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Date: Tue, 12 Sep 2006 12:37:50 +0200
From: Wolfgang Grandegger <wg@domain.hid>
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Subject: Re: [Xenomai-core] No hardware interrupts with xenomai on ppc405
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To: Matthias Fuchs <matthias.fuchs@domain.hid>
Cc: Jan Kiszka <jan.kiszka@domain.hid>, xenomai@xenomai.org

Matthias Fuchs wrote:
> On Monday 11 September 2006 20:13, Wolfgang Grandegger wrote:
>> In 2.6 the interrupts are disabled by default. Then the attached patch 
>> for Xenomai should help.
>>
>> Wolfgang.
>>
> Your patch also works fine. Now what's the recommended solution? I noticed 
> that Philippe already checked in an Adeos fix.

As mentioned, in Linux 2.6 (generic IRQ layer), IRQs are disabled by 
default in kernel/irq/handle.c:

   irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
         [0 ... NR_IRQS-1] = {
                 .status = IRQ_DISABLED,
                 .handler = &no_irq_type,
                 .lock = SPIN_LOCK_UNLOCKED
         }
   };

Till now, I haven't found IPIPE/Xenomai related code removing the 
IRQ_DISABLED bit. But I wonder why it's working for x86. Maybe I have 
missed something.

In Linux 2.4, the "status" field is initialized to 0 (in 
arch/ppc/kernel/irq.c) not making trouble:

   irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned =
         { [0 ... NR_IRQS-1] = { 0, NULL, NULL, 0, SPIN_LOCK_UNLOCKED}};

At least my CAN PCI card on a MPC5200 works fine.

Philippe, do we really need these ugly PIC patches?

Wolfgang.