Re: dev

Alan Cox (
Sat, 2 Nov 1996 10:21:00 +0000 (GMT)

> I'm insterested in the idea of this so-called 'devfs', which I believe
> to be already implemented in FreeBSD (any comments on that implementation).

Only one: Why the hell is it in the kernel ?

> 1. Number of entries. I've just looked at my system and I have well over
> 650 entries and I have nothing special on system.

All taking no data blocks. Relax. You can also prune them down if it
worries you

> 2. Many unused entries. A standard setup will create many entries, even
> though you don't need them. Having unused entries affects the lookup of
> /dev.

Microscopically (if you dont believe me apply the cache profiling patch)

> 3. When accessed, the atime on the /dev file will be updated. This means
> that when null, zero etc. is used, an update of the atime is required,
> this may not cause a significant impact, however, the atime on the /dev
> file does not provide any useful information. There is currently a

Its used by things like lastlogin, by some security monitors etc

> - Kernel bloating.
> This is the only reason I've seen against the idea of the devfs, and this is
> certainly an issue to be concerned with. Although I've used the term devfs,
> It doesn't mean a completely different FS to procfs but more likely a integral
> part of it.

If you ignore the IMHO bogus atime argument in your list you can do the
rest in userspace and build /dev from a master /devices or similar. We
don't need a kernel module for it.