nixos -> Can't see "Network Tablet" in xinput list

[srghma]

$ sudo networktablet
GfxTablet driver (protocol version 2) is ready and listening on 0.0.0.0:40118 (UDP)
Hint: Make sure that this port is not blocked by your firewall.

$ sudo xinput list
⎡ Virtual core pointer                          id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ USB OPTICAL MOUSE                         id=11   [slave  pointer  (2)]
⎜   ↳ USB OPTICAL MOUSE  Consumer Control       id=13   [slave  pointer  (2)]
⎣ Virtual core keyboard                         id=3    [master keyboard (2)]
    ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]
    ↳ Power Button                              id=6    [slave  keyboard (3)]
    ↳ Asus Wireless Radio Control               id=7    [slave  keyboard (3)]
    ↳ Video Bus                                 id=8    [slave  keyboard (3)]
    ↳ Power Button                              id=9    [slave  keyboard (3)]
    ↳ Sleep Button                              id=10   [slave  keyboard (3)]
    ↳ USB OPTICAL MOUSE  Keyboard               id=12   [slave  keyboard (3)]
    ↳ USB2.0 VGA UVC WebCam: USB2.0 V           id=14   [slave  keyboard (3)]
    ↳ Asus WMI hotkeys                          id=15   [slave  keyboard (3)]
    ↳ AT Translated Set 2 keyboard              id=16   [slave  keyboard (3)]
    ↳ USB OPTICAL MOUSE  Consumer Control       id=17   [slave  keyboard (3)]

$ cat /etc/X11/xorg.conf.d/10-evdev.conf
#
# Catch-all evdev loader for udev-based systems
# We don't simply match on any device since that also adds accelerometers
# and other devices that we don't really want to use. The list below
# matches everything but joysticks.

Section "InputClass"
        Identifier "evdev pointer catchall"
        MatchIsPointer "on"
        MatchDevicePath "/dev/input/event*"
        Driver "evdev"
EndSection

Section "InputClass"
        Identifier "evdev keyboard catchall"
        MatchIsKeyboard "on"
        MatchDevicePath "/dev/input/event*"
        Driver "evdev"
EndSection

Section "InputClass"
        Identifier "evdev touchpad catchall"
        MatchIsTouchpad "on"
        MatchDevicePath "/dev/input/event*"
        Driver "evdev"
EndSection

Section "InputClass"
        Identifier "evdev tablet catchall"
        MatchIsTablet "on"
        MatchDevicePath "/dev/input/event*"
        Driver "evdev"
EndSection

Section "InputClass"
        Identifier "evdev touchscreen catchall"
        MatchIsTouchscreen "on"
        MatchDevicePath "/dev/input/event*"
        Driver "evdev"
EndSection

xserver config https://github.com/srghma/dotfiles/blob/d34e09a078521326a0657012f016ce6e04a84e41/nixos/root/services/default.nix#L83-L120

gfxtablet is added here https://github.com/srghma/dotfiles/blob/d34e09a078521326a0657012f016ce6e04a84e41/nixos/root/environment/default.nix#L181

[srghma]

$ realpath $(whereis networktablet) 
/home/srghma/networktablet:
/nix/store/wiphsmvzfg3hjywdnl2dhrv2fr934yry-gfxtablet-uinput-driver-1.4/bin/networktablet

[redfish64]

I also use nixos and had the same problem. I noticed that in /var/log/X.0.log it showed that the tablet was rejected with the message:

[ 3951.940] (EE) event20 - Network Tablet: libinput bug: missing tablet capabilities: resolution. Ignoring this device.

I was able to fix this by adding a resolution value for "pressure" and recompiling. I'm not sure what resolution in terms of pressure is, but it fixed it.

Here is the patch: z.txt