devfs

[Ed Sweetman]

On Sun, 2002-08-18 at 17:53, Barry K. Nathan wrote:
> On Sun, Aug 18, 2002 at 07:36:47PM +0100, Sean Neakums wrote:
> > commence  Ed Sweetman quotation:
> [snip]
> > > the devfs documentation says it doesn't need to have devfs mounted
> > > to work, but this doesn't seem to be true at all.
> > 
> > If it does say exactly that, then it is outrageously wrong.
> 
> Starting at line 722 of
> linux-2.4.19/Documentation/filesystems/devfs/README:
> 
> > In general, a kernel built with CONFIG_DEVFS_FS=y but without mounting
> > devfs onto /dev is completely safe, and requires no
> > configuration changes.
> 
> I skimmed through the documentation and it appears to assume that you're
> not deleting all the stuff in /dev before switching over to devfs.

This has nothing to do with not mounting devfs and still using devfs to
work with devices.   If devfs is not mounted but you're still using
devfs, you shouldn't need anything in /dev.   The documentation says you
can use devfs without mounting and This is what i'm saying is
problematic and doesn't seem possible in normal usage.   It's an
optional config so are we using devfs when we dont mount it or not?  
and if not, then why make not mounting it an option ? 

If it's using the old device files in /dev then how can it be using
devfs and how can accessing physical inodes on the disk be intentional
to devfs? 

> Right, there's no way around that. If you deleted everything in /dev --
> which you're not supposed to do -- then there's no way for anything to
> find any devices if devfs isn't enabled. (And you should have a rescue
> CD around anyway -- you never know when you might need it! BTW, what
> distribution are you (Ed) using? Some distributions have special boot
> options you can use when booting their install CDs to get into a rescue
> mode.)
> 
> In any event, it might be a good idea to make the documentation a bit
> more explicit about this, and I might send a patch to the mailing
> list later today.

I'm not talking about booting without devfs enabled being the problem, i
know booting without devfs enabled I'll have issues booting the system
without physical /dev entries, i was referring to having devfs enabled
and not mounting it.  Which according to the documentation should be
perfectly functional and valid.  This is not the case though.   devfs
should not require the old /dev entries at all since it doesn't use them
so why would keeping them be required at all when using it (not counting
the "if i want to not use devfs" argument).  This is what should be
cleared up in the documentation.