Re: [debian-knoppix] Problem understanding how knoppix works
Ok, let see if I can explain it as brief as posible and make it
First, the Knoppix boots on two stages, first using the initrd method
(if you mount the boot.img image from the CD in the directory KNOPPIX
with the loop module, you'll find that it use syslinux to boot from a
fat disk and inside you'll find an archive called miniroot.gz, this is
the initrd filesystem compressed, you can uncompress it and mount it
with loop again, after that you'll find a script called linuxrc that
does the first boot process, it searchs all devices and partition
looking for the KNOPPIX image, mount it and do other stuff, look at the
script that is a bash one).
The before mentioned script also creates the ramdisk, the directory
structure for temporal writable files (as for example /tmp, /var,
etc...) and mount the KNOPPIX compressed image with the cloop module
that is the loop module modified to use compression on the fly to
compress the 2 Gb of the Knoppix filesystem into a 700 Mb image, the
script mounts the image on /KNOPPIX. After that, it swaps the / to the
one created on ramdisk (before it was using the / on the initrd filesystem).
Then, the second stage begins finnish the boot process as an almost
normal Debian system by calling the init process that runs the script
/etc/init.d/knoppix-autoconfig bash script that configure the rest of
the system (for example, calls the hardware detection program).
I'm sure that I'm forgeting lot of things probably, but the best way to
understand how all this works is to look at the two scripts mentioned so
you can learn the fundamental process of how it works.
I also suggest reading the documentation of the syslinux package as the
documentation of the initrd process that you can find on the
Documentation directory of the linux kernel tree.
Greettings and I hope this clarify a little more how all this works, I
also has pending the task of writing a nice documentation about what I
have learned of this great project when I begin working on a customized
CD for my university, if someone wants to help on this or are doing
something similar please let me know.
Mihai Tanasescu wrote:
I've read some of the knoppix documentation and I still can't figure out
how it all works.
I'm having problems with all those knoppix mounts.
I saw that /home and /usr are mounted under /ramdisc which is RAM memory
emulated from /dev/shm (usually it emulates half of the total RAM
memory). I presume the /usr directory is taken from the cd and placed
But when I issue a du -k under the root directory I see a KNOPPIX one
occupying about 2 Gb of space. How is this possible? while the rest
occupies a total of 700 Mb (exactly the cd size).
And what is realy that device /dev/root which is mounted as "/"? I want
to understand the concept behind this.
And if I modify with vim the file lets say /etc/resolv.conf where does
he save it afterwards ? as the file resides in /etc/ on /dev/root which
is mounted as "/". and /dev/root is mounted from the cd..and it seems
And the directory structure on " /" look exactly like the one under the
KNOPPIX folder.(the only difference being that / occupies 700 Mb not
counting the knoppix folder it contains)
Please help me understand the way this works. (and how knoppix emulates
and uses the system ram). or give me some relevant material that
explains this process of organizing files and running programs and
allowing the user to modify files that are not mounted in ramdisc but
are on a cd.(like the ones in /etc ).
debian-knoppix mailing list