Tips

Creating a bootfloppy
Passwords

Creating a bootfloppy

There are times when you might need a floppy to boot a system from. Here's a step-by-step example on creating a bootup floppy you can use to boot Linux from.

(NOTE: chos compiled for kernel 2.x doesn't seem to work with floppies under kernel 1.x and vice versa.)

Normal bootfloppy
Standalone/rescue bootfloppy

Normal bootfloppy

This kind of bootfloppy is always good to have. With it you can boot your system after some program has modified your MBR. E.g. after having installed a new OS in your box. This kind of bootfloppy is required when setting up the rewrite feature.

Create a configuration file. The files should be set up as follows:
Path is any path but /boot is not a good choice since your normal system bootup files are kept there. /boot/bfloppy is fine. You can have the files on the floppy but that is not necessary unlike with standalone setup.
Everything else in the file can be as in your normal hd configuration.
Copy the binaries in path possibly creating the directory.
Run chos

Standalone/rescue bootfloppy

With this kinda bootfloppy you can boot any system since all necessary stuff to boot a system is on the floppy.

The first step is, of course, to create a config file. The following config file lines will tell chos to search for it's binary files and save other files on first floppy drive. bindir=/floppy chos.map=/floppy/chos.map chos.background=/floppy/chos.background install=/dev/fd0 Also setup a Linux kernel that exists on the floppy.. linux "Linux" { image=/floppy/my_linux ... }
Now that you have a config file, mount the damn floppy: (someone)/chos_path/$ mount /floppy and copy chos binaries and your kernel there: (someone)/chos_path/$ cp ./bin/* /floppy (someone)/chos_path/$ cp where_ever_my_kernel_is /floppy
And finally run chos: (root)/chos_path/$ chos -v -c the_config_file_I_created

The above let's you boot the kernel of a floppy, but you still need to have a root filesystem on a hard or floppy disk or an NFS image. If you want to make a real 'rescue' floppy, there are the chances:

Copy all the necessary binaries to set the system up and running and do the things you want on the same or another floppy (Linux will prompt you to insert the floppy). You need '/bin/sh' at least.
You might want to use statically compiled binaries since shared libc, not to mention libg++, is pretty huge, which leaves you no space for the actual binaries... You must add something like 'root=/dev/fd0' on the Linux command line.
If one floppy isn't big enough, create a compressed ramdisk. See '/usr/src/linux/Documentation/ramdisk.txt' for information on creating one.
If you want to use an initial ramdisk, the ramdisk image must be small enough to fit on the same floppy with the kernel and chos data. (That's due chos at the moment only supporting regular-file initrds. I should add support for initrd devices.)

Passwords

Suppose you wanted other users to only be able start Linux (or some other OS) here's what you do:

Set a password (password=my_password)
For those OSes you allow others to boot, set the password off or in case of Linux probably to 'restricted'. (In image configuration: password=no|restricted)

Here's an example configuration that

automagically starts Linux unless a modifier key is being held down ...
... and requires a password to start DOS or to manually enter Linux a command line

install=/dev/hda
password=salasana	# salasana = Finnish for password
autoboot=not_pressed

linux "Linux" {
	image=/boot/vmlinuz
	password=restricted
	cmdline=vga=EXTENDED root=/dev/hda4
}

bootsect "DOS" {
	image=/dev/hda1
}