make multiple i/o apics work by mapping gsis to ioapic intins
correctly:

- fix off-by-one error in mapping gsi interrupts to ioapics.
- use the intin and not the gsi when building the interrupt,
- make acpi apic mapping errors more informative.
- create a fake interrupt type (instead of just using 0) MTint for
acpi mapped interrupts through the ioapic.  this decision might
need further consideration.

Reference: /n/atom/patch/applied2013/acpiioapics
Date: Mon Aug 26 19:47:54 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/ioapic.c	Mon Aug 26 19:42:04 2013
+++ /sys/src/nix/k10/ioapic.c	Mon Aug 26 19:42:04 2013
@@ -88,7 +88,7 @@
 		a = xioapic + i;
 		if(!a->useable)
 			continue;
-		if(gsi >= a->ibase && gsi <= a->ibase+a->nrdt){
+		if(gsi >= a->ibase && gsi < a->ibase+a->nrdt){
 			if(intin != nil)
 				*intin = gsi - a->ibase;
 			return a - xioapic;
@@ -149,8 +149,8 @@
 
 	apic = &xioapic[apicno];
 	if(!apic->useable || intin >= apic->nrdt)
-		panic("ioapic: intrinit: usable %d: bus %d apic %d intin %d dev %d lo %.8ux\n",
-			apic->useable, busno, apicno, intin, devno, lo);
+		panic("ioapic: intrinit: usable %d nrdt %d: bus %d apic %d intin %d dev %d lo %.8ux\n",
+			apic->useable, apic->nrdt, busno, apicno, intin, devno, lo);
 
 	rdt = rdtlookup(apic, intin);
 	if(rdt == nil){
--- /sys/src/nix/k10/acpi.c	Mon Aug 26 19:42:04 2013
+++ /sys/src/nix/k10/acpi.c	Mon Aug 26 19:42:04 2013
@@ -225,6 +225,8 @@
 enum {
 	Iointr,
 	Lintr,
+
+	MTint	= 0,		/* fake interrupt type, equivalent to fixed */
 };
 
 static u32int
@@ -253,21 +255,21 @@
 			return 0;
 		case Iointr:
 			if((apic = ioapiclookup(apicno)) == nil){
-				print("apic: ioapic unusable %d\n", apicno);
+				print("ioapic%d: ioapic unusable\n", apicno);
 				return 0;
 			}
 			if(intin >= apic->nrdt){
-				print("apic: id beyond nrdt: %d\n", apicno);
+				print("ioapic%d: intin %d >= nrdt %d\n", apicno, intin, apic->nrdt);
 				return 0;
 			}
 			break;
 		case Lintr:
 			if((apic = lapiclookup(apicno)) == nil){
-				print("apic: lapic unusable %d\n", apicno);
+				print("lapic%d: lapic unusable\n", apicno);
 				return 0;
 			}
 			if(intin >= nelem(apic->lvt)){
-				print("apic: intin beyond lvt: %d\n", intin);
+				print("lapic%d: intin beyond lvt: %d\n", apicno, intin);
 				return 0;
 			}
 			USED(apic);
@@ -288,7 +290,7 @@
 	default:
 		print("apic: bad irq type %d\n", inttype);
 		return 0;
-	case 0:					/* INT (fake type, same as fixed) */
+	case MTint:				/* INT (fake type, same as fixed) */
 		v |= polarity | trigger;
 		break;
 	case MTnmi:				/* NMI */
@@ -351,8 +353,10 @@
 	uint apicno, intin, polarity, trigger;
 	u32int i;
 
-	if((apicno = gsitoapicid(gsi, &intin)) == -1)
+	if((apicno = gsitoapicid(gsi, &intin)) == -1){
+		print("acpi: addirq: no apic for gsi %d bus %d.%d\n", gsi, bustype, busno);
 		return;
+	}
 	DBG("addirq: gsi %d %s busno %d irq %d flags %.8ux\n",
 		gsi, bustype == BusPCI? "pci": "isa", busno, irq, flags);
 	polarity = flagstopolarity(bustype, flags);
@@ -363,8 +367,8 @@
 		return;
 	}
 
-	i = apicmkintr(Iointr, 0, polarity, trigger, apicno, gsi);
-	ioapicintrinit(bustype, busno, apicno, gsi, irq, i);
+	i = apicmkintr(Iointr, MTint, polarity, trigger, apicno, intin);
+	ioapicintrinit(bustype, busno, apicno, intin, irq, i);
 }
 
 static char*
@@ -489,6 +493,7 @@
 	Lapicen		= 1,
 };
 
+#define acpiinit(x)	mpsinit(x)	/* temporary hack */
 void
 acpiinit(int maxmach)
 {
@@ -535,7 +540,7 @@
 			print("acpi: ignoring nmi source\n");
 			break;
 		case 0x04:	/* Local APIC NMI */
-			print("acpi: lapic nmi %.2ux flags %.4ux lint# %d (ignored)\n",
+			DBG("acpi: lapic nmi %.2ux flags %.4ux lint# %d (ignored)\n",
 				p[2], (uint)get16(p+3), p[5]);
 			break;
 		case 0x05:	/* Local APIC Address Override */