The Boot Loader Showdown

Francesca writes "What utility do practically all Linux users use, regardless of their job or expertise? A boot loader. In this article from IBM, see how a boot loader works, meet two popular loaders -- LILO (LInux LOader) and GNU GRUB (GRand Unified Boot loader) -- and review the pros and cons of each." From the article: "Most simply, a boot loader loads the operating system. When your machine loads its operating system, the BIOS reads the first 512 bytes of your bootable media (which is known as the master boot record, or MBR). You can store the boot record of only one operating system in a single MBR, so a problem becomes apparent when you require multiple operating systems. Hence the need for more flexible boot loaders."

Comments

Re:AMD64

[Svenne]

Of course, LILO doesn't work with AMD64

Yes it does. It's working just fine for me, thank you very much. I'm using Ubuntu AMD64 with LILO, since I couldn't quite get the hang on GRUB which was installed by default.

NT Loader

[teslatug]

The author says "Unlike the Linux boot loaders, the majority of Windows boot loaders will not allow you to load Linux."

I don't know what he calls a majority, but the NT loader (used by Windows NT, 2K, XP, 2003) can boot Linux. It's just that Microsoft is being a pain about it. You have to first dd the first 512 bytes of your partition, save those to a file, and create an entry in boot.ini which points to that file.
For example:
dd if=/dev/hda1 of=/mnt/cpart/linux.mbr bs=512 count=1

[Boot Loader]
Timeout=5
Default=multi(0)disk(0)rdisk(0)partition(4)\WINNT
[Operating Systems]
multi(0)disk(0)rdisk(0)partition(4)\WINNT="Microso ft Windows 2000 Professional" /fastdetect
C:\linux.mbr = "Linux"

Let's see some more bootloaders!

[SanityInAnarchy]

I don't have the links, but Google is your friend:

XOSL -- Xtended Operating System Loader

Pros:
- an actual GUI in a bootloader
- support for loading keystrokes into the keybuffer, which gives it indirect support for simpler keystroke-based bootloaders like Lilo -- it can "type" in a kernel name for Lilo to load.
- relatively easy to install from Win98 -- I believe it can even use a FAT partition to store its stuff on.
- Password protection, can boot a default entry after a timeout.
- Entirely configurable from inside the bootloader -- and it's user-friendly, due to the built-in windowing system.

Cons:
- Not much direct support for anything. While it can load Linux through Grub or Lilo, and it can boot CDs through SmartBootManager, it's really a very simplistic x86 bootloader with a very advanced GUI.
- Support for booting a default requires a timeout, meaning that 90% of the time, when you're just booting the default OS, you have to wait an extra few seconds or press a keystroke -- and if you don't want to boot the default OS, you have to hit a key at just the right time to select a different one.
- Doesn't seem to be configurable outside the bootloader, meaning if you download a howto on configuring XOSL, you have to print it out and reboot in order to configure.

GRUB: Grand Unified Bootloader

Pros:
- Only bootloader I know of that supports the Multiboot spec, which unfortunately is a "standard" supported by only one bootloader (Grub) and one OS (Hurd) -- but it's still pretty cool that Grub could, in theory, insert kernel modules on boot, eliminating most initrds.
- Contains a built-in commandline and actual FS support, so a mistyped or forgotten menu entry is no problem -- type it in manually to boot, then fix the menu entry from your main OS, not a rescue disk.
- Powerful menu system -- the "configfile" command allows for multiple nested menus. Password protection.
- Config file is readable an Unix-ey, and is a plain Unix text file parsed directly by Grub -- no need to type a command after each kernel update.
- Supports booting from PXE (giving multiple netbooted images as a menu)
- Supports booting from CD, allowing an easy menu to access multiple kernels and tools like memtest86.

Cons:
- Like XOSL, it lacks actual support for booting from CDs or net. You can install it to a CD or Net, in which case you can probably also boot stuff from the hard drive, but if it's run from the hard drive, it can't boot CD or net.
- Lacks XOSL's keybuffer feature (which is probabyl unique), meaning if you want to use SmartBootManager to boot a CD, you will see the Grub menu, and then the SBM menu.
- Since it groks FSes, you may need a separate /boot partition if it doesn't natively support your / partition.
- Commandline, while useful, really only protects you from typos in grub.conf. It doesn't protect you from forgetting to install Grub to the MBR in the first place, or reinstalling if the stage 1.5 files got physically moved around.
- Like XOSL, booting a default requires a timeout.

NTLDR -- NT Loader

Pros:
- Already installed on Windows NT based OSes.
- Supports NTFS, and can boot most x86 boot images if they are available on the boot NTFS partition.
- Plain-text config file.

Cons:
- No native support for anything but NT and chainloading (x86 boot images)
- Menu system is bad. It seems locked into a 30 second timeout, and like XOSL and GRUB, you have to have the timeout to have a default.
- No native support for booting other partitions -- this can be accomplished by putting Grub or another bootloader into an image file, but it's not a trivial process, especially considering you have to redo it often.
- Not open source. It has limitations, and you can't do a damn thing about it.

Lilo -- Linux Loader

Pros:
- Dirt simple. No flashy menus or windows or FS support -- it just loads a kernel and goes.
- Plain text config file, with a simple command t