Difference between revisions of "PXE"
(Adding a slash on dnsmasq configuration)
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Revision as of 23:38, 12 October 2012
The Preboot eXecution Environment allows you to boot the installation media using a network interface (with an appropriate option-rom that supports PXE on the target), independent of any storage devices.
Archiso makes it fairly trivial to use the official install media directly to set up PXE booting and, unlike earlier methods (archboot), does not require any modification and can be used as-is.
Download the latest official install media from your favorite mirror.
--2012-10-06 22:06:37-- http://hive.ist.unomaha.edu/archlinux/iso/latest/archlinux-2012.10.06-dual.iso Resolving hive.ist.unomaha.edu... 2620:d5:0:22bb::dead:beef, 22.214.171.124 Connecting to hive.ist.unomaha.edu|2620:d5:0:22bb::dead:beef|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 435159040 (415M) [application/x-iso9660-image] Saving to: ‘archlinux-2012.10.06-dual.iso’ 100%[====================================================================================>] 435,159,040 109MB/s in 3.9s 2012-10-06 22:06:41 (109 MB/s) - ‘archlinux-2012.10.06-dual.iso’ saved [435159040/435159040]
Next mount the image:
# mkdir -p /mnt/archiso # mount -o loop,ro archlinux-2012.10.06-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
For those still using sysvinit:
# rc.d start dnsmasq
Due 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
# rc.d stop dnsmasq
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