PXE
From Wikipedia:Preboot Execution Environment:
- 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. This works well when you already have a server set up.
Preparation
Get the latest official install media from download page.
Next mount the image:
# mkdir -p /mnt/archiso # mount -o loop,ro archlinux-2017.12.01-x86_64.iso /mnt/archiso
Server setup
You will need to setup a DHCP, TFTP, and HTTP server to configure networking, load pxelinux/kernel/initramfs, and finally load the root filesystem (respectively).
The Arch ISO currently only supports BIOS-style PXE booting. See FS#50188 for more information.
Arch Netboot does support UEFI-style booting if you require that. Rest of this page focuses on the ISO however.
Network
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 will 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.
Configure dnsmasq:
# /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/lpxelinux.0 dhcp-option-force=209,boot/syslinux/archiso.cfg dhcp-option-force=210,/arch/ dhcp-option-force=66,192.168.0.1 enable-tftp tftp-root=/mnt/archiso
Start dnsmasq.service
.
HTTP
Thanks to archiso_pxe_http
initcpio hook and archiso_pxe_nfs
initcpio hook in archiso, it is possible to boot from HTTP or NFS. Among all alternatives, darkhttpd is by far the most trivial to setup (and the lightest-weight).
First, install the darkhttpd package.
Then start darkhttpd using 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/
Note that it is important that the server is running on port 80
. If you start darkhttpd without root access it will default to 8080
. The client will try to access port 80 and the boot will fail.
Installation
For this portion you will 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.
Boot
Looking at journald on the PXE server will provide some additional insight to what exactly is going on during the early stages of the PXE boot process:
# journalctl -u dnsmasq.service -f
dnsmasq-dhcp[2544]: DHCPDISCOVER(eth1) 00:1a:64:6a:a2:4d dnsmasq-dhcp[2544]: DHCPOFFER(eth1) 192.168.0.110 00:1a:64:6a:a2:4d dnsmasq-dhcp[2544]: DHCPREQUEST(eth1) 192.168.0.110 00:1a:64:6a:a2:4d dnsmasq-dhcp[2544]: DHCPACK(eth1) 192.168.0.110 00:1a:64:6a:a2:4d dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/pxelinux.0 to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/whichsys.c32 to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe_choose.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/ifcpu64.c32 to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe_both_inc.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_head.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe32.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_pxe64.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/archiso_tail.cfg to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/vesamenu.c32 to 192.168.0.110 dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/syslinux/splash.png to 192.168.0.110
After you load pxelinux.0
and archiso.cfg
via TFTP, you will (hopefully) be presented with a syslinux boot menu with several options, where you can select Boot Arch Linux (x86_64) (HTTP).
Next the kernel and initramfs (appropriate for the architecture you selected) will be transferred, again via TFTP:
dnsmasq-tftp[2544]: sent /mnt/archiso/arch/boot/x86_64/vmlinuz to 192.168.0.110 dnsmasq-tftp[2544]: 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 will eventually end up at the normal live system root zsh prompt.
Post-boot
Unless you want all traffic to be routed through your PXE server (which will not work anyway unless you set it up properly), you will want to stop dnsmasq.service
and get a new lease on the install target, as appropriate for your network layout.
You can also kill darkhttpd; the target has already downloaded the root filesystem, so it is no longer needed. While you are at it, you can also unmount the installation image:
# umount /mnt/archiso
At this point you can follow the Installation guide.
Alternate Methods
As implied in the syslinux menu, there are several other alternatives:
NFS
You will need to set up an NFS server with an export at the root of your mounted installation media, which would be /mnt/archiso
if you followed #Preparation. After setting up the server, add the following line to your /etc/exports
file:
/etc/exports
/mnt/archiso 192.168.0.0/24(ro,no_subtree_check)
If the server was already running, re-export the filesystems with exportfs -r -a -v
.
The default settings in the installer expect to find the NFS at /run/archiso/bootmnt
, so you will need to edit the boot options. To do this, press Tab on the appropriate boot menu choice and edit the archiso_nfs_srv
option accordingly:
archiso_nfs_srv=${pxeserver}:/mnt/archiso
Alternatively, you can use /run/archiso/bootmnt
for the entire process.
After the kernel loads, the Arch bootstrap image will copy the root filesystem via NFS to the booting host. This can take a little while. Once this completes, you should have a running system.
NBD
Install the nbd package and configure it:
/etc/nbd-server/config
[generic] [archiso] readonly = true exportname = /srv/archlinux-2017.12.01-x86_64.iso
Start nbd.service
.
Existing PXE Server
If you have an existing PXE server with a PXELINUX system setup (e.g. a combination of DHCP and TFTP), you can add the following menu items to your /tftpboot/pxelinux.cfg/default
file in order to boot Arch via your preferred method:
LABEL archlinux MENU LABEL Arch Linux x86_64 LINUX /path/to/extracted/Arch/ISO/arch/boot/x86_64/vmlinuz INITRD /path/to/extracted/Arch/ISO/arch/boot/intel_ucode.img,/path/to/extracted/Arch/ISO/arch/boot/amd_ucode.img,/path/to/extracted/Arch/ISO/arch/boot/x86_64/archiso.img APPEND archisobasedir=arch archiso_http_srv=http://httpserver/path/to/extracted/Arch/ISO/ SYSAPPEND 3 TEXT HELP Arch Linux 2018.09.01 x86_64 ENDTEXT
You can replace archiso_http_srv
with archiso_nfs_srv
for NFS or archiso_nbd_srv
for NBD (see usage examples in arch/boot/syslinux/archiso_pxe.cfg
file resided on ArchLinux iso). Whichever method you choose, you must pass ip=
parameter to instruct the kernel to bring up the network interface before it attempts to mount the installation medium over the network. Passing BOOTIF=
is required when there are several wired interfaces on the client side and/or you want resolv.conf to be already configured inside booted archiso. You can use sysappend mask 3 (which is 1+2) to pass these parameters automatically. For available boot parameters see README.bootparams.
Low memory systems
The 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.
copytoram=n
and archiso_pxe_http
are mutually exclusive.Troubleshooting
DHCP interface rename bug
FS#36749 causes default predictable network interface renaming to fail and then dhcp client to fail because of it. A workaround is to add the kernel boot parameter net.ifnames=0
to disable predictable interface names.
VirtualBox cannot boot while real machine can
When using VirtualBox to test your configuration, virtual machine is stucked at
Probing EDD (edd=off to disable)... ok
But pxe booting with real machine works fine. The problem may be because you have set several cpu cores to your client machine, and you set its type as Other and version as Unknown (64 bit). So VirtualBox does not know which paravirtualization interface to use by default. Adding loglevel=7 kernel parameter lets you see that machine was actually stuck at
[ 0.063697] smp: Bringing up secondary CPUs... [ 0.103768] x86: Booting SMP configuration:
To resolve this, either use one cpu core, or go to machine settings -> System -> Acceleration and set one of the following paravirtualization interface: Minimal, Hyper-V, KVM.
VirtualBox falls out to EFI shell
Currently VirtualBox does not support PXE booting in UEFI mode. See this. You can try qemu instead. Alternatively you can use VMware Workstation 15.0.2 (it supports uefi pxe boot) or just a real hardware.