Just to stimulate some discussions, I tried to bring some pieces of answers.


-----Original Message-----
From: [EMAIL PROTECTED] on behalf of ROSSIER Daniel
Sent: Fri 3/24/2006 4:38 PM
To: xenomai-core@gna.org
Subject: [Xenomai-core] Timer IRQ propagation
 
 

Hi,

 

We have some doubts about how the things work between i-pipe & xenomai 
regarding the timer.

 

1-  First, when Xenomai is registered, the 10ms timer of Linux is stolen by the 
Xenomai domain. How

is the 10ms timer preserved? is it registered as a timer by the pod ?

 
> Ok, silly question: the 10ms timer (or 1ms timer) is managed by Linux 
> directly with its own list of timers; this doesn't affect Xenomai's timer 
> list.


2-       When a timer IRQ is received, we understood that the IRQ is ack'd and 
masked by handle_irq() and sent to the domains through walk_pipeline() 
including Linux; but we have some doubts about that since the timer ISR of 
Linux first acknowledges the interrupt, and it seems that it acknowledges 
physically (hw ack); we expected that the acknowledgement would be a virtual 
ack in the Linux domain since the ack has been made previously by handle_irq(). 
In our case (ARM arch), the ack actually corresponds to a mask and therefore 
the timer IRQ is masked by Linux once it gets,  and we then suspect some loss 
of timer interrupts.

have we understood correctly the mechanism? Any idea about this behaviour? Is 
it normal?

 
> Still unclear to me; the ack would be done in the timer ISR; however in the 
> (ARM) patch we have, ipipe performs a hardware ack; I've seen in the x86 
> patch that adeos makes nothing within __ipipe_ack_system_irq(). I guess the 
> last behaviour is correct, isn't it?


Thanks in advance

 

Daniel

 

 

 



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