How to boot several CD iso files in a DVD
------Edited 22/8/07 I used the same idea to boot the 7 iso off a USB pen drive and reported it in Post #5-------------------
I wrote this thread because someone asked if it is possible to do such thing in another forum. I think it can be done, tried it out and documented result in JustLinux.
Steps at a glance
(1) Open a directory, say /iso.
(2) Mount each iso file on a loop back device and copy its content to /iso directory
(3) Copy Grub's stage2_eltorito into /iso directory
(4) Write a Grub menu using the isolinux.cfg from each iso file
(5) Use bash command mkisofs to create a large iso file from /iso directory
(6) Burn the large iso file into a DVD using K3B
Not every iso is suitable to co-exist with others in a DVD. This is because they may use the same directory names.
A little bit of theory
Among about 95% of Linux iso meant to be booted from a CD or DVD will have the de facto boot loader called isolinux, written by Peter Anvin. It has a configuration file called isolinux.cfg. The isolinux syntax is very similar to Grub and so one can substitute isolinux with Grub.
Isolinux can also multi-boots. I am just more comfortable with grub and know it can deliver what I want. Grub is preferred because we can communicate with Grub during boot time and correct any mistake as we go along. That is very useful with a read-only DVD. Isolinux does not offer this flexibility.
Grub has only one file for booting a CD or DVD. This file is called stage2_eltorito available in every Linux that has Grub. It is stored in /boot/grub or /grub directory. The Grub Manual has steps showing how to create a CD or DVD booted by stage2_eltorito.
This is just a big folder for storing several iso files. The iso files have to be expanded first into the normal format first. I use an existing directory in /abit ,rounded up 7 iso files and created the following subdirectories
for 7 distros of Damn Small Linux, Slax, Mepis, Grafpuppy, Ubunu, Parted Magic and SystemrescueCD. Their version numbers are stated in the menu.lst below.
I use “-boot” for the folder names because some distros may have their own folders using the distro own names, for example slax and pmagic.
I wrote a script called mountiso to execute the two lines of commands
This allows me to mount any iso file by bash command, say for iso slax-6.0.0-rc5.iso
saikee@saikee-desktop:~$ cat /abit/saikee/Desktop/mountiso
mount -t iso9660 -o ro,loop=/dev/loop0 $1 /mnt/cdrom
The Slax iso when expanded shows two directories of /boot and /slax inside
/bin/bash mountiso slax-6.0.0-rc5.iso
I can then copy the expanded iso file in /mnt/cdrom into the folder I created in Step-1
root@saikee-desktop:/abit/saikee/Desktop# ls /mnt/cdrom
I have to repeat Step-2 for each iso file.
cp -R /mnt/cdrom/* /abit/iso/slax-boot/
The folder /abit/iso will be eventually a DVD iso and so to make it bootable by Grub we must have
(a) a directory called /boot/grub
(b) statge2_eltorito inside /boot/grub
I was using an installed Ubuntu 7.04 to do the above work and so Ubuntu's /boot/grub has all the information I need. Therefore all I need to do is to copy the content of Ubuntu's /boot/grub directory into /abit/iso after creating the directories there first
at this stage all the Grub files will be available as shown below
cp /boot/grub/* /abit/iso/boot/grub/
root@saikee-desktop:/home/saikee# ls /abit/iso/boot/grub
default fat_stage1_5 menu.lst~ stage1 xfs_stage1_5
device.map jfs_stage1_5 minix_stage1_5 stage2
e2fs_stage1_5 menu.lst reiserfs_stage1_5 stage2_eltorito
This is by far the most difficult thing to explain. I shall only do it by example. Slax in the above is the perfect system for this type of illustration. The above information shows it has two directories of “/slax” and “/boot” so the first thing I have to do is to move the /slax directory from /abit/iso/slax-boot to /abit/iso, leaving only the /boot there for reference only. This is because when the DVD is booted the installer has been written to search only the root directory whereas the /boot directory is the one I can control by telling Grub where to find it. I can't put /boot in the root directory because many distros have /boot too.
I now show how to get the isolinux.cfg by repeating just the "ls" command going into deeper level each time.
The part of the isolinux.cfg that is of interest to me has only two lines I have highlighted in red
root@saikee-desktop:/home/saikee# ls /abit/iso/slax-boot/
root@saikee-desktop:/home/saikee# ls /abit/iso/slax-boot/boot
bootinst.bat bootlilo.sh dos isolinux syslinux vmlinuz
bootinst.sh chain.c32 initrd.gz mt86p vesamenu.c32
root@saikee-desktop:/home/saikee# ls /abit/iso/slax-boot/boot/isolinux
isolinux.bin isolinux.boot isolinux.cfg
root@saikee-desktop:/home/saikee# cat /abit/iso/slax-boot/boot/isolinux/isolinux.cfg
MENU LABEL Slax Graphics mode (KDE)
APPEND vga=769 initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw autoexec=xconf;kdm
MENU LABEL Slax Graphics mode with Persistent Changes
APPEND vga=769 initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw changes=/slax/slaxsave.dat autoexec=xconf;kdm
MENU LABEL Slax Graphics mode, Copy To RAM
APPEND vga=769 initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw copy2ram autoexec=xconf;kdm
MENU LABEL Slax Graphics VESA mode (1024x768)
APPEND vga=769 initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw autoexec=kdm
MENU LABEL Slax Text mode
APPEND vga=normal initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw
MENU LABEL Run Memtest utility
I now show the end result of the Grub menu, which must be stored as /abit/iso/boot/grub/menu.lst, and the red is the conversion.
You will see I have only changed “KERNEL” with “kernel” and correctly located the where about of the kernel “vmlinuz” to be found in directory /slax-boot/boot. Remember after you have brun the DVD iso the /abit/iso front end will disappear.
root@saikee-desktop:/home/saikee# cat /abit/iso/boot/grub/menu.lst
title DSL 4.0
kernel /DSL-boot/boot/isolinux/linux24 ramdisk_size=100000 init=/etc/init lang=us apm=power-off vga=791 nomce noapic quiet BOOT_IMAGE=knoppix
title Slax 6.0.0 rc5
kernel /slax-boot/boot/vmlinuz vga=769 ramdisk_size=6666 root=/dev/ram0 rw autoexec=xconf;kdm
title GrafPup 2.0
kernel /grafpup-boot/vmlinuz root=/dev/ram0 vga=0x312 loglevel=1 PMEDIA=idecd
title Mepis 6.9.5
kernel /mepis-boot/boot/vmlinuz init=/etc/init vga=normal quiet drvr=vesa
title SystemrescueCD 0.3.7 label fb1024
kernel /systemcd-boot/isolinux/rescuecd root=/dev/ram0 init=/linuxrc vga=791 looptype=squashfs loop=/sysrcd.dat dokeymap cdroot splash=silent splash=silent
title ubuntu 6.10 desktop safe ^graphics mode
kernel /casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper xforcevesa ramdisk_size=1048576 root=/dev/ram rw quiet splash --
title Parted Magic 1.8
kernel /pmagic-boot/isolinux/bzImage noapic root=/dev/ram0 init=/linuxrc ramdisk_size=100000 skip
The isolinux specifies the ram disk file as a parameter of the KERNEL statement with “initrd=/boot/initrd.gz” forming part of the command structure. In Grub I have separated it into a proper “initrd” statement. That is all I needed to change an iso booting with isolinux to booting with Grub. I do not touch other parameters at all.
To summarize the step of converting an iso booting from isolinux to Grub the steps are
- (i) copy the isolinux's KERNEL statement into Grub's menu.lst
- (ii) changed “KERNEL” to “kernel”.
- (iii) Adjust the directory name so that Grub can find the kernel
- (iv) remove the “initrd=xxxxx” parameter in the KERNEL statement of ioslinux.cfg and use the same as a separate “initrd” statement in Grub's menu.lst. Do not forget to remove the “=” sign and amend the partition reference.
I could have just done two iso to make the thread shorter but decided to put 7 iso files in because there are 6 examples showing how isolinux can be converted to Grub. One of the 7 has Grub already and I have shown how we could modify it too to multi-boot. The isolinux information is left at the rear of the thread in case any reader may find more information useful.
This has to be the easiest thing in life for creating your own bootable DVD. Just follow the steps outlined in the Chapter 3.4 of Grub Manual.
I wrote a script call makeiso just to do just that
I issue the makeiso command in directory /abit. The end product of the about command is a large iso file call grub.iso
root@saikee-desktop:/home/saikee# cat /abit/makeiso
root@saikee-desktop:/abit# mkisofs -R -b boot/grub/stage2_eltorito -no-emul-boot -boot-load-size 4 -boot-info-table -o grub.iso iso
To burn the grub.iso I just called up K3B and clicked the file name. The DVD, with 1.8 Gb from the 7 distros, was ready in 6 minutes. I used a re-writeable DVD.
Conclusion : I now have a DVD that boots 7 distros successfully.
The above information is also useful/sufficient for any user wanting to create his/her customized bootable CD/DVD
---------------------------------------------------------- The following information are included just for the reference purpose only --------------------------------------------------
For completeness I enclose the relevant parts of the isolinux.cfg from the other distros below. The menu.lst I wrote is already given at the above.
DSL's isolinux.cfg is in /boot/isolinux directory. Its “KNOPPIX” directory should be available in the / directory
Grafpuppy isolinux.cfg is in / directory. Its “image” directory plus all files ending with sfs should be available in the / directory
APPEND ramdisk_size=100000 init=/etc/init lang=us apm=power-off vga=791 initrd=minirt24.gz nomce noapic quiet BOOT_IMAGE=knoppix
Mepis uses Grub and its menu.lst is in /boot/grub directory. Its “mepis” directory should be available in the / directory.
append root=/dev/ram0 initrd=initrd.gz splash vga=0x312 loglevel=1 PMEDIA=idecd
SystemrescueCD has isolinux.cfg in /isolinux directory. Its “bootdisk” directory and sysrcd.dat should be available in the / directory.
title Vesa (if display problem or if vmware)
kernel /boot/vmlinuz init=/etc/init vga=normal quiet drvr=vesa
Parted Magic isolinux.cfg is in /isolinux directory. Its “pmagic” file should be available in the / directory.
append root=/dev/ram0 initrd=rescuecd.igz init=/linuxrc vga=791 looptype=squashfs loop=/sysrcd.dat dokeymap cdroot splash=silent
Ubuntu is a difficult one as it has so many directories needed to be available in the / directory. I just copied everything. The isolinux.cfg is in /isolinux directory and I used only this portion
MENU LABEL ^1. Boot Parted Magic using the default settings
* version: 1.8, (C) 2007, Patrick Verner
* Disclaimer: Author not responsible for any mishap caused by this software.
APPEND noapic initrd=initrd.gz root=/dev/ram0 init=/linuxrc ramdisk_size=100000 skip
Lastly the complete content of my /abit/iso (before turning into the iso), looks like this
menu label ^Start or install Ubuntu
append file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.gz ramdisk_size=1048576 root=/dev/ram rw quiet splash --
root@saikee-desktop:/abit/saikee/Desktop# ls /abit/iso
bin DSL-boot KNOPPIX pool sysrcd.dat vesamenu.c32
boot graf_200.sfs mepis preseed sysrcd.md5 zdrv_200.sfs
bootdisk grafpup-boot mepis-boot programs systemcd-boot
casper img pics slax ubuntu
disctree install pmagic slax-boot ubuntu-boot
dists isolinux pmagic-boot splashpm.png usbstick.htm