NForce2, Ross Dickson's timer patch on 2.6.1

PATCH Jesse Allen 3 participants 3 messages Jan 12, 2004

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Jesse Allen

author

2004-01-12 17:36 UTC #0 lore raw

Hi Ross,

I have a version of your timer patch (io_apic.c) for kernel 2.6.1. It is attached. I have been monitoring a problem with it. It seems that with the patch, I gain 1 seconds time over 10 minutes (roughly). So I gain about 2-3 mintues a day. I haven't taken exact measurements, but I know it ends up about 20 minutes difference after a week. This is not good, which would require resetting the time often.

I tried the 2.6.1 kernel without the timer patch. The timer is now back in PIC mode, and interrupt 7 has the old noise. Synched the time with my watch. At first, I noticed no gain in time over 10 minutes. However the next day, I found it gained 1-2 seconds. Now it is about 7 seconds ahead a few days later now. This is much better.

So I'm left to thinking, the patch does two things, maybe one thing right, and one possibly very wrong:

1) It does place the timer in APIC mode.
2) But the timer seems to be fed extra interrupts, maybe the same that is found on irq 7 without the patch (is this possible?)

I remember someone making a comment which might explain the issue:
http://marc.theaimsgroup.com/?l=linux-kernel&m=107098440019588&w=2

I don't think the patch was much different now than it was then. So I think there is something wrong with setting up the timer this way. I don't know if you worked something out with Maciej. I don't know much about interrupt controller programming so... if maybe you can explain to me anything I'm missing. For now I've dropped the patch.

Jesse

PS: I have run with disconnect on, and without your ack patch since I got that
surpise BIOS update. No lockups have occurred in the past month, since that. So the disconnect problem is a BIOS bug. (Shuttle has not responded)

PSS: CC me, I'm not subscribed right now.

arch/i386/kernel/io_apic.c +45 -1

@@ -2194,9 +2194,53 @@
 			return;
 		}
 		clear_IO_APIC_pin(0, pin1);
-		printk(KERN_ERR "..MP-BIOS bug: 8254 timer not connected to IO-APIC\n");
+		printk(KERN_ERR "..MP-BIOS bug: 8254 timer not connected to IO-APIC INTIN%d\n",pin1);
 	}
 
+#if defined(CONFIG_ACPI_BOOT) && defined(CONFIG_X86_UP_IOAPIC)
+	/* for nforce2 try vector 0 on pin0
+	 * Note 8259a is already masked, also by default
+	 * the io_apic_set_pci_routing call disables the 8259 irq 0
+	 * so we must be connected directly to the 8254 timer if this works
+	 * Note2: this violates the above comment re Subtle but works!
+	 */
+	printk(KERN_INFO "..TIMER: Is timer irq0 connected to IO-APIC INTIN0? ...\n");
+	if (pin1 != -1) {
+		extern spinlock_t i8259A_lock;
+		unsigned long flags;
+		int tok, saved_timer_ack = timer_ack;
+		/*
+		 * Ok, does IRQ0 through the IOAPIC work?
+		 */
+		io_apic_set_pci_routing ( 0, 0, 0, 0, 0); /* connect pin */
+		unmask_IO_APIC_irq(0);
+		timer_ack = 0;
+
+		/*
+		 * Ok, does IRQ0 through the IOAPIC work?
+		 */
+		spin_lock_irqsave(&i8259A_lock, flags);
+		Dprintk("..TIMER 8259A ints disabled?, imr1:%02x, imr2:%02x\n", inb(0x21), inb(0xA1));
+		tok = timer_irq_works();
+		spin_unlock_irqrestore(&i8259A_lock, flags);
+		if (tok) {
+			if (nmi_watchdog == NMI_IO_APIC) {
+				disable_8259A_irq(0);
+				setup_nmi();
+				enable_8259A_irq(0);
+				check_nmi_watchdog();
+			}
+			printk(KERN_INFO "..TIMER: works OK on IO-APIC INTIN0 irq0\n" );
+			return;
+		}
+		/* failed */
+		timer_ack = saved_timer_ack;
+		clear_IO_APIC_pin(0, 0);
+		io_apic_set_pci_routing ( 0, pin1, 0, 0, 0);
+		printk(KERN_ERR "..MP-BIOS: 8254 timer not connected to IO-APIC INTIN0\n");
+	}
+#endif
+
 	printk(KERN_INFO "...trying to set up timer (IRQ0) through the 8259A ... ");
 	if (pin2 != -1) {
 		printk("\n..... (found pin %d) ...", pin2);

Daniel Drake

2004-01-12 18:43 UTC #1 lore raw

Hi,

I can confirm this activity, my clock has been skewing recently, but I had not made the link myself that this started happening after I started using the APIC/IOAPIC nforce fixes.

If theres any debug info I can provide let me know. I run an AMD XP2600+ on an Abit NF7-S V2.0 motherboard.

Daniel

Quoted 25 lines · Jesse Allen

Hi Ross,
I have a version of your timer patch (io_apic.c) for kernel 2.6.1. It is attached. I have been monitoring a problem with it. It seems that with the patch, I gain 1 seconds time over 10 minutes (roughly). So I gain about 2-3 mintues a day. I haven't taken exact measurements, but I know it ends up about 20 minutes difference after a week. This is not good, which would require resetting the time often.
I tried the 2.6.1 kernel without the timer patch. The timer is now back in PIC mode, and interrupt 7 has the old noise. Synched the time with my watch. At first, I noticed no gain in time over 10 minutes. However the next day, I found it gained 1-2 seconds. Now it is about 7 seconds ahead a few days later now. This is much better.
So I'm left to thinking, the patch does two things, maybe one thing right, and one possibly very wrong:
1) It does place the timer in APIC mode.
2) But the timer seems to be fed extra interrupts, maybe the same that is found on irq 7 without the patch (is this possible?)
I remember someone making a comment which might explain the issue:
http://marc.theaimsgroup.com/?l=linux-kernel&m=107098440019588&w=2
I don't think the patch was much different now than it was then. So I think there is something wrong with setting up the timer this way. I don't know if you worked something out with Maciej. I don't know much about interrupt controller programming so... if maybe you can explain to me anything I'm missing. For now I've dropped the patch.
Jesse
PS: I have run with disconnect on, and without your ack patch since I got that surpise BIOS update. No lockups have occurred in the past month, since that. So the disconnect problem is a BIOS bug. (Shuttle has not responded)
PSS: CC me, I'm not subscribed right now.

Matt H.

2004-01-12 18:55 UTC #2 lore raw

In reply to Jesse Allen

Ditto here, using nforce2. I've been up for about a week and a half and my clock is skew'ed by at least 20 mins .

Matt H.

Quoted 41 lines · Jesse Allen

Hi Ross,
I have a version of your timer patch (io_apic.c) for kernel 2.6.1. It is attached. I have been monitoring a problem with it. It seems that with the patch, I gain 1 seconds time over 10 minutes (roughly). So I gain about 2-3 mintues a day. I haven't taken exact measurements, but I know it ends up about 20 minutes difference after a week. This is not good, which would require resetting the time often.
I tried the 2.6.1 kernel without the timer patch. The timer is now back in PIC mode, and interrupt 7 has the old noise. Synched the time with my watch. At first, I noticed no gain in time over 10 minutes. However the next day, I found it gained 1-2 seconds. Now it is about 7 seconds ahead a few days later now. This is much better.
So I'm left to thinking, the patch does two things, maybe one thing right, and one possibly very wrong:
1) It does place the timer in APIC mode.
2) But the timer seems to be fed extra interrupts, maybe the same that is found on irq 7 without the patch (is this possible?)
I remember someone making a comment which might explain the issue:
http://marc.theaimsgroup.com/?l=linux-kernel&m=107098440019588&w=2
I don't think the patch was much different now than it was then. So I think there is something wrong with setting up the timer this way. I don't know if you worked something out with Maciej. I don't know much about interrupt controller programming so... if maybe you can explain to me anything I'm missing. For now I've dropped the patch.
Jesse
PS: I have run with disconnect on, and without your ack patch since I got that surpise BIOS update. No lockups have occurred in the past month, since that. So the disconnect problem is a BIOS bug. (Shuttle has not responded)
PSS: CC me, I'm not subscribed right now.