Re: devfs vs udev, thoughts from a devfs user

[Chris Friesen <cfriesen@nortelnetworks.com>]

Mike Bell wrote:

> Why does it make management easier to have no predictable name for a
> device?

I believe this is a misconception.

Udev uses standard rules by default.  If the end-user (or their distro) 
wants to add additional rules or override these rules, they can do that.

> I think the space savings are a pretty good reason alone. Add to that
> the fact I think devfs would be a good idea even if it cost MORE
> memory... You can mount a devfs on your RO root instead of needing to
> mount a tmpfs on /dev and then run udev on that.

Don't you have to explicitly mount /dev as type devfs?  How is this 
different than mounting it as tmpfs?

> A devfs gives
> consistant names for devices in addition to the user's preferred
> user-space dictated naming scheme. 

Udev gives consistant names unless you explicitly override it.

> A devfs means even with dynamic
> majors/minors, even if you have new hardware in your system, your /dev
> at least has the devices it needs.

So does udev.

The real gain with devfs is that you don't need to have any userspace 
intervention to get /dev/ populated with a baseline set of device nodes. 
  As long as the udev code is sufficiently robust and compact, I don't 
have a problem with needing a userspace daemon.  Anyone that *really* 
cares about compactness (embedded people, for instance) is going to use 
a static /dev tree pruned down to the bare minimum.  For everyone else, 
the overhead of having udev running should be unnoticeable.

Chris


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