On 11-01-25 12:07 AM, Mark Lord wrote:

On 11-01-25 12:04 AM, Mark Lord wrote:

..

quoted

The EVIOCGKEYCODE ioctl is supposed to return KEY_RESERVED for unmapped
(but value) keycodes, and only return -EINVAL when the keycode itself
is out of range.

That's how it worked in all kernels prior to 2.6.36,
and now it is broken.  It now returns -EINVAL for any unmapped keycode,
even though keycodes higher than that still have mappings.

Actually, what changed could be something different:
it's possible that this bug was always there,
and older kernels had a more complete default keymap
for the remote than that in 2.6.36+, thereby never
triggering the bug.  But I don't know that, and my best
efforts to-date to locate any of this in the kernel
have been futile.  Oh well.  :)

quoted

This is a bug, a regression, and breaks userspace.
I haven't identified *where* in the kernel the breakage happened,
though.. that code confuses me.  :)

Note that this device DOES have "flat scancode space",
and the kernel is now incorrectly signalling an error (-EINVAL)
in response to a perfectly valid query of a VALID (and mappable)
keycode on the remote control

The code really is a valid button, it just doesn't have a default mapping
set by the kernel (I can set a mapping for that code from userspace and it works).

This is a BUG.  Returning -EINVAL here is entirely wrong.