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-rw-r--r--Documentation/filesystems/nfs/nfsroot.txt35
1 files changed, 29 insertions, 6 deletions
diff --git a/Documentation/filesystems/nfs/nfsroot.txt b/Documentation/filesystems/nfs/nfsroot.txt
index a1030bea60d3..d2963123eb1c 100644
--- a/Documentation/filesystems/nfs/nfsroot.txt
+++ b/Documentation/filesystems/nfs/nfsroot.txt
@@ -5,6 +5,7 @@ Written 1996 by Gero Kuhlmann <gero@gkminix.han.de>
Updated 1997 by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
Updated 2006 by Nico Schottelius <nico-kernel-nfsroot@schottelius.org>
Updated 2006 by Horms <horms@verge.net.au>
+Updated 2018 by Chris Novakovic <chris@chrisn.me.uk>
@@ -79,7 +80,7 @@ nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:
- <dns0-ip>:<dns1-ip>
+ <dns0-ip>:<dns1-ip>:<ntp0-ip>
This parameter tells the kernel how to configure IP addresses of devices
and also how to set up the IP routing table. It was originally called
@@ -178,9 +179,18 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:
<dns1-ip> IP address of secondary nameserver.
See <dns0-ip>.
- After configuration (whether manual or automatic) is complete, a file is
- created at /proc/net/pnp in the following format; lines are omitted if
- their respective value is empty following configuration.
+ <ntp0-ip> IP address of a Network Time Protocol (NTP) server.
+ Value is exported to /proc/net/ipconfig/ntp_servers, but is
+ otherwise unused (see below).
+
+ Default: None if not using autoconfiguration; determined
+ automatically if using autoconfiguration.
+
+ After configuration (whether manual or automatic) is complete, two files
+ are created in the following format; lines are omitted if their respective
+ value is empty following configuration:
+
+ - /proc/net/pnp:
#PROTO: <DHCP|BOOTP|RARP|MANUAL> (depending on configuration method)
domain <dns-domain> (if autoconfigured, the DNS domain)
@@ -189,13 +199,26 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:
nameserver <dns2-ip> (tertiary name server IP)
bootserver <server-ip> (NFS server IP)
- <dns-domain> and <dns2-ip> are requested during autoconfiguration; they
- cannot be specified as part of the "ip=" kernel command line parameter.
+ - /proc/net/ipconfig/ntp_servers:
+
+ <ntp0-ip> (NTP server IP)
+ <ntp1-ip> (NTP server IP)
+ <ntp2-ip> (NTP server IP)
+
+ <dns-domain> and <dns2-ip> (in /proc/net/pnp) and <ntp1-ip> and <ntp2-ip>
+ (in /proc/net/ipconfig/ntp_servers) are requested during autoconfiguration;
+ they cannot be specified as part of the "ip=" kernel command line parameter.
Because the "domain" and "nameserver" options are recognised by DNS
resolvers, /etc/resolv.conf is often linked to /proc/net/pnp on systems
that use an NFS root filesystem.
+ Note that the kernel will not synchronise the system time with any NTP
+ servers it discovers; this is the responsibility of a user space process
+ (e.g. an initrd/initramfs script that passes the IP addresses listed in
+ /proc/net/ipconfig/ntp_servers to an NTP client before mounting the real
+ root filesystem if it is on NFS).
+
nfsrootdebug