On 23/01/13 09:12, David Armstrong wrote: > On 22/01/13 13:47, Bas Laarhoven wrote: >> On 22-1-2013 13:36, Yishin Li wrote: >>> 從我的 iPhone 傳送 >>> >>> Bas Laarhoven <s...@xs4all.nl> 於 2013/1/22 下午8:07 寫道： >>> >>>> On 21-1-2013 22:20, Michael Haberler wrote: >>>>> Am 21.01.2013 um 20:10 schrieb Gilles Chanteperdrix: >>>>> >>>>>> On 01/21/2013 02:32 PM, Michael Haberler wrote: >>>>>> >>>>>>> Am 21.01.2013 um 12:56 schrieb Gilles Chanteperdrix: >>>>>>>>> question: does a RTC time warp have any possible bearing on >>>>>>>>> Xenomai operations? >>>>>>>> No, it should not, Xenomai uses its own clock, which is set only >>>>>>>> once upon boot, so, is unaffected by Linux wallclock time >>>>>>>> changes... or should be. >>>>>>> it might not be Xenomai after all. Uhum. >>>>>>> >>>>>>> the bughunt safari tribe has decided to focus on class 'duh' problems >>>>>>> and resolves to shut up until red hands are spotted. >>>>>> I would still put the check in the timer "set_next_event" callback, just >>>>>> in case... >>>>> I assume Bas will give the postmortem shortly - he nailed the issue; the >>>>> RTC boot timewarp makes for a lost DHCP lease midflight and NFS freezing, >>>>> making it look like a kernel hang. >>>>> >>>>> relieved, >>>>> >>>>> - Michael >>>> Michael said it all, there's not much for me to add. I'll summarize the >>>> case for the records ; ) >>>> >>>> Lesson learned: Change only one variable at a time and don't assume >>>> anything! >>>> >>>> I had been using a NFS mounted filesystem with the Beaglebone for over a >>>> year now without problems and got used to it's reliability (as I was >>>> used to in a corporate environment in the past). >>>> Because the Xenomai software was built with libraries (eabihf) not >>>> compatible with my (eabi) system I switched to the Ubuntu image Michael >>>> built, and everything seemed to work fine. Except that the (xenomai) >>>> kernel froze out after around 50-60 minutes of uptime. With the JTAG >>>> debugger I could see the kernel still running, but all applications >>>> (both text and X via SSH, and console via serial/USB connection) seemed >>>> frozen and there was no output indicating what was going on. Of course >>>> the xenomai kernel was the first suspect. But that proved to be a >>>> mistake. With hindsight, knowing the cause of the freeze now, I wonder >>>> why I haven't gotten the NFS connection time-out message on the console, >>>> but for some reason or another that isn't generated in this case. >>>> >>>> The underlying problem is that the Beaglebone has no battery backed >>>> real-time clock. This gives (only) a serious problem (freeze) with (1) a >>>> network mounted NFS root filesystem and (2) an initial kernel time lying >>>> in the past and (3) a DHCP lease time shorter than some multiple (in >>>> this case 2x) of the required system uptime. >>>> >>>> Ubuntu (and maybe Debian too) systems are obviously not designed to >>>> start with a completely wrong real-time clock value. And the dhclient >>>> (as many other programs) is not designed to handle the large time step >>>> that's generated once the clock is set properly sometime during the boot >>>> process. >>>> Note that if the filesystem is on local storage (e.g. FLASH or >>>> harddisk), there will only be a short disruption of the network >>>> connection and it's likely that the problem won't be noticed at all. >>>> >>>> A final solution hasn't been found yet: I prefer a workaround without >>>> changing the dhclient or some other standard program. I think it would >>>> suffice to acquire a new lease right after the time-step has been made. >>>> This has to be done without giving up the previous lease (that has >>>> expired because of the time-step), because that would cause the system >>>> to freeze again. Suggestions on how to do this are welcome. I can't >>>> spend much more time on this issue this week. >>>> >>>> -- Bas >>> How about using static IP for NFS mounted rootfs? >> If you're not using DHCP this problem shouldn't affect you. >> >> -- Bas >>> -Yishin >>> >>> ------------------------------------------------------------------------------ >>> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, >>> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current >>> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft >>> MVPs and experts. ON SALE this month only -- learn more at: >>> http://p.sf.net/sfu/learnnow-d2d >>> _______________________________________________ >>> Emc-developers mailing list >>> Emc-developers@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-developers >> ------------------------------------------------------------------------------ >> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, >> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current >> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft >> MVPs and experts. ON SALE this month only -- learn more at: >> http://p.sf.net/sfu/learnnow-d2d >> _______________________________________________ >> Emc-developers mailing list >> Emc-developers@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-developers > ok i dont mind being shot down in flames , but would adding a RTC module > be a answer > for example :-) > > http://www.ebay.co.uk/itm/New-Arduino-I2C-RTC-DS1307-AT24C32-Real-Time-Clock-Module-For-AVR-ARM-PIC-/170794819927?pt=UK_BOI_Electrical_Comp > > although i must admit it ends up having all sorts of a rats nest for now > , and if theirs no other answer > and we end up making an interface for the Beagle the it could be more > permamant > > i mention the above rtc only for the fact that i have one laying around > > > > > ------------------------------------------------------------------------------ > Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, > MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current > with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft > MVPs and experts. ON SALE this month only -- learn more at: > http://p.sf.net/sfu/learnnow-d2d > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers regarding the rtc
just for completeness heres a kernel driver to suit https://github.com/cncbasher/linux-arm-am33x i have a schematic also , should anyone need it ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
