Editing Kboot.conf

Editing Kboot.conf is something you will have to do some time, Kboot.conf controls your boot options, the kernel you want to boot in, the resolution, etc etc. The problem is that even one typo can screw up your system, forgot an '='? You won't be able to boot... That's why you will want to make a copy every time you edit your kboot.conf (or any other system file).

Note: if you end up with an unbootable system, use this guide to get it running again!

Now, back to kboot.conf:
To start editing you have to use the terminal,
open one and type the following:

Sudo gedit /etc/kboot.conf
OR
Sudo nano /etc.kboot.conf

Gedit and Nano are both little applications to edit files, Gedit is more advanced and also supports an undo function, making it the safest of the two.

Now where in the editor you will see some lines of code similar to this:

message=/etc/kboot.msg
default=Xubuntu 720P
timeout=5
Xubuntu 720P='/boot/vmlinux initrd=/boot/initrd.img root=UUID=ccecbd73-3924-4e7e-b783-9d8c85eff8a2 quiet video=ps3fb:mode:131'
Xubuntu Backup='/boot/vmlinux initrd=/boot/initrd.img root=UUID=ccecbd73-3924-4e7e-b783-9d8c85eff8a2 quiet video=ps3fb:mode:131'

We'll break it down line by line

message=/etc/kboot.msg
This points to the file containing the message when you boot using the defailt bootloader, You could edit that if you want

default=Xubuntu 720P
This sets the default boot option, in my case the one I named Xubuntu 720P.

timeout=5
This is the time after which the default option will be loaded, I set it to 5 seconds so I can still select another option if I want to.

Xubuntu 720P='/boot/vmlinux initrd=/boot/initrd.img root=UUID=ccecbd73-3924-4e7e-b783-9d8c85eff8a2 quiet video=ps3fb:mode:131'
Xubuntu Backup='/boot/vmlinux initrd=/boot/initrd.img root=UUID=ccecbd73-3924-4e7e-b783-9d8c85eff8a2 quiet video=ps3fb:mode:131'
Now we're getting to the important lines, this is where it all happens and this is also where you want to make sure you don't make any misstakes! If you think you made a typo, don't try to find it but start all over again (by just quitting without saving) or using gedit's undo feature.
Anyways,,, Everything before "='/boot/vmlinux" is the actual name of the option, you could make it anything you want really, I'm using Petitboot, so I don't have to worry about it being easy to type at kboot:... You can make it as fancy as you want, but at least make sure the name makes sense (Xubuntu 720P, will obviously boot Xubuntu, with 720P as resolution).

='/boot/vmlinux initrd=/boot/initrd.img
This is the kernel you wan't to boot, you can find them at "/boot". VMlinux and Initrd.img point to the kernel version, When (if) you start compiling your own kernels you can replace vmlinux and initrd.img with your newly compiled kernel, just make sure you always have a backup (In my case a second option called "xubuntu backup")

root=UUID=ccecbd73-3924-4e7e-b783-9d8c85eff8a2
This is the part you DON'T want to touch, you WILL be left with an unbootable system, and it WILL be hard to find the error! Theres no point in editing it anyways (at least not for us).

quiet
This is a simple one, it basically hides some of the text you see when you boot, you can delete it if you like white text scrolling on your screen.

video=ps3fb:mode:131
This is where we set our resolution, (720P fullscreen in my case). You will get to know more about this if you follow the guide to get rid of those black borders around your screen!
NOTE: If you did not follow SwiftBiscuit's guide to remove the black borders DO NOT copy the above line, as you haven't installed fbset it won't work. If you happened to copy it anyway, you can always boot the "old" option to change it back.

General rules when editing your kboot.conf

• Always make a backup (just copy the original text in kboot.conf)
• Think you made a misstake? Start over, unless you are 110 percent sure you know what went wrong.
• When editing an option, always have a backup option, just incase the one you edited doesn't work anymore
• Don't forget to save after editing! (yes that happened to me before...)