Adam,
Adam Feigin wrote:
I guess this might be a little ot for this thread but maybe not. I'm
a newbie to all of this stuff but judging from the archives freebsd
seems to be the OS of choice for these highly accurate NTP servers.
Why is the case? Is there something specific to it that makes it more
suitable for this application than say some of the other BSD's or
Linux?
Well, FreeBSD had one of the earliest PPSAPI implementations, so its
well tested, and it works extremely well.
Linux still does not have a PPSAPI implementation in the "standard"
kernel. As of 2.6.31, its sort of kinda of halfway there, but not
completely, and I've never been able to get it to work. I'm sure one
can, if ones time in not very valuable.
Actually, one problem is that glibc is (was?) publishing an older
variant of the PPSAPI than the kernel actually supports. This is due to
an unfortunate decission to let kernel-API being made available directly
to be used by applications be declared by glibc rather than following
the kernel. The NTPD finds the glibc variant of the header and uses the
older interface version regardless of the fact that the kernel has
advanced since the glibc took its snapshot out of the early 2.x series.
The correct way would be either to let glibc discover the actual kernel
abilites or just provide the kernel-call wrappers and let the kernel
provide the actual header file.
Usually the glibc approach is correct, but for PPSAPI it is not.
Updating glibc to the current version heals puts a japanese paper wall
in front of the problem, but you haven't properly healed the wound.
FreeBSD works right out of the box (okay, you'll need to add the PPS
option to the kernel configuration).
To a higher degree things are integrated there in this respect.
Cheers,
Magnus
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