GSoC 2015: Raspberry Pi 2 Support

Tue Jun 2 11:01:21 UTC 2015

Dr. Joel,

So we can't say something solely on the basis of this result?
On 2 Jun 2015 16:28, "Rohini Kulkarni" <krohini1593 at 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.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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