add support in systemd-logind to ignore some input device

[vvavrychuk]

Component

systemd-logind

Is your feature request related to a problem? Please describe

I allocate uinput input device and passthrough it to QEMU using virtio-input. I don't want this uinput device to affect my host system. But, we I send KEY_POWER to this uinput input device, then systemd-logind power offs my host system.

Describe the solution you'd like

libinput has LIBINPUT_IGNORE_DEVICE udev property which I can use for Wayland to ignore specific device, see for details https://wayland.freedesktop.org/libinput/doc/latest/ignoring-devices.html

It would be great if systemd supports similiar property, such as SYSTEMD_IGNORE_DEVICE.

Describe alternatives you've considered

I have achieved success by writting udev rule that resets ID_INPUT_KEY property, 61-uinput.rules:

SUBSYSTEM=="input", KERNEL=="event*", ATTRS{name}=="my-name", ENV{ID_INPUT_KEY}="0"

But, this solution is udev execution order dependent. It has to be after 60-input-id.rules to overwrite ID_INPUT_KEY assigned by input_id builtin and before 70-power-switch.rules which assigns power-switch tag according to ID_INPUT_KEY property.

The systemd version you checked that didn't have the feature you are asking for

No response

[yuwata]

I think it is better to use hwdb for such purpose. See 60-input-id.hwdb.

[vvavrychuk]

@yuwata I am not sure how hwdb can help. From what I see 60-input-id.hwdb sets ID_INPUT_KEY, etc. based on some modalias (i.e. for specific devices). But, input_id assigns ID_INPUT_KEY if there is any EV_KEY event type supported by input.

I am not sure there is any other solution, since libinput/wayland already seems to be facing similiar problem and solved it by adding LIBINPUT_IGNORE_DEVICE property in udev with corresponding handling in libinput.

[yuwata]

Creating a custom .hwdb file for your keyboard model with ID_INPUT_KEY=0 or ID_INPUT_KEY= (empty assignment), and call systemd-hwdb update and udevadm trigger /dev/input/eventXX should work, as udev calls input_id first, then load entries from hwdb. So, the setting in hwdb has a higher priority. See 60-input-id.rules .

[vvavrychuk]

Thank you!