Re: [PATCH] creating link /dev/root to device / is mounted from

[Matthias Schwarzott <zzam@gentoo.org>]

On Samstag, 21. April 2007, Kay Sievers wrote:
> On 4/21/07, Matthias Schwarzott <zzam@gentoo.org> wrote:
> > On Freitag, 20. April 2007, Kay Sievers wrote:
> >
> > Well, our initramfs
>
> Hmm, the issue should only occur _without_ an initramfs-image, right?
> It's a different code path in the kernel, that should not happen when
> initramfs code mounts /, then /proc/mounts has matching entries.
>
> > does not move its /dev to new mounted root filesystem,but
> > we get a completely fresh tmpfs.
>
> Sure, we all just mount an empty tmpfs without any moving of nodes.
> The thing is, the kernel does not create /dev/root in /dev of the root
> on disk, it's in the kernel's initramfs, which every kernel has, even
> when you don't use an cpio-image to pupulate it during bootup.
Yeah - but I meant some initramfs images do mount a tmpfs - and /dev/root on 
it, and later move that mounted fs onto the its final position.

>
> > We also can just have a program to write out major/minor of "/" and then
> > mknod it (outside of udev)
> > But I really like a link better.
> > Here I also can search udev-database (or whatever)
> >
> > For example when /usr is already mounted (for udevinfo):
> > dev_nr=$(root_get_dev_nr)
> > dev_path=$(udevtrigger --verbose --attr-matchÞv=${dev_nr})
> > dev_name=$(udevinfo -q name --path ${dev_path})
> > ln -s /dev/${dev_name} /dev/root
>
> Yeah, sure, a link looks a bit nicer, but I'm not sure that it's worth
> all this effort.
>
Depends :)

Only thing that I dislike on this solution is that it needs udevinfo that is 
in /usr/bin, make it impossible to do it right after udev has been started, 
but in another init-script.

> Btw, how is your system doing an fsck on the rootfs? What device node
> is it using?
It just uses the device node listed in fstab :)

Yeah, that is the other possibility - if fstab has a entry for "/" just create 
a symlink there. (But here it can differ from the real used device.)

Matthias

-- 
Matthias Schwarzott (zzam)

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