The Gentoo Linux alternative installation method howto Travis Tilley This HOWTO is meant to be a repository of alternative Gentoo installation methods, for those with special installation needs such as lack of a cdrom or a computer that cant boot cds. 0.1 23 Feb. 2002 About this document

Currently, if you want to install Gentoo Linux, you dont have all too many options to choose from. This limits Gentoo's userbase to those that can install via the methods available in howtos and those that can figure out tricky ways of installing Gentoo themselves. This document serves to provide information on installation techniques to those that need them, and to be a place to put your wacky installation methods. If you have an installation method that you yourself find usefull, or have devised an amusing way of installing gentoo... please dont hesitate to write something up and send it to me.

 netboot install

The requirements for a netboot install are a tftp server and a computer that can either netboot itself via bios or a floppy drive used to boot GRUB or another network bootloader. A dhcp server might also be necessary. Of course, you will also need the latest build ISO, which can be found at http://www.ibiblio.org/gentoo/snapshots/build/ix86-linux-gnu/

overview

In order to load images off the network, the first thing a netboot machine must do is obtain an ip. There are multiple ways of obtaining an ip, and any one of them will do. Personally, I prefer to use GRUB for everything, but if your computer supports booting from a network already then grub might not be necessary, even if it might be easier to just use GRUB's ifconfig command instead of setting up a bootp or dhcp server.

Once your computer has obtained an ip, the next logical step is to find out what you are going to be booting and where it might be held. Once again, it would be easiest to do this with GRUB commands as opposed to setting up a bootp or dhcp server. You will also need to specify how to obtain an initrd and tell the kernel that it will be using this as it's root filesystem.

With your kernel loaded and root filesystem mounted, you may proceed with installation as normal. The build image could be loaded from a cd, or it can be downloaded from the network via tftp.

Using GRUB

To use GRUB for network booting purposes, you must first have GRUB compiled with support for your network card. It doesn't matter if you install to floppy, or to the hard drive of the computer you wish to install Gentoo on. If your install target already has GRUB with network support installed, then you are one step ahead. GRUB can be downloaded from ftp://alpha.gnu.org/gnu/grub/

A configure example for enabling tulip support, the network card in my box:

swift grub-0.91 # ./configure --enable-tulip --prefix=/usr
swift grub-0.91 # make && make install

If you are currently in Gentoo and wish to install GRUB using Gentoo tools, then you need to install step by step in order to configure in support for your network card. An example for using ebuild to install GRUB with tulip support:

swift root # cd /usr/portage/
swift portage # ebuild sys-apps/grub/grub-0.91.ebuild unpack
swift portage # cd /var/tmp/portage/grub-0.91/work/grub-0.91/
swift grub-0.91 # ./configure --prefix=/usr --sbindir=/sbin --mandir=/usr/share/man --infodir=/usr/share/info --enable-tulip
swift grub-0.91 # make
swift grub-0.91 # touch /var/tmp/portage/grub-0.91/.compiled
swift grub-0.91 # cd /usr/portage/
swift portage # ebuild sys-apps/grub/grub-0.91.ebuild install
swift portage # ebuild sys-apps/grub/grub-0.91.ebuild qmerge

Now that we have the GRUB shell itself installed, we need to install to a boot sector. There are two ways of doing this. You can use the GRUB shell itself, or you can use a provided script called grub-install. It is preferable to use grub-install when installing GRUB to a floppy.

grub-install example:

swift root # mkfs.ext2 /dev/fd0
swift root # mount /dev/fd0 /mnt/floppy/
swift root # grub-install --root-directory=/mnt/floppy/ '(fd0)'
swift root # umount /mnt/floppy/

grub-install does not always work... and isn't always the best way to install GRUB. And since the GRUB shell works exactly like GRUB would when booted via the boot sector, it might be more desirable just to use the GRUB shell. Here is an example of how to use the GRUB shell to install GRUB to a floppy:

swift root # mkfs.ext2 /dev/fd0
swift root # mount /dev/fd0 /mnt/floppy/
swift root # mkdir -p /mnt/floppy/boot/grub/
swift root # cp -v /usr/share/grub/i386-pc/* /mnt/floppy/boot/grub/
swift root # grub
grub> root (fd0)
grub> setup (fd0)
grub> quit
swift root # umount /mnt/floppy/

Now that we have a bootable GRUB floppy, we need to set up a tftp server for loading our kernel and initrd. if you use inetd, then you need a tftp server installed (I suggest netkit's tftp server) and a line in your /etc/inetd.conf that looks like this:

tftp	dgram	udp	wait	nobody	/usr/sbin/tcpd	in.tftpd

To install the netkit tftp server under gentoo linux, emerge net-misc/netkit-tftp

There is an ebuild for xinetd... if you prefer to use this than feel free to do so. However I do not use xinetd, and do not know how to set up tftp with it. If you use it and such, please send it edits on how to get xinetd working and I will include them in this howto.

Now that we have our tftp server ready, we need a kernel and a root initrd to put in it. You can compile a custom kernel yourself, but make sure it has all the things necessary for running gentoo (like devfs) and for netbooting (like initrd support). The root initrd will be the rescue.gz included in the gentoo ISO.

Mounting an ISO file without burning it to cd requires loopback filesystem support. 
swift root # mkdir /tftpboot
swift root # mount -o loop ./build-ix86-1.0_rc6-r14.iso /mnt/cdrom/
swift root # cp /mnt/cdrom/isolinux/kernel /mnt/cdrom/isolinux/rescue.gz /tftpboot
swift root # chmod 644 /tftpboot/*
swift root # umount /mnt/cdrom/

Boot the machine you want to install to with your incredibly usefull grub floppy. Once booted you need to specify a way for the machine to get an ip, specify where to get a kernel and it's options, and where to get it's initrd.

grub> ifconfig --address=192.168.0.10 --server=192.168.0.2
grub> root (nd)
grub> kernel /tftpboot/kernel devfs=nomount vga=normal load_ramdisk=1 prompt_ramdisk=0 ramdisk_size=18580 root=/dev/ram0 rw
grub> initrd /tftpboot/rescue.gz
grub> boot
You can also use bootp and dhcp to configure your ip via grub. Use the bootp and dhcp commands.

Now that you have your machine booted, you can install as normal. Refer to the from source cd install howto.