"showkey -s" prints incorrect scan codes

"showkey -s" prints incorrect scan codes

[Vincent Lefevre]

Under Debian/unstable (package kbd 2.9.0-1), "showkey -s" prints
completely incorrect scan codes, and doesn't even print anything
for the Fn key (while evtest does).

This is apparently a known bug:
  https://wiki.archlinux.org/title/Keyboard_input

Except from this wiki, I couldn't find any mention of this bug,
so this was rather surprising.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)

Re: "showkey -s" prints incorrect scan codes

[Alexey Gladkov]

On Wed, Sep 16, 2026 at 04:23:30AM +0200, Vincent Lefevre wrote:
> Under Debian/unstable (package kbd 2.9.0-1), "showkey -s" prints
> completely incorrect scan codes, and doesn't even print anything
> for the Fn key (while evtest does).
> 
> This is apparently a known bug:
>   https://wiki.archlinux.org/title/Keyboard_input
> 
> Except from this wiki, I couldn't find any mention of this bug,
> so this was rather surprising.

This is written directly in the man page:

  In  2.6  kernels raw mode, or scancode mode, is not very raw at all.
  Scan codes are first translated to key codes, and when scancodes are
  desired, the key codes are translated back. Various transformations are
  involved, and there is no guarantee at all that the final result
  corresponds to what the keyboard hardware did send. So, if you want to
  know the scan codes sent by various keys it is better to boot a 2.4
  kernel. Since 2.6.9 there also is the boot option atkbd.softraw=0 that
  tells the 2.6 kernel to return the actual scan codes.

So this is a problem that has been known for a very long time. By saying
that, I don't mean that it shouldn't be fixed.

showkey is a very old utility, and I have to admit I had completely
forgotten about a feature like getting scancodes. I think I could add
support for evdev to get the correct result.

I added the --device={DEV,all} option, which specifies which device to
use.  If it is an evdev device, a new mechanism for retrieving scancodes
will be used. You can simply run:

  ./showkey --device=all --scancodes

Could you try it in the for-master branch ?
Does this behavior of the utility seem normal to you?

https://github.com/legionus/kbd/compare/master...refs/heads/for-master

-- 
Rgrds, legion