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Re: interrupt handling


On Mon, 2004-07-12 at 02:58, Ashutosh wrote:
> Dear all,
> 
> We had ported eCos on ARM7. I want to know about the context switching
> between two threads. When a thread is running and a interrupts occurs, ISR
> is executed and after completion of ISR , DSR is posted. When DSR is
> executed , and a thread with higher priority is also running, Then context
> switch takes place to the highest priority thread. I am not able to
> understand how this switching takes places from DSRs.
> I have gone through the source code and documents also but could not found
> any thing, which can remove my doubts.

Incorrect - DSRs always run to completion, they cannot be blocked or 
scheduled.   If another interrupt comes along, further ISR processing 
will happen, but then you return to the DSR until [they] it completes.
Only when all DSRs have completed will you return to the highest 
priority runnable thread.

-- 
Gary Thomas <gary@mlbassoc.com>
MLB Associates


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