[ECOS] Re: DSR stops running after heavy interrupts. Bug found?

Nick Garnett nickg@ecoscentric.com
Mon Apr 10 09:36:00 GMT 2006


 Sergei Organov <osv@javad.com> writes:

> Andrew Lunn <andrew@lunn.ch> writes:
> 
> [...]
> 
> > However, from what you are saying it sounds like there needs to be
> > another comparison afterwards. Something like:
> >
> >         and     r0,r0,#2 // CYG_ISR_CALL_DSR
> >         beq     17f
> 
> No, bit checking of the ISR return value is performed inside the
> interrupt_end() routine:
> 
>     if( isr_ret & Cyg_Interrupt::CALL_DSR && intr != NULL ) intr->post_dsr()


Exactly. And there are other housekeeping things that go on in
interrupt_end() which cannot be skipped. The most important of these
is decrementing the scheduler lock.

I don't really see how the original poster's problem is fixed by
trying to skip interrupt_end(), I would only expect doing that to
aggravate the problem. The scheduler lock is acquired early in
interrupt processing -- before the ISR is called and we know whether
there is a DSR to call. interrupt_end() decrements the scheduler lock
and as a side-effect may cause any DSRs to be called.

As Andrew has suggested, I think Joe's best way of working out what is
happening is to switch on instrumentation and see if he can track down
the extra increments of the scheduler lock.

-- 
Nick Garnett                                 eCos Kernel Architect
http://www.ecoscentric.com            The eCos and RedBoot experts


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