SMP on Xilinx Zynq

[Joel Sherrill]

On February 28, 2015 2:37:32 PM CST, "Maldonado, Sergio E." <smaldona at slac.stanford.edu> wrote:
>I have CONFIGURE_SMP_MAXIMUM_PROCESSORS set to 2 and defined the symbol
>bsp_processor_count, also 2.
>
>Sometime last year, I was able to get SMP working with both cores, but
>I see that the RTEMS code base has advanced significantly since.

I don't have the hardware and am not in a position to try it on qemu. Hopefully someone with hardware will try it soon.

>Thanks,
>
>Sergio
>
>On Feb 28, 2015, at 12:27 PM, Joel Sherrill <joel.sherrill at OARcorp.com>
> wrote:
>
>> 
>> 
>> On February 28, 2015 12:38:54 PM CST, "Maldonado, Sergio E."
><smaldona at slac.stanford.edu> wrote:
>>> Hello,
>>> 
>>> Attempting to get SMP working on my Xilinx Zynq platform.  
>>> I'm currently running RTEMS compiled from the head of the git repo
>>> master branch (as of 2/28/15), so I should have the latest updates.
>>> 
>>> The problem I have is that multitasking does not work when both
>cores
>>> are enabled.
>>> 
>>> I'm looking for some input on what could be going wrong and how to
>fix
>>> it.
>>> 
>>> Scenario:
>>> 
>>> At system boot, I can verify that core 0 completes RTEMS boot_card
>>> initialization, and starts multitasking.
>>> However, Core 0 does _not_ execute the Init task entry point and
>>> instead goes straight to its idle loop.
>>> 
>>> Meanwhile, Core 1 starts and executes until it reaches the first
>>> _CPU_Context_Switch/_CPU_Context_Restore call.
>>> If I step into Core 1, I can see that it never returns from this
>>> routine and stays in an infinite loop of the following instructions
>> 
>> Did you configure multiple cores? There are SMP specific
>configuration parameters such as number of cores in the system.
>> 
>>> 
>>> 83		bne	.L_check_thread_dispatch_necessary
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:131
>>> 131		GET_SELF_CPU_CONTROL	r2, r3
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:134
>>> 134		ldrb	r4, [r2, #PER_CPU_DISPATCH_NEEDED]
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:135
>>> 135		cmp	r4, #0
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:136
>>> 136		beq	.L_check_is_executing
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:80
>>> 80		add	r3, r1, #ARM_CONTEXT_CONTROL_IS_EXECUTING_OFFSET
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:81
>>> 81		ldrexb	r4, [r3]
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:82
>>> 82		cmp	r4, #0
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:83
>>> 83		bne	.L_check_thread_dispatch_necessary
>>> (gdb) s
>>> ?? ()
>>> at
>>>
>../../../../../../../../src/c/src/../../cpukit/score/cpu/arm/cpu_asm.S:131
>>> 131		GET_SELF_CPU_CONTROL	r2, r3
>>> (gdb) s
>>> ...
>>> 
>>> 
>>> Consequently, the Init task entry point is never executed by either
>>> core, and the system does not complete startup.
>>> 
>>> Any thoughts on why Core 1 will not complete its transition to
>>> multitasking?
>>> 
>>> Here's a piece of information that might be useful:
>>> 
>>> When I configure RTEMS SMP with just 1 processor, the system
>>> successfully starts multitasking and the Init task entry point
>_does_
>>> get executed by Core 0.
>>> 
>>> Thank you,
>>> 
>>> Sergio Maldonado - SLAC
>>> 
>>> _______________________________________________
>>> users mailing list
>>> users at rtems.org
>>> http://lists.rtems.org/mailman/listinfo/users
>> 
>> --joel

--joel