Re: IO-APIC on nforce2 [PATCH] + [PATCH] for nmi_debug=1 + [PATCH]

[Ian Kumlien]

On Mon, 2004-05-10 at 13:37, Ross Dickson wrote:
> Craig Bradney wrote
> 
> >Well.. 2.6.6 is released.. and THANK YOU Linus and all the patch 
> > writers.. we have nforce2 fixes in the released kernel now. I'm just 
> > waiting for a gentoo-dev-sources release now.. 
> >
> >Craig 
> 
> MOMENT PLEASE.
> ALMOST complete nforce2 support. Job not done yet.

Damn =)

> Unfortunately 2.6.6 still has the old check_timer code which inhibits
> nmi_watchdog=1 on all nforce2 from working by having timer_ack=1
> when checking io-apic pit routing.
> 
> It is a hardware issue - NOT A BUGGY BIOS ISSUE inside the integrated 
> nforce2 interrupt routing.

So it should be in.

> To my understanding IT WILL NEVER BE FIXED BY A BIOS REVISION and 
> after reading the 8259 datasheets I think it is a mistake within the
> existing code to have the timer_ack on there in the first place. 

The "breaking" machine could be blacklisted instead.

> I would still like to see Maciej's check_timer patch in the kernel. It was
> pulled after only a single user mobo complaint was posted yet it helps
> both nforce2 and ibm bios pc's. To my knowledge little effort was made
> by that user to accomodate the patch - it was just outright pulled in spite
> of its benefit to others?

Hummm, and now ppl seem to be forcing 4k stacks that breaks my laptop to
a level of non usability.. =P

> Who do we ask to revisit this? Linus? the io-apic.c maintainer? or the one
> user with a complaint?

Perhaps there should be a workaround option, ie like acpi=force etc.

> That patch that was dropped by Linus? after appearing in 2.6.3-mm3. 
> For those nforce2 users with problems of clock skew with the timer into pin0
> routing, that patch gave a virtual wire timer routing which worked well.

> It also works around serious problems for ibm users who also want it in.
> http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-04/4421.html

Rediffed it against 2.6.6
But i don't see how the virtual wire mode was done, i just rediffed the
patch that i found.

-- 
Ian Kumlien <pomac () vapor ! com> -- http://pomac.netswarm.net
--- linux/arch/i386/kernel/io_apic.c.orig	2004-05-10 14:08:00.000000000 +0200
+++ linux/arch/i386/kernel/io_apic.c	2004-05-10 14:12:17.000000000 +0200
@@ -2159,6 +2159,10 @@
 {
 	int pin1, pin2;
 	int vector;
+	unsigned int ver;
+
+	ver = apic_read(APIC_LVR);
+	ver = GET_APIC_VERSION(ver);
 
 	/*
 	 * get/set the timer IRQ vector:
@@ -2172,11 +2176,15 @@
 	 * mode for the 8259A whenever interrupts are routed
 	 * through I/O APICs.  Also IRQ0 has to be enabled in
 	 * the 8259A which implies the virtual wire has to be
-	 * disabled in the local APIC.
+	 * disabled in the local APIC. Finally timer interrupts
+	 * need to be acknowledged manually in the 8259A for
+	 * do_slow_timeoffset() and for the i82489DX when using
+	 * the NMI watchdog.
 	 */
 	apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
 	init_8259A(1);
-	timer_ack = 1;
+	timer_ack = !cpu_has_tsc;
+	timer_ack |= nmi_watchdog == NMI_IO_APIC && !APIC_INTEGRATED(ver);
 	enable_8259A_irq(0);
 
 	pin1 = find_isa_irq_pin(0, mp_INT);
@@ -2194,7 +2202,8 @@
 				disable_8259A_irq(0);
 				setup_nmi();
 				enable_8259A_irq(0);
-				check_nmi_watchdog();
+				if (check_nmi_watchdog() < 0)
+					timer_ack = !cpu_has_tsc;
 			}
 			return;
 		}
@@ -2217,7 +2226,8 @@
 				add_pin_to_irq(0, 0, pin2);
 			if (nmi_watchdog == NMI_IO_APIC) {
 				setup_nmi();
-				check_nmi_watchdog();
+				if (check_nmi_watchdog() < 0)
+					timer_ack = !cpu_has_tsc;
 			}
 			return;
 		}

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