[ntp:questions] new driver development

Martin Burnicki martin.burnicki at meinberg.de
Wed Mar 30 09:22:27 UTC 2011


Dave Hart wrote:

> On Tue, Mar 29, 2011 at 7:41 UTC, Martin Burnicki
> <martin.burnicki at meinberg.de> wrote:
>> Whether addressing of either mode is done by separate driver numbers
>> (which I still find a good idea in this case, since SHM is a generic
>> driver), or by a mode number for the existing SHM driver, is a totally
>> different question.
> 
> I'm leaning towards using the existing shared memory layout and
> protocol for units 0-3, which until relatively recently were the only
> possibilities, and POSIX named shared memory with new, safer layout
> and protocol for units 4 and up.  gpsd today only provides 0-3.  0 & 1
> have root-only permission, while 2 & 3 are world-writable.  I'm also
> tending towards ntpd never creating the POSIX named shared memory nor
> relying on its presence to configure the clock, but attempting to open
> it read-only if it's not already on each poll, and close it if there
> are no updates for a timeout period.

Sounds good to me.

Martin
-- 
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany




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