Console keyboard events and accessibility

Hi,

Some blind people use a kernel engine called Speakup which uses hardware
synthesis to speak what gets displayed on the screen.  They use the
PC keyboard to control this engine (start/stop, accelerate, ...) and
also need to get keyboard feedback (to make sure to know what they are
typing, the caps lock status, etc.).

To tell the truth, the way it's currently done in Speakup is just ugly:
it patches the kernel to have it call its own function, and modifies the
fn_handler array on the fly to get called when these should have been
:o)

As patching the kernel is never an easy thing for end users, and since
there might be other interesting uses, I wondered whether we could add a
notifier list for keyboard events.  Attached is a (not-even-compiled!)
patch that does this: call the list with a KBD_KEYCODE event, and
if anyone returns NOTIFY_STOP, don't go further (key was eaten).
Then according to the situation, call the list with a KBD_UNICODE or
KBD_KEYSYM event, and if anyone returns NOTIFY_STOP, don't go further.
That way, kernel modules may grab some shortcuts for their own uses or
monitor key presses.

You may wonder why this can't be done at the input layer.  The problem
is that what people want to monitor is the console keyboard, i.e. all
input keyboards that got attached to the console, and with the currently
active keymap (i.e. keysyms, not only keycodes).

What do people think about this?

Samuel