linux/Documentation/filesystems/nfs
Chris Novakovic c04d2cb200 ipconfig: Write NTP server IPs to /proc/net/ipconfig/ntp_servers
Distributed filesystems are most effective when the server and client
clocks are synchronised. Embedded devices often use NFS for their
root filesystem but typically do not contain an RTC, so the clocks of
the NFS server and the embedded device will be out-of-sync when the root
filesystem is mounted (and may not be synchronised until late in the
boot process).

Extend ipconfig with the ability to export IP addresses of NTP servers
it discovers to /proc/net/ipconfig/ntp_servers. They can be supplied as
follows:

 - If ipconfig is configured manually via the "ip=" or "nfsaddrs="
   kernel command line parameters, one NTP server can be specified in
   the new "<ntp0-ip>" parameter.
 - If ipconfig is autoconfigured via DHCP, request DHCP option 42 in
   the DHCPDISCOVER message, and record the IP addresses of up to three
   NTP servers sent by the responding DHCP server in the subsequent
   DHCPOFFER message.

ipconfig will only write the NTP server IP addresses it discovers to
/proc/net/ipconfig/ntp_servers, one per line (in the order received from
the DHCP server, if DHCP autoconfiguration is used); making use of these
NTP servers is the responsibility of a user space process (e.g. an
initrd/initram script that invokes an NTP client before mounting an NFS
root filesystem).

Signed-off-by: Chris Novakovic <chris@chrisn.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-24 13:40:42 -04:00
..
00-INDEX Documentation/: update 00-INDEX files 2014-02-10 16:01:40 -08:00
Exporting VFS: don't keep disconnected dentries on d_anon 2017-12-25 20:22:07 -05:00
fault_injection.txt Doc: nfs: Fix typos in Documentation/filesystems/nfs 2016-03-09 16:13:04 -07:00
idmapper.txt doc: ReSTify keys-request-key.txt 2017-05-18 10:33:51 -06:00
knfsd-stats.txt Documentation: remove overloads-avoided counter from knfsd-stats.txt 2015-05-04 12:02:44 -04:00
nfs-rdma.txt Documentation: Fix dead URLs to ftp.kernel.org 2017-03-29 15:46:06 -06:00
nfs.txt NFS: Add nfs4_unique_id boot parameter 2012-10-01 15:33:33 -07:00
nfs41-server.txt nfsd: update documentation for pNFS support 2015-02-02 18:09:43 +01:00
nfsd-admin-interfaces.txt nfsd: document kernel interfaces for nfsd configuration 2012-08-21 17:42:03 -04:00
nfsroot.txt ipconfig: Write NTP server IPs to /proc/net/ipconfig/ntp_servers 2018-04-24 13:40:42 -04:00
pnfs-block-server.txt nfsd: pNFS block layout driver 2015-02-05 14:35:18 +01:00
pnfs-scsi-server.txt nfsd: add SCSI layout support 2016-03-18 11:42:53 -04:00
pnfs.txt nfs: remove the objlayout driver 2017-04-20 15:51:23 -04:00
rpc-cache.txt Documentation/: it's -> its where appropriate 2010-04-23 02:09:52 +02:00
rpc-server-gss.txt Doc: nfs: Fix typos in Documentation/filesystems/nfs 2016-03-09 16:13:04 -07:00