Re: What's the accurate meaning of the macro "RTEMS_MULTIPROCESSING" and "RTEMS_SMP"?

Sebastian Huber sebastian.huber at
Tue Jul 23 07:33:01 UTC 2013

On 2013-07-23 09:20, Hailin Guo wrote:
> I am porting RTEMS to a multiprocessor CPU whoes architecture is very
> non-mainstream. When I read the source, I am confused about the macro
> "RTEMS_MULTIPROCESSING" and "RTEMS_SMP". And in the document of RTEMS
> Applications C User's Guide, there is also no talk about "RTEMS_SMP".
 > Who can explain to me about the two macros' meaning?

The RTEMS_MULTIPROCESSING is supported for a long time and is also known as 
asymmetric multiprocessing.  Here message passing is used to synchronize objects.

The RTEMS_SMP is new to RTEMS and work in progress.  One RTEMS instance will 
run on multiple processors.

> And how does RTEMS boot
> from multiprocessor?

At the moment there is no documentation for this.  The realview_pbx_a9_qemu_smp 
BSP runs on the Qemu simulator and has SMP support.  You may have a look at the 
BSP sources.

See also the comments in percpu.h for Per_CPU_State.

Sebastian Huber, embedded brains GmbH

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