GSoC 2015: Raspberry Pi 2 Support
krohini1593 at gmail.com
Thu May 28 15:11:34 UTC 2015
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
On Tue, May 5, 2015 at 10:42 PM, Joel Sherrill <joel.sherrill at oarcorp.com>
> On 5/5/2015 11:11 AM, Rohini Kulkarni wrote:
> 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
> 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
> And any differences need to be analyzed to pick the least intrusive way to
> alternate implementations. Or enable special code like the Pi2 SMP support
> 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
> 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
> 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.
> On 1 May 2015 12:45, "Rohini Kulkarni" <krohini1593 at gmail.com> wrote:
>> 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 & Developmentjoel.sherrill at OARcorp.com On-Line Applications Research
> Ask me about RTEMS: a free RTOS Huntsville AL 35805
> Support Available (256) 722-9985
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