Interrupt prioritization on linux for ppc440
ebs at ebshome.net
Sat Apr 16 08:12:35 EST 2005
On Fri, Apr 15, 2005 at 02:36:51PM -0700, Shawn Jin wrote:
> The home-made interrupt controller PIC supports interrupt priorities
> and critical/non-critical interrupts. I found that the current kernel
> doesn't support interrupt priorities.
Yes, we don't have IRQ priorities on 4xx. Theoretically, they can be
emulated in get_irq, but I really don't think it's worth it.
> Is this observation true? Is
> there any existing patch to support that?
I'm not aware of such patch existence.
> I noticed that the implementation of ppc4xx_pic.c disables all
> critical interrupts during initialization. To support critical
> interrupts, is it so simple that we change the handler of critical
> exception from CriticalInput to do_IRQ in head_44x.S?
No, it's not that simple. Linux doesn't support a notion of critical
IRQs versus normal ones. Until there is an infrastructure for this, it
doesn't make any sense to implement 4xx support.
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