GSoC 2015: Raspberry Pi 2 Support

Tue Jun 2 10:58:09 UTC 2015

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.sherrill at oarcorp.com> wrote:

>
>
> On June 2, 2015 5:58:33 AM EDT, Rohini Kulkarni <krohini1593 at 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
> ><krohini1593 at 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.sherrill at 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" <krohini1593 at 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.sherrill at 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
>
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