RE: [Xen-ia64-devel][PATCH]Change to new interrupt deliver mechanism

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Doi.Tsunehisa@xxxxxxxxxxxxxx write on 2006年12月5日 12:05:
> Hi,
> 
>   I've investigated it, but I couldn't find the method to get GSI of
> platform-pci for PV-on-HVM driver. There is convert functions like
> isa_irq_to_vector() in linux kernel source.
> 
>     [arch/ia64/kernel/apci.c]
>     int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
> 
>     [arch/ia64/kernel/iosapic.c]
>     inline int gsi_to_vector (unsigned int gsi)
> 
>   But, these functions are not EXPORT_SYMBOLE, thus we can't use them
> for kernel module.
> 
>   So, I think that..
> 
>   * Hypervisor becomes to be able to use both GSI and Vector for
>     callback irq.
>     - For example, if it is normal value, HV accepts it as GSI.
>       If it is value which is set MSB, HV accepts it as Vector.
>   * If hypervisor gets Vector as callback irq, hypervisor finds the
>     GSI for the pseudo device from virtual interrupt controller
> setting. 
> 
>   What do you think about this method ?

Hi Doi,

There is only one IOAPIC in IPF,
So irq is equal to GSI,

The sequence of platform_pci interrupt deliver is like below.

1. platform-pic.c cal set_callback_irq to tell HV the irq.

2. if there are callcack_irq, HV converts irq to vector by asking for VIOSAPIC,
    and HV directly pend this vector to one VCPU,

Can this sequence work?

Thanks
--Anthony



> 
> Thanks,
> - Tsunehisa Doi

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