What happened to hotplug?

[Bill Moseley]

Is hotplug still used in Gutsy?  My (simple) understanding was that
the kernel would run hotplug on device changes, and then the hotplug
scripts would notifiy udev and hal of the changes.  Something like
this description[1].

Well, seems like the kernel is enabled:

    $ fgrep HOTPLUG /boot/config-2.6.22-14-generic  | grep =y
    CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG=y
    CONFIG_HOTPLUG=y
    CONFIG_ACPI_HOTPLUG_CPU=y
    CONFIG_HOTPLUG_CPU=y
    CONFIG_HOTPLUG_PCI_COMPAQ_NVRAM=y
    CONFIG_HOTPLUG_PCI_CPCI=y


But, no hotplug:

    $ file /proc/sys/kernel/hotplug
    /proc/sys/kernel/hotplug: empty

    $ ls /sbin/hotplug
    ls: /sbin/hotplug: No such file or directory


So man udev(7) says that it's notified directly the kernel.

Since udev has the "RUN" feature does that replace the need for
hotplug for loading modules and running scripts on device connection?

Indeed, it somewhat looks that way, since there's a:

    /etc/udev/rules.d/90-modprobe.rules


What is also a source of confusion is why are the modprobe rules "90"
instead of a lower number.  Wouldn't the modules need to be loaded
before udev can create the /dev/* entries?




[1] http://www.tummy.com/journals/entries/kevin_20041219_131044



-- 
Bill Moseley
moseley at hank.org