I had Gentoo installed on my machine for a while, but I decided today to try Slackware 11. I repartitioned and formatted the drives, then I told the installer to install LILO. (Whether or not Grub is superior to LILO isn't something I'm experienced enough to concern myself with.)

The installation finished fine and I restarted. But Grub is still there, asking me what OS to boot into. I hit Gentoo Linux--which is the only option--and it tries booting into /dev/hdb3, which used to be where Gentoo's / was located. I tell it to boot into /dev/hda1 and it works fine from there.

I'm just wondering why Grub didn't get erased during the reformat. My guess is it was installed to the MBR? And also, how I can either get rid of it, or at least fix it so it doesn't try booting into the wrong directory.

I would have stuck with grub personally...

Anyhoo, you can use the grub command line to boot your slack. Hit 'c' when you are at the menu, and you will see a 'grub>' prompt. Now you want to tell it where you kernels are. This will depend on whether you have a seperate '/boot' partition ot not. Assuming you do:
And that's it, it should be booted. The grub shell has tab completion, so if you don't remember the name of your kernal you can do:
grub> kernel /[Tab]
and it will print all files in /boot.

If you do not have a seperate /boot partition, then post back your partition table, and I'll mke adjustments to the syntax for you.

Grub is usually installed on the MBR, yes.

grub sees hard drives in order the BIOS sees them, but it does not skip like Linux would. In other words, if you have something plugged into Primary IDE master, it will be hda in Linux; in grub, it's hd0. If you then have something else plugged into secondary master, in Linux, it's seen as hdc, but in grub, it's seen as hd1 (becasue there's nothing attached to primary slave).

The same goes for partitions, in grub, the first partition is 0, the second 1, the third 2, regardless of what Linux (or fdisk) sees them as... it could be 1, 2 5, 8 in Linux, but it will be 0,1,2,3 in grub. make sense?

Knowing that, you need to install grub on the correct drive. To do this, get to a prompt, run "grub" (probably need to be root), and do the following:

Alternatively, you could add another option on your grub menu to boot either gentoo or slackware. To do this, just add an enrty in /boot/grub/menu.lst that looks something like this:

of course, make sure the paths are correct from the root of the drive that holds /boot, not the root of the linux file system (in the above example, /boot is its own partition, so there's no need to include "/boot" in the paths).


edit: DOH! bulliver beat me to it. oh well.

ah, thanks to the both of you.

I didn't have a /boot/grub because I reformatted during the slackware installation, so grub was living in my MBR and I didn't know how to configure it.