[Xen-devel] [rfc][patch] use of IRQ_LEVEL to remove strcmp()s

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

Ok this is blind, but it builds, so please take it more as a suggestion,
There are a sequence of strcmp()s in irq.c to detect if an IO-APIC is  
level or edge triggered.
Perhaps (borrowing form Linux) with the use of IRQ_LEVEL, we can  
detect this more efficiently?
Side Note: I believe that "ioapic_ack_new" is the same as IRQ_PER_CPU.

Signed-off-by: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>
--

diff -r 72f9c751d3ea xen/include/xen/irq.h
--- a/xen/include/xen/irq.h     Wed Apr 19 18:32:20 2006 +0100
+++ b/xen/include/xen/irq.h     Wed Apr 19 15:44:50 2006 -0400
@@ -22,6 +22,7 @@ struct irqaction
#define IRQ_PENDING     4       /* IRQ pending - replay on enable */
#define IRQ_REPLAY      8       /* IRQ has been replayed but not acked yet */
#define IRQ_GUEST       16      /* IRQ is handled by guest OS(es) */
+#define IRQ_LEVEL       64      /* IRQ level triggered */
#define IRQ_PER_CPU     256     /* IRQ is per CPU */
/*
diff -r 72f9c751d3ea xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c    Wed Apr 19 18:32:20 2006 +0100
+++ b/xen/arch/x86/io_apic.c    Wed Apr 19 15:44:50 2006 -0400
@@ -701,9 +701,10 @@ static inline void ioapic_register_intr(
static inline void ioapic_register_intr(int irq, int vector, unsigned  
long trigger)
{
     if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
-        trigger == IOAPIC_LEVEL)
-        irq_desc[vector].handler = &ioapic_level_type;
-    else
+        trigger == IOAPIC_LEVEL) {
+           irq_desc[vector].handler = &ioapic_level_type;
+           irq_desc[vector].status = IRQ_LEVEL;
+    } else
         irq_desc[vector].handler = &ioapic_edge_type;
}
@@ -2044,8 +2045,11 @@ int ioapic_guest_write(unsigned long phy
         }

         /* Set the correct irq-handling type. */
-        irq_desc[IO_APIC_VECTOR(new_irq)].handler = new_rte.trigger ?
-            &ioapic_level_type: &ioapic_edge_type;
+       if (new_rte.trigger) {
+               irq_desc[IO_APIC_VECTOR(new_irq)].handler = &ioapic_level_type;
+               irq_desc[IO_APIC_VECTOR(new_irq)].status = IRQ_LEVEL;
+        } else
+               irq_desc[IO_APIC_VECTOR(new_irq)].handler = &ioapic_edge_type;

         if ( old_irq != new_irq )
             add_pin_to_irq(new_irq, apic, pin);
diff -r 72f9c751d3ea xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c        Wed Apr 19 18:32:20 2006 +0100
+++ b/xen/arch/x86/irq.c        Wed Apr 19 15:44:50 2006 -0400
@@ -356,26 +356,13 @@ int pirq_acktype(int irq)
     desc = &irq_desc[vector];
-    /*
-     * Edge-triggered IO-APIC interrupts need no final acknowledgement:
-     * we ACK early during interrupt processing.
-     */
-    if ( !strcmp(desc->handler->typename, "IO-APIC-edge") )
-        return ACKTYPE_NONE;
-
-    /* Legacy PIC interrupts can be acknowledged from any CPU. */
-    if ( !strcmp(desc->handler->typename, "XT-PIC") )
-        return ACKTYPE_UNMASK;
-
-    /*
-     * Level-triggered IO-APIC interrupts need to be acknowledged on  
the CPU
-     * on which they were received. This is because we tickle the  
LAPIC to EOI.
-     */
-    if ( !strcmp(desc->handler->typename, "IO-APIC-level") )
-        return ioapic_ack_new ? ACKTYPE_EOI : ACKTYPE_UNMASK;
-
-    BUG();
-    return 0;
+    if (desc->status & IRQ_LEVEL) {
+       if (desc->status & IRQ_PER_CPU || ioapic_ack_new)
+            return ACKTYPE_EOI;
+        else
+            return ACKTYPE_UNMASK;
+    }
+    return ACKTYPE_NONE;
}
int pirq_guest_bind(struct vcpu *v, int irq, int will_share)



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