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>
Fully document the format used by the /proc/net/pnp file written by
ipconfig, explain where its values originate from, and clarify that the
tertiary name server IP and DNS domain name are only written to the file
when autoconfiguration is used.
Signed-off-by: Chris Novakovic <chris@chrisn.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
ic_do_bootp_ext() is responsible for parsing the "ip=" and "nfsaddrs="
kernel parameters. If a "." character is found in parameter 4 (the
client's hostname), everything before the first "." is used as the
hostname, and everything after it is used as the NIS domain name (but
not necessarily the DNS domain name).
Document this behaviour in Documentation/filesystems/nfs/nfsroot.txt,
as it is not made explicit.
Signed-off-by: Chris Novakovic <chris@chrisn.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The previous patch renamed several files that are cross-referenced
along the Kernel documentation. Adjust the links to point to
the right places.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This patch fix spelling typos found in Documentation/filesystems/nfs
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
A dhcp server may provide parameters to a client from a pool of IP
addresses and using a shared rootfs, or provide a specific set of
parameters for a specific client, usually using the MAC address to
identify each client individually. The dhcp protocol also specifies
a client-id field which can be used to determine the correct
parameters to supply when no MAC address is available. There is
currently no way to tell the kernel to supply a specific client-id,
only the userspace dhcp clients support this feature, but this can
not be used when the network is needed before userspace is available
such as when the root filesystem is on NFS.
This patch is to be able to do something like "ip=dhcp,client_id_type,
client_id_value", as a kernel parameter to enable the kernel to
identify itself to the server.
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
On small systems (e.g. embedded ones) IP addresses are often configured
by bootloaders and get assigned to kernel via parameter "ip=". If set to
"ip=dhcp", even nameserver entries from DHCP daemons are handled. These
entries exported in /proc/net/pnp are commonly linked by /etc/resolv.conf.
To configure nameservers for networks without DHCP, this patch adds option
<dns0-ip> and <dns1-ip> to kernel-parameter 'ip='.
Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Tested-by: Jan Weitzel <j.weitzel@phytec.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Change all "arch/i386" to "arch/x86" in Documentaion/,
since the directory has changed.
Also update the files which have changed their filename
in the meantime accordingly.
Signed-off-by: Wanlong Gao <wanlong.gao@gmail.com>
[jkosina@suse.cz: reword changelog]
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
As a convenience, introduce a kernel command line option to enable
NFSROOT debugging messages.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Now it's possible to update the DNS record for $HOST_NAME with
ip=::::$HOST_NAME::dhcp
CC: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We're adding enough nfs documentation that it may as well have its own
subdirectory.
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
