[ntp:questions] Symmetricom BC635 reference clock for linux

David L. Mills mills at udel.edu
Tue May 27 19:27:27 UTC 2008


Greg,

Not to put a blunt point on it, but Symmetricom did buy out all the 
competition and skewed the product line toward extremely expensive 
solutions. Why not put up candidate source code with appropriate 
disclaimers, including no support whatsoever?

Dave

Greg Dowd wrote:

> I don't think the issue is the competition.  In the past decade, I
> haven't seen more than a handful of people actively trying to create
> refclocks for the pci card.  The more likely issue is actually the
> business model.  There is no money in it and the support cost is
> incredibly high due to the variety of implementation skill levels and
> supported platforms.  Keep in mind that we are responsible for
> supporting a half dozen platforms from Windoze to VxWorks.  And there
> are a half dozen flavors of blades as well (pci, vme, vxi).  At least
> there used to be.  The skill level to write, maintain and support native
> mode drivers in each of those platforms is quite high.  Therefore, most
> of the drivers leverage an abstraction tool to isolate the memory mapped
> data transfers.  Because of this, we have to blind parts of the driver
> using binary modules.  And, in linux, we need to compile for the kernel
> and you can see that it starts getting sticky from there.  Now, the
> customer wants something "free" because it's linux, right?  But a few,
> not all, of them will contact tech support, and then development
> engineering, 25-30 times during the integration of the code into their
> system because they type "make" and for some reason, the results are not
> what they expected.  What the majority of customers have told us is that
> the average cost of integration is much higher than buying an appliance
> for ntp use.  Not a little higher, a lot higher.  
> 
> There are still plenty of projects (e.g., observatories or labs) where
> they reuse the card or have a custom application and they take the time
> but there we sell a SDK with example code and support.  My guess is that
> we still lose money but it enables the hardware so we amortize the cost.
> 
> For guys/gals who are just hacking for fun or one-off projects, I try to
> help them out with source code or advice.  
> 
> 
> Greg Dowd
> gdowd at symmetricom dot com (antispam format)
> Symmetricom, Inc.
> www.symmetricom.com
> "Everything should be made as simple as possible, but no simpler" Albert
> Einstein
> 
> -----Original Message-----
> From: questions-bounces+gdowd=symmetricom.com at lists.ntp.org
> [mailto:questions-bounces+gdowd=symmetricom.com at lists.ntp.org] On Behalf
> Of Andy Helten
> Sent: Tuesday, May 27, 2008 8:16 AM
> To: questions at lists.ntp.org
> Subject: Re: Symmetricom BC635 reference clock for linux
> 
> Richard B. Gilbert wrote:
> 
>>Michael Hardy wrote:
>>  
>>
>>>Has anyone developed the reference clock to the symmetricom BC635PCI 
>>>card under linux? There was chatter on this but the thread ended. The
> 
> 
>>>name Rob appeared in the thread an it appeared he developed the 
>>>driver. I would greatly appreciate help getting this reference clock 
>>>since symmetricom appears to have no interest in providing one
>>>
>>>Thanks
>>>Mike Hardy
>>>    
>>
>>I think there is an NTP driver for this device.  For the hardware 
>>device driver, you will have to look to Symmetricom or write your own.
> 
> Writing
> 
>>  a hardware device driver is not for the faint at heart!  You need an
> 
> 
>>excellent knowledge of how the hardware works and how the O/S you are 
>>using interfaces with devices. An error in a device driver has the 
>>potential to crash the system!
>>
>>I'm fairly certain that Symmetricomm offers some software support 
>>(device drivers, etc.) for some operating systems and hardware 
>>platforms but you will need to get the details from them.
> 
> NTP has BC635 reference clock support as of version 4.2.4p0 in
> refclock_bancomm.c.  The reference clock support does expect the
> Symmetricom driver, but it wouldn't be difficult to write one since the
> only real support needed is reading the time register.  No interrupt
> support is needed and, depending on your IRIG setup, possibly no BC635
> configuration is necessary.  However, the Symmetricom device driver for
> linux was only $250 one year ago, so it is hardly worth your time.
> 
> One hint if you purchase the Symmetricom driver is that you will need to
> convert their static library (.a) into a shared library for use with
> NTP.  Then configure NTP to use that shared library.  This prevents
> modifying NTP to use the static library.  Symmetricom provides no help
> in this arena (I asked originally) because, to paraphrase them, they
> would be competing with themselves if they helped other folks build NTP
> time boxes.  Nice, huh?
> 
> Andy
> 
> 
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