macOS M1 kernel panics when flashing to pi pico

[jceaser]

When I run tinygo flash -o app.uf2 -target=pico I frequently, but not always, get a kernel panic. The computer freezes and after what I assume is a watchdog kicks in, the computer reboots. On boot up I get the message that I can report the issue to apple. Attached here is the kernel panic.

In another ticket (#3106) I read that this issue does not come up with a USB hub, this does not seam to be the case.

I'm running:

• Mac OS X: 26.5.2 (25F84)
• tinygo version 0.41.1 darwin/arm64 (using go version go1.25.12 and LLVM version 20.1.1)

Target device is a keyboard with a Pi Pico:
https://1upkeyboards.com/shop/keyboard-kits/diy-40-kits/pi50-keyboard-kit/

I don't really know where to go from here, but I can provide more info on request.

error.txt

[rdon-key]

I don't have a Mac, so I cannot reproduce this issue or provide direct macOS support. However, the panic log in error.txt shows that the kernel panic occurred in Apple's USB CDC/serial driver stack while tinygo was running. Issue #3106 appears to show a very similar failure.

This may be a macOS USB CDC port-handling issue, possibly triggered by the 1200-baud reset used before flashing. Since the behavior may depend on the USB environment or selected serial port, it would be useful to rule out TinyGo selecting the wrong port.

Could you run:

tinygo ports

Then explicitly specify the Pico's port when flashing:

tinygo flash -target=pico -port=/dev/cu.usbXXXX .

Please let us know whether the kernel panic still occurs.

[jceaser]

I have not forgotten about this, in fact I have been compiling changes most days and as of now 2 weeks have gone by. Using you advice with the -port flag I have not had a crash. I don't know when we want to call success, but I think you are on to something. Are we still looking at a bug or is not using -port a user error? Personally I think that Apple is to blame for all kernel crashes but proving that to them may take more energy then we collectivily have, so is there a bug on this side?

My command:
tinygo flash -o keyboard.uf2 -target=pico -port=/dev/cu.usbmodem1401

[rdon-key]

Thanks for testing. This is not user error.

The kernel panic itself is an Apple/macOS issue. There may be room to improve automatic port detection, but there are also limits to what TinyGo can reliably determine.

[jceaser]

Understood. I will say it has been quite frustrating at first. Now I don't trust any call to flash without the -port flag, so it really is a matter of what you want users to do with this tool. At this point I can not recommend any use of the automatic port detection.