Subject: Re: [PATCH V7 1/8] ntp: add ADJ_SETOFFSET mode bit

From: john stultz <johnstul-r/[email-masked]>
Date: Tue, 21 Dec 2010 13:59:44 -0800

On Wed, 2010-12-22 at 06:13 +0900, Kuwahara,T. wrote:
> On Wed, Dec 22, 2010 at 4:37 AM, john stultz <johnstul-r/[email-masked]> wrote:
> > adjtimex is a linux specific interface, which is compatible but not
> > identical to the ntp specified interfaces. The ntp client code already
> > has Linux specific modifications, so I don't think we have to worry
> > about 0x40 specifically being reserved by the NTP client.
> 
> But struct timex is not linux-specific...

It is if you're compiling against linux's timex.h file. 

We already have a number of differences compared with BSD's timex mode
definitions:
We have ADJ_TICK: 0x4000, which is MOD_CLKB in FreeBSD.
We also have ADJ_OFFSET_SINGLESHOT and ADJ_OFFSET_SS_READ which allow
adjtimex act like the original ntp_adjtime.

The key bit is that we map the shared MOD_* definitions that the NTP
client uses to the linux specific ADJ_* values in the linux timex.h

However, your concern does bring up a good point: 0x40 is MOD_PPSMAX in
BSD, and we should at-least check to make sure that the PPS code that is
currently floating around on the lists and is in akpm's tree hasn't
already reserved that bit.

Rodolfo, Alexander: Any comments here?

thanks
-john