Re: [gentoo-user] Re: Beta test Gentoo with mdev instead of udev; version 3

[Michael Mol <mikemol@gmail.com>]

On Thu, Jan 5, 2012 at 5:01 AM, Nicolas Sebrecht <nsebrecht@piing.fr> wrote:
> The 05/01/12, Pandu Poluan wrote:
>
>> And mdev might be a 'toy' to you, but embedded Linux developers will
>> vehemently disagree with you.
>>
>> And based on the responses in this thread, server guys will also
>> disagree with you.
>
> On the embedded side, we need udev much more than you think to support
> bluetooth, tablet and so. Android uses udev. This is even more true when
> we know that users will expect to have any plugged-in devices at
> whatever boot time or runing system be working out of the box. BTW, this
> is not a major problem since embedded devices already often use initramfs.
>
> On servers, I wouldn't be surprised that hypervisor tools will expect
> /dev/cdrom instead of /dev/sr0.
> AFAIK, mdev doesn't provide persistent device names and changing a
> ethernet card might result in a highly broken system where udev will let
> all interfaces working but the changed one.  Worse, I think mdev might
> change of device names upon reboot so that all ethernet devices can be
> mixed up in ways like eth0 -> eth1, eth1 -> eth3 and eth2 -> eth0.

FWIW, I had a /dev/cdrom symlink long before *devfs* even existed, let
alone udev.

Also, ethN numberings are generally stable until and unless you do
some strange BIOS tweaking or hardware changes, and should be able to
be stabilized in the event the instability comes from some racy module
loading mechanism.

udev's attempts at stabilizing network interfaces have made things
worse more often than I've heard of it making them better. Hit any
search engine for "eth0 missing 70-persistent-net.rules".

(Apologies for anyone who sees this message in such a result; just
delete /etc/udev/rules.d/70-persistent-net.rules, and you should get
eth0 back.)
-- 
:wq