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Re: [Xen-devel] [PATCH][RFC] pv-ops: fix shared irq device passthrough

On 10/30/09 02:29, Han, Weidong wrote:
> All devices will call probing_irq in startup_pirq, which bind pirq to event 
> channel. But now probing_irq always returns false, then all pirqs are not 
> shareable. In my system, a PCI NIC, an USB controller and an IDE interface 
> device share the same IRQ 18. Because above reason, pirq 18 is set not 
> shareable. So when I hide the PCI NIC, and assign it to guest, it fails in 
> guest_bind_pirq, therefore the PCI NIC in guest cannot work, even impact the 
> devices who share the IRQ 18.
> If don't want to change __setup_irq code like my patch does, current 
> probing_irq is useless (always return false). The problem is there is almost 
> no information in desc can be used in probing_irq if desc->action is NULL. 
> Keir, do you have any ideas?

I think the intent of probing_irq is to detect irqs which are being used
to probe for an interrupt during driver initialization.  This should
only be used for things like ISA which don't have any way to explicitly
find out what irq a device is attached to.

Given that ISA devices aren't very interesting and no driver should need
to do that kind of probing under Xen, I wonder if we can't just remove
the whole test?


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