On Mon, Dec 27, 2021 at 11:31:21PM +0100, Vincent Danjean wrote: > On a plain (with more than two bytes) file, the second poll succeed. > On /proc/bus/input/devices, the second poll hangs. > Note: this is an old behavior. I initially observe it on an embeded system > with > a 4.1 kernel.
/proc is no real filesystem. It simply does not support poll, because the output is generated while you are reading it, so it does not know when anything changes. See also https://unix.stackexchange.com/questions/74713/how-frequently-is-the-proc-file-system-updated-on-linux?rq=1 If you want to know about hardware changes, use udev or listen to kernel netlink messages. Bastian -- Earth -- mother of the most beautiful women in the universe. -- Apollo, "Who Mourns for Adonais?" stardate 3468.1
