FAO: Ingo Molnar (Spurious APIC interrupts)

Alex Buell (alex.buell@tahallah.demon.co.uk)
Fri, 29 Jan 1999 20:11:06 -0500 (EST)


Your e-mail seems to be down at the moment :o( so I'm copying this to the
l-k list in the hope you'll get this.

On Fri, 29 Jan 1999, MOLNAR Ingo wrote:

> > > cool! Could you run this for a day or so and tell me wether there are gone
> > > forever, or just getting more rare?
> >
> > I'm doing that now with 2.2.1 (They still happen with 2.2.1!), and will
> > let you know if they still are happening when I get back from work
> > tonight.

Ok, just got in from work. Checked logs and there's no sign of spurious
APIC interrupts. I guess we can write this off as fixed =). To make life
easier, here's a patch for 2.2.1.

Apply within the linux/arch/i386/kernel directory.

--- smp.c.orig Fri Jan 29 08:27:15 1999
+++ smp.c Fri Jan 29 18:40:21 1999
@@ -726,9 +726,8 @@
* also, put the APIC into flat delivery mode.
*/
value = apic_read(APIC_LDR);
- value &= ~APIC_LDR_MASK;
- value |= SET_APIC_LOGICAL_ID(0xff);
- apic_write(APIC_LDR,value);
+ value = (1<<hard_smp_processor_id());
+ apic_write(APIC_LDR,value);

value = apic_read(APIC_DFR);
value |= SET_APIC_DFR(0xf);

Cheers,
Alex

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