SMP on Xilinx Zynq

[Maldonado, Sergio E.]

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.

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
>> 
>> _______________________________________________
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> 
> --joel