admin-guide/nfs/nfsroot.rst

10 	Updated 2006 by Nico Schottelius <nico-kernel-nfsroot@schottelius.org>
18 In order to use a diskless system, such as an X-terminal or printer server for
19 example, it is necessary for the root filesystem to be present on a non-disk
21 Documentation/filesystems/ramfs-rootfs-initramfs.rst), a ramdisk (see
22 Documentation/admin-guide/initrd.rst) or a filesystem mounted via NFS. The
24 of this text 'client' means the diskless system, and 'server' means the NFS
34 built-in during configuration. Once this has been selected, the nfsroot
38 along with the types of autoconfiguration to support. Selecting all of
48 told what root fs device to use. And in the case of nfsroot, where to find
49 both the server and the name of the directory on the server to mount as root.
54   This is necessary to enable the pseudo-NFS-device. Note that it's not a
55   real device but just a synonym to tell the kernel to use NFS instead of
59 nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
63   <server-ip>	Specifies the IP address of the NFS server.
65 		(see below). This parameter allows the use of different
68   <root-dir>	Name of the directory on the server to mount as root.
70 		replaced by the ASCII-representation of the client's
73   <nfs-options>	Standard NFS options. All options are separated by commas.
88 ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns0-ip>:<dns1-ip>:<nt…
89   This parameter tells the kernel how to configure IP addresses of devices
91   nfsaddrs, but now the boot-time IP configuration works independently of
101   parameter (without all the ':' characters before).  If the value is
106   <client-ip>	IP address of the client.
109   <server-ip>	IP address of the NFS server.
122 		The address of the autoconfiguration server is used.
124   <gw-ip>	IP address of a gateway if the server is on a different subnet.
133   <hostname>	Name of the client.
138 		If specified and DHCP is used, the user-provided hostname (and NIS
144   <device>	Name of network device to use.
148 		autoconfiguration requests out of all devices,
152 		In the case of options
158 		into the kernel will be used, regardless of the value of
172 		format "ip=dhcp,client-id-type,client-id-value"
176   <dns0-ip>	IP address of primary nameserver.
183   <dns1-ip>	IP address of secondary nameserver.
184 		See <dns0-ip>.
186   <ntp0-ip>	IP address of a Network Time Protocol (NTP) server.
197   - /proc/net/pnp:
200 	domain <dns-domain>			(if autoconfigured, the DNS domain)
201 	nameserver <dns0-ip>			(primary name server IP)
202 	nameserver <dns1-ip>			(secondary name server IP)
203 	nameserver <dns2-ip>			(tertiary name server IP)
204 	bootserver <server-ip>			(NFS server IP)
206   - /proc/net/ipconfig/ntp_servers:
208 	<ntp0-ip>				(NTP server IP)
209 	<ntp1-ip>				(NTP server IP)
210 	<ntp2-ip>				(NTP server IP)
212   <dns-domain> and <dns2-ip> (in /proc/net/pnp) and <ntp1-ip> and <ntp2-ip>
214   they cannot be specified as part of the "ip=" kernel command line parameter.
221   servers it discovers; this is the responsibility of a user space process
237   The default value of this parameter is "/init".  If the specified
241   A description of the process of mounting the root file system can be
242   found in Documentation/driver-api/early-userspace/early_userspace_support.rst
252 - Booting from a floppy using syslinux
273 		method of booting.
275 - Booting from a cdrom using isolinux
287      	This can be written to a cdrom using a variety of tools including
297 - Using LILO
312 - Using GRUB
317 - Using loadlin
319 	loadlin may be used to boot Linux from a DOS command prompt without
321 	thoroughly tested by the authors of this document, but in general
323 	to the configuration of LILO.
327 - Using a boot ROM
329 	This is probably the most elegant way of booting a diskless client.
331 	authors of this document are not aware of any no commercial boot
332 	ROMs that support booting Linux over the network. However, there
333 	are two free implementations of a boot ROM, netboot-nfs and
334 	etherboot, both of which are available on sunsite.unc.edu, and both
335 	of which contain everything you need to boot a diskless Linux client.
337 - Using pxelinux
343 	"kernel <relative-path-below /tftpboot>". The nfsroot parameters
346 	see Documentation/admin-guide/serial-console.rst for more information.
360   The rest of the IP layer autoconfiguration code has been written
363   In order to write the initial version of nfsroot I would like to thank
364   Jens-Uwe Mager <jum@anubis.han.de> for his help.