Re: [RFC] irq handling code consolidation (common part)

From: David Mosberger (davidm@napali.hpl.hp.com)
Date: Thu Jan 02 2003 - 13:30:08 EST


>>>>> On Tue, 24 Dec 2002 09:03:31 +0300, "Andrey Panin" <pazke@orbita1.ru> said:

  Andrey> Hi all, this patch moves some common parts of irq handling
  Andrey> code to one place. Arch specific patches will follow. Patch
  Andrey> for i386 is tested and performed well, but other arch
  Andrey> specific patched are not. Please take a look.

  Andrey> Please CC me answering this letter, I'm not subscribed to
  Andrey> lkml currently.

+/*
+ * Controller mappings for all interrupt sources:
+ */
+irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
+ [0 ... NR_IRQS - 1] = {
+ .handler = &no_irq_type,
+ .lock = SPIN_LOCK_UNLOCKED,
+ }
+};

This isn't good. For example, NUMA platforms with per-CPU irqs want
to allocate the irq descriptors in local memory. On ia64, we
introduced a minimal irq-descriptor API for this purpose:

        /* Return a pointer to the irq descriptor for IRQ. */
        static inline struct irq_desc * irq_desc (int irq);

        /* Extract the IA-64 vector that corresponds to IRQ. */
        static inline ia64_vector irq_to_vector (int irq);

        /*
         * Convert the local IA-64 vector to the corresponding irq number.
         * This translation is done in the context of the interrupt domain
         * that the currently executing CPU belongs to.
         */
        static inline unsigned int local_vector_to_irq (ia64_vector vec);

I think the platform-independent part of the code really would only
need the first routine irq_desc(). The other two are ia64-specific.

BTW: if you haven't done so already, I'd suggest to take a look at
arch/ia64/kernel/irq.c. I tried to keep this code as close as
possible to the x86 version. There shouldn't be anything in there
that isn't wanted for a good reason.

Thanks,

        --david
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