line "AppleBCM5701Ethernet" and corresponding string-line
6. Saved the edit and closed the Terminal
7. Rebooted to Mac OS X (when I did this Mac OS X started loading system after password input and suddenly rebooted in middle of loading, after asking for the password again system loaded up normally
8. Preferences -> Network now shows the Thunderbolt Ethernet Adapter correctly and the connection is working
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PS.
Looking back what could have caused the Thunderbolt Ethernet Adapter to suddenly stop working I remembered that I had installed VirtualBox 5.0.14 just days before and after first restart after that the adapter stopped working. This might be totally unrelated to the real cause, but was only thing that came to mind.