[ntp:hackers] [Gpsd-dev] Possible shm problem: Structure alignment?

Terje Mathisen terje at tmsw.no
Fri Mar 25 19:25:30 UTC 2011

Gary E. Miller wrote:
> Hash: SHA1
> Yo Terje!
> On Fri, 25 Mar 2011, Terje Mathisen wrote:
>> I have started to look more closely at the shm driver, and one issue that's
>> quite obvious is in the shmTime{} struct:
> That is what ntpd tells us to do.  You need to get them to fix it
> and we will follow.

OK, I'll note this as a bug.

Any fix _will_ break the current interface and require simultaneous 
updates on both programs.

I suggest we work out all the details, then define a new 'mode' value to 
indicate the new layout/interface definition: This way an old ntpd won't 
try to interpret the new layout and mess it all up quite badly.

> As you point out, it is a known issue that it fails on mixed 32/64 bit
> systems.
> Parts of this conversation are leaking onto gpsd-dev but the real discussion
> is on ntp-hackers, so to effect change, go there.

Oops, I didn't notice that this particular thread wasn't cross-listed 
like the " A lightweight synchronization mechanism for shared memory " 

I've been on the NTP Hackers list for ~15 years or so, my personal 
server (http://norloff.org/ntp) holds both the stable and dev Windows 
binaries I try to compile every few weeks or so.

- <Terje at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

More information about the hackers mailing list