From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Seeger Date: Wed, 23 Dec 2015 13:05:00 -0500 Message-ID: <2558065.W1DNnPs8ZD@wirbelwind> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [Xenomai] userspace absolute timer value Reply-To: steven.seeger@nasa.gov List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai@xenomai.org 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