legacy interrupts on pci interrupt establish path.

[Cherry G.Mathew <cherry%zyx.in@localhost>]

Hello,

I'd like to propose the following diff:

diff -r e8efcad62fc7 -r deb181d94ab1 sys/arch/x86/pci/pci_intr_machdep.c
--- a/sys/arch/x86/pci/pci_intr_machdep.c	Wed Aug 22 14:12:30 2018 +0000
+++ b/sys/arch/x86/pci/pci_intr_machdep.c	Wed Aug 29 07:40:56 2018 +0000
@@ -294,9 +294,7 @@
 			return ENOENT;
 		*pic = &ioapic->sc_pic;
 		*pin = APIC_IRQ_PIN(ih);
-		*irq = APIC_IRQ_LEGACY_IRQ(ih);
-		if (*irq < 0 || *irq >= NUM_LEGACY_IRQS)
-			*irq = -1;
+		*irq = -1; /* PCI doesn't use legacy irq */
 	}
 #endif
 
afaiu, legacy irq is only relevant to the isa_interrupt_establish..()
path or when IOAPIC support is disabled in the kernel. 

With PCI and -D NIOAPIC support, the {ioapic, pin} tuple are
reprogrammed onto specific lapic vectors and any boot time/ BIOS
legacy irq mappings are thus overridden.

I'm open to revising my understanding of this.

Patches have been tested on native by gson@

http://www.gson.org/netbsd/bugs/build/i386-cherry/2018/2018.08.27.16.30.51/test.log
http://www.gson.org/netbsd/bugs/build/amd64-cherry/2018/2018.08.27.16.30.51/test.log

This will also help with a separate unifying XEN related patch.

Please let me know if you have any objections to committing this.

-- 
~cherry