Re: how the interrupt handler(ISR) knows the source of interrupt ?

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Hi Erik,

On 3/29/07, Erik Mouw <mouw@xxxxxxxxxxxx> wrote:
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On Thu, Mar 29, 2007 at 12:57:39PM +0530, sandeep lahane wrote:
> On 3/29/07, Rajat Jain <rajat.noida.india@xxxxxxxxx> wrote:

[trim lots of irrelevant quoted text]

> >2) When the IRQ occurs, the kernel invokes EACH and every ISR hooked
> >onto that IRQ (Not just the ISR that actually services the device).
> I think this is one of the reasons why Linux is not a real time OS,
> please CMIIW.

No, that has nothing to do with it because this is a hardware
limitation. The only way to figure out which device triggered the IRQ
is to check each individual device connected to that IRQ line. Because
checking the interrupt status is highly device specific, the only
sensible way would be to let the ISR for the device figure out. You
always have to do that, even with an RTOS.


I only wrote this part : "2) When the IRQ occurs, the kernel invokes
EACH and every ISR hooked onto that IRQ (Not just the ISR that
actually services the device)."

The part "I think this is one of the reasons why Linux is not a real time OS,
please CMIIW" is not mine.

You're replying to the wrong mail

:-)

Rajat

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