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 & > developmentjoel.sherr...@oarcorp.com On-Line Applications Research > Ask me about RTEMS: a free RTOS Huntsville AL 35805 > Support Available (256) 722-9985 > > -- Rohini Kulkarni
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