Re: [gpsd-users] NTP for more than two PPS-capable devices

[Gary E. Miller]

Yo Eric!

On Wed, 14 Jan 2015 10:04:41 -0500
"Eric S. Raymond" <address@hidden> wrote:

> If it is not real, how do you know how many segments NTP will
> support.  Is there a way to ask it?

Here is some doc:

"SYSV IPC creates a shared memory segment with a key value of 0x4E545030
+ u, where u is again the clock unit. (This value could be hex-decoded
as 'NTP0', 'NTP1',..., with funny characters for units > 9.) "

ntp_refclock.c line 193 does truncate unit to a u_char, so 256 would be
the upper limit.  I see some overflow issues, in refclock_shm.c line
126, so 207 is probably the max useable.

If you wanted to stick to ASCII (no good reason to) you would have about
80.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588