KDGKBENT and unicode

From: tike64
Date: Wed Sep 24 2008 - 09:59:22 EST


Dear linux-kernel,

I am trying to read keyboard in raw mode (K_MEDIUMRAW, to be exact). I hope to avoid reading all the keymaps from the kernel to the application for keycode translation. Therefore I call KDGKBENT ioctl for every keycode I get from the tty. Basically this works except, when the translation result is an unicode keysym or should I say the unicode value happens to be greater than 0xFF, I get K_HOLE.

This observation seems to be in harmony with the drivers/char/vt_ioctl.c code. There I learned that, if I had the keyboard in the K_UNICODE mode, I could get directly the 16 bit unicode values.

So I have two options:

1) Read the keymaps in K_UNICODE mode and do the translations myself while in K_MEDIUMRAW mode

2) For each keycode switch to K_UNICODE mode, ask the translation from kernel, switch back to K_MEDIUMRAW mode and read the next keycode (the continuous switching might have severe side effects).

The question is am I correct so far or am I miserably confused? Aren't there any smarter ways to do the translation?

The next question probably must be how do I handle CAPS with kernel keymaps? As the CAPS sensitivity is encoded in the type field of keysym value, it is lost when the value is 16 bit unicode. I am seeing this phenomenon in ordinary VT when I manage to load some keysyms as 16 bit unicode.

--

Timo
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