remaster knoppix with squashfs

[wangji]

KnoppixRemastering-with-squashfs-guidance.
Foreword.
This is not a howto ;there are so many good knoppixremasteringhowto around ,so I only discuss the main points with enough details so anyone could
switch from cloop-to-squashfs remastering.
Introduction.
Let me put aside zisofs,zftree ,but only give here a comparison of cloop and squashfs :compression ratio and runtime .Let me call
knoppix.clp the usual knoppix image obtained with cloopcompress the isofile (or mkiso piped thru createcompressfs )
knoppix.sqf the knoppix image of the same structure using mksquashfs.
compression ratio sqfs 689655Kb in 34 minutes
cloop 729163Kb in 43.7minutes (a small gain of 5% and 10 min in favor of sqfs ) Source=2082Mb
runtime
In order to avoid errors induced by bad behaviour of cdrom-reading (aleas due to dust ,mechanics & feedback-control )the runtime measures are
done directly on running knoppix-image sitting on hard drive in both compression cases .In both cases mkzftree of a huge /usr is measured.
runtime-sqfs 27min25s (985.3Mb/1769Mb)
runtime-cloop 27min59s (985Mb/1785Mb)
Almost no difference in runtime.So we must consider other factors to favor the one or the other.
The cloop are compiled in modules ,so don't touch the kernel ;but in fact it is almost impossible -without too much contorsion if ever possible-to mount
the clooped image with another-version-kernel.One needs to boot with the same-version-numbered-kernel to be able to insmod cloop !
The squashfs has to be compiled with patched kernel ;but any other-version-patched-kernel can "mount loopback" the image.Now,each time one changes
the kernel,one needs at least patch modifying the cmdline-length from 256 to 512 characters (a line in /linux/include/asm-i386/setup.h ) to keep
Klaus'idea of having a flexible command line .For amateur-developer-remastering the last solution makes life easy !
Philosophy
To switch from cloop to squashfs just replace the make-image. and of course the loopback mount the image during booting phase
Requirements
1 Get the kernel and the squashfs patch (squashfs.sourcefore.net ; latest version 2.0-alpha) .Modify setup.h as said ,patch with squashfs,compile.
compile the "mksquashs-tools" directory to get the binary "mksquashfs" and put in /usr/bin .
2 Get a copy of /KNOPPIX to some /remaster ;replace in /remaster the following directories to reflect the new kernel
/boot /lib/modules/2.6.x /usr/src/linux-2.6.x (this is standard kernel playing game ) and any eventual add/remove apps !
3 create the image: mksquashfs /remaster /outside-remaster-dir/knoppix
This line replaces the mkisofs ...| create_compressed_fs ...>knoppix.
4 modify linuxrc (from miniroot.gz or initrd.gz ) by commenting out the lines
(after scsi driver,at the paragraph "try to find cdrom" )
#insmod -f /modules/cloop.*o file=/cdrom/KNOPPIX/KNOPPIX
#mountit /dev/cloop /KNOPPIX "-o ro" || FOUND_KNOPPIX=""
insert there a line
mount /cdrom/KNOPPIX/KNOPPIX /KNOPPIX -o loop ,ro || FOUND_KNOPPIX=""
This mounts the image as squashfs tree.The rest is independant of compression mechanism.
Do not forget to change vmlinuz (new) when building the isocd.Some other version uses insmod cloop and losetup the loopback file ,it 's quite similar.
The Fun
By remaking the sqfs images of diferents knoppix-like-distro (cebit-3.4,quantian-openmosix,pollix,kurumin,physicstools...) with kernel-2.6.6 and put them
all in a /KNOPPIX ext2-directory ,I am able to boot any of them with just a boot-cd-15Mb and typing ...a label !
Have fun,

[covici]

I would love to do this, but I cannot compile cloop for my kernel, how did you copy the compressed file system to uncompress it so you could play with it?

Thanks.

[wangji]

just boot the cd you want; at boot prompt ,type
knoppix 2 to get into unix_console
you are on a ramfs ,in which /KNOPPIX contains the whole
uncompressed files (mepis or berry would be in /linux or /berry
directories)
just #cp -a /KNOPPIX/* /where you want to dir/
in this way the uncomprssion is done by the original author of the cd's cloop !!! and you avoid the problem o mismatching between
your cloop_compiled and the original one !
just mksquashfs th at structure and you are done
(almost)

[covici]

Hi. OK, I have now run into the problem that the builtin mount does not except -o loop option -- how did you get around this -- did you use a different mount somehow?

[wangji]

I suspect you compile your kernel with loopbackfs as module !!
you have to insmod-modprobe loop-module
If ,it's still the old kernel,which distro you startoff to play with ?
Look at .config around filesystem
in my case,when compile 2.6.6 I just have loopback as builtin !

[covici]

I mean that you cannot say mount -o loop because mount does not acceppt loop as an option so no matter how you compile the kernel the built in mount is not going to work (at least that is what it looks like if you look at the code in mount.c in the ash-knoppix). So what would be the command line that would work or did you use another mount command?

I suspect you compile your kernel with loopbackfs as
module !!
you have to insmod-modprobe loop-module
If ,it's still the old kernel,which distro you startoff to play with ?
Look at .config around filesystem
in my case,when compile 2.6.6 I just have loopback as builtin !

[wangji]

this is why I ask which distro you play with !
If you pick up the miniroot.gz from prometeusX_iso or physicstools-squashfs_iso then that ash allows you to do so !
the busybox from peanut.gz allows you to play with fun

[covici]

I see, I was still using the KNOPPIX ash and that is my problem -- I didn't use any distro but compiled my kernels from vanilla sources -- I can fix the loop.o problem and if I can find those ash things I am done!

Do you have a link to the ones you mentioned, this would be great!

Thanks so much for your help.

[wangji]

http://sf.gds.tuwien.ac.at/b/br/brpr...PrometeusX.iso

1 ftp://ftpthep.physik.uni-mainz.de/pub/physicstools/
2 ftp://ftp.ibiblio.org/pub/linux/dist...s/physictools/
3 *http://www.vnlug.org/knoppix-vi/physicstools-1.0.iso
* *http://www.vnlug.org/knoppix-vi/phys...ls-1.0.iso.md5
* *http://www.vnlug.org/knoppix-vi/physicstools-1.0.lsm
(I am not sure the 3rd contains squashfs;but the two first are ok)
if on hurry,or your connection is slow,have an email_add_temporary somewhere and put it here I will send there
miniroot.gz(around 1Mb gz),or just ash (945kb non-gz)

[covici]

My Email address is covici@ccs.covici.com if you could send the miniroot.gz this would be very good.

In the meantime, I did try busybox which has a lot of nice things in it, but there is something wrong when it tries to exec static/ash it hangs and this is true even by hand, so their exec is broke and this may mean that iit is unusable.

Thanks.