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Re: Newbie question: running devfsd forces implicit mount of /proc?

To: "David Gilbert" <ad_gilbert@xxxxxxxxxxx>
Subject: Re: Newbie question: running devfsd forces implicit mount of /proc?
From: Richard Gooch <rgooch@xxxxxxxxxxxxxxx>
Date: Mon, 15 Jul 2002 13:04:11 -0600
Cc: russell@xxxxxxxxxxxx, devfs@xxxxxxxxxxx
In-reply-to: <F222RMs2XrLz42wXBMq00014fb6@xxxxxxxxxxx>
References: <F222RMs2XrLz42wXBMq00014fb6@xxxxxxxxxxx>
Sender: owner-devfs@xxxxxxxxxxx
David Gilbert writes:
> Whoops! I wasn't suggesting it was a problem - I'm just trying to
> understand better what's going on. I have a theory but I dont know how
> the mechanics work:
> 
> When devfsd runs, it still creates some symlinks. This happens even
> though I dont have any REGISTER .* MK[NEW|OLD]COMPAT entries in my
> devfsd.conf. The key symlink in question is /dev/fd which is a symlink
> to /proc/self/fd. Now, I assume to make the symlink the target must
> exist (is this right?), therefore /proc needs to be mounted. So,
> 'magically' (Hmmm), /proc is mounted.

Nope. You can make a symlink even without the destination
existing/being mounted.

> Unfortunately, this is where I run out of it.. I can't find any
> references to mount(2) in the devfsd code.

Indeed, there isn't.

> So how is magic happening?? (I'm also an aetheist...)
> 
> Just to be sure I wasn't imagining things, I booted my kernel with the
> 'init=/bin/bash' option to bypass _all_ the init stuff. A quick check of
> /proc proved that it was not mounted and a check of /dev showed no
> /dev/fd. I then ran devfsd /dev and sure enough /dev/fd -> /proc/self/fd
> appeared and /proc was mounted and ready.

Do you have any kind of module autoloading enabled? Whether in the
kernel config or in /etc/devfsd.conf ?

                                Regards,

                                        Richard....
Permanent: rgooch@xxxxxxxxxxxxx
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