linux/Documentation
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
..
ABI RTC for 4.17 2018-04-10 10:22:27 -07:00
accelerators
accounting
acpi
admin-guide ARM: 2018-04-09 11:42:31 -07:00
aoe
arm MTD changes: 2018-04-06 12:15:41 -07:00
arm64 ARM: 2018-04-09 11:42:31 -07:00
auxdisplay
backlight
block
blockdev
bpf
bus-devices
cdrom
cgroup-v1 page cache: use xa_lock 2018-04-11 10:28:39 -07:00
cma
connector
console
core-api textsearch: fix kernel-doc warnings and add kernel-api section 2018-04-16 18:53:13 -04:00
cpu-freq cpufreq: Drop cpufreq_table_validate_and_show() 2018-04-10 08:40:45 +02:00
cpuidle cpuidle: Add definition of residency to sysfs documentation 2018-04-09 13:44:37 +02:00
crypto crypto: doc - clarify hash callbacks state machine 2018-03-31 01:33:02 +08:00
dev-tools There's been a fair amount of activity in Documentation/ this time around: 2018-04-03 13:35:51 -07:00
device-mapper dm verity: add 'check_at_most_once' option to only validate hashes once 2018-04-03 15:04:29 -04:00
devicetree Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-21 16:32:48 -04:00
doc-guide
driver-api MTD changes: 2018-04-06 12:15:41 -07:00
driver-model
early-userspace
EDID
extcon
fault-injection
fb
features arch: remove obsolete architecture ports 2018-04-02 20:20:12 -07:00
filesystems ipconfig: Write NTP server IPs to /proc/net/ipconfig/ntp_servers 2018-04-24 13:40:42 -04:00
firmware_class
fmc
fpga
gpio
gpu Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
hid
hwmon
i2c
ia64
ide
iio
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input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2018-04-05 13:21:57 -07:00
ioctl
isdn Documentation/isdn: check and fix dead links ... 2018-03-26 12:31:13 -04:00
kbuild Kconfig updates for v4.17 2018-04-03 16:28:01 -07:00
kdump
kernel-hacking
laptops
leds
lightnvm
livepatch livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
locking
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md
media media: extended-controls.rst: transmitter -> receiver 2018-04-04 08:05:20 -04:00
memory-devices
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networking docs: ip-sysctl.txt: fix name of some ipv6 variables 2018-04-19 15:20:09 -04:00
nfc
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openrisc
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PCI
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perf
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power PM / hibernate: Make passing hibernate offsets more friendly 2018-03-30 12:01:20 +02:00
powerpc
pps
process Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-15 16:12:35 -07:00
pti
ptp ptp: Fix documentation to match code. 2018-03-26 12:13:21 -04:00
rapidio
RCU
s390
scheduler
scsi
security
serial
sh
sound
sparc
sphinx
sphinx-static
spi
sysctl taint: add taint for randstruct 2018-04-11 10:28:35 -07:00
target
thermal thermal: Add cooling device's statistics in sysfs 2018-04-02 21:49:01 +08:00
timers
trace New features: 2018-04-10 11:27:30 -07:00
translations
usb
userspace-api
virtual KVM: trivial documentation cleanups 2018-03-28 22:47:06 +02:00
vm page cache: use xa_lock 2018-04-11 10:28:39 -07:00
w1
watchdog
wimax
x86 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-15 16:12:35 -07:00
xtensa
.gitignore
00-INDEX
atomic_bitops.txt
atomic_t.txt
bcache.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
cachetlb.txt
cgroup-v2.txt
Changes
circular-buffers.txt
clearing-warn-once.txt
clk.txt
CodingStyle
conf.py
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt
digsig.txt
DMA-API-HOWTO.txt
DMA-API.txt
DMA-attributes.txt
DMA-ISA-LPC.txt
docutils.conf
dontdiff
efi-stub.txt
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-per-CPU-kthreads.txt
kobject.txt
kprobes.txt
kref.txt
ldm.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lsm.txt
lzo.txt
mailbox.txt
Makefile
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memory-hotplug.txt
men-chameleon-bus.txt
nommu-mmap.txt
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pnp.txt
preempt-locking.txt
pwm.txt
rbtree.txt
remoteproc.txt
rfkill.txt
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt
SAK.txt
sgi-ioc4.txt
siphash.txt
SM501.txt
smsc_ece1099.txt
speculation.txt
static-keys.txt
SubmittingPatches
svga.txt
switchtec.txt
sync_file.txt
tee.txt
this_cpu_ops.txt
unaligned-memory-access.txt
vfio-mediated-device.txt
vfio.txt
video-output.txt
xillybus.txt
xz.txt
zorro.txt