Originally posted by: Sureshot324
Ok, thanks for the info.
Just out of curiosity though, where exactly is the boot loader stored? Surely all the graphics, etc. can't all fit in the master boot record. Finally, how do you edit the config of a boot loader?
Your right about the graphics and stuff.
A master boot record is stored in the first sector of the harddrive. A sector is 512 bytes, the first 445 or so bytes is reserved for the boot record, 64 bytes contains the partition information, and there is 2bytes for a "signature" or something that is probably only used by dos stuff (I have no clue)
My picture I made to be displayed in the bootloader is 43k alone.
Nowadays the boot loader is more of a pointer.
For instance lilo (common linux bootloader for x86) runs it in stages, and it corrisponds to the LILO that is displayed has each letter that pops up as the different stages get loaded, so if it fails at LI then you know how far it got.
The first stage is stored in the MBR itself, it's job is to take the bios information provided and then read the second stage from the HD partition and load that into memory, and that (I think, don't take this a gospel fact or anything) does the memu display and loads the kernel when you select the item you want to boot.
Grub is much more sophisticated then lilo and can do nice things like trick the normal brain-dead windows installer into thinking that the partition arrangements are different then they realy are (like make it so that you can install win9x into a extended partition or whatnot.)
Grub is becoming more and more common. What I like is that grub has a rudementary command line interface so you can modify and create new boot entries on the fly during boot up. (good for getting around the occasional typo).
Grub's config is /boot/grub/menu.lst and/or /boot/grub/grub.conf and often has symbolic links to /etc/grub.conf. Different versions use different stuff, so everybody just has symbolic links to every config file just in case.
Lilo's config is /etc/lilo.conf.
After editing lilo you have to rerun the lilo command to make the changes stick, but grub the changes are automatic.
They use different syntaxs and setups, but they can be VERY simple. Most distros add a bunch of extra comments and options that can be safely deleted with no side effects. There are plenty of online docs and samples describing the details, so I won't go into it so much.