Hi,

I'm trying to understand irq and irql. I used softice to observe my system
and found the following:

Interrupt irq irql
A 3 4
B 4 9

Suppose When I run ISR for interrupt A(irq=4, irql=9), interrupt B comes.
From CPU point of view, B, which has a higher priority, can interrupt A. But
from Windows point of view, the irql of B is 4 which is less than current
irql of A(9). Therefore, B can't interrupt A.

What does HAL do for this case?

Thanks,
Min

Higher irql always interrupt lower one, no matter what irq no. is.
that's B(4) can't interrupt A(9) in your case.

Hi,

I'm trying to understand irq and irql. I used softice to observe my system
and found the following:

Interrupt irq irql
B 3 4
A 4 9

Suppose when I run ISR for interrupt A(irq=4, irql=9), interrupt B comes.
From CPU point of view, B, which has a higher priority, can interrupt A.
But
from Windows point of view, the irql of B is 4 which is less than current
irql of A(9). Therefore, B can't interrupt A.

My understanding is that interrupt is a CPU issue. As long as B's irq has a
higher priority than A, it can always interrupt A. But this is conflict
with the irql point of view. Can anyone explain?

Thanks,
Min

Windows (namely, HAL) applies it's own priorities by masking other interrupts in the PIC.

--PA

"Min Wang" <minwang_2003@hotmail.com> wrote in message news:SjMEd.80854$dv1.51084@edtnps89...