On June 2, 2015 7:29:52 AM EDT, Hesham ALMatary <heshamelmat...@gmail.com> wrote: >Hi, > >Aren't the MMU/Caches enabled by default for RPi [1]?
Yes but I recall that the setup is different on the Pi2 and Alan disabled the code to to work at all. >[1] >https://github.com/RTEMS/rtems/blob/master/c/src/lib/libbsp/arm/shared/mminit.c > >On Tue, Jun 2, 2015 at 12:18 PM, Joel Sherrill ><joel.sherr...@oarcorp.com> wrote: >> >> >> On June 2, 2015 7:01:21 AM EDT, Rohini Kulkarni ><krohini1...@gmail.com> wrote: >>>Dr. Joel, >>> >>>So we can't say something solely on the basis of this result? >> >> I don't think so. If Linux performs the same, then what you did is as >good as it gets. >> >> However, if Linux is faster then some setting still isn't right. >> >> You need a reference measurement to have any confidence. It is >possible you did something but didn't actually turn the cache (or all >the cache) on. >> >>>On 2 Jun 2015 16:28, "Rohini Kulkarni" <krohini1...@gmail.com> wrote: >>> >>>I have not run it under linux on pi2 yet. Will have to run and check >>>the result. >>> >>>On 2 Jun 2015 16:16, "Joel Sherrill" <joel.sherr...@oarcorp.com> >wrote: >>> >>> >>> >>>On June 2, 2015 5:58:33 AM EDT, Rohini Kulkarni ><krohini1...@gmail.com> >>>wrote: >>>>HI, >>>> >>>>I tried running the dhrystone benchmark with some changes for >>>cache/mmu >>>>set up. >>>> >>>>However, the output shows a reduction in performance. >>>>The time to run through the dhrystone has increased from 12 to 13 >and >>>>dhrystones run per second decreased. >>>> >>>>According to this result, things were better with caches disabled. >>>> >>>> >>>>I have been working on this since two days and could not figure out >an >>>>improvement. Any pointers? >>> >>>How did it do under Linux on the Pi2? >>> >>> >>>>Thanks. >>>> >>>> >>>> >>>>On Thu, May 28, 2015 at 8:41 PM, Rohini Kulkarni >>>><krohini1...@gmail.com> wrote: >>>> >>>>Hi All, >>>> >>>>I have to implement the cache coherency support for Cortex A7. But >for >>>>A7 MPCore, unlike for A9, I am not able to find any register >>>>description for the Snoop Control Unit from the TRM. >>>> >>>>I need help here on how to proceed. >>>> >>>>Additionally for A9 there is a single bit for A9 in the Auxiliary >>>>Control Register which enables cache broadcast operations. The >>>register >>>>format is different for A7 and again I am unable to find how to >>>achieve >>>>the same for A7. >>>> >>>>Thanks! >>>> >>>> >>>> >>>> >>>> >>>>On Tue, May 5, 2015 at 10:42 PM, Joel Sherrill >>>><joel.sherr...@oarcorp.com> wrote: >>>> >>>> >>>> >>>>On 5/5/2015 11:11 AM, Rohini Kulkarni wrote: >>>> >>>>Hi, >>>> >>>>I am working with the code for bsp hooks. I am referring to existing >>>>ARM multicore bsp codes, zync mainly. >>>> >>>>1. There are existing hooks for the raspberry pi. Where should the >>>code >>>>for the Pi2 hooks be added? >>>> >>>>The Pi and Pi2 are remarkably similar so Pi2 should be placed inside >>>>the Pi BSP directory. >>>>There is already a Pi2 variant of that code built. But we know >>>specific >>>>places where there >>>>are variances. Depending on the scope of what is different, it can >be >>>>as simple as >>>>a cpp conditional in a .h to select a value or two implementations >of >>>a >>>>single method >>>>and the Makefile.am picking the right file to build based on the >board >>>>variant. >>>> >>>>The big question to always ask is: Is this specific to the Pi2 and >>>>incompatible with the Pi? >>>> >>>>Since the Pi BSP is still missing capabilities, it is likely code >>>>common to both will >>>>be added this summer. For example, did the mailbox interface change? >I >>>>don't know >>>>but would guess that it didn't. Each new capability added needs >that >>>>added. >>>> >>>>And any differences need to be analyzed to pick the least intrusive >>>way >>>>to provide >>>>alternate implementations. Or enable special code like the Pi2 SMP >>>>support which >>>>is dependent on --enable-smp and being a Pi2. >>>> >>>>2. Am I right in understanding that I will have to implement A7 >>>>specific functions as have been for A9? I am referring specifically >to >>>>the arm-a9mpcore-start.h >>>> >>>>Yes. >>>> >>>>If the code is very similar between the a7 and a9, then a discussion >>>>on devel@ should occur to decide the best way to minimize >duplication. >>>> >>>>If you end up with a7 specific code, you should follow the location >>>and >>>> >>>>naming patterns already established. That places it in >>>>libbsp/arm/shared/... >>>>so it can be used by any BSP with the right SMP core. >>>> >>>> >>>>I am referring to existing codes to locate and get hold of what >needs >>>>to be done in the hooks. However, being new to such implementations, >I >>>>am taking longer to understand the details. Any suggestions that >might >>>>help here are welcome >>>> >>>>The answer will depend on the factors listed above. When code can >>>>be shared, we want to share it across as many BSPs as makes sense. >>>>When it is unique to a specific BSP **variant** (e.g. Pi vs Pi2), >then >>>>you want to find the way to account for the variation in the least >>>>intrusive code way possible. >>>> >>>>Thanks! >>>> >>>>On 1 May 2015 12:45, "Rohini Kulkarni" <krohini1...@gmail.com> >wrote: >>>> >>>> >>>>Hi, >>>> >>>>Excited to be a part of this edition of GSoC! Thanks to everybody >for >>>>helping me get here and congratulations to all the participating >>>>students! >>>> >>>>So, now getting to work, firstly I wish to know, specifically from >my >>>>mentors, any changes that must be made to my proposed project or >>>>schedule. >>>> >>>>Secondly, are there any specifics for the development blog that we >>>need >>>>to create for the project? Over time what is the blog expected to >>>>convey. >>>> >>>>Also, I have to create a new wiki page for my project as none >exists. >>>I >>>>want to know how to add one. >>>> >>>>-- >>>> >>>>Rohini Kulkarni >>>> >>>> >>>>-- Joel Sherrill, Ph.D. Director of Research & Development >>>>joel.sherr...@oarcorp.com On-Line Applications Research Ask me about >>>>RTEMS: a free RTOS Huntsville AL 35805 Support Available (256) >>>722-9985 >>>> >>>> >>>> >>>> >>>> >>>>-- >>>> >>>>Rohini Kulkarni >>>> >>>> >>>> >>>> >>>>-- >>>> >>>>Rohini Kulkarni >>> >>>--joel >> >> --joel >> _______________________________________________ >> devel mailing list >> devel@rtems.org >> http://lists.rtems.org/mailman/listinfo/devel --joel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
