Installing Debian GNU/Linux 3.0 For Intel x86
Chapter 10 - Technical Information on the Boot Floppies

10.1 Source Code

The boot-floppies package contains all of the source code and documentation for the installation floppies.

10.2 Rescue Floppy

The rescue floppy has an Ext2 file system (or a FAT file system, depending on your architecture), and you should be able to access it from anything else that can mount Ext2 or FAT disks. The Linux kernel is in the file linux.bin. The file root.bin is a gzip-compressed disk image of a 1.4MB Minix or Ext2 file system, and will be loaded into the RAM disk and used as the root file system.

10.3 Replacing the Rescue Floppy Kernel

If you find it necessary to replace the kernel on the rescue floppy, you must configure your new kernel with these features linked in, not in loadable modules:

• RAM disk support (CONFIG_BLK_DEV_RAM)

• Initial RAM disk (initrd) support (CONFIG_BLK_DEV_INITRD)

• Kernel support for ELF binaries (CONFIG_BINFMT_ELF)

• Loop device support (CONFIG_BLK_DEV_LOOP)

• FAT, Minix, and Ext2 file systems (some architectures don't need FAT and/or Minix file systems — see the source) For Intel x86, Minix file support is not required, but MSDOS and ext2 are.

• Socket filtering for DHCP (CONFIG_FILTER)

• Packet socket, also for DHCP (CONFIG_PACKET)

• Unix domain sockets for system logging — is provided as a module in the vanilla flavor (CONFIG_UNIX)

Be sure that the kernel you plan to use does NOT have CONFIG_DEVFS set. CONFIG_DEVFS is not compatible with the installer.

Download a set of boot floppies: root, rescue, and driver disks. You need to know that bf2.4, idepci, and compact use flavored kernels. One reason to use the ide or compact sets, for instance, is that they have only 1 or 2 driver disks and your custom kernel will likely have all the drivers you need built in. The downside is that it requires an extra manual step unless you built your custom kernel with the same flavor name (see make-kpkg in the kernel-package). You may also see some error messages regarding modules.

To compile a customised kernel, it is recommended to configure the kernel very similar to the one that you wish to replace. You should get the kernel-source package that have been used to build the kernel and copy the .config file from the rescue disk (see below).

Mount the rescue disk image, something like the following.

             mount -t auto -o loop rescue.bin /mnt

Assuming you used /mnt as the mount point, copy your custom kernel to /mnt/linux.bin. Next run the script rdev.sh which resides in /mnt, which assumes it will find the kernel as described here.

If you want to be complete about it, you'll also want to gzip the System.map from your custom kernel as sys_map.gz, and the config as config.gz, and place them in /mnt.

Now you can umount your disk image and burn your floppies. You will probably want to ``Install Kernel and Driver Modules'' using the floppies you just built to get your custom kernel installed on the hard drive. This is why having one driver disk is nice.

If you are using a disk set featuring a flavored kernel, you will need to switch to tty2 by pressing Alt and F2 keys together, and hit Enter to get a prompt. Type ls /target/lib/modules to see where the driver disk put your modules. Then uname -r to find out where the modules should be. You'll then want to do something suitable like the following.

     	mv /target/lib/modules/* /target/lib/modules/`uname -r`

Now you may exit out of the shell and return to tty1. If you didn't perform the last step properly, then ``Configure Device Driver Modules'' won't find any modules and thus will be sad.

You'll also want to replace the modules.tgz file on the driver floppies. This file simply contains a gzip-compressed tar file of /lib/modules/kernel-version; make it from the root file system so that all leading directories are in the tar file as well.

10.4 Preloading Existing Modules

If you need an essential driver in order to access the harddisk or installation source device, you can use existing modules instead of recompiling the whole kernel. You can preload driver modules from a floppy disk before mounting the root partition. To prepare such a floppy, you will need:

• Another box running Linux, a floppy drive and the usual tools

• Alternatively, a Win32 machine, using the usual Windows tools and GNU tar and gzip (or Winzip)

• a freshly formatted floppy disk

• pen and paper

Here are the steps to create the preload disk, assuming that you are on a Linux box and plan to use the bf2.4 flavor later:

• Mount your Debian CD-ROM in /cdrom

• Create a temporary directory and change to it (cd /tmp; mkdir work; cd work)

• Extract the kernel and modules for the flavor that you want to install with...

       su
       tar -zxvf /cdrom/debian/dists/woody/main/disks-i386/current/bf2.4/drivers.tgz
       tar -zxvf modules.tgz
       less lib/modules/2.4.18-bf2.4/modules.dep
  

• Read the modules.dep file, locate the modules that you are looking for, and note their dependencies. Note the order in which the modules depend on each other. Do the same for each dependency, unless you have a list of modules that can be loaded without dependencies.

• Copy all required modules to a separate location.

• Format your floppy disk, create the msdos filesystem (mformat a:).

• Make a directory called boot on the floppy disk. Copy all required modules to this directory.

• You can use this disk to preload modules. Do not lose your notes, you may need them to load the modules in the correct order.

Installing Debian GNU/Linux 3.0 For Intel x86