.\" $NetBSD: diskless.8,v 1.11 1997/06/16 07:50:35 mrg Exp $ .\" .\" Copyright (c) 1994 Gordon W. Ross, Theo de Raadt .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd October 2, 1994 .Dt DISKLESS 8 .Os .Sh NAME .Nm diskless .Nd booting a system over the network .Sh DESCRIPTION The ability to boot a machine over the network is useful for .Xr diskless or .Xr dataless machines, or as a temporary measure while repairing or re-installing filesystems on a local disk. This file provides a general description of the interactions between a client and its server when a client is booting over the network. The general description is followed by specific instructions for configuring a server for diskless Sun clients. .Pp .Sh OPERATION When booting a system over the network, there are three phases of interaction between client and server: .Pp .Bl -tag -width 1.2 -compact .It 1. The PROM (or stage-1 bootstrap) loads a boot program. .It 2. The boot program loads a kernel. .It 3. The kernel does NFS mounts for root. .El .Pp Each of these phases are described in further detail below. .Pp In phase 1, the PROM loads a boot program. PROM designs vary widely, so this phase is inherently machine-specific. Sun machines use .Tn RARP to determine the client's .Tn IP address and then use .Tn TFTP to download a boot program from whoever sent the .Tn RARP reply. HP 300-series machines use the .Tn HP Remote Maintenance Protocol to download a boot program. Typical personal computers may load a network boot program either from diskette or using a special PROM on the network card. .Pp In phase 2, the boot program loads a kernel. Operation in this phase depends on the design of the boot program. (The design described here is the one used by Sun and NetBSD/hp300.) The boot program: .Pp .Bl -tag -width 2.2 -compact .It 2.1 gets the client IP address using .Tn RARP . .It 2.2 gets the client name and server .Tn IP address by broadcasting an .Tn RPC / BOOTPARAMS / WHOAMI request with the client IP address. .It 2.3 gets the server path for this client's root using an .Tn RPC / BOOTPARAMS / GETFILE request with the client name. .It 2.4 gets the root file handle by calling .Xr mountd 8 with the server path for the client root. .It 2.5 gets the kernel file handle by calling .Tn NFS lookup on the root file handle. .It 2.6 loads the kernel using .Tn NFS read calls on the kernel file handle. .It 2.7 transfers control to the kernel entry point. .El .Pp In phase 3, the kernel does NFS mounts for root. The kernel repeats much of the work done by the boot program because there is no standard way for the boot program to pass the information it gathered on to the kernel. The procedure used by the kernel is as follows: .Pp .Bl -tag -width 2.2 -compact .It 3.1 The kernel finds a boot server using the same procedure as described in steps 2.1 and 2.2 above. .It 3.2 The kernel gets the .Tn NFS file handle for root using the same procedure as described in steps 2.3 through 2.5 above. .It 3.3 The kernel calls the .Tn NFS getattr function to get the last-modified time of the root directory, and uses it to check the system clock. .El .Sh CONFIGURATION Before a client can boot over the network, its server must be configured correctly. This example will demonstrate how a Sun client might be configured -- other clients should be similar. .Pp Assuming the client's hostname is to be "myclient", .Pp .Bl -tag -width 2.1 -compact .It 1. Add an entry to .Pa /etc/ethers corresponding to the client's ethernet address: .Bd -literal -offset indent -compact 8:0:20:7:c5:c7 myclient .Ed This will be used by .Xr rarpd 8 . .Pp .It 2. Assign an IP address for myclient in your .Pa /etc/hosts or DNS database: .Bd -literal -offset indent -compact 192.197.96.12 myclient .Ed .Pp .It 3. If booting a Sun machine, ensure that .Pa /etc/inetd.conf is configured to run .Xr tftpd 8 in the directory .Pa /tftpboot . .Pp If booting an HP 300-series machine, ensure that .Pa /etc/rbootd.conf is configured properly to transfer the boot program to the client. An entry might look like this: .Bd -literal -offset indent -compact 08:00:09:01:23:E6 SYS_UBOOT # myclient .Ed .Pp See the .Xr rbootd 8 manual page for more information. .Pp .It 4. If booting a SPARC machine, install a copy of the appropriate diskless boot loader (such as .Pa /usr/mdec/boot ) in the .Pa /tftpboot directory. Make a link such that the boot program is accessible by a file name composed of the client's IP address in HEX, a dot, and the architecture name (all upper case). For example: .Bd -literal -offset indent -compact # cd /tftpboot # ln -s boot C0C5600C.SUN4 .Ed .Pp For a Sun3 machine, the name would be just C0C5600C (the sun3 PROM does not append the architecture name). The name used is architecture dependent, it simply has to match what the booting client's PROM wishes to it to be. If the client's PROM fails to fetch the expected file, .Xr tcpdump 8 can be used to discover which filename the client is trying to read. .Pp If booting an HP 300-series machine, ensure that the network boot program .Pa SYS_UBOOT (which may be called .Pa uboot.lif before installation) is installed in the directory .Pa /usr/mdec/rbootd . .It 5. Add myclient to the bootparams database .Pa /etc/bootparams : .Bd -literal -offset indent -compact myclient root=server:/export/myclient/root .Ed .Pp .It 6. Build the swap file for myclient: .Bd -literal -offset indent -compact # mkdir /export/myclient # cd /export/myclient # dd if=/dev/zero of=swap bs=16k count=1024 .Ed This creates a 16 Megabyte swap file. .Pp .It 7. Populate myclient's .Pa / filesystem on the server. How this is done depends on the client architecture and the version of the NetBSD distribution. It can be as simple as copying and modifying the server's root filesystem, or perhaps you need to get those files out of the standard binary distribution. .Pp Note that, unlike SunOS, you need to create a mount point for the client's swap: .Bd -literal -offset indent -compact # mkdir /export/myclient/root/swap .Ed .Pp .It 8. Export the required filesystems in .Pa /etc/exports : .Bd -literal -offset indent -compact /usr -ro myclient # for SunOS: # /export/myclient -rw=myclient,root=myclient # for NetBSD: /export/myclient -maproot=root -alldirs myclient .Ed .Pp If the server and client are of the same architecture, then the client can share the server's .Pa /usr filesystem (as is done above). If not, you must build a properly fleshed out .Pa /usr partition for the client in some other place. .Pp If your server was a sparc, and your client a sun3, you might create and fill .Pa /export/usr.sun3 and then use the following .Pa /etc/exports lines: .Bd -literal -offset indent -compact /export/usr.sun3 -ro myclient /export/myclient -rw=myclient,root=myclient .Ed .Pp .It 9. Copy and customize at least the following files in .Pa /export/myclient/root : .Bd -literal -offset indent -compact # cd /export/myclient/root/etc # cp fstab.nfs fstab # cp /etc/hosts hosts # echo myclient > myname # echo 192.197.96.12 > hostname.le0 .Ed .Pp Note that "le0" above should be replaced with the name of the network interface that the client will use for booting. .Pp .It 10. Correct the critical mount points and the swap file in the client's .Pa /etc/fstab (which will be .Pa /export/myclient/root/etc/fstab ) ie. .Bd -literal -offset indent -compact myserver:/export/myclient/root / nfs rw 0 0 myserver:/usr /usr nfs rw 0 0 myserver:/export/myclient/swap none swap sw,nfsmntpt=/swap .Ed .Pp Note, you must specify the swap file in .Pa /etc/fstab or it will not be used! .El .Sh FILES .Bl -tag -width /usr/mdec/rbootd -compact .It Pa /etc/ethers Ethernet addresses of known clients .It Pa /etc/bootparams client root pathname .It Pa /etc/exports exported NFS mount points .It Pa /etc/rbootd.conf configuration file for HP Remote Boot Daemon .It Pa /tftpboot location of boot programs loaded by the Sun PROM .It Pa /usr/mdec/rbootd location of boot programs loaded by the HP Boot ROM .El .Sh "SEE ALSO" .Xr rarpd 8 , .Xr ethers 5 , .Xr tftpd 8 , .Xr bootparamd 8 , .Xr bootparams 5 , .Xr mountd 8 , .Xr exports 5 , .Xr nfsd 8 , .Xr rbootd 8 , .Xr reboot 8