From: Steven Seeger <steven.seeger@nasa.gov>
To: xenomai@xenomai.org
Subject: Re: [Xenomai] userspace absolute timer value
Date: Wed, 23 Dec 2015 13:05:00 -0500 [thread overview]
Message-ID: <2558065.W1DNnPs8ZD@wirbelwind> (raw)
All,
The issue that I had with userspace absolute time to start a timer (what
latency test does) was due to a quirk on my board where the powerpc timebase
was coming up as 0xdXXXXXXXXXXXXXXX which was causing the 32-bit userland to
lose precision when getting the monotonic clock value. The latency test gets
the time, adds a millisecond, and uses this time to start the process. However
on my machine the time was way off due to the loss of precision. (there were
more than 2^32 seconds, but time_t is only 32-bit) On my board adding some
code to set the timebase to 0 in head_44x.S and that cleared up all the
issues. Everything is working for me now. This appears to be a problem with
how cobalt deals with 64-bit ns counters and 32-bit userspace clocks, however
I could be missing something.
Steven
next reply other threads:[~2015-12-23 18:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-23 18:05 Steven Seeger [this message]
2015-12-23 18:43 ` [Xenomai] userspace absolute timer value Gilles Chanteperdrix
2015-12-23 19:14 ` Steven Seeger
-- strict thread matches above, loose matches on Subject: below --
2015-12-15 1:19 Steven Seeger
2015-12-22 16:59 ` Philippe Gerum
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