From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4FD0DF23.2030909@wanadoo.fr> Date: Thu, 07 Jun 2012 19:04:35 +0200 From: Thierry Bultel MIME-Version: 1.0 References: <4FBCB442.5030208@wanadoo.fr> <4FBCB64E.6090209@xenomai.org> <4FBCB89A.9090801@wanadoo.fr> <4FBCD8EC.60305@xenomai.org> In-Reply-To: <4FBCD8EC.60305@xenomai.org> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Subject: Re: [Xenomai] iMX6 support List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles Chanteperdrix Cc: xenomai@xenomai.org Hi, I have another question about the iMX6, it is about the TSC emulation . I have been told that the Pentium TSC could not be accurate enough for a one of our application that performs high precision data acquisition. Can we expect a better accuracy with the TSC emulation based on the ARM timer or not ? Is this based on the CCNT that is cycle-accurate ? Thanks Thierry Le 23/05/2012 14:32, Gilles Chanteperdrix a écrit : > On 05/23/2012 12:14 PM, Thierry Bultel wrote: >> Le 23/05/2012 12:05, Gilles Chanteperdrix a écrit : >>> On 05/23/2012 11:56 AM, Thierry Bultel wrote: >>>> Hi, >>>> >>>> We are looking in a replacement solution for our obsolete >>>> pentium-Celeron calculator. >>>> For many reasons, we would like to switch to the ARM architecture. >>>> The aimed CPU is the iMX6 Quadcore. >>>> >>>> Freescale provides a patched 2.6.35 and 2.6.38 kernel that do not have >>>> all the peripherals (the CAN seems to be missing) >>>> and Emtrion, a CPU module manufacturer, say they provide the additional >>>> patches to have the complete BSP. >>>> It is likely a 2.6.35 only, though. >>> Xenomai for mx6q does not exist for linux 2.6.35. It only exists for >>> freescale branch for 2.6.38, or 3.0, as a separate set of patches to >>> apply before and after the Adeos patches for the vanilla kernel. For >>> further details, see ksrc/arch/arm/patches/README in xenomai 2.6 sources. >> Thanks, yes, as I said, I am aware that the very first work for me will >> be to get >> the non-xenomai 2.6.38 kernel fully working >>> Furthermore, we have some stability issues with Xenomai for mx6q with >>> 3.0, the issues looking a lot like an issue with cache. We would ned to >>> recheck 2.6.38 to see if it had the same issues, but I would bet it does. >>> >> Actually my concern was to know if there were currently developments >> on that CPU. The fact that they are remaining bugs is not a concern, >> as long as they would be likely be corrected in the coming months. >> Do these bugs also exist on the mx6 single core ? > I was unable to reproduce the cache issue on single core, but I have not > tested enough to be absolutely sure that we do not have it. The issue is > sufficiently rare that it may go unnoticed during one test, and appear > during the next. >