Help: install other linux in gentoo subfolder...

n0nuf · n00b Joined: 29 Apr 2005 Posts: 5 Location: MO USA

Good morning.

I have a working install of gentoo 3.12.21-r1 x86_64. Is it possible to create a folder : /funtoo and untar a fully functional funtoo backup into that folder and then use Grub2 to 'boot' into that folder as if it were the main linux partition?

I am trying to install multiple additional linux distros onto the same partition using unique folders.

the /funtoo (/dev/sda4/funtoo) folder has the entire funtoo distro including its own /boot, /sys, /proc, etc folders.

Physical schema:

/dev/sda1 EFI +32M
/dev/sda2 /boot +1024M
/dev/sda3 swap +16G
/dev/sda4 / +482G (gentoo install)

This method should hide/mask the contents of the top level gentoo linux distro and appear as if the folder /funtoo is actually the root of /dev/sda4 .

Grub2 should load and use the /funtoo/boot/vmlinux-funtoo-debian and /funtoo/boot/initramfs-funtoo-debian kernels with this config.

Granted, I could chroot into this folder, but that is not what I am after as some functionality is unavailable in a chroot environment.

If possible, how do I setup grub.cfg, /funtoo/etc/fstab, etc config files to support this configuration?

Any information, guidance, step-by-step instruction appreciated. Alternatively, if this is not possible, please tell me how do do this effectively.

V/r,
Scott

RazielFMX · l33t Joined: 23 Apr 2005 Posts: 835 Location: NY, USA

I'm going to assume grub under EFI works the same as grub under BIOS (I use rEFInd on my EFI box, so don't know much about grub and EFI interaction).

1) Copy your /dev/sda4 contents somewhere safe. Hopefully you are mounting drives by their partlabel (since you have this nice option with EFI and gpt partioning).
2) Delete /dev/sda4 using gfdisk.
3) Create /dev/sda4 with the same lable it used to have using gfdisk with some space for /funtoo.
4) Create /dev/sda5 for your funtoo install.
5) Drop the original contents of /dev/sda4 to /dev/sda4 and update fstab as required. Add an entry for /dev/sda5 with or without auto-mounting (probably with a mount point of /funtoo).
6) In your grub.conf, set a boot entry pointing to the partition for /funtoo (hd(0,4)/boot/...). Or, you can use /boot in Gentoo as /boot for funtoo as well and just have a nice kernel list there.

TL;DR: You need a separate physical partition for /funtoo to do what you want.

NeddySeagoon · Posted: Tue Jun 17, 2014 8:01 pm Post subject:

n0nuf,

The easy way is to run funtoo in a Virtual Machine of some sort.

If funtoo was in a file, you could have the initrd loopback mount the file as the root filesystem.
Thats what the liveCD does with a read only squashfs file.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

n0nuf · n00b Joined: 29 Apr 2005 Posts: 5 Location: MO USA

Thank you for your replies...

Basically, I want to know if it is possible to replace the root mount point: " /dev/sda4 / (root) " with a 'subfolder ON /dev/sda4 as in: /dev/sda4/funtoo or /dev/sda4/RHEL ... etc.

I do NOT want to use different partitions. That would be too easy. :-)

I want to have multiple flavors of Linux on a single partition with one overarching 'master' linux install. I imagine the structure would look like this:

/dev/sda1 = EFI
/dev/sda2 = BOOT
/dev/sda3 = SWAP
/dev/sda4 = / (root) <- master OS which is currently Gentoo

... Child OS #1 ...

/dev/sda4/funtoo = / (root)
/dev/sda4/funtoo/boot = BOOT

... Child OS #2 ...

/dev/sda4/RHEL = / (root)
/dev/sda4/RHEL/boot = boot

... and so on ...

GRUB2 would be configured so that the Gentoo (master OS) boot was used, OR the Funtoo folder (child #1) /boot was used, OR the RHEL folder (child #2) /boot was used so the specific/unique Kernel (vmlinux + initramfs) for each distro could be activated at boot.

Yes, I could copy all the different Kernels to the master /boot partition and Grub them, but then I would have the issue of keeping all of the distro specific folders/files separated, and I do NOT want to share folders between distros. If I had subfolders, then that folder would essentially become the / (root) of the distro and operate from there with all of the necessary folders (/proc, /dev/, /bin, etc).

I have thought about 'chroot' and 'pivot_mount', but don't see how they would function like a partition mounted linux install. I have also thought about virtualization, but again, that would be the easy way out instead of finding a solution to the stated problem. :-)

I hope this has made my intentions clearer.

V/r,
-S

szatox · Advocate Joined: 27 Aug 2013 Posts: 3129

NeddySeagoon · Posted: Wed Jun 18, 2014 5:37 pm Post subject:

szatox,

How do you get write access to /dev/sda4/<some_dir> when /dev/sda4 is apparently not mounted?

n0nuf,

Is LVM cheating ?
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.