Booting quickly

There are some people out there who lament about it taking two or three minutes to boot linux. They are people with who want their computers to boot faster. Well, there are some things you can do to do this, and some will be discussed here.

Open source BIOSen
There is a project called coreboot. There is also a page about this on Wikipedia. These clever people have written a BIOS you can flash into your computer, which enable you for example have a linux kernel up in a fraction of a second.

They count the memory
Some BIOSen painstakingly check all the memory every time they turn on. The ZX Spectrum has to, to identify if it has 16K or 48K of memory installed. In the nineties, it was ernormously satisfying to watch your 486 count all the way up to 24 megabytes, if your friend had only 16. Today this feature is pretty much useless, so you could turn it off if your BIOS has the option to do so. If your memory chips start dying though, you probably won't notice until you're trying to troubleshoot random crashes and kernel panics.

Enable only the things you need
Many drivers initialise hardware, and this takes time. Do you ever use the integrated modem on your motherboard? If not, then why have support for this compiled into the kernel? If you think you'll ever use it, then just choose 'M' and load it when you do.

Parameters
If you get a little warning that says something about TSC and unstable clocksource while the kernel seems to pause for a second, then you can add the parameter "notsc".

There's also a parameter "fastboot", but I don't really understand what it does.

Way to the Init
Init is the first program the kernel will load on boot up, and is responsible for providing users with a sensible environment. It starts all other programs that are running on the computer.

XDM
The customary way is for this to start with the "default" run level. If you want to start it earlier in the boot process, then do

to take it out of the default runlevel and then

Your computer will be ready to let you log in sooner, but some things will not be ready until a short time after. Some people consider this a cheat, and others (myself included) are reminded of a terrible computer running Windows XP which continued rattling the hard drive and responding very slowly for a few minutes after log in.

If you use GDM or some other heavy login manager, then be aware that this is not the fastest way to start an X session. There are slimmer alternatives out there. Some use startx after logging in at the console.

Suspend/Resume
It might be that you actually don't have to boot up. Linux hardly ever needs to boot and has stayed up for years at a time. If you have no need to dual boot, you can suspend to RAM or disk and resume in a flash.

Keeping a different operating system on the same computer
The author for a while kept Haiku on his laptop for whenever he wanted to have a computer up in seconds to send a quick e-mail or look something up in an on-line dictionary or show my friends some pictures from my holiday. It took something like 4 seconds to boot Haiku into a usable desktop.