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 be able to 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

You can try adapting the steps found here:

http://unix.stackexchange.com/questi...on-a-partition

If you don't mind me asking - what is it you are trying to do? It may be much much easier just to use separate partitions. If shared space is your concern, maybe you can look at using ZFS (although not sure how easy it is to boot that). ZFS will let you create multiple partition spaces all using shared space. Then you should be able to just mount those as usual.

Fang:

Thank you for your reply...

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

Don't know if it could be done with folders, but I'm pretty sure you could boot disk images under the same partition.

I think that is where the custom initrd comes in from the post I linked. What you would pretty much have to do is build a custom initrd that will mount the folder over the root with a -o bind.

There are a couple of big gotchas though - anything that updates the initrd (kernel updates, etc) will break it. Pretty much everything out there I know of is designed to be partition-based. So it probably can be done, but it'll take a lot of work, and won't be very upgrade safe

If you modify /usr/share/initramfs-tools/scripts/local, any time the initrd.img gets updated, it should update with the changes you've made.