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

To: rgooch@xxxxxxxxxxxxxxx
Subject: Re: Newbie question: running devfsd forces implicit mount of /proc?
From: "David Gilbert" <ad_gilbert@xxxxxxxxxxx>
Date: Tue, 16 Jul 2002 18:22:53 +0100
Cc: devfs@xxxxxxxxxxx
Sender: owner-devfs@xxxxxxxxxxx
Richard,

Yes I have module autoloading enabled. devfsd.conf has 'LOOKUP .* MODLOAD' and my kernel config has the kernel module loader (CONFIG_KMOD=Y). The modules.devfs is bog standard as per the devfsd v1.2.25 tarball and my local modules.conf only has a few alias entries - one for the cdrom, one for ppp and two for ppp compression modules.

Anyway so much for the symlink theory - I should have remembered how many times I've created dangling symlinks... ;-)

Cheers
David


----Original Message Follows---- From: Richard Gooch <rgooch@xxxxxxxxxxxxxxx> To: "David Gilbert" <ad_gilbert@xxxxxxxxxxx> CC: russell@xxxxxxxxxxxx, devfs@xxxxxxxxxxx Subject: Re: Newbie question: running devfsd forces implicit mount of /proc? Date: Mon, 15 Jul 2002 13:04:11 -0600

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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