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Friday, October 16, 2020

Using all-Apple Thunderbolt hardware to kill my MacBook

My thrashing and crashing with my new 2020 MacBook Air and Thunderbolt devices has another chapter: I can now reproduce it without a funny Thunderbolt 3 dock! Yep, that's right, I've reduced it to a set of Thunderbolt devices which have one common trait:

They all were made by Apple.

There's no Belkin dock and there's no OWC dock. Nope. This is Apple on Apple badness now.

Here's what you do.


Initial connections:

Log catcher:

Run netcat on another machine someplace that your MBA can connect to. Have it listen on a port. You'll need to watch this for activity later.

Steps to break the box:

  1. Make initial connections. Restart machine.
  2. Log in from external keyboard.
  3. Start log stream in Terminal: log stream 2>&1 | nc host port &
  4. Apple menu -> Sleep
  5. Wake machine from external mouse
  6. Apple menu -> Sleep
  7. Disconnect TB3->TB2 adapter from MBA
  8. Wait for log stream to stop (this may take a minute or two)
  9. Reconnect TB3->TB2 adapter to same port on MBA
  10. Attempt to wake the machine from external keyboard or mouse

At this point, it will fail to wake from the external devices. You will have to wake it up from the internal keyboard/trackpad. If the external keyboard and mouse are somehow still working, go back and try it again, but wait longer for the log stream to stop. This is important - it HAS to be all the way asleep. Look for things like "linkStatus 0" or "kIONetworkLinkStateInactive" or even "unplug=0" and wait a good 15-20 seconds after it seems idle to make it sure it really is sleeping.

Only then, proceed to the next steps.

Steps to crash the machine using only Apple hardware:

  1. Apple menu -> sleep
  2. Disconnect TB3-TB2 adapter from MBA
  3. Wake (using built-in keyboard/trackpad)

At this point, the display should light up briefly, and then go out. A few seconds later, the Apple logo will appear as the machine reboots by itself. You have just caused it to panic, and when you next log in, it will ask you to send in a crash report.

Feel free to send them to this URL along with whatever choice thoughts you may have on the matter.