Some questions about mdev

Denys Vlasenko vda.linux at
Mon Aug 16 12:40:08 UTC 2010

On Thu, Aug 12, 2010 at 5:19 PM, Alexander Griesser <support at> wrote:
> Hey there,
> I’m using the latest busybox version (1.17.1) and have a few questions: I’m
> using mdev and whenever I repartition a harddisk during an install script, I
> have to run `mdev –s` manually after having partitioned the harddisk,
> otherwise the device file for the partition is not
> available.
> So let’s say I want to create a partition on /dev/sda, the device file for
> /dev/sda is here of course because mdev caught that during bootup, but when
> I do then create a new partition using fdisk, /dev/sda1 hasn’t
> been created automatically so I have to run `mdev –s` so this file gets
> created, then I can put a filesystem on the partition.
> Is that by design or am I missing something here? I have added mdev to the
> kernel hotplug mechanism by doing that (of course):
> echo /sbin/mdev >/proc/sys/kernel/hotplug

You need to debug the problem. Does mdev get called when you create
/dev/sda1 via fdisk? You can check it this way: create /sbin/
which does something like:

echo >>/tmp/mdev.trace
date >>/tmp/mdev.trace
echo "Params: $*" >>/tmp/mdev.trace
env | sort >>/tmp/mdev.trace
exec /sbin/mdev "$@"

and install it as hotplug handler instead of /sbin/mdev.
Then create /dev/sda1 and examine /tmp/mdev.trace
and post the results to the ml.


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