[ECOS] Re: On ARM7 can one of FIQ/IRQ be used for non-eCos stuff?

Grant Edwards grante@visi.com
Wed Apr 2 17:23:00 GMT 2008

On 2008-04-02, Chris Zimman <czimman@bloomberg.com> wrote:

>> From looking at the ARM/arch hal stuff, it looks like eCos
>> expects to handle both IRQ and FIQ interrupts.  AFAICT, all of
>> the interrupt sources in my part (Samsung S3C4530) can be
>> assigned to either IRQ or FIQ.
>> Is there any reason why eCos has to have control of both
>> interrupt sources if all of the peripherals which eCos is
>> handling are on just one of them?
> Just change the FIQ vector to point to your handler.  I don't
> know of anything that uses FIQ right now anyhow.

I just double-checked the initialization code for my HAL (it's
a custom one), and it is indeed configuring all of the
interrupts currently in use to use IRQ, so nothing is using

However, there quite a few spots in the arm/arch interrupt and
exception handling code where FIQ is being disabled.  It looks
like I'd have to fork the arch code and modify it to prevent it
from disabling FIQ.

I suppose the right thing to do would be to make the arm/arch
stuff configurable via CDL so that it would use either FIQ or
IRQ or both.

Grant Edwards                   grante             Yow! ... I want FORTY-TWO
                                  at               TRYNEL FLOATATION SYSTEMS
                               visi.com            installed within SIX AND A
                                                   HALF HOURS!!!

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