RE: Unmounting and ejecting the root fs on shutdown.

From: Per Erik Stendahl (
Date: Wed Feb 28 2001 - 11:12:03 EST

Oops, I almost missed this one. High-volume mailinglists... :-)

> > Hello Per , Has anyone gotten back to you on this subject ?
> > I as well am very interested in any information about releiving
> > this difficulty . Tia , JimL
> >
> Such a CD would be very nice; one or two people do have this already,
> though. Have you tried using a ramdisk for root, and mounting
> the CD as
> /usr?

Well, doing this on your own certainly will teach you a lot about
Linux I tell you. :-)

I still dont know how to make the kernel unlock and eject the CD on
shutdown. I haven't been able to pinpoint the shutdown sequence in
the kernel sources yet. :-)

What I do know now is how to make the kernel not lock the CD in the
first place. Simply ioctl(/dev/cdrom, CDROM_CLEAR_OPTIONS, CDO_LOCK)
from /linuxrc in the initrd. This way I can remove the CD anytime
I please which is enough for me. And I dont have to patch the kernel.

Mounting a ramdisk for / is doable (I think) but kludgy since you have
to symlink or mount so many subdirectories. Right now I only have /var
in a ramdisk (and why _WHY_ is /etc/mtab located in /etc and not
in /var??).

Anyways the CD works - and yes, being able to boot Linux w/o touching
the harddrives or the network is nice! :-) I might even put it on the
web once I get it cleaned up. Though the ISO is ~200 Mb.

/Per Erik Stendahl
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