Is it posible to install one distro from another?

[game_core]

Hi! I am runing a fedora core 4 linux, and want to instal the 386 version of 64 studio.
Studio 64 is on a standard 700 mb cd-rom instalation iso.
The question is: can I mount, and reboot from the iso (while on the fedora drive) without burning the cd? Or can I install it in any other way?

[Zelmo]

Well, you can't mount the ISO as a loopback device and then boot from it, since all devices get unmounted during shutdown. You need a physical device that's recognized as bootable by the BIOS.

One thing you could do is check whether the new distro will let you make a boot floppy (or USB), and then install from the hard drive. I've done that with older versions of SuSE. Just be sure the install files on the hard drive are on a separate partition than what you're installing to, so that you don't overwrite them during installation.

[saikee]

I have tried this method but the success rate depends on how the distro is put together. For example some installers keep going back to find a CD to load the required files so without the CD rom it will fail eventually.

The sucess rate is rather poor. I would say out of 10 sytems you may get 3 installed this way.

The scheme basically mounts the iso image on a loop back device first.

The expanded filing system is then copied into a temporary area in the hard disk.

It is then booted manually by Grub using the isolinux configuration (isolinux is invariably used as the boot loader for a CD but a small number of recent distros started to use Grub by its stage2_eltorito.

Once booted up the distro can be installed in anywhere just like it is from a CD.

[Juan Pablo]

You can install Gentoo using a chroot enviromment and a couple of tarballs

[game_core]

I made something like this:
I mount-looped the instalation iso, and extracted the vmlinuz, and initrd (was ia a .gz).
Then copied them to my /boot as vmlinuzSt, and initrdSt.img.
Edited the /etc/grub.conf:

...
title Studio
        root (hd0,1)
        kernel /boot/vmlinuzSt
        initrd /boot/initrdSt.img

and installed it

/sbin/grub-install

Rebooted, and chosed Studio from the grub menu. The instalation program started, but failed to find the cd in drive (gues why), and didn't asked about a path to the .iso (i heard that some inatallers do this). Then little menu started with few options-I started the shell.
Mounted my fedora / into /mnt/hdd, and then tried to mount-loop my 64studio-install_1.0.0_i386.iso in the /cdrom, but it failed (no loopback device present).

So I returned to my fedora, and extracted the whole .iso to /stud/ dir.

So the next time I ran the installation process, I just made a

mount --bind /mnt/hdd/stud /cdrom

Now I had my instalation cd in the /cdrom/ dir :P, so exited the shell, and retried the detection of cd. It failed (that my computer still tried to read from the real drive) . The check of cd integrity failed also.

I must know if there is a method for making the installer thing that it mounted the cd.
Or maybe /cdrom/ is not the place where it mounts it? Maybe it mounts only one specific dir or something?

[saikee]

I didn't do it inside a Linux as you have done so.

I use a Linux to mount the iso on a loop back device as per the limk. I then copy the /mnt/cdrom into a temporary hard disk directory.

I then reboot and use a bootable Grub floppy to get me a Grub prompt.

I can use Grub's cat command to display the isolinux.cfg and boot the new Linux manually using the correct kerenl name and initrd with all the "append" pararmeters passed to the kernel.

Like I said some installers may have been written with the CDrom as the source of the files whereas others may just find them within the directory available.

As I was booting directly off Grub and had no access to a kernel I couldn't possibly alter the installer behaviour. Thus my comment of the poor 3 success in the 10 trials. I have not pursue the matter further. It is poosible that there are a few tricks available in Grub to bridge the gap. In the mean time I find it more convenient to waste a new CD than ploughing through the Grub literature. If you have to look it up then I would search Grub4Dos as it has various tricks documented.

Hope the above helps

[game_core]

I found out the: (cd-rom root)/isolinux/isolinux.cfg

with such entries:

...

DEFAULT install

LABEL install
	kernel /install/vmlinuz
	append vga=normal initrd=/install/initrd.gz ramdisk_size=16000 root=/dev/ram rw preseed/file=/cdrom/.disk/preseed debconf/priority=high mirror/suite=etch   --

...

And found that the file (cd-rom root)/.disk/preseed is somekind responsible for somevariables and the cd-rom/ramdisk structure, so acording to this my new /etc/grub.conf entry looks
like this:

...
title Studio
        root (hd0,1)
        kernel /boot/vmlinuzSt
        initrd /boot/initrdSt.img
        ramdisk_size=16000 root=/dev/ram rw preseed/file=(hda2)/stud/.disk/preseed debconf/priority=high mirror/suite=etch

I found that now the cd is recognized after i mount-bind it from the shell, but the setup
proces fails, becouse it can't see the symlinked files.
For example the path /cdrom/dists/stable/Release should probably point to /cdrom/dists/64studio/Release (/cdrom/dists/stable is an empty file).This hapens probably becouse there is nothing in /cdrom/ when it is executing (preseed/file=(hda2)/stud/.disk/preseed ).

Any ideas?

[saikee]

Ah, I wouldn't boot the iso image that way but use the configuration as found in the syslinux.cfg as follow (by a bootable Grub floppy made in accordance with Chapter 3.1 of Grub Manual or any way to get a Grub prompt)

Assuming the expanded iso image is temporarily stored in partition (hd0,1)

 root (hd0,1)
kernel /install/vmlinuz vga=normal ramdisk_size=16000 root=/dev/ram rw preseed/file=/cdrom/.disk/preseed debconf/priority=high mirror/suite=etch
initrd=/install/initrd.gz 
boot

I believe at this stage I am merely substituting syslinux with Grub and trying to boot up the iso image as though it is from the CD.