[CentOS] The relationship between udev and MAKEDEV

Filipe Brandenburger filbranden at gmail.com
Tue Oct 28 13:54:07 UTC 2008


Hi,

On Tue, Oct 28, 2008 at 00:21, Clint Dilks <clintd at scms.waikato.ac.nz> wrote:
> 2. Is modifying /etc/makedev.d/01linux-2.6.x likely to cause me issues in
> future ?

Possibly, since this file is owned by the MAKEDEV rpm. If there is an
upgrade in MAKEDEV, it may overwrite this file. Or if it doesn't, but
there was an addition of a new device there, you would not get the new
device. I would say it would be safer to create a separate file
instead of modifying those.

>From man MAKEDEV:

CONFIGURATION CONFLICTS: In the event that the set of configuration
files contains multiple rules for a given device name, MAKEDEV will
use all of them.  The end result is typically that the last rule given
 (either  by  virtue  of being  listed  below all other matching rules
in the same file, or by being listed in a file which is read after all
others which contain alternate rules) will apply.  MAKEDEV reads the
set of configuration files in sorted order, so this misfeature can be
exploited dependably.

So I believe if you restore the 01linux-2.6.x file to its original
state and create a 99local file with your customized rule, it should
work. Try to do that in a test environment and let us know how that
goes.

I cannot answer your other questions about why it's created with
MAKEDEV and not by udev itself, unfortunately I don't know enough of
udev or of /dev/net/tun to be able to tell why it's done like this.

HTH,
Filipe


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