netdev - Re: [PATCH 7/8] ipconfig: Write NTP server IPs to /proc/net/ntp

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Date:   Sat, 7 Apr 2018 16:25:20 +0100
From:   Chris Novakovic <chris@...isn.me.uk>
To:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH 7/8] ipconfig: Write NTP server IPs to /proc/net/ntp

On 07/04/2018 05:09, Chris Novakovic wrote:
> 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/ntp. 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 "<ntp-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/ntp, 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@...isn.me.uk>

Sorry, I just spotted a minor typo in the commit message and
documentation in this patch --- I'll send a v2 shortly.