[colug-432] blacklist usb device

[Rick Hornsby]

On 7/31/23 18:03, Jeff Frontz wrote:
> I suspect it's the keyboard/trackpad coming up, finding that macos
> isn't there (because it didn't get the right secret handshake or
> whatever), and disconnecting -- only to try it all again in hopes that
> the right OS finally boots.

I no longer have the keyboard/etc hardware for this device to try, but 
in general on other mac laptops I have here the keyboard and trackpad 
are detected and behave properly in Linux without any issues. I don't 
think there's - at least in these old models - any sort of "wrong os. no 
keyboard for you!" going on. I don't think.

> Can you disable that particular bus?

Short of figuring out which controller chip it is on the board and 
removing it, I'm not sure how to do that? Was thinking maybe there's a 
way by flipping something in NVRAM, I can see loads of stuff in 
/sys/firmware/efi/efivars/, a handful of files have semi-recognizable 
names. Most of the files are named 
"MokListXRT<some-integer>-605dab50-e046-4300-abb6-3dd810dd8b23"

The file contents all looks like binary data - nothing human readable.

The more I think about it the more I think the udev rules are working - 
but they're too late. udev is maybe just acting on events supplied to it 
by the kernel. It has to be fixed at a lower level. So the solution 
seems to be - somehow disable that USB bus as you suggested, or tell the 
kernel (before it fires off an event) to ignore those devices.