1
2  Introduction
3
4The Linux 2.6 hotplug interface introduced a new approach. Instead of spawning
5a new process for each event, thus possibly creating an unmanagably large
6ammount of processes, the events (uevents) are written into a PF_NETLINK 
7socket.
8
9The uevent has following format:
10actiontype@ENVVAR=VALUE\0[ENVVAR=VALUE\0[...]]
11
12The actiontype might be "add" or "remove". The action is also exported in an
13environmental variable ACTION.
14
15Reading these events by a single daemon that performs relevant actions is a
16far better approach, as it also allows smart distribution of resources and
17processing by rules, both of these features being used in both udev and
18hotplug2.
19
20The old /proc/sys/kernel/hotplug interface is still kept though, and can be 
21used. If a valid value is passed to it, the application specified in the procfs
22entry gets executed along with the new method of sending event through netlink
23socket.
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