Arch Linux

/dev/psaux was the mouse input file in Linux 2.4. Now, it is /dev/input/mice.
That fact can be confirmed by looking at the file drivers/input/Kconfig in the Linux kernel tree:


72 config INPUT_MOUSEDEV_PSAUX
73 bool "Provide legacy /dev/psaux device"
74 default y
75 depends on INPUT_MOUSEDEV
76 ---help---
77 Say Y here if you want your mouse also be accessible as char device
78 10:1 - /dev/psaux. The data available through /dev/psaux is exactly
79 the same as the data from /dev/input/mice.
80
81 If unsure, say Y.


Obviously it's not a big deal to keep the legacy /dev/psaux, but /dev/input/mice _is_ the correct choice, and won't change gpm's behavior as can be discerned by the above.