SMP support for Raspberry Pi 2

[Joel Sherrill]

On August 8, 2015 3:17:01 PM CDT, Rohini Kulkarni <krohini1593 at gmail.com> wrote:
>Can mailboxes be useful here? Nothing else that is coming to my mind
>

They may be and I am seeing references to ARM's own mpcore which uses the GIC. This appears to be SOC specific but ARM has recommendations which may be followed by the SOC manufacturer

>On Sun, Aug 9, 2015 at 1:44 AM, Rohini Kulkarni <krohini1593 at gmail.com>
>wrote:
>
>Hi,
>
>I am stuck at how to set up IPI for Pi 2. This is a document I have
>referred to get an idea of interrupts. Would be great to get some help
>on how to proceed.
>
>
>On Fri, Jul 31, 2015 at 7:33 PM, Joel Sherrill
><joel.sherrill at oarcorp.com> wrote:
>
>
>
>On 7/31/2015 8:11 AM, Rohini Kulkarni wrote:
>
>Hi,
>
>How is the number of processors to be used for an application
>specified?
>The used count minimum of that supported in hardware and that
>configured. How to specify the latter?
>
>
>https://docs.rtems.org/doc-current/share/rtems/html/c_user/Configuring-a-System-SMP-Specific-Configuration-Parameters.html#Configuring-a-System-SMP-Specific-Configuration-Parameters
>
>and see the smptests. Many of which do specify the maximum.
>
>Thanks.
>
>On 29 Jul 2015 15:29, "Sebastian Huber"
><sebastian.huber at embedded-brains.de
><mailto:sebastian.huber at embedded-brains.de>> wrote:
>
>
>
>    On 29/07/15 11:52, Rohini Kulkarni wrote:
>
>
>
>On Tue, Jul 28, 2015 at 12:24 PM, Sebastian Huber
><sebastian.huber at embedded-brains.de
><mailto:sebastian.huber at embedded-brains.de>
><mailto:sebastian.huber at embedded-brains.de
><mailto:sebastian.huber at embedded-brains.de>>> wrote:
>
>             Hello Rohini,
>
>             please use the devel list.
>
>             On 28/07/15 07:41, Rohini Kulkarni wrote:
>
>                 Hi,
>
>           I wish to understand where the interprocessor interrupts are
>           used during the boot process. During final initialization of
>                 SMP I can see
>
>                 rtems_interrupt_handler_install(
>                       ARM_GIC_IRQ_SGI_0,
>                       "IPI",
>                       RTEMS_INTERRUPT_UNIQUE,
>                       bsp_inter_processor_interrupt,
>                       NULL
>                     );
>
>         Raspberry Pi 2 does not have the generic interrupt controller.
>            Interrupt routing will have to be handled differently. So I
>         wish to understand how/ where it is used. I suppose this might
>                 be the problem.
>
>
>      Sorry, that the documentation is so scattered.  I think we should
>      move everything into the CPU Architecture Supplement. It would be
>     nice if you can help to improve the documentation since you have a
>             different view point.
>
>       You must install the IPI during the system initialization. It is
>      raised via the _CPU_SMP_Send_interrupt() function, for an example
>             see arm-a9mpcore-smp.c.
>
>I could locate the function in  arm-a9mpcore-smp.c. but it would be
>helpful if I can know where this being called from, a deeper call
>hierarchy, so that I can ascertain this is a problem. I can see a
>Send_messgae function call this. But don't know where the send message
>is being called from.
>
>
>You can run one of the SMP tests on the realview_pbx_a9_qemu_smp BSP on
>Qemu and set a break point to _CPU_SMP_Send_interrupt() if you want to
>know how it is used.
>
>    --
>    Sebastian Huber, embedded brains GmbH
>
>    Address : Dornierstr. 4, D-82178 Puchheim, Germany
>    Phone   : +49 89 189 47 41-16
>    Fax     : +49 89 189 47 41-09
>
>E-Mail  : sebastian.huber at embedded-brains.de
><mailto:sebastian.huber at embedded-brains.de>
>    PGP     : Public key available on request.
>
>  Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>
>
>-- 
>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