The eCos, QNX, ChorusOs irq handling API

Till Straumann strauman at SLAC.Stanford.EDU
Thu Feb 20 23:52:15 UTC 2003

Valette Eric wrote:

> Great. BTW you did not answer about the possibility to mask the current 
> opepnpic irq via a mask and issue the openpic acknowledge ASAP. I 
> have'nt OPENPIC doc anymore but from memory I did not find means to do 
> it. Maybe worth investaigating because as you pointed out, the code is 
> suboptimal. You cannot find agains broken hardware API :-)

I am just browsing a Raven OpenPIC doc - it seems that i DOES have a 
'mask' bit. It says:

"MASK. Setting this bit disables any further
interrupts from this source. If the mask bit is
cleared while the bit associated with this interrupt
is set in the IPR (interrupt pending register), the
interrupt request will be generated."

It seems, that indeed the EOI could be done prior to running the
user handler although that would require managing
interrupt priorities in software by means of the MASK bits
or the "interrupt task priority register" (using the latter
is probably a much better idea).
(if EOI is done after running the user handler, we can
use the hardware priority management)

OOOPS: looking at that code, I see an interesting
cascade of bugs - hold on, I'll post that one later...

-- Till

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