general hotplug/udev questions

[rich turner <rich@storix.com>]

i am looking at the way suse 9.3 is using hotplug and udev to load
network device modules, and want to know if this is specific to suse or
if hotplug/udev is using this method and will be used by other
distributions going forward.

keep in mind that i am not using the initrd (which is initramfs) that
suse distributes, or their mkinitrd to create it. i have a process that
creates an initrd (old-school, not initramfs), which works on any
distribution (2.4 and 2.6 kernels).

my problem is that my network modules are not being loaded when the
system boots. on all previous distibutions it was a matter of adding the
network devices as an alias in /etc/modprobe.conf and then the network
startup scripts would handle loading the module when the device was
brought up:
alias eth0 sis900

what i am seeing on suse 9.3 is that in their initrd (initramfs) they
are using klibc and are echoing /sbin/hotplug.sh
to /proc/sys/kernel/hotplug. this is the contents of /sbin/hotplug.sh:

#!/bin/sh
#
# /sbin/hotplug.sh
# $Id: hotplug.sh,v 1.1 2005/01/20 10:38:11 hare Exp $
#
# Simple hotplug script for initramfs
# Records all events if requested and starts up udev
#
# Records all events if requested
if [ -d /events -a -x /sbin/hotplugeventrecorder ] ; then
    /sbin/hotplugeventrecorder $1 2>/dev/null
fi
AGENT=/sbin/udev
if [ -x $AGENT ]; then
    exec $AGENT $@
    echo "couldn't exec $AGENT"
fi
exit 1

they will then copy all entries that are created in /events
to /lib/klibc/events and mount it up using tmpfs so they can access them
when exiting the initrd.

then within their boot.coldplug init script, they take those events and
load the modules.

because my linuxrc does not create events or mount /lib/klibc/events in
the initrd, then boot.coldplug does not load the network modules.

i realize i can load the network modules in the initrd and everything
would be golden, but that is not the purpose of the initrd. in my
opinion we already do to much in the initrd because the distributions
dont do enough (or do it correctly) in their init scripts. we try to
keep the initrd's purpose to do only enough to mount the root
filesystem.

it is important that our process remain generic across all distributions
because we need to support many other distributions.

does anyone have an opinion as to whether suse's current method will
become the standard?

it appears that udevstart.static creates events but /sbin/udevstart does
not. why is that?

is /sbin/hotplugevenrecorder an executable being distributed by suse or
is it something that will be coming in the maintained udev?

even though we use udevstart in the initrd, is there any real purpose to
echoing something (/sbin/udev, /sbin/udevsend, /bin/true) out
to /proc/sys/kernel/hotplug while in the initrd?

it is my experience that udev only handles devices that you would expect
to find in /dev. how could it have any effect on network interfaces? is
this a product of hotplug or udev?

i apologize for the long message, but i do appreciate any feedback.

rich turner



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