Re: [gentoo-amd64] Please get me straight about sysvinit vs. systemd, udev vs eudev vs mdev, virtuals and other things...

[Mark Knecht <markknecht@gmail.com>]

On Mon, Mar 3, 2014 at 1:51 PM, Frank Peters <frank.peters@comcast.net> wrote:
> On Mon, 3 Mar 2014 11:20:50 -0800
> Mark Knecht <markknecht@gmail.com> wrote:
>
>>
>> While I understand your point these two comments contradict each
>> other, or more accurately, the first was inaccurate in the sense that
>> someone needed to create your /dev entry, either udev or you, it
>> didn't matter. Once it was there your scanner worked, correct?
>>
>
> With USB devices things are a bit different.  If I plug in a USB
> gadget, the kernel will report a certain device.  If I then unplug
> it and then immediately replug it, the kernel will report a different
> device even though it is the same USB gadget.  For this reason, udev
> can alleviate the uncertainty by automagically constructing the
> correct device node.
>

OK, fair enough. However from the outside udev doesn't look like
magic, at least the way I used it as it's mostly about my modifying
some file to say 'this USB ID is this dev, this MAC address is this
network', and so on and so on.

While I'm arguably the least experienced person on this list I'm sure
someone with your skills could figure out your own scripts to do that
sort of thing, should you choose to.

> However, until recently, USB scanners were accessed through a kernel
> module and this allowed a static node to be created in the /dev tree.
> Using the kernel module access, SANE could always find the scanner.
> For some reason, the scanner module has been eliminated from the
> kernel and now udev is unconditionally necessary for scanner access
> (unless the user employs an awkward workaround).
>
> This represents the future trend.  Udev will be an absolute, total
> requirement for everything.
>
> Admittedly, my views are in the (exteme?) minority.  So it's goodbye
> simplicity and hello complicated junk.
>
> I used to have a lot of fun building and tweaking my Linux system,
> but that experience is fading fast.
>
> Frank Peters
>
>

Well Frank, you and I have been around here long enough to remember
each other and get old enough to start forgetting how long we've been
around here. Like you it used to be more fun. Probably like you I used
to be a lot younger too! :-)

Cheers,
Mark