Firmware: Issue with Disabling Extensions While Booting

[jcm-1]

Mac84 and I have discovered an issue using hootswitch in the ADB chain while trying to disable extensions during boot.

If you hold shift while powering up the Mac, it doesn't seem to accept the keypress for disabling extensions, unless you wait until the activity light blinks, generally.

Details

• If you hold shift before the light blinks: it will never work.
• If you hold shift -just as- the serial console says it has received a "cmp x rst" from the Mac: whether it works or not is somewhat random.
• If you hold shift after the light blinks (but before the Welcome to Macintosh message, obviously): it almost always works.

From a 10,000 foot view from a non-programmer: it seems like the firmware is not "rescanning" devices for events after a reset has been received from the computer.

[saybur]

I confirmed the problem here too, surprised I hadn't noticed this before. Underlying issue seems to be that real keyboards resend key-down events following an ADB reset; the virtualized keyboard interface failed to do this, so the previously-sent Shift key down event is lost.

I added an experimental key-down tracking system in the most recent commit that implements post-reset resending. Some (extremely) light testing shows it works well enough to disable extensions on my IIci. Let me know if it fixes the problem for y'all.