[ltp] empty keyboard adapter holds built-in keyboard for ransom

[linux-thinkpad@linux-thinkpad.org]

I plug in my two-pronged adapter here on Debian, dmesg says:
input: Generic USB K/B as /devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.0/input/input8
generic-usb 0003:13BA:0017.0002: input,hidraw1: USB HID v1.10 Keyboard [Generic USB K/B] on usb-0000:00:1d.1-2/input0
input: Generic USB K/B as /devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.1/input/input9
generic-usb 0003:13BA:0017.0003: input,hidraw2: USB HID v1.10 Mouse [Generic USB K/B] on usb-0000:00:1d.1-2/input1

The "funny" thing is that I only have a mouse attached to that adapter.
No keyboard, as I intend to just use my Thinkpad's built in keyboard.

So I start xdm, and voila: I either have to
1. Go to town to buy a keyboard to attach to that adapter, or
2. Unplug the adapter, and cold reboot via the power button, as there is
no way xdm will listen to any key on the keybord... no leaving the xdm
login screen via ALT CTRL F1 etc.

Why can't xdm accept input from all devices at once like it usually
does?

Why does plugging in this certain adapter mean that the built-in
keyboard is disabled! Why can't the "clit"^H^H red button pointer and
additional USB mouses also still continue working at the same time?

/var/log/Xorg.0.log says:
(II) The server relies on HAL to provide the list of input devices.
	If no devices become available, reconfigure HAL or disable AllowEmptyInput.