Re: [RFC XEN PATCH 6/6] tools/libs/light: pci: translate irq to gsi

[Jan Beulich <jbeulich@xxxxxxxx>]

On 17.03.2023 00:19, Stefano Stabellini wrote:
> On Thu, 16 Mar 2023, Jan Beulich wrote:
>> So yes, it then all boils down to that Linux-
>> internal question.
> 
> Excellent question but we'll have to wait for Ray as he is the one with
> access to the hardware. But I have this data I can share in the
> meantime:
> 
> [    1.260378] IRQ to pin mappings:
> [    1.260387] IRQ1 -> 0:1
> [    1.260395] IRQ2 -> 0:2
> [    1.260403] IRQ3 -> 0:3
> [    1.260410] IRQ4 -> 0:4
> [    1.260418] IRQ5 -> 0:5
> [    1.260425] IRQ6 -> 0:6
> [    1.260432] IRQ7 -> 0:7
> [    1.260440] IRQ8 -> 0:8
> [    1.260447] IRQ9 -> 0:9
> [    1.260455] IRQ10 -> 0:10
> [    1.260462] IRQ11 -> 0:11
> [    1.260470] IRQ12 -> 0:12
> [    1.260478] IRQ13 -> 0:13
> [    1.260485] IRQ14 -> 0:14
> [    1.260493] IRQ15 -> 0:15
> [    1.260505] IRQ106 -> 1:8
> [    1.260513] IRQ112 -> 1:4
> [    1.260521] IRQ116 -> 1:13
> [    1.260529] IRQ117 -> 1:14
> [    1.260537] IRQ118 -> 1:15
> [    1.260544] .................................... done.

And what does Linux think are IRQs 16 ... 105? Have you compared with
Linux running baremetal on the same hardware?

Jan

> And I think Ray traced the point in Linux where Linux gives us an IRQ ==
> 112 (which is the one causing issues):
> 
> __acpi_register_gsi->
>         acpi_register_gsi_ioapic->
>                 mp_map_gsi_to_irq->
>                         mp_map_pin_to_irq->
>                                 __irq_resolve_mapping()
> 
>         if (likely(data)) {
>                 desc = irq_data_to_desc(data);
>                 if (irq)
>                         *irq = data->irq;
>                 /* this IRQ is 112, IO-APIC-34 domain */
>         }