Difference between revisions of "PXE"
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# mkdir -p /mnt/archiso
# mkdir -p /mnt/archiso
# mount -o loop,ro archlinux-
# mount -o loop,ro archlinux--dual.iso /mnt/archiso}}
== Server setup ==
== Server setup ==
Revision as of 11:13, 20 January 2013
- The Preboot eXecution Environment (PXE, also known as Pre-Execution Environment; sometimes pronounced "pixie") is an environment to boot computers using a network interface independently of data storage devices (like hard disks) or installed operating systems.
In this guide, PXE is used to boot the installation media with an appropriate option-rom that supports PXE on the target.
Download the latest official install media from here.
Next mount the image:
# mkdir -p /mnt/archiso # mount -o loop,ro archlinux-20*-dual.iso /mnt/archiso
You'll need to setup a DHCP, TFTP, and HTTP server to configure networking, load pxelinux/kernel/initramfs, and finally load the root filesystem (respectively).
Bring up your wired NIC, and assign it an address appropriately.
# ip link set eth0 up # ip addr add 192.168.0.1/24 dev eth0
DHCP + TFTP
You'll need both a DHCP and TFTP server to configure networking on the install target and to facilitate the transfer of files between the PXE server and client; dnsmasq does both, and is extremely easy to set up.
# pacman -S dnsmasq
# vim /etc/dnsmasq.conf
port=0 interface=eth0 bind-interfaces dhcp-range=192.168.0.50,192.168.0.150,12h dhcp-boot=/arch/boot/syslinux/pxelinux.0 dhcp-option-force=209,boot/syslinux/archiso.cfg dhcp-option-force=210,/arch/ enable-tftp tftp-root=/mnt/archiso
# systemctl start dnsmasq.service
Thanks to recent changes in archiso, it is now possible to boot from HTTP (archiso_pxe_http initcpio hook) or NFS (archiso_pxe_nfs initcpio hook); among all alternatives, darkhttpd is by far the most trivial to setup (and the lightest-weight).
# pacman -S darkhttpd
Then startusing our /mnt/archiso as the document root:
# darkhttpd /mnt/archiso
darkhttpd/1.8, copyright (c) 2003-2011 Emil Mikulic. listening on: http://0.0.0.0:80/
For this portion you'll need to figure out how to tell the client to attempt a PXE boot; in the corner of the screen along with the normal post messages, usually there will be some hint on which key to press to try PXE booting first. On an IBM x3650 F12 brings up a boot menu, the first option of which is Network; on a Dell PE 1950/2950 pressing F12 initiates PXE booting directly.
/var/log/messages.log on the PXE server will provide some additional insight to what exactly is going on during the early stages of the PXE boot process:
# grep dnsmasq /var/log/messages.log | cut -d' ' -f5-
dnsmasq-dhcp: DHCPDISCOVER(eth1) 00:1a:64:6a:a2:4d dnsmasq-dhcp: DHCPOFFER(eth1) 192.168.0.110 00:1a:64:6a:a2:4d dnsmasq-dhcp: DHCPREQUEST(eth1) 192.168.0.110 00:1a:64:6a:a2:4d dnsmasq-dhcp: DHCPACK(eth1) 192.168.0.110 00:1a:64:6a:a2:4d dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/pxelinux.0 to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/whichsys.c32 to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe_choose.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/ifcpu64.c32 to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe_both_inc.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso_head.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe32.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe64.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/archiso_tail.cfg to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/vesamenu.c32 to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/syslinux/splash.png to 192.168.0.110
After you load
archiso.cfg via TFTP, you'll (hopefully) be presented with a syslinux boot menu with several options, two of which are of potential usefulness to us.
Boot Arch Linux (x86_64) (HTTP)
Boot Arch Linux (i686) (HTTP)
depending on your CPU architecture.
Next the kernel and initramfs (appropriate for the architecture you selected) will be transferred, again via TFTP:
dnsmasq-tftp: sent /mnt/archiso/arch/boot/x86_64/vmlinuz to 192.168.0.110 dnsmasq-tftp: sent /mnt/archiso/arch/boot/x86_64/archiso.img to 192.168.0.110
If all goes well, you should then see activity on darkhttpd coming from the PXE-target; at this point the kernel would be loaded on the PXE-target, and in init:
1348347586 192.168.0.110 "GET /arch/aitab" 200 678 "" "curl/7.27.0" 1348347587 192.168.0.110 "GET /arch/x86_64/root-image.fs.sfs" 200 107860206 "" "curl/7.27.0" 1348347588 192.168.0.110 "GET /arch/x86_64/usr-lib-modules.fs.sfs" 200 36819181 "" "curl/7.27.0" 1348347588 192.168.0.110 "GET /arch/any/usr-share.fs.sfs" 200 63693037 "" "curl/7.27.0"
After the root filesystem is downloaded via HTTP, you'll eventually end up at a root zsh prompt with that fancy grml config.
Unless you want all traffic to be routed through your PXE server (which won't work anyway unless you set it up properly), you'll want to kill and get a new lease on the install target, as appropriate for your network layout.
# systemctl stop dnsmasq.service
You can also kill; the target has already downloaded the root filesystem, so it's no longer needed. While you're at it, you can also unmount the installation image:
# umount /mnt/archiso
At this point you can follow the official installation guide.
As implied in the syslinux menu, there are several other alternatives:
Installand configure it:
# vim /etc/nbd-server/config
[generic] [archiso] readonly = true exportname = /dev/disk/by-label/ARCH_201208
copytoram initramfs option can be used to control whether the root filesystem should be copied to ram in its entirety in early-boot.
It highly recommended to leave this option alone, and should only be disabled if entirely necessary (systems with less than ~256MB physical memory). Append
copytoram=n to your kernel line if you wish to do so.