Re: What are the real ioapic rte programming constraints?

[Zwane Mwaikambo]

On Sun, 11 Feb 2007, Eric W. Biederman wrote:

> > 2.15.2 PCI Express* Legacy INTx Support and Boot Interrupt
> > http://download.intel.com/design/chipsets/datashts/30262802.pdf
> 
> Ouch.  And this kind of thing isn't exactly uncommon.
> 
> However if we have the irqs also disabled in the i8259 we should
> be safe from actually receiving this interrupt (even if it generates
> bus traffic), and when we enable the irq since it is level triggered  
> we should still get an interrupt message.
>
> It isn't immediately obvious where the i8259 irq enable/disable
> happens.  So i"m having trouble auditing that bit of code.
>
> Plus we can get very strange things like the irq number changing
> and the sharing rules being different when going through the i8259.
> So irqN may be irqM when going through the i8259.
> 
> As long as we aren't using anything on the i8259 including the timer
> in ExtINT mode we can disable every interrupt pin and not worry about
> interrupts from that source.

We do the 8259 mask in setup_IO_APIC_irq. does anyone have access to an 
E7520/E7320 system for testing?

Cheers,
	Zwane

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