nForce3 (Compaq R3000) timer fix

Jung-uk Kim jkim at
Wed Jan 26 08:49:16 PST 2005

This is (hopefully) the last patch of the series, which fixes infamous 
'8254 timer not connected to IO-APIC' problem for nForce2+.  Linux 
people had a hack here:

(Note: 2.6.10 has more refined version.)

The attached patch requires the previous 'skip_timer_override' hack 
posted here:

After the patch, you need to set 'hw.apic.skip_set_extint=1' from 
loader or loader.conf.  Be careful with spelling; this is 'apic', not 
'acpi' this time. ;-)

With verbose boot logging, we should see:

	ioapic0: intpin 0 -> ISA IRQ 0 (edge, high)

instead of:

	ioapic0: Routing external 8259A's -> intpin 0
	ioapic0: intpin 0 -> ExtINT (edge, high)

I was able to run this laptop overnight without 'device atpic'. ;-)  I 
think somebody (jhb and peter, I guess) should double check if this 
is okay.  I tried many combinations including 'options SMP' and all 
seemed to be fine so far.

Finally I can run this laptop at full speed (2 GHz) under heavy load 
with 'acpi_ppc' driver!


Jung-uk Kim
-------------- next part --------------
--- src/sys/amd64/amd64/io_apic.c.orig	Fri Oct  8 01:21:14 2004
+++ src/sys/amd64/amd64/io_apic.c	Tue Jan 25 21:49:50 2005
@@ -148,6 +148,9 @@
 TUNABLE_INT("hw.apic.mixed_mode", &mixed_mode_active);
+static int skip_set_extint = 0;
+TUNABLE_INT("hw.apic.skip_set_extint", &skip_set_extint);
 static __inline void
 _ioapic_eoi_source(struct intsrc *isrc)
@@ -551,7 +554,7 @@
 		 * and that pins 1-15 are ISA interrupts.  Assume that all
 		 * other pins are PCI interrupts.
-		if (intpin->io_vector == 0)
+		if (intpin->io_vector == 0 && skip_set_extint != 1)
 			ioapic_set_extint(io, i);
 		else if (intpin->io_vector < IOAPIC_ISA_INTS) {
 			intpin->io_bus = APIC_BUS_ISA;

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