# "Activating mdev" when using udev

## SunMar

Hi,

I tried to search for this but couldn't find a solution. I noticed that when my system boots after the kernel is loaded it shows the message:

```

>> Activating mdev

/init: line 334: can't create /proc/sys/kernel/hotplug: nonexistent directory

```

After some searching on other mdev/udev issues I did manage to figure out that the error comes from the linuxrc script used by genkernel (found at /usr/share/genkernel/defaults/linuxrc):

```

327 # Initialize mdev

328 good_msg 'Activating mdev'

329 

330 # Serialize hotplug events

331 touch /dev/mdev.seq

332 

333 # Setup hotplugging for firmware loading

334 echo /sbin/mdev > /proc/sys/kernel/hotplug

```

I use "genkernel all" to build my kernel, but the thing is that I use udev (in the kernel CONFIG_GENTOO_LINUX_UDEV=y), mdev is not installed (/sbin/mdev also doesn't exist).

Is there a way to fix this error without having to create a custom linuxrc script for genkernel to use?

Sincerely,

SunMar.

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## eccerr0r

Someone else had a problem with the missing hotplug file though he had a custom initramfs

https://forums.gentoo.org/viewtopic-t-1003920-highlight-.html

Also something is really wrong - mdev should be linked to busybox... is this a canned initramfs?

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## SunMar

Thanks the the reply. /sbin/mdev is not available because busybox is not compiled with the mdev USE flag, and hotplug is not available because the kernel is compiled without CONFIG_UEVENT_HELPER. But the issue isn't that those aren't available, it's rather that the init script tries to use them while they are unavailable. Not sure what you mean with a canned initramfs.

Perhaps I should file a bug report for this instead, but I wanted to check first that it's not some kind of configuration mistake.

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