from the comment:
	if we find a gsi for an i/o apic that does not exist, and the gsi
	belongs to a bus that does not exist, assume that both belong to
	a processor that does not exist, and do not complain.

this was observed in a 2p system with 1 installed p(ackage).  there were
a number of gsis for pci bus 128 which did not exist, and the gsi numbers
were not covered by any discovered i/o apic.  this is a bit of an assumption,
but i think it's a safe bet that the bios writer accidentally included these
interrupts, or didn't bother removing them.

Reference: /n/atom/patch/applied2013/nixmissioapic
Date: Wed Sep 18 15:01:18 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/acpi.c	Wed Sep 18 14:58:51 2013
+++ /sys/src/nix/k10/acpi.c	Wed Sep 18 14:58:51 2013
@@ -347,6 +347,24 @@
 	}
 }
 
+/*
+ * if we find a gsi for an i/o apic that does not exist, and the gsi
+ * belongs to a bus that does not exist, assume that both belong to
+ * a processor that does not exist, and do not complain.
+ */
+static int
+havebus(int bustype, int busno)
+{
+	Pcidev *p;
+
+	if(bustype != BusPCI)
+		return 1;
+	for(p = nil; p = pcimatch(p, 0, 0); )
+		if(BUSBNO(p->tbdf) == busno)
+			return 1;
+	return 0;
+}
+
 static void
 addirq(int gsi, int bustype, int busno, int irq, int flags)
 {
@@ -354,7 +372,8 @@
 	u32int i;
 
 	if((apicno = gsitoapicid(gsi, &intin)) == -1){
-		print("acpi: addirq: no apic for gsi %d bus %d.%d\n", gsi, bustype, busno);
+		if(havebus(bustype, busno))
+			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",
--- /sys/src/nix/k10/ioapic.c	Wed Sep 18 14:58:51 2013
+++ /sys/src/nix/k10/ioapic.c	Wed Sep 18 14:58:51 2013
@@ -94,7 +94,7 @@
 			return a - xioapic;
 		}
 	}
-	print("gsitoapicid: no ioapic found for gsi %d\n", gsi);
+//	print("gsitoapicid: no ioapic found for gsi %d\n", gsi);
 	return -1;
 }