Dual Boot Gentoo & Ubuntu

generic_genus · n00b Joined: 26 Apr 2005 Posts: 9

Hey, to help educate my little brother about linux I installed ubuntu-6.06 on a spare partition as I didn't want him messing with my gentoo installation and wanted him to install a distribution for himself. The installation went fine (atleast the files were placed on the partition) however for whatever reason ubuntu didn't install a boot manager which I thought would be no problem.

I added Ubuntu to lilo.conf, ran lilo which reported no problems, then rebooted and ubuntu failed to boot (gentoo still boots fine). It appears the initrd boots giving me a shell but complains about the target filesystem not having /sbin/initctl and not being able to mount /proc /dev etc... so my question is how do I configure lilo from gentoo to boot both distros?

The contents of my lilo.conf:

St. Joe · Apprentice Joined: 13 Apr 2005 Posts: 242 Location: USA

welp · Posted: Sun Jul 09, 2006 4:13 pm Post subject:

No offence, but I would suggest that you use GRUB rather than lilo. If you use GRUB, you can follow the howto at: http://gentoo-wiki.com/HOWTO_Dual_boot
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generic_genus · n00b Joined: 26 Apr 2005 Posts: 9

The /mnt/ubuntu is needed (lilo complains cannot find file if not used), the first configuration attempt used your suggested config but didn't work so I added the /mnt/ubuntu to solve this and lilo doesn't complain.

I've considered using grub but I've always used lilo since I first installed linux 5 years ago and until now I've never really had a reason to change. Why would I be offended by you making a sensible suggestion? However, since I have lilo installed I would prefer a lilo solution. Ofcourse if there is no known lilo solution I will change to grub, despite the fact I find the config file syntax illogical (though thats probably just because it is unfamiliar). Also the howto you pointed to and 99% of those available are generally for a linux system and an "other" OS e.g. windows/BSD

I'm thinking of creating a shared boot partition for both gentoo and ubuntu (i.e. place both gentoo kernels and ubuntu kernels on the same seperate partition), however I'd rather not re-install. I suppose I could just use the same kernel, but I want the two distros to be as independent as possible since ubuntu is for my 13 year old brother to break and hopefully learn something.

Another point is the howto here http://www-128.ibm.com/developerworks/linux/library/l-dboot.html seems to use a config very similar to mine but uses two identical distros, so is my problem related to some kind of difference between ubuntu & gentoo init?

So in summary:
*Anyone get any other ideas about what I'm doing wrong?
*Will this definitely work with grub?

BlackEdder · Posted: Sun Jul 09, 2006 8:55 pm Post subject:

lilo does not complain because it can find the kernel image, but when booting the image isn't in /mnt/ubuntu anymore and that will give you problems, but I don't know how to do it except when you use a separate /boot partition with the kernel images for both gentoo and ubuntu on it. BTW ubuntu did overwrite my mbr without asking, so are you sure the install finished?

generic_genus · n00b Joined: 26 Apr 2005 Posts: 9

It said it was finished so all I can say is yes, booting the ubuntu install using the kernel off the install CD works fine, so I'd say it was installed fine. The auto-generated menu.lst seems to be in order (and seems to have detected my gentoo install aswell, which is nice) however doing "grub-install /dev/hdb" does not work. Is this correct command to run? as I'm ignorant of all things grub, I'm getting the feeling this may be beacuse I boot from the second physical drive.

Also as far as I understood lilo, it does not deal with files at boot it usese a physical address, so the mount point is irrelevant at boot (since no partitions are mounted). I believed the big reason for using grub was that it does refer to files at boot, or am I wrong?

idella4 · Posted: Mon Jul 10, 2006 8:34 am Post subject:

generic_genius,

yes, booting off the second drive does cause 'issues'. That's where it gets all tangled.
I've tried it a few times and consistently get a grub error at boot.
Rule of thumb is to boot off the first drive, then everything 'behaves' normally.
It's something I've not done yet, but if you're in that position, why don't you try treating b as a when
using grub-install /dev/...
As a rule I use grub-install and cite a home partition rather than an mbr of a drive.
e.g. grub-install /dev/hdb2 or whatever is the home partition.

once you get a working grub, it's just a matter of adding valid entries to /boot/grub/menu.lst of the selected hosting linux system.
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generic_genus · n00b Joined: 26 Apr 2005 Posts: 9

Everything is working , ubuntu had kindly placed grub on the first disk all correctly configured, just my bios was set to boot off the second. So to dual-boot two linux distros you have to place the boot manager on the first physical HDD (/dev/hda), just to clarify for anybody reading this in the future with a similar partition scheme to me.

And idella your second suggestion of placing grub on /dev/hdb2 or some other partition doesn't work.

In hindsight this is the first thing I should have done, but simple solutions aren't always the most obvious. Oh well, thanks for your help everybody, it's appreciated.

idella4 · Posted: Tue Jul 11, 2006 6:10 pm Post subject:

that doesn't surprise me. There are so many factors that influence. All just part of learning and figuring it all out.
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