grub 2 sees but won't boot salix on dual boot Ubuntu/Salix

[mises_fan]

A slightly unusual situation. My onboard SATA controller has gone on strike. I've ordered a new motherboard but for the moment I'm limited to a usb connected external hard drive. So, no CD (it's a SATA Internal) means if I screw up the bootloader I'm SOL until I get my new mobo. And if none of the installation CDs I've burned in the past work (which is quite possible, they are all kind of old and not in the greatest condition -- and the ghost of Murphy lives in my house) I'll still be SOL. So I booted the Salix iso (not a real CD, the iso on my external usb hard drive) and installed it to the first partition where a borked Debian was sacraficed. But when it came time to install LILO I chickened out, because if I screw up the bootloader, with no CD drive, I don't see a pathway to fixing that until my new hardware comes and I get a little panicky when comtemplating the idea of having NO working computer for a few days. So I booted into Lubuntu Precise with Mate on another partition and ran update-grub. Rebooted. Salix was on the Grub menu. Cool. But when I select Salix it starts and fails during the text in tty part of the boot process. [BTW, my highest praise to whoever had the good sense to make the default font in the tty big enough for a normal human to read. Why is such a common sense thing so darn rare in the nix world?]. So I presume update-grub put a line in one of grub-2's eleventy-seven config files that is ALMOST right but not quite. I'm thinking that if I can find the right file, and the not-quite-right line and edit it appropiately, it should boot Salix fully and that this would be a low risk way of attempting it that shouldn't put my Ubuntu Precise installation at risk. I realise y'all mostly aren't grub fans, and I'm interested in trying LILO later but my experience with messing with bootloaders is that are 10 ways to break it for every way that works. That's why I'm looking to try a minimalist change that is extremely unlikely to put my sole remaining bootable OS at risk.

Any suggestions?

[gapan]

Hi and welcome to the forums.

First of all, it's easy to avoid getting locked out of your PC until you get a new SATA controller. Just write any linux live distribution in a USB thumbdrive and you can screw up and fix anything after that.

Now, I haven't used grub2 in ages, but I believe the main configuration file is /boot/grub/grub.cfg and maybe there are more files in /etc/grub.d/. Start with the main file and if nothing is there move to the directory with the other files.

[mimosa]

I recommend Salix Live 13.37. You can install grub from the repos. It has a nice graphical utility called Lilosetup, should you want to use lilo, but be aware that in your situation, it won't quite work. It is likely to try to boot at least one of your installations using the wrong kernel. This is easily enough fixed, but I dare say you'd rather stick with the devil you know for now.

Another thing you can do if you have a spare USB stick is make a boot stick during installation of Salix. Then as long as you can boot from that, you can get into Salix, without messing with your existing bootloader arrangements.

[Adys]

Before updating grub, since you are booting from a different media you would need to mount your relevant partitions and chroot, before grub-update. That's why it fails to boot your installed OS.

Some links:

https://help.ubuntu.com/community/Grub2
https://wiki.archlinux.org/index.php/GRUB
http://www.supergrubdisk.org

Salix Live (13.37) with LiloSetup GUI should take care of you concerns regarding LILO.