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Re: interrupt handling
- From: Gary Thomas <gary at mlbassoc dot com>
- To: ashutoshvyas at tataelxsi dot co dot in
- Cc: ecos-discuss at sources dot redhat dot com
- Date: Mon, 12 Jul 2004 06:47:32 -0600
- Subject: Re: [ECOS] interrupt handling
- Organization: MLB Associates
- References: <002401c467ee$68c53ad0$5514010a@telxsi.com>
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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