BSP question: nested interrupts?

[Sebastian Huber]

On 2014-04-28 13:32, Ben Gras wrote:
> Dear all,
>
> I have a question about managing interrupts in a BSP that I have not been able
> to answer satisfactorily by looking at other BSP code, nor looking throught the
> documentation or googling. Or asking on the IRC channel :)
>
> My question is: are BSPs expected to allow nested interrupts? Specifically,
> must bsp_interrupt_dispatch() turn interrupts on before calling
> bsp_interrupt_handler_dispatch for everything else to work properly?

If you want nested interrupts, then you can do it like this BSP:

http://git.rtems.org/rtems/tree/c/src/lib/libbsp/arm/lpc24xx/irq/irq-dispatch.c

>
> Some BSPs do this, some don't. In the Beagle BSP I can do this by masking the
> currently active interrupt and then enabling them at the CPU level; but
> enabling all interrupts before the hw-specific handler is called won't deassert
> the irq at the peripheral so I'm having trouble seeing how that should work.

This is the job of the interrupt controller.  It must block interrupts of lower 
or equal priority.

>
> Example: if we are in a timer ISR and loop on polling the uptime ticks, do we
> expect the ticks to be able to increase? I'm wondering if any of the remaining
> failing tests are due to this. But also what the best shape of a BSP is.
>
> Thanks!
>
>
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Sebastian Huber, embedded brains GmbH

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