Nothing has changed, it's just configurable now for setups which don't
use the "fork-bomb" anymore.
Do nothing, leave it at the default value, if you are unsure about
your setup. If your system works without it, you save a few cycles at
bootup.
We can't really tell, it entirely depends on the distro, setup, udev
integration, initramfs. Old initramfs setups might need it, even on a
udev system without any /sbin/hotplug like stuff installed. You would
need to look in your initramfs image if it contains a /sbin/hotplug.
Thanks,
Kay
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