loop (and ntfs) bootfrom support in linuxrc and minirt

The reason I am posting is that I had come across this long thread as I was writing a patch to the linuxrc to allow you to use a loop mounted iso without first needing to mount a cloop. Now I'm using the patch I came across here for linuxrc along with a few other files and have even tried out booting from ntfs using the supplied grub. It lets you use bootfrom=/dev/xxx/abc/k*.iso even if the iso is on an ntfs partition and it also lets you use a bootloader (like grub) with just the kernel and minirt copied out off the iso. If you have a boot loader you can setup (e.g. grub which could be simply chained onto your windows (98 to xp anyway) boot loader as desribed in that long thread) and can loopmount the iso images (daemon tools is free as in coke on windows for this) then if the following changes were made to original knoppix releases it would be simple to download an iso, extract a couple of files and then boot entirely from hard disk without burning. Once I had this working with 3.6, I tried 3.7. It boots with the 3.6 kernel and minirt, but I wanted to use the kernel from 3.7 and remake the minirt from 3.7 so I knew I was consistent. So I wrote a script to extract the kernels and rebuild the minirt files for another Knoppix (so far only tested kernel 2.6 with 3.7, suspect it will work fine with remasters aswell though if they only have one kernel it might need adjusting, I will test 2.4 and dsl shortly).

First things first is you need to make a folder which you will be building, lets say /root/build/. Inside this folder you need to make a folder called "other" which should contain the following, all copied from minirt2[46]_ntfs.gz files that comes with grubc (you can cp -a the whole modules and static folders from the minirt and then delete all the extra stuff):

Code:

---

/root/build/other/:
total 8
drwxr-xr-x  4 root root 4096 2004-11-07 12:49 minirt24
drwxr-xr-x  4 root root 4096 2004-11-07 12:59 minirt26

/root/build/other/minirt24:
total 8
drwxr-xr-x  2 root root 4096 2004-11-07 12:51 modules
drwxr-xr-x  2 root root 4096 2004-11-07 12:48 static

/root/build/other/minirt24/modules:
total 176
-rwxr-xr-x  1 root root 129868 2003-12-31 05:47 insmod.modutils
-rwxr-xr-x  1 root root  41190 2004-04-21 18:31 rmmod

/root/build/other/minirt24/static:
total 428
-rwxr-xr-x  1 root root 431896 2004-06-01 09:36 busybox
lrwxrwxrwx  1 root root      7 2004-11-07 13:29 mkdir -> busybox
lrwxrwxrwx  1 root root      7 2004-11-07 13:29 mount -> busybox
lrwxrwxrwx  1 root root      7 2004-11-07 13:29 umount -> busybox

/root/build/other/minirt26:
total 8
drwxr-xr-x  2 root root 4096 2004-11-07 13:00 modules
drwxr-xr-x  2 root root 4096 2004-11-07 13:02 static

/root/build/other/minirt26/modules:
total 72
-rwxr-xr-x  1 root root 24754 2004-01-15 09:32 insmod
-rwxr-xr-x  1 root root 41190 2004-04-21 18:31 rmmod

/root/build/other/minirt26/static:
total 428
-rwxr-xr-x  1 root root 431896 2004-06-01 09:36 busybox
lrwxrwxrwx  1 root root      7 2004-11-07 13:29 mkdir -> busybox
lrwxrwxrwx  1 root root      7 2004-11-07 13:29 mount -> busybox
lrwxrwxrwx  1 root root      7 2004-11-07 13:29 umount -> busybox

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Can someone explain the original sources of the above file so they can be recreated?

You also need to copy the patch for linuxrc (linuxrc26_ntfs.diff) from the root of one of the minirt2x_ntfs.gz files to /root/build.

Also in /root/build (or wherever your are building things) you need to put a blank minirt file named minirt.blank.img which you can make with the following:

Code:

---

dd if=/dev/zero of=/root/build/minirt.blank.img bs=4096 count=1125
mke2fs -L "KNOPPIX miniroot" -b 1024 -N 8192 -O none -F -q -m 0 /root/build/minirt.blank.img || exit 1

---

Next you need to put the following into a script, say /root/new-minirt.sh and edit it to make sure the paths at the start are right (ISOFILE is the new iso you want the minirt for, BUILDROOT is where you are building everything):

WARNING, this script I have given worked fine for me, but it's not meant to be perfect and if it hoses your system I'm sorry but it's really here to document the steps to get it working as much as for others to run it. It is the script I used (though with a different BUILDROOT) under 3.6 to create the files I needed to boot the 3.7 I'm in now so it's not horribly broken I don't think :-D

Code:

---

#!/bin/sh
ISOFILE="/mnt/hda6/distros/live/knoppix_3.7_PC-Welt.iso"
CLOOPFILE="KNOPPIX/KNOPPIX"
BUILDROOT="/root/build"

# mount the iso
echo "Trying to umount iso and cloop from an old run, ignore errors"
umount $BUILDROOT/iso
umount $BUILDROOT/cloop
umount $BUILDROOT/minirt
losetup -d /dev/cloop1
echo "Mounting iso"
mkdir -p $BUILDROOT/iso||exit
mkdir -p $BUILDROOT/cloop||exit
mkdir -p $BUILDROOT/minirt||exit
mount -o loop,ro $ISOFILE $BUILDROOT/iso||exit

# create the temporary build area
echo "Make folders"
TEMPDIR=$BUILDROOT/`date +%Y%m%d%H%M` || exit
mkdir -p $TEMPDIR/common || exit
mkdir -p $TEMPDIR/2.4/modules||exit
mkdir -p $TEMPDIR/2.6/modules||exit
mkdir -p $TEMPDIR/old||exit
mkdir -p $TEMPDIR/minirt24.dir||exit
mkdir -p $TEMPDIR/minirt26.dir||exit
mkdir -p $TEMPDIR/boot||exit

# copy the minirts to temp and unzip them
echo "Copy and extract minirt"
cp -a $BUILDROOT/iso/boot/isolinux/minir*.gz $TEMPDIR/old||exit
gunzip $TEMPDIR/old/minir*.gz||exit

# copy kernels to boot folder
echo "Copy kernels"
cp -a $BUILDROOT/iso/boot/isolinux/linux* $TEMPDIR/boot||exit

# mount the cloop
echo "Setup and mount cloop"
losetup /dev/cloop1 $BUILDROOT/iso/$CLOOPFILE||exit
mount -o loop,ro /dev/cloop1 $BUILDROOT/cloop||exit

# copy the insmod.modutils to common
echo "Copying insmod.modutils"
cp -a $BUILDROOT/cloop/sbin/insmod.modutils $TEMPDIR/common||exit

# Loop through kernels
echo "Starting Kernels Loop"
for KERNEL in `ls $BUILDROOT/cloop/lib/modules/|grep ^2` ; do
case $KERNEL in 2.4.*) KDIR=2.4; RT=minirt24; ;; 2.6.*) KDIR=2.6; RT=minirt26; ;; esac

# copy the modules to 2.4 and 2.6 folders
echo "Copying modules"
for MODULE in fs/ntfs/ntfs drivers/block/loop; do
cp -a $BUILDROOT/cloop/lib/modules/$KERNEL/kernel/$MODULE.*o $TEMPDIR/$KDIR/modules||exit
done

ls $TEMPDIR/$KDIR/modules/*.ko | perl -e 'while(<>){chomp;s/\s*$//;$in=$_;$out=$_;$out=~s/\.ko$/.o/;system("mv $in $out\n");}'||exit

# mount the minirt
echo "mount minirt"
mount -o loop,ro $TEMPDIR/old/$RT $BUILDROOT/minirt||exit

# copy the contents of the minirt to a folder
echo "Copy minirt contents to folder"
cp -a $BUILDROOT/minirt/* $TEMPDIR/$RT.dir||exit

# umount the minirt and delete the old copy
echo "umount minirt"
umount $BUILDROOT/minirt||exit
rm $TEMPDIR/old/$RT

# copy the insmod.modutils and modules into the folder
echo "copy insmod.modutils and modules to minirt folder"
cp -a $TEMPDIR/$KDIR/modules/* $TEMPDIR/$RT.dir/modules/||exit
cp -a $TEMPDIR/common/insmod.modutils $TEMPDIR/$RT.dir/modules||exit

# copy the "other" files into the folder
echo "Copying other files into minirt"
cp -a $BUILDROOT/other/$RT/* $TEMPDIR/$RT.dir||exit

# patch the linuxrc
echo "Patch linuxrc"
cp -a $BUILDROOT/linuxrc26_ntfs.diff $TEMPDIR/$RT.dir||exit
patch $TEMPDIR/$RT.dir/linuxrc < $TEMPDIR/$RT.dir/linuxrc26_ntfs.diff||exit

# copy the blank minirt to a new file and loop-mount rw
echo "Create new miniroot and mount it"
cp -a $BUILDROOT/minirt.blank.img $TEMPDIR/boot/$RT||exit
mount -o loop,rw $TEMPDIR/boot/$RT $BUILDROOT/minirt||exit

# copy the folder into the minirt
echo "copy in content to new minirt"
cp -a $TEMPDIR/$RT.dir/* $BUILDROOT/minirt/||exit

# umount the minirt
echo "Unmount the new minirt"
umount $BUILDROOT/minirt||exit

# gzip the minirt
echo "Gzip up the minirt"
gzip $TEMPDIR/boot/$RT||exit

# Finished, do we have another kernel to do?
echo "Finished loop for $KERNEL"
done

# umount the cloop and iso
echo "Unmounting the cloop"
umount $BUILDROOT/cloop||exit
losetup -d /dev/cloop1||exit
umount $ISOFILE
echo "Done"

---

Note that what it builds will be in a folder in /root/build/, the folder I made is called 200411072234 (meaning it was created at 22:34 on 7 Nov 2004), i.e. it makes a new folder for each run (so you'll want to delete out duds). Inside this folder is a boot/ folder which has the 2 kernels and 2 minirt files.

The only issue left here is that I am not copying across the japanese nls modules (for language support) and I also haven't removed the changes for those modules from the linuxrc patch. I will see if I can copy ALL the nls modules into the linuxrc and load them all (or would they autoload) but that will add about 250k to the minirt (thats an educated guess for 2.6 it could be more) so if this went into the original knoppix people might have to remake the minirt more often, stripping things back out if they wanted to add any extra modules. As it is it works fine for me (windows/ntfs system is in English, in Ireland if that impacts it) with the minirt increased from 773k/782k to 1111k (2.4 and 2.6 are now only 580b different in size) and increase of about 330k but a substantial increase. After booting up it looks like nls_iso8859_1 is supporting the ntfs, what codepages are required elsewhere (I can guess for Japan)? All of them? Would it be reasonable to say your paths have to be intelligible in iso8859-1 and not include all the nls pages?

Finally I'm going to post a mail about this to the developers list as it seems the original author has had no luck getting a response. In the meantime if you are remastering, the above should work to add support for this to your remaster.